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Gear / Technical Help => Microphones & Setup => Topic started by: Gutbucket on January 06, 2018, 03:37:13 PM

Title: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 06, 2018, 03:37:13 PM
Continuation from the original thread here- http://taperssection.com/index.php?topic=96009.msg1279052#msg1279052 (http://taperssection.com/index.php?topic=96009.msg1279052#msg1279052)

DANG! OMT with the sideways supercards angled forward +/-45 degrees most certainly works in a small club (a good sounding one at least) as long as you can manage to shoe-horn it in there and keep everyone happy.  So good in fact I plan to play with angling those sideways facing supers forward outdoors to see if it works equally well everywhere.  I'll definitely be revising the OMT suggestion for small rooms (crappy ones remain to be tested, but I'm not overly motivated to explore that front). Listening today to last night's recording directly off the DR-680 via headphones using the 680's internal monitoring mixer I prefer not doing the Mid/Side mixing thing with the rear facing channel when the spaced +/-45 degree supercards are also in use, but rather just bringing it channel up with the appropriate level, panned to center.  Played back in surround with all six channels feeding their own speakers (no mixing, just mult'ing the single rear-facing microphone  channel to two back speakers, omnis routed to the side surrounds and sub) the way it handles audience chatter and room sound is really impressive.  All that is there, more of it in fact compared to the 2ch stereo mix, but the separation of it from the main stuff in front actually improves clarity of the vocalist and on-stage stuff and makes it easier to hear around the elements which would otherwise be distracting and cluttering.  I'll certainly be exploring this angle more.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on January 06, 2018, 05:45:03 PM
bump to join thread. Kung Fu 2017-12-16 OMT up now:
https://archive.org/details/kungfu2017-12-16.24akgck22ck61
to compare, here is kindms AKGck1x (cardiods) PAS recording:
https://archive.org/details/kungfu2017-12-16.akgck1x

snap is close up of both rigs
rig1] (AKG c460b|ck22 omni's spread 108 cm + AKG ck3 fwd and ck61ULS rear|naiant actives (black windscreens).
rig2] AKG ck1x on AKG collette (middle pair of large Shure AW81S)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 08, 2018, 07:19:38 PM
I provided an audio patch out to the music club's regular video taper this past weekend while trying out 6ch OMT in a small club.  Below are links to a couple YouTube clips he's posted which will give some idea of baseline performance in this kind of situation.

Caveats!-  Audio here is a raw 6ch>2ch monitor mix made on-the-fly out of the DR-680.  No listening was done, much less proper balancing, EQ or any other post production.  Balance, mix levels and panning of the 6 OMT microphone channels were simply a best guess.  Deep omni bass content overloads the input of the small video recorder at times.  Subjected to video recorder's file compression and of course YouTube data compression, yada, yada & hand-waving.. At least it's something to give you all a taste of what OMT can do in a small club.  Unfortunately the video taper didn't run for Mingo Fishtrap which was the best sounding set of the weekend after Bettye LaVette, and of an entirely different genre (full NOLA-ish band with funky organ & horn section).  Recording location was from the same column the video cam is mounted to. It's hard to tell from the video, but that's basically the far left side of the room, in-line with the left PA, about 15' away from the stage.

Bettye Lavette (Elenor Rigby > Love Rein O'ver Me) - https://youtu.be/N1oq2ZqfKt8 (https://youtu.be/N1oq2ZqfKt8)

Tim Palmieri solo happy-hour-
(You Enjoy Myself ~ Linus & Lucy ~ Blackbird ~ Wish You Were Here ~ YEM ~ Golden Slumbers ~ Carry That Weight ~ YEM ~ Wipe Out ~ Louie Louie ~ Blister In The Sun)- https://youtu.be/D-ALOX7_13c (https://youtu.be/D-ALOX7_13c)
(Hits From The Bong)- https://youtu.be/Xgvdbzn3cB8 (https://youtu.be/Xgvdbzn3cB8)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on January 10, 2018, 02:44:27 PM
Thanks a lot for sending your recordings. Rocksuitcase, it is great to have your OMT and Kindms's single pair for comparison. Overall I prefer the OMT version, there is great sense of space. And I like the warm sound on Kindms recording. But maybe that is possible to tune it on OMT by an equalizer.

Gutbucket, you have my big respect for a 6ch on-the-fly mix. It is a very pleasant listening. I'm surprised that it sounds so spatially even when you were close to the left PA. How much did you space supercards?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on January 10, 2018, 03:22:56 PM
Thanks a lot for sending your recordings. Rocksuitcase, it is great to have your OMT and Kindms's single pair for comparison. Overall I prefer the OMT version, there is great sense of space. And I like the warm sound on Kindms recording. But maybe that is possible to tune it on OMT by an equalizer.

Gutbucket, you have my big respect for a 6ch on-the-fly mix. It is a very pleasant listening. I'm surprised that it sounds so spatially even when you were close to the left PA. How much did you space supercards?
The kicker about the comparison is the room itself is typically difficult to get good vocals on an AUD recording. Toad's place is basically a rectangular width room with the stage in the middle against one long wall with the soundbooth, hence mic stand location being about 40 feet from the stacks, again centered in the rectangle. When I would run with Blues Traveler's permission, I would run up in the crows nest, which is where Matt set up his official streaming/recording cameras along with the SBD feed into them. So, to read that the OMT has "great sense of space" makes me truly smile as this is the characteristic most missing from other recordings in there. Also, when you like the warmth of the ck1x recording, that tells me those mics worked well with his SD pre-amp.  I agree with your assessment as well, the OMT is more "realistic" while the ck1x has nice warmth if maybe a bit  boomy in the low frequencies.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on January 10, 2018, 04:49:01 PM
I think the warm difference with Kindms recording is not because preamp. OMT contains omnis, it should be more warm than Kindms's cards. Maybe It would help to highlight in eq lower frequencies of the omnis. I do not know if the word "warm" is right. Do not take me as someone who can advise. Better to wait for others.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 10, 2018, 05:12:31 PM
kuba- Yes, you can easily adjust the overall tonal balance via EQ, but that's not the only way.  You can also do so via the level balance between the omnis and the center mics.  So for instance, with a quick and dirty mix straight out of the DR-680 recorder using it's built-in monitor mixer that provides no EQ ability, I can dial up the omnis a bit more and the center mic(s) down a bit to tilt the tonal balance towards more bass and less treble, or vice versa.  Of course it helps if I'm actually listening while making those decisions. It happened to work out pretty well in the Youtube samples above just by knowing what monitor mix balances I've used in the past, even though I wasn't actually listening when I dialing it in for that patch-out.

This is where the flexibility in mixing OMT begins to come into play - and what really makes it advantageous in shaping whatever you come home with into something which works optimally for the listener.

Using EQ you can adjust overall tonal balance in a few ways- EQing each element separately before combining the channels and/or EQ'ing the resulting 2 channel mix after combining things.  So for example you can EQ the omnis primarily for what they are contributing to the bottom end, while EQ'ing the center mic or pair more for what they are doing in the midrange and top end.  And after combining the channels you can EQ the full 2-channel mix.  Typically I do both, but with different things in mind..

Actually, I sort of consider three separate corrective 'steps' or stages in putting together the finished product, and EQ is an important element in each of those steps, second in importance only to general signal integrity and level.  Looks like it's time to start outlining my process for mixing OMT.  I'll offer you a basic outline of what I do before blathering more philosophy about mixing and this approach in particular.

Basic OMT mixing in 3-steps-

1) First I'll do base-line corrective stuff to each channel.  Mentally asking myself things like- "Does this single channel have any problems?"; "Do the two omni channels sound similar in tonal balance and have a good level balance between them?" If not I'll compare just those channels and adjust one or the other as necessary to get them both sounding about the same.  That imbalance could due to some particularity about where I was setup in the venue, the PA, my recording trims being off, a misbehaving microphone or whatever.  In any case, I make sure each channel is okay on its own and more or less matches its pair in tonality if it has one.  Then I'll make sure they work together well as a pair, balancing the level between the two so that the stereo image is centered when listing just to that pair on it's own.  When I'm done with this step I have a good-sounding, well-balanced omni pair (channels 1 & 2), a good-sounding center channel (ch 3), a good sounding rear-facing channel (ch 4), and a good sounding pair of Left/Right supercardioid pair (ch's 5 & 6).  If using a center forward-facing coincident-pair instead of front/rear-facing mics, channels 2 & 3 are treated as a pair instead of independent channels.  Lock the individual channels of each of these pairs together so that you can adjust the level of the pair as a whole without upsetting its balance in the next step where you'll be balancing each pair against the other.

2) Then I'll do the mixing/combining part- setting up the mix balance between these elements.  This is where it gets fun and is probably the most subjective part of putting everything together. 

I usually start with the omni pair and build from that.  We already have it sounding good on its own so just pull up the level on that pair.  Hard-pan those omnis hard-Left and hard-Right.  Don't worry about any "hole in the middle" of the stereo image at this point if there is one (probably not unless they were quite widely spaced).  Next bring up your single center channel panned to center.  You've already gotten that sounding decent tonally, so just listen to what it does as you raise the it's level and it combines with the omnis.  Play around with it.  I find there are often three ways to work it, it depends on the recording and type of music, and there is no wrong answer- either the center level is about the same as the omnis acting as an "equal player", the center is lower in level and basically "fixes whatever is lacking with the omnis", or the center level is higher than the omnis and sort of dominates the mix.  I'll come back to this later as there are many different things going with this center/sides balance thing besides getting a solid stereo image, and the best choice will be one which finds an optimal balance between all those things.  For now, just listen for a solid soundstage between Left to Right which a reinforces the center content nicely, such that everything sounds balanced and you really miss it when you mute the center channel.  Don't worry about tonal concerns, how well you can understand the vocals, how distant it sounds or things like that at this point.

If you've recorded a center coincident-pair instead of a single center channel, pan both channels of the pair panned to center.  That effectively makes it a single monophonic center channel.  Balance it's level with the omnis as described above first, then play with panning the center Left and Right channels outwards by the same amount (symmetrically).  Try it fully hard-panned to either side as well as in all positions in-between.  The nice thing about having a coincident center pair is that you can pan this pair however you want without creating phase-conflicts.   Listen for a good, even image-blend between the center and sides.  You might like it best with no center spread at all (both mics of the center pair panned center), with fully hard-panned to either side, or somewhere inbetween.  Again there is no rule here other than getting it sounding good.  In general you are likely to end up with a center pair panned less widely than you normally would without the omnis in the mix.  Sometimes I'll pan them just a minimal bit to either side, but that slight panning makes a big difference in getting a smooth blend across the full soundstage and keeping the center from sounding separate and overly point-like.  If you mute the omni channels you might be surprised to find how narrow your choice sounds on its own.  That's an indication of how mic configurations need to change when used in combination with one another (taken care of by the OMT mic setup) and is helpful to hear to understand how each of the parts combine to make a sum greater than the parts.

Take your time here, work up a few different balances between center/sides (and center spread if you have a pair there) and listen to them for a while to see which one works best and sticks with you.  Often it may become apparent that what was sounding really good at first doesn't hold up under longer listening or only works for that particular section or song.  Try to find whatever balance works well for the entire concert and holds your interest without anything about it bothering you after a listening for a while.

If you have a rear-facing microphone, bring that up last panned to center.  The optimal level on the rear-facing channel will vary a lot depending on the situation, the room, the audience, etc.  You'll probably want to use more of it when listening to the sections between songs and during quieter numbers when the audience is quiet, and less of that during louder numbers, or when the audience is talking back there.

3) Once you have a mix you like, you can fine-tune the 2-channel mix bus or the resulting two channel mix output if you choose to edit that separately.  We are now to the point were we do the same things we would to any normal two-channel recording- EQ the whole thing (more subtle overall-tonal tweaks at this point), normalize, track, fade, whatever.


To me it helps to think of those 3 steps as follows:

The first step mostly about "fixing problems" and getting to a good level playing field starting point.
The second step is the "creative mixing" part where most of the gross (and subtle) decisions which have the greatest creative input on the the result are made.
The final step is the "mastering" part.  Putting the final polish on the thing and otherwise prep'ing it for release.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 10, 2018, 05:22:03 PM
Later I'll describe more subtle things you can do which really make this technique powerful, like EQ'ing the center channel differently to reduce conflict with the sides or to enhance vocal clarity and presence without the entire recording becoming too bright, and other stuff like that which comes after step 2 but before step 3 in the basic outline above.   Similarly, there are advanced EQ decisions you can make to the other channels- the omnis, the rear-facing channel, etc, which work in combination to create a greater sum than each of the parts in isolation.  As you move toward these more advance steps you'll begin to push the channels away from their "everything sounds as good as it can on its own" starting point of step 1, in a way somewhat analogous to ending up with a more narrow center X/Y pan in step 2 than you otherwise would for that pair on its own.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on January 10, 2018, 05:52:04 PM
I love to read it. This is huge help. I will try to write more in the morning.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 10, 2018, 06:04:30 PM
I think the warm difference with Kindms recording is not because preamp. OMT contains omnis, it should be more warm than Kindms's cards. Maybe It would help to highlight in eq lower frequencies of the omnis. I do not know if the word "warm" is right. Do not take me as someone who can advise. Better to wait for others.

Also consider that while it's useful to compare the overall sound of both in deciding if this is worthwhile or not, its very difficult to make specific comparisons of tonality or whatever because as explained above, Rocksuitcase's mix is his subjective choice, not only because he's applying EQ, but because of his choices of level balance, and OMT is always going to be more subjective in this way because we have to make these decisions in creating any 2-channel stereo mix from it.

I also noted more low frequency energy "warmth" in kindms' ck1x cardioid pair recording.  I personally don't find it too much or boomy but like that tonal balance.  Tonally, I prefer it's low-frequency balance to the OMT mix, at least on the gear I'm listening through, even though it lacks other traits I like in the OMT recording such as the sense of openness and spatial dimension.  Rock, please don't take this the wrong way, but I generally find your mixes a bit light on the bottom up through the lower midrange to my ear.  I haven't mentioned that previously because its a subtle subjective thing, but it's been stirring around in my head for a while and I think this is a good comparison to explore that a bit more.

The big OMT post production variables - subjective mix choices and what our monitoring is revealing (or not)-

Again these are subjective choices we make in putting the resulting recording together, but those choices are entirely dependent on what our monitoring is telling us.  It's not just really easy to correct for some minor (or major) imbalance in our playback monitoring when making decisions about what to do with the mix, we will in fact always do that unless we've specifically learned how to compensate for the deficiencies of our monitoring.  That's tough, because then the goal is to intentionally make it "not sound as good as it can" on our monitoring system but adhere what we have learned it needs to sound like there to sound correct everywhere else (on balance).  This is the well known mix-translation problem, and it is actually aggravated by this super flexible system of OMT mixing where we gain more control over everything.  It's one of the big reason's I've not released more stuff before now because I've long recognized my monitoring is the weakest link in my own recording-mixing-monitoring chain.  I know what to do but I don't trust my monitoring enough.  Okay so I'm a bit too much of a perfectionist there with respect to being a "taper", but that's partly because I know that once it's out there I'll never really have a second chance for a re-do.  That said, I'm getting closer to setting up a monitoring system I feel like I can trust, and the biggest issues there are getting the bottom and lower-midrange right.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 10, 2018, 06:15:43 PM
Gutbucket, you have my big respect for a 6ch on-the-fly mix. It is a very pleasant listening. I'm surprised that it sounds so spatially even when you were close to the left PA. How much did you space supercards?

Thanks.  I'll get mixed versions up at some point.  I can make a few of my raw recorded OMT files available to anyone here to play with as well.  It would be fun to see how different each person's resulting mix ends up.  I also hope to up-load some auditory examples of building a mix step by step.

I'll remeasure my rig to confirm but the general spacing was about 5' total on the omnis and about half that on the L/R supercardioids angled 45 degrees forward.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 10, 2018, 06:50:47 PM
Took a few photos with my phone last weekend trying to show the OMT setup in that room.  Tough to make out against the black ceiling in a dark room, but here are a few snaps.  These four show sort of an overview of the room and the relationship between the recording position, PA and stage.

First is the view of Tim Palmieri on stage as seen from the recording position (no rig in frame).

Second is the view from side-stage/bar-entrance (rig is at the column, stand placed on a table around the column, stand running up the front column edge closest to center stage, mics up high).

Third is the view from the back half of the room not quite all the way to the rear wall.  Video guy jumped up on on a chair all excited about the Phish tunes. (Mic-stand and 3 of the 4 supercards can be seen, left supercard obscured by column, both omnis obscured by darkness)

Fourth is from the SBD during Betty LaVette (you can see the outward extension of the right omni past the right supercardioid in this one - flush-mounted into the black ball at the end of the antenna).

Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 10, 2018, 07:06:25 PM
Here are some crappy closeups of the OMT array-

First two are of the array during setup.  Stand hasn't been raised yet above the video cam which made the YouTube clips posted above, omnis are still retracted (you can see that the omnis retract in to the same position as the Left/Right supercards, except the Left ommi's telescopic arm now retracts only part-way due to a splint repairing a break)

Third shows the array from below.  The rear facing mic is up against the column.  You can see the angle of the right supercard and the position-relationship between the the supers in frame (front and rear-facing supers have an bigger windscreens than the Right supercard).

Blurry forth shows the array as seen from a perspective closer to the center of the room, raised fully above the video camera.

The miniature DPA omnis are mounted in my DIY sphere accessories to make them somewhat directional (and eliminate potential eye-pokes).  Here I pointed them +/- 45 degrees to the front.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on January 11, 2018, 08:02:50 AM
Oddball microphone technique is a beautiful thing. The following may be useful for those who are beginners like me. I started with two microphones. It took me a long time to understand the relationship between distance, angles, polar patterns (The stereophonic zoom - Michael Williams). I only made audience recordings this time. Then I tried onstage recordings with two or even four microphones or sbd feed. Here I needed to get a little more of theory (sound frequency, comb filtering, basics of sound propagation) And I also needed to use a little bit of post processing e.g. little eq or little shift of the stereo image.  And from there, it is already close to the OMT.

I am from Europe and hobby taping is not popular here. I got all the information from this forum. Great thanks to everyone from forum.

But why am I writing it? I was surprised by one thing. I'm music lover but I am a very simple, low-cost listener, I have no sound education and I'm working outside the music industry. But I noticed that the more I record, the more aspects I can distinguish in the recording. I did not expect that. I am just at the beginning because recording is only a hobby and I'm doing it for joy. But I know our brain has the ability to train listening skills and it may be unobtrusive, step by step. Things, that with I've fought in the past, are easy, fast and effortless to solve for me today. Of course, I get new obstacles that I didn't see in the past. If anyone is hobby taper like me and thinking about trying the OMT, do it. It will cost time and effort and the final recordings may not be good. But that's not important,  for sure recordings will come out better next time.

The big OMT post production variables - subjective mix choices and what our monitoring is revealing (or not)-
and also my ability, how subtle details I am able to distinguish. OMT is an ideal learning opportunity.

I can make a few of my raw recorded OMT files available to anyone here to play with as well.  It would be fun to see how different each person's resulting mix ends up.  I also hope to up-load some auditory examples of building a mix step by step.
I'm excited. It will be fun. And that would be a great help too.

Thanks for your photos. I should buy a selfphone with a camera (I'm an old school) because taking pictures of my rigs. I can see on your photo that the rear microphone could not be in the axle, but that is negligible. It reminded me my recording of Medeski and Mule. I used the rear microphone in Mid / Side. On your advice, I delayed the rear microphone before entering in the Mid / Side . The resulting sound was more pleasant to me. But as you say, these are very subtle things.

Thank you for sharing OMT with us. I see how much effort you gave in development. I appreciate Rocksuitecase help too. I found another beautiful part in taping because OMT.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 11, 2018, 09:06:57 AM
Thanks for the kind words kuba. And your interest.  I too find that the deeper I get into this the more I can hear, and the more I understand the more I enjoy the music on a deeper level.  Figuring out the puzzle is a big part of the fun for me, as is sharing what I've figured out here with anyone else who may be interested.  Part of what makes this so interesting is that live-music taping, especially from the audience, is a unique form of recording which benefits from unique solutions which don't really apply to, or come directly from, more common forms of audio recording.

The journey is the destination.

record > listen > revise technique
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on January 11, 2018, 09:35:54 AM
Learning recordings reminds me yoga. Yoga says that with the rough mind we can only see rough things. With more subtle mind, we can see subtle things too. We have to know the rough mind to get to the subtle. The same thing applies to the recordings. Sometimes I wondered if the sound masters are able to listen to an amateur recordings. If they are not disturbed by all the rough things that I do not hear. It's probably the same answer as in yoga, it's not disturbing them. I am sorry for light turn.

Part of what makes this so interesting is that live-music taping, especially from the audience, is a unique form of recording which benefits from unique solutions which don't really apply to, or come directly from, more common forms of audio recording.
I totally agree. Audience recordings have special magic.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on January 11, 2018, 09:54:31 AM
I think the warm difference with Kindms recording is not because preamp. OMT contains omnis, it should be more warm than Kindms's cards. Maybe It would help to highlight in eq lower frequencies of the omnis. I do not know if the word "warm" is right. Do not take me as someone who can advise. Better to wait for others.

Also consider that while it's useful to compare the overall sound of both in deciding if this is worthwhile or not, its very difficult to make specific comparisons of tonality or whatever because as explained above, Rocksuitcase's mix is his subjective choice, not only because he's applying EQ, but because of his choices of level balance, and OMT is always going to be more subjective in this way because we have to make these decisions in creating any 2-channel stereo mix from it.

I also noted more low frequency energy "warmth" in kindms' ck1x cardioid pair recording.  I personally don't find it too much or boomy but like that tonal balance.  Tonally, I prefer it's low-frequency balance to the OMT mix, at least on the gear I'm listening through, even though it lacks other traits I like in the OMT recording such as the sense of openness and spatial dimension.  Rock, please don't take this the wrong way, but I generally find your mixes a bit light on the bottom up through the lower midrange to my ear.  I haven't mentioned that previously because its a subtle subjective thing, but it's been stirring around in my head for a while and I think this is a good comparison to explore that a bit more.
Gut- no offense taken; kuba- I took another listen in my preferred "ideal" listening environment-my car-lol and definitely hear what you are saying "warmth" wise; to my ears the cymbals and high end is EX, but the low end is a bit sterile. I do wish I had some better mixing tools/software.
To the major point- ever since deploying OMT and learning to do the mixes I have had an inferior DAW listening situation in that the bass is always too boomy in my set-up. Therefore, at the beginning of seriously mixing OMT (Greyfox 2016) Gutbucket had mentioned one mix being way light in bass freq's. That event had an issue with the bass being so loud in the PA that the artists onstage as well as audience members complained so much the artists' complaints are during their set on the recordings!
I have finally obtained a nice subwoofer and feel my monitor environment is "better" for me to make mixing decisions. I will add that I typically do not finalize my mix before I take the working file into my car and listen to it all the way through. That has influenced me to make changes. What I am hearing you guys say is I am reducing the bass a bit too much in these mixes. Once mixed to two channels, I have been typically EQ'ing under 400Hz ->20Hz using graphic EQ and taking it down 4-6dB. This is further emphasized by the fact that kindms does zero EQ'ing with his two channel mixes (and I typically do very little to no EQ'ing of two channel takes).
Sooooo, in conclusion of this aspect; I hear what exactly you say regarding the Kung Fu OMT vs ck1x. Again, not going to go back and re-do it timewise, howwever, I haven't released the 16 bit yet;' maybe I will go in and do a different 2 channel EQ on it and ask what you guys hear.
As a request to you both re this "to little bass-low mids" topic, would you mind listening to the Twiddle OMT and compare it to taperchris' card mix? The PA had HUGE amounts of bass, but it wa so clean, I didn't reduce as much 400 on down as I did with the Kung Fu.
https://archive.org/details/twiddle2017-12-30.24akgck22ck3
https://archive.org/details/Twiddle2017-12-30.tcca.flac16

Great discussion so far. I just had a thought that I save my EQ curves in Audacity and could possibly take screenshots and title them properly such that it may be a part of learning/teaching/discussing mixing the OMT.
 
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on January 11, 2018, 12:44:14 PM
Do not worry, it's a good recording for me and 90% of people. But I understand when something can be improved, I would have done it.

These are interesting things for me. The imperfections can be better heard when two records of the same music can be compared. But e.g. Gutbucket's sample - I can not distinguish it's imperfections, it is above my distinctive ability. So the recording is perfect from my point of view. On the other hand, Gutbucket can distinguish these details, so he has better experience of music than I do and he can enjoy it more than me. Recording is an art.

You mentioned that you were using Audacity. Can you change or turn on/off EQ during playback in Audacity? It was not possible a few years ago. If is it still then comparison and decision making is very difficult. In a lot of programs, the effects can be changed or turned on/off by one click during playback. You can hear (and repeatedly) the difference immediately, so you have easier decision making.

As a request to you both re this "to little bass-low mids" topic, would you mind listening to the Twiddle OMT and compare it to taperchris' card mix? The PA had HUGE amounts of bass, but it wa so clean, I didn't reduce as much 400 on down as I did with the Kung Fu.
https://archive.org/details/twiddle2017-12-30.24akgck22ck3
https://archive.org/details/Twiddle2017-12-30.tcca.flac16

OTM has warmth, it's enjoyable listening for me. Maybe Chris used too much bass reduction. Did Chris have a stand near you?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on January 11, 2018, 12:57:14 PM
As a request to you both re this "to little bass-low mids" topic, would you mind listening to the Twiddle OMT and compare it to taperchris' card mix? The PA had HUGE amounts of bass, but it wa so clean, I didn't reduce as much 400 on down as I did with the Kung Fu.
https://archive.org/details/twiddle2017-12-30.24akgck22ck3
https://archive.org/details/Twiddle2017-12-30.tcca.flac16

OTM has warmth, it's enjoyable listening for me. Maybe Chris used too much bass reduction. Did Chris have a stand near you?
Chris's stand was about 4 feet behind and 10 feet Left of mine (which was DFC front row balcony). I think the sound on this two channel master is about as excellent as I've ever heard from both my own gear/mixing AND the band's PA perspective. The bass player, Zdnek Gubb, was simply KILLING it LOUDLY; he must have gotten new gear for Christmas as he was grinning from ear to ear and kept pointing up with one finger toward his tech/monitor guy. Sooooo, the warmth is/was in the room and on the original recording. That said, I treated the original Omni vs center channels similarly as the Kung Fu EQ wise. As Gutbucket says and you confirmed, some of this is very subjective AND does point out what some tapers have told me is their reasons for wanting to stick with two channels- They can record it and process it with a lot less work than the OMT. I say OMT is worth a try in about 75% of all situations we find ourselves taping in.
Audacity still does not allow one to monitor in real time the EQ. What I do is load the working file into foobar, play with the EQ there, then emulate those settings with Audacity. As far as EQ and post processing goes, I REALLY need to invest in Izotope.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on January 11, 2018, 01:52:10 PM
I understand very well the reasons for wanting to stick with two channels. Post processing is sometimes tedious for me.

I use Reaper as recommended in the forum. You can try it for free and full version is around 70 bucks. I think it is fully sufficient for OMT. The beginnings were difficult as I moved from Audacity. But now it's good. The huge advantage is that I can make any change during playback and hear it right away. The changes can be manual or preset. For example, I can set that I want to amplify the center microphone by 2db. And with one click I can turn this gain on/off during listening. I can chase any effects too, so mixing Mid / Side is then simple. If you decide to try it in the future, I like to help you with I will know.

Edit:
https://archive.org/details/twiddle2017-12-30.24akgck22ck3
https://archive.org/details/Twiddle2017-12-30.tcca.flac16
I listened to Chris's recording more. It is great recording, he captured space better than OMT. It is nice to see that you can make so good recording with Chris Church mics (ha ha I own them too).
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 11, 2018, 05:50:10 PM
Gave a quick listen again to both Twiddle recordings and both sound very good and well-balanced EQ-wise to me.  The bottom sounds like it's in proper proportion to the top, at least on these AT in-ear phones I'm using from this computer.

I'm quite impressed by Chris's CA-14 Twiddle recording, especially its up-front sense of presence and directness.  The instrumentation and vocals sound not-overly-distant and big.  It's very interesting exploring what produces that listening sensation in a recording, and ways of working the balance between "solid up-front presence" and "open spatial dimensionality", but that's a discussion to explore more in-depth later.   In any case, Chris' recording made with Church-Audio cards through a Church-Audio battery box is a great example of how excellent recordings can be made using non-pedigree mics in simple setups given the right situation.  And that raises a couple important points-

Low-cost mics can make great recordings in the right situation.  Most tapers know this and many have experienced it themselves.  The flip side is consistency.  Higher quality mics are capable of making good recordings more consistently.  Similarly OMT as a technique is considerably more complex than running a straight pair of mics, but one thing which makes it valuable is that it can make good recordings more consistently.   Which is really an entirely separate argument than how good it is capable of sounding in an optimal situation.  It dramatically increases the odds of success in our favor, albeit at the cost of more complexity and post work.

The other thing is that it works nicely with lower-cost mics and actually makes pedigree mics less necessary to achieve that kind of improved consistency.  It's the "whole being greater than the sum of the parts" thing again, but on the microphone side instead of the mixing side of things this time.  Done correctly, OMT can cover some of the problems commonly heard with lower-cost mics in simple 2-mic setups in less than ideal situations.  It's one reason why I was okay with putting my Microtech Gefells away and using the miniature DPAs instead, at around half the cost or less, after testing and comparing identical OMT recordings made using both (those comparisons being vital in making such decision).  Years back in the previous thread I was using low-cost miniature AT directional mics to proof-test this.  It worked very well and is partly what convinced me to eventually settle on using the miniature DPAs exclusively even in situations in which I would ordinarily pull out the lovely MGs.  I contemplated building a "budget 6-channel OMT" setup as inexpensively as possible using all miniature Church-Audio, Naiant, AT, or other inexpensive mics at that point.  How inexpensively could I actually do it and how would the recordings compare?  It would be enlightening to compare the same recording made by such a rig and my current miniature DPA-based rig.  I may still might do that at some point, parlty to further explore the idea and partly to have a second rig.  I also think it would be a cool way to promote our TS member mic builders if it works well.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 11, 2018, 05:56:23 PM
Quote from: kuba e
I understand very well the reasons for wanting to stick with two channels. Post processing is sometimes tedious for me.
Quote from: Rocksuitcase
[This points] out what some tapers have told me is their reasons for wanting to stick with two channels- They can record it and process it with a lot less work than the OMT.

Truth!  If a taper is averse to having to do much to a recording afterwards other than tracking and FLACing, this path will not be the most appropriate one to take!  OMT requires a post-processing commitment- a curse and a blessing.  To my way of thinking, the need to do the post-work is perhaps the main reason NOT to pursue this for most folks.   Also- I've worked my rig to make setup super easy, but that's not going to be the case for most tapers.  Everything in my rig is already attached, plugged in and wired so I just extend the arms, point the mics, power-up and roll - and can do all that considerably faster than the time it takes most tapers to set-up a typical 2-mic rig.  But that's obviously not how most will do it.  For most tapers, a perhaps equal yet different burden will be dealing with the complexities of hauling the mics and gear, setting up prior to making the recording and breaking everything down afterwards.  Rocksuitcase, your OMT setups with kindms amaze me in that way.  I have to imagine it's a lot of work to setup and break them down.  Kudos to you guys for doing that, and also to you for bearing the mix-down burden afterwards!

Quote from: Rocksuitcase
Audacity still does not allow one to monitor in real time the EQ. What I do is load the working file into foobar, play with the EQ there, then emulate those settings with Audacity. As far as EQ and post processing goes, I REALLY need to invest in Izotope.
Quote from: kuba e
The huge advantage is that I can make any change during playback and hear it right away. The changes can be manual or preset. For example, I can set that I want to amplify the center microphone by 2db. And with one click I can turn this gain on/off during listening. I can chase any effects too, so mixing Mid / Side is then simple.

I have a hard time imagining trying to do this without being able to immediately hear the influence of whatever change I'm making while making it, and the ability to easily go back and forth to determine if what I'm doing is moving things in the right direction or not.  That feed-back loop is so vitally important to me.  Especially when fine-tuning things.  Also, I tend to work iteratively, going back and forth constantly between listening to specific things I'm adjusting verses listening to the whole in an more overall gestalt way, then back again.  That back and forth mental-flow would be highly compromised without immediate feedback.  Big respect for successfully working that way.  I don't own Izotope but admire it, great tools.  But far more important I think is the simple ability to have that immediate listening feedback loop in play.  My humble advice is to first change your editing software K!  I suspect you'll never look back once you do and wonder why you hadn't done so earlier.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on January 11, 2018, 05:59:27 PM
Audacity still does not allow one to monitor in real time the EQ.

Try the TDR Nova plugin.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on January 11, 2018, 07:04:04 PM
Quote from: Rocksuitcase
Audacity still does not allow one to monitor in real time the EQ. What I do is load the working file into foobar, play with the EQ there, then emulate those settings with Audacity. As far as EQ and post processing goes, I REALLY need to invest in Izotope.
  Big respect for successfully working that way.  I don't own Izotope but admire it, great tools.  But far more important I think is the simple ability to have that immediate listening feedback loop in play.  My humble advice is to first change your editing software K!  I suspect you'll never look back once you do and wonder why you hadn't done so earlier.
No humbly about it. I have known I should switch ever since I started working with the DR680. I think the Izotope I need is their mastering focused one. Someone offered me a cracked version, but I feel I should pay them for their work as well as any support they offer. This gets OT for this thread, but I will bring it up and ask what folks think in the appropriate thread. Thanks to you and kuba for critically listening and offering food for my thought!
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on January 13, 2018, 12:05:21 PM
The Pink Talking Fish set before Kung Fu OMT style: same rig as in the Kung Fu rig pics
http://taperssection.com/index.php?topic=184981.msg2252069#msg2252069
https://archive.org/details/ptf2017-12-16.24akgck22ck61

I did mix this one less and reduced a bit less under 400Hz than the Kung Fu- however, being the opening set, less audience in the room, not exact comparison.
These guys are fun!
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on January 13, 2018, 07:27:38 PM
OK,... I hope I'm not trolling in the wrong waters here,....
This morning,... Gude Head basked in the shade of the DeccaShrub.

DeccaShrub:
DPA4060 baffled omni pair, with single CM3 @ 0º apprx. *18+inches forward of vertical mic stand stanchion
*= clamp body depth, + 1ft extension rod, + 90ºangle adaptor, + mic body length,... or perhaps as much as 18" forward of mic stand. -2ft? I didn't meaure it.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on January 13, 2018, 09:19:25 PM
^^^^^^^^^^^^^^
My out loud response was: "That is fucking sweet!"
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on January 13, 2018, 09:44:21 PM
I ran a DeccaShrub like that as an experiment a long time ago; 2009?. I was just recently listening to the result, and, I was quite surprised.  The performance had a contrabass duet at the center of the stage, surrounded by the balance of the Octet players.  Even with two big basses passing solos back, and forth, at the center of the stage, the separation and isolation was quite apparent and shocking. You'd think that those two big boys playing hard at under 100hz would want to mono-blob to center, right?,.. especially with a center mic.  Nope, great imaging, and even cutting into the rear of the "U" between them.
So, I decided today was the day to break it out again, an try it.
I just tossed it into the digishizzer blender thingy, and, it came out sounding quite nice (except the constant SoCal friggin air condtioning systems,..AHHHHHHH!!! Fuck, I want to kill something). I ran the baffled omni pair at 3.5dB over the CM3-0º, until I found enough of the center player.
Now, for the next rounds, which will be next weekend.

Gude wore his new power cyborg eyes in front of the Consort of the first time. The tenor violinist, center most player, was cracking up the whole time; loved it!
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: 108Ω on January 14, 2018, 09:14:55 PM
Best way to mic a goat with the winds?

(https://thechive.files.wordpress.com/2018/01/daily-afternoon-randomness-in-hq-43-photos-2525.jpg?quality=85&strip=info&w=728&h=402&crop=1&zoom=2)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on January 16, 2018, 02:20:45 PM
I stumbled across this on LMA and thought it qualified as an oddball setup:
Quote
2 DAK 5245 Microphones and 2 Realistic PZM Mics(Mounted on 1'x 1'x 3/8" plexiglass)... Note: This was recorded with 2 sets of mics, 4 channels, mixed down to 2 channels. The mics were mounted on a stand 8' in height.
Source: https://archive.org/details/gd1993-06-13.111953.aud.dak5245-pzm.orchardpark-ny.flac16
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 16, 2018, 04:40:49 PM
Mike- your Decca-shrub setup reminds me of what Jurg Jecklin was doing later on.  The main visual difference being he was embedding the center forward facing cardioid mic into a slot in the baffle so that it was more or less flush with the front edge of the disk.  Can't remember the other changes, other than also using a second disk baffle setup behind the main mic position with cardioids instead of omnis facing rear-wards.  He actually sent me a surround SACD with some recordings made with that when I'd asked a bunch of questions about his setups and ideas years ago, but I don't have a SACD player and so have only heard the standard 2-channel Jecklin disk versions which are on the red-book stereo layer of the SACD.

A somewhat similar 3-channel baffle setup I though alot about back in the day was using two identical baffles spaced apart by a foot or two, each with an omni on its outer-side like 1/2 of a typical Jecklin disk setup.  Then play with a center mic placed in the middle between the two baffles.  The center mic could be a 3rd omni or a forward-facing directional mic.  I suspect that would work nicely.  You might be able to run that for one of your recordings with that group but probably not for a recording with audience unless the entire setup was down low in front of the front row of seats or something.  It would be hard to see around with the double baffles.

heathen- Interesting find. I was intending to play around with mounting my omnis on small plexiglass boundary plates long ago, but it just wasn't practical, so I ended up mounting them in smaller spherical baffles instead.    That ended up being better anyway for other reasons.  Interesting effort on their part recording to tape in that era, even if the resulting recording is bright, "spitty" and has no real bottom end to it at all (bummer Phil).  IMHO they should have started with a pair of spaced omnis and built on that.

Mala-resistance- You don't trust natural wind and rain to 'dust' your goat?  Your boom operator is showing in frame!  Extra credit for the pastel windjammer, though.  I was pretty charged up to find a bunch of big-horn sheep along the Snake River while there for the eclipse this past summer.  Those Idaho big-horns are nealry the same color as the rocks and much harder to make out against the background compared to yours, even when relatively close as viewed from the raft, drinking at the water's edge.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on January 16, 2018, 09:43:00 PM
This is my first try at DeccaShrub, from back in 2009/2010, and the only other time that I've run it.
I'm likely going to try it again this next weekend, a couple of times.
At any rate,... the first time, back '09/'10

In the most recent effort, I was extended further forward for this reason,... I'd put a layer of heatshrink over my 1' horizontal extension, which wasn't there in 09; for vanity, because the old stuff was looking ratty, so I went over it.. That extra layer of heat shrink kept me from passing the extension through my clamp, for a tighter adjustment.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on January 17, 2018, 09:24:12 PM
OK,...
How about a theory, expressed, but, not yet attempted?
That of,... combining the attributes of a DeccaTree, with that of a Boundary Layer, and, with the thought of the boundary layer also being a rearwarly baffled micing? All from first row center.
My mind plays evil tricks on me at times, and this thought keeps coming back.
The DeccaBoundaryBaffledLayer Technique.

To the image,...
This church has a low divider wall in front of the first row seats.  The center is an aisle.
I was thinking about using this wooden wall, and its trim feature as both a boundary layer, and rearward baffling. And running a single mic, on a single stand, forward of the wall by the typical 3'.
The aisle is likely 4'+->5' wide; so somewhat close to the Decca spread. The boundary layer and baffling would make up for the width.
The single forward mic on a stand,... low profile.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on January 18, 2018, 10:31:26 AM
So, maybe more detail in your proposed config?
By boundary layer, are you saying you will tape a mic to the wooden wall, or put it 3 feet out on a short stand? Which ever one you plan, are you also going to use the pictured baffle with omni's in addition to this single mic, and/or adding a single mic at each side of the center aisle using the wall as the baffle? Which mic in front of the wall- your CM3's?
 
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on January 18, 2018, 10:38:09 AM
Yes, taping the 4060's to the walls, on either side as boundary layer, taped tight to the wall; and the CM3, forward from the wall, by 3' forward, on center.

You can see the outer banding trim of the wall, as something similar to a 1x4 band around what is a plywood wall. My thought, is that 90º mitered corner would be a nice place to tuck a boundary omni, as it would baffle the mic from the opposite side, providing isolation, and boundary layer effect.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on January 18, 2018, 11:36:24 AM
Yes, taping the 4060's to the walls, on either side as boundary layer, taped tight to the wall; and the CM3, forward from the wall, by 3' forward, on center.

You can see the outer banding trim of the wall, as something similar to a 1x4 band around what is a plywood wall. My thought, is that 90º mitered corner would be a nice place to tuck a boundary omni, as it would baffle the mic from the opposite side, providing isolation, and boundary layer effect.
:hmmm:
Seems like an idea which might provide you with some nice "wide stereophonic" imaging with the outer boundary omnis. I dig the concept (and think your idea is 'sound'). Apologies for bad pun!   
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 18, 2018, 07:47:45 PM
Ya mon, give it a go. 

I'd suggest not setting the CM3 too far forward of the boundary-mounted DPAs.  I'd probably try it with the CM3 directly in line with them unless that blocks the isle too much.  That way first arrival of direct sound from the stage in front hits all three mics simultaneously, eliminating any potential need for delays or time alignment.

I think Decca tree triangle with the center mic moved forward of the other two works because it was originally intended to be hung pretty far forward over the conductor's head, basically projecting over and into the orchestra which surrounds it on three sides.  When the group containing all sound sources of interest are predominantly forward of the recording position I think its best to keep the direct arrivals time-aligned with each other by flattening the triangle into something more like three in a line.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on January 19, 2018, 01:44:58 PM
This is another version that I did, a year ago or more. I didn't call it deccashrub for this one, but I am now.
Originally, I'd intended to do a quasi-M/S, with dipole omni and center mic. But that all became more than I was wanting to do, as my ears tend to burn out, and, i move on.
So, rather than the dipole/center quasi-M/S mix, I mixed it as what you're describing in bringing the forward mic back into time alignment (but it was already done that way in mastering).

This is that rig,..., and once again, I'm flying under another Deccatree.... and this one is even equipped with a GoPro cam up near the point mic.

AND,... there is that wall I'm turning into a baffle tonight.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on January 20, 2018, 02:21:33 AM
And, test firing complete.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on January 20, 2018, 07:04:53 PM
What is it?
two recordings happening there.
1) Baffled omni pair, on center, as safety copy.
2) the experiment; two DPA4060's as spaced omni, boundary layer, rearward and side baffled omnis, and, CM3 at 0º
all time aligned.

trying to help with this image, below:
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on January 21, 2018, 05:55:47 AM
2) the experiment; two DPA4060's as spaced omni, boundary layer, rearward and side baffled omnis, and, CM3 at 0º
all time aligned.
It is very interesting. Do you know how side baffles influence sound? Maybe it will be interesting to use spaced baffles for the first set and the second without.
I don't know a lot about boundary layers. It is just layman view. Is not it better to put them in the middle of the wood wall? The edge of the wall should influence the sound.

This setup reminded me what I was thinking about OMT when I tried it. Maybe better is to start with three mics. I can more concentrate how the middle mic work and train my listening skills. And then, when I get more certainty I can add fourth mic.

Best way to mic a goat with the winds?

108Ohm, if you have courage, you can record without extension rod too.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on January 21, 2018, 08:39:17 AM
I just posted the Marcus King Opener to Twiddle using Spread Omnis 108 cm with Hyper cards in XY 60 degrees in the middle:
http://taperssection.com/index.php?topic=185099.0
https://archive.org/details/marcusking2017-12-30.akgck22ck3/marcusking2017-12-30-24akgck22ck3t10.flac

I'm not as happy with this mix as the Twiddle, but the sound was no where near as crisp and clear as the Twiddle.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on January 21, 2018, 08:56:39 AM
2) the experiment; two DPA4060's as spaced omni, boundary layer, rearward and side baffled omnis, and, CM3 at 0º
all time aligned.
It is very interesting. Do you know how side baffles influence sound? Maybe it will be interesting to use spaced baffles for the first set and the second without.
I don't know a lot about boundary layers. It is just layman view. Is not it better to put them in the middle of the wood wall? The edge of the wall should influence the sound.

This setup reminded me what I was thinking about OMT when I tried it. Maybe better is to start with three mics. I can more concentrate how the middle mic work and train my listening skills. And then, when I get more certainty I can add fourth mic.


Its still early on, and too soon to be too critical. But, I am very pleased with what I'm hearing.

The side baffles worked wonderfully in keeping everybody in thier place. They kept the center image more open for the center mic.  The center mic clearly displays the rear of the ensembles "U" formation, the mids. I feel this its in large part due to the side baffles.

Regarding placement on the wall,...
It is a short wall to begin with. So, it limits just what you can do as far as being too high or too low.  The floor on either side of the center aisle is ceramic tile, and highly reflective, so my thought was that being higher was going to be better than the lower area.  I decided to stay clower to the center aisle, as going wider put me closer to active players, and I didn't want to highlight anyone in this, as much as trying for the overall blending.

My thoughts are it has high potential.
If i had it to do all over again, I'd put some baffling under the piano; I'd like to have had the bass violin travel bags under the piano, for example. In one song, Bach BWV-1054 COncerto for Keyboard, the lid was opened, and that made a whole different sound in its presence.  Most of the show was played with the lid closed, which for this recording, made the piano less present.
But, the stage is small, and, they tried to bring him into the fold by pushing the piano as far into the setting as possible.  Always something.
I knew the piano was going to be bright, but, wanted to run the pattern anyway, and, just suck it up.  It turned out far better than I'd thought, with it being so close.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on January 21, 2018, 09:10:04 AM
What is it?
two recordings happening there.
1) Baffled omni pair, on center, as safety copy.
2) the experiment; two DPA4060's as spaced omni, boundary layer, rearward and side baffled omnis, and, CM3 at 0º
all time aligned.

trying to help with this image, below:
I'm digging this approach Mike. glad it looks as if you are liking the results as well.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on January 21, 2018, 09:29:59 AM
Here are a couple of samples:


Bach BWV-1054 Concerto for Keyboard w/ open lid - mp3 partial
https://soundcloud.com/user-271082364/deccaboundarybaffledlayer-sample
Genesis - Its Gonna Be Better - mp3 partial
https://soundcloud.com/user-271082364/deccaboundarybaffledlayer-sample2

The piano is bright!  I went into this knowing that was going to be a possible problem.  It worked out better than I thought, and I'm quite happy wit the result; but, the piano is a bit bright due to its proximity.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on January 21, 2018, 10:41:39 AM
A couple of oddball two-mic setups here: http://taperssection.com/index.php?topic=185036.msg2252999#msg2252999
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on January 21, 2018, 01:54:58 PM
Here are a couple of samples:


Bach BWV-1054 Concerto for Keyboard w/ open lid - mp3 partial
https://soundcloud.com/user-271082364/deccaboundarybaffledlayer-sample
Genesis - Its Gonna Be Better - mp3 partial
https://soundcloud.com/user-271082364/deccaboundarybaffledlayer-sample2

The piano is bright!  I went into this knowing that was going to be a possible problem.  It worked out better than I thought, and I'm quite happy wit the result; but, the piano is a bit bright due to its proximity.
I listened to sample1 about 4 hours ago, now it seems sample 2 has been pulled. Hard to know your "bright" without a reference to your "dark" piano-wise, BUT I thin it sounds good overall tonally, separation of individual instrumentation seems right.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on January 21, 2018, 02:01:59 PM
I did a different sample of the same track on sample.2, and pulled the original. That should be a good link to the new sample, though.
The first sample built too slowly for a partial sample, so I grabbed a different take.

Bright,... maybe I should have said strong presence? You will not be left for want of piano.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on January 21, 2018, 03:40:02 PM
I did a different sample of the same track on sample.2, and pulled the original. That should be a good link to the new sample, though.
The first sample built too slowly for a partial sample, so I grabbed a different take.

Bright,... maybe I should have said strong presence? You will not be left for want of piano.
Yes, there IS piano!  :clapping:
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on January 21, 2018, 11:41:35 PM
And thats the softer, slower, Adagio portion of the concerto.
The rehearsal of the concerto had the lid closed.  Then, surprise, surprise,.. the show had the lid open for the concerto, and closed for the balance of the show, softening it considerably.

Today,... lid open for the whole show, with the open lid facing the audience.
I bagged the first row, right side seat, and we stored all of our gear on the left first row seat, as the piano was so close to that row, anyone sitting there woud have had there face stuffed full of piano.
So, I utilized the hardwood church pews as the boundary layer, rearward baffle, and i taped the foam rem pieces to the sides of the pews as side baffling.
It record, and eft the first row seats to a really nice couple that comes to the shows (all of them), and I went and sat in the rear side.

I somehow managed to run two complete sets of blank files with Gude and the R09HR. They soundchecked out just fine; I hit record, saw levels, and time rolling on record; walked away. I get home to find two 41 minute blank stereo files that weighed in about 2gb of blankness, totally flat-lined. Gremlins.

And,... more time logged in the shade of another D'Tree.

Conclusion of test firing:
Total potential for exploration.  I would very much like to do this again without the piano.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on January 22, 2018, 12:08:46 AM
OK,... I've worked with the gal that is the furthest to the left in the image above, #4441, for a couple of years now. Her name is Sarah O'Brien.
We've gotten along wonderfully. Always a really nice smile, and kind words.
I found out friday that she was the lead cellist for Yanni for 23 years, and leader of his orchestra.
They are together in this video segment: https://www.youtube.com/watch?v=U7ag2S7iLxk
I've always been amazed at her playing, but, never knew the background.
So, just today, I was asking her about that, and she said that she got her "in" with the Consort with Beth Folsom, the soprano violin player, who, was also with Yanni for a long long time.
I had no idea that I was so close to new ageyness.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 22, 2018, 03:15:09 PM
Those samples sound quite good to me Mike.  I like the hefty sense of spatial width from the wide omnis as well as the detailed yet flattering perspective on the ensemble it provides.  Good "division of labor" amongst the three mics, avoiding phase interaction conflicts in the 2-channel mix-down.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 01, 2018, 04:19:01 PM
Came across an AES paper which explores a setup quite similar to OMT in a number of ways.  I just started reading it at lunch today so I won't speculate too much or offer my opinion until I have a chance to fully digest it.  However, I wanted to share the link here as there are some obvious parallels with what I'm doing.  Generally, the idea of using spaced arrangements consisting of multiple coincident pairs to facilitate manipulation of the recording afterwards. More specifically, I immediately noticed similarities to my  idea of turning the 6-ch OMT side facing supercardioids into coincident Mid/Side arrangements as illustrated in the advanced section of the OMT booklet - modifications I want to experiment with next, using 8 channels total.  More on this later..

Technical content warning- This is AES paper type reading dealing with hall acoustics, surround recording and listening psychoacoustics.  No math, but some non-superficial technical acoustics type stuff.

It can be viewed or downloaded at the site below, which is where I found it upon browsing other papers from the University of Huddersfield Repository.  That page states:

"Download PDF:
Sorry, we are unable to provide the full text but you may find it at the following location(s):"

The links which follow are dead ends, however the full paper may be either viewed directly or downloaded as a PDF from the preview window found a bit further down around mid-page.

A New Multichannel Microphone Technique for Effective Perspective Control (by Hyunkook Lee) (https://core.ac.uk/display/1652654?source=2&algorithmId=13&similarToDoc=96772301&similarToDocKey=CORE&recSetID=b93145ea-9aa7-446c-814d-1987546195bd&position=2&recommendation_type=same_repo&otherRecs=96771466,1652654,96768276,59875,96772067)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on February 13, 2018, 10:08:47 PM

Two channel stereo - Baffled Boundary Layer
result:
Quote from: cello player
Mike...the recording sounds amazing!!! Thank you so so much!!! I can't thank you enough...I was supposed to be practicing other music today, but I've just been sitting and listening to the recording. The balance is fantastic and the sound quality is wonderful!!! Others have recorded us in the past, but I want you to know that your recording is the best we have ever had.

referencing the DPA4060 pair taped to the brick wall, on either side of the post, below; Baffled Boundary Layer
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 14, 2018, 11:28:51 AM
Right on. 

Liking how you used the column as a baffle between the boundary mounted 4060s taped to the wall.  That seems to me an excellent setup for that room.  If you are able to, it would be interesting to do the same using the opposing wall and center column behind the stage, high enough over the piano that you have a more-or-less direct line of sight to the strings.  You should be able to do that without much if any visual impact at all as long as you can set it up early so as to be out of the way of the performers.  That would get improved proximity to the sources and push the audience further back in the auditory perspective.  Only one way to know if that really works better or not.

Feels pretty good to get that kind of feedback from the musicians, no?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 14, 2018, 01:19:37 PM
Received special permission to record at Snarky Puppy's Ground Up festival last weekend, upon promising to keep the recordings private and provide them to the music label for audience-reaction and ambience in their potential live multitrack releases.  This is a fantastic musician-centric festival held in a small a park along the beach, quite intimate as it is capped at 2000 attendees per day.  Outstanding talent, heart and mindset by all involved- the musicians, the audio support crew, the festival organizers and staff and the attendees.  Got in with their recording engineer to provide him my files and hear his.  They were multitracking all performances and had up a pair of spaced omnis at the soundboards of both stages.  I moved my 6ch OMT rig back and forth between the two stages.

A few photos..  here's my setup at the smaller stage-

Last photo is the kicked-back hammock perspective of the rig and stage.  A nice spot to chill while keeping an eye on things.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 14, 2018, 01:27:22 PM
A few of my setup at the main bandshell stage-

First photo is of my rig as viewed from below. Like at the other stage, the recording engineers spaced omnis are visible as well (Earthworks employed at this stage).
Second is from the recording position (Wood Brothers)
Third and fourth are is from the recording position (Snarky Puppy)
Last is the view out the window looking West from Miami Beach across Biscayne Bay towards the Miami skyline from the top floor of the hotel hosting the last-night shows.  Posting this one simply because I found it a cool photo with the reflected ballroom lights interposed against the sky.

Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on February 14, 2018, 01:29:18 PM
Mike- +T great use of the wall/post. So awesome to get feedback like that!

Gut, great photos, I dig the one straight up  at the blue FL sky! (only a  bit upstate NY jealous!)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: noahbickart on March 13, 2018, 08:32:07 AM
People might want to check out this, done with a 4 channel OMT rig. 60cm spaced omnis, with a hyper as the mid in a m/s pair mixed mostly to mid:

16bit: http://bt.etree.org/details.php?id=598540
24bit: http://bt.etree.org/details.php?id=598541

Mike Gordon, Scott Murwaski, Robert Walter, John Kimock, Craig Myers

March 10, 2018
Brookln Steel, New York, NY

Location: SBD Cage, just R of Center
Source: Schoeps mk3 (60cm AB) + Schoeps mk41v/mk8 (m/s)> Nbob actives> Sound Devices mixpre6 (channels 1-4 @ 24bit 48 kHz)
Transfer: Mixpre6> Macbook Pro (via usb-c)> Reaper (DSP)> Sound Studio (Fades & Tracking)> xACT (Tagging and Flacing)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 13, 2018, 10:00:25 AM
Thanks Noah.  What are your thoughts about it?

BTW folks, as a point of comparison, Noah has also made available his 2-channel mk4 recording from the same show-

mk4v (25cm @ 70 degrees) :
16bit: http://bt.etree.org/details.php?id=598538 (http://bt.etree.org/details.php?id=598538)
24bit: http://bt.etree.org/details.php?id=598538 (http://bt.etree.org/details.php?id=598538)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: noahbickart on March 13, 2018, 01:15:51 PM
Thanks Noah.  What are your thoughts about it?

I think it worked well.

My only real issue is the large bar needed for appropriate spacing. It requires a heavier larger stand.

On Saturday night, I probably had a chance to go FOB, but turned it down because I was committed to the big stand.

Sunday night in Albany, where I was poised for FOB, I ran three pairs, all of which sound great. but there was no way I could have used the big omni bar there.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 13, 2018, 03:15:09 PM
Thanks and agreed- I see the need to space the omnis sufficiently as the most imposing setup constraint for OMT, assuming one is already setup to run more than 2 channels.  And it doesn't help that it seems the more spacing one can get between the omnis the better the result, at least as a general trend with this.

Both of these recordings sound good to me. I did EQ'd each separately before making a comparison (and then compared the two both with and without EQ), and found it interesting that I came up with a very similar although slightly different curve for each.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on March 28, 2018, 01:48:31 PM
Well, sometimes you find things when you least expect to.
Objective of the morning: Find/learn about a Pintle tow hitch system.
Found:
(http://i.ebayimg.com/images/g/ZqEAAOSwmfhX2I2W/s-l300.jpg)
https://www.homedepot.com/p/TowSmart-Solo-Hitch-Alignment-System-1280/206798835


Telescoping, extends from 10.5" to 43" each w/ hardish foam ball ends with *2.5" balls. Heavy magnetic bases.

*measured this morning.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on March 28, 2018, 02:32:51 PM
Do I ever leave anything alone?
Only in the bag, on the way home...

Found out:
Magnets just push out of the channels. This exposed mounting scheme of a pop rivet into the body of the tubing.
Determined: Childs play to mod further.
Pop Rivets will be removed, and machine screw replacements. At the magnet channel, matching all-thread connector female ferrules will be attached so that the magnetic bases can be utilized, or, the machine screws can be used to connect the two spreaders into a single unit.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on March 28, 2018, 03:57:45 PM
http://taperssection.com/index.php?topic=185887.0
Rig pics of recent 2 day festival where we did two different OMT variants.
Friday variant was: Friday - AKGck22 omni spread 108 cm > Grace V2@+25dB 2 x AKGck3 XY 60' (PAS) in center >> Tascam DR680
The SAT variant:                  AKGck22 omnis about 15 feet apart >Grace V2; 2 x ck3' hypers crossed 60' (PAS) in center > Grace V3
Approximate locations are same center location; Friday we had the Manfrotto triple bar limitation of about 108cm spread; Saturday we were able to spread them using three stands.

In our opinions this wide spread resulted in a kick ass recording.
More will be added in here later to support the discussion. LMA links:
https://archive.org/details/jgb2018-03-24.akgck3_ck22                  SAT
https://archive.org/details/ggw2018-03-23.akgck3_ck22                 FRI

What I noticed between the two days differing setups is the wide spread omnis certainly have more "uniqueness" to the signal with very little correlation between the two channels. Unfortunately what we did is nowhere near scientific; each day had different acts, and although the same PA was used, on Saturday the JGB FOH was doing SIM measurements using a measurement mic close slightly above the floor area thus IMO the overall sound quality was 15-20% "Better" than Friday.
Another notable process: we had the center pair of hypers crossed PAS which essentially was about 60' maybe closer to 50' (as recommended by GB)
edited to answer GB's questions below
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 29, 2018, 04:31:15 PM
For anyone lurking, or wondering what the OMT hubbub is all about,  Rocksuitcase and Kindms's recording of JGB with Melvin Seals last Sat is an excellent example of what this technique is capable of, and is in my opinion indeed quite kickass!  Its comparatively easier to make a recording of this quality from well FOB in the sweet spot, but not so easy from 50' back near the back of the room in an indoor hall.

Link to that recording (again)- https://archive.org/details/jgb2018-03-24.akgck3_ck22 (https://archive.org/details/jgb2018-03-24.akgck3_ck22)

Quote
What I noticed between the two days differing setups is the wide spread omnis certainly have more "uniqueness" to the signal with very little correlation between the two channels.

Yes, exactly.  Low correlation between the wide omnis providing the big open ambience, fat bottom, and a nicely diffuse representation of the audience + High correlation between the coincident PAS hyper center pair providing clear focus and imaging of the direct sound from the PA and stage.. with the right amount of blend between the them.  Two complementary pieces of the puzzle which go hand in hand and work especially well in combination partly because they are sufficiently different enough from each other.  This is the core essence from which the technique is constructed - each part contributes something different, and no part works optimally on its own without the other (which is the necessary leap of faith in really taking the technique to the next level and making the most of it), so that in combination the sum of the separate elements produces something greater than any of the individual parts.

That leap of faith thing is the tough part, yet is essential to really wring the most from OMT.  It's much more comfortable to build upon 2-channel stereo techniques we've a preference for from personal experience and general practice, which are certainly true for for 2-channel recording in general (things like near-spaced stereo pairs in the center, wider X/Y angles in the center, pointing all the mics toward the stage, not overly-wide omni spreads, etc).   It's really ingrained in us.  I still find myself convincing myself to push further outside the envelope of "known good" stereo practice sometimes with regards to advancing the technique further in pursuit of the sound, man, the sound!


I gave a quick listen to the Friday GGW for comparison, and yes the difference in sound quality in PA optimization is apparent.  I can mentally "listen around" that when listening for other attributes of the recording which correspond the differences in your recording setup over the two days and I suspect others reading this can mentally do the same, as long as I know what variables didn't change.  With that in mind, can you clarify a bit on what was different other than the much wider omni spacing (15' verses 42"), the bands themselves, and the PA optimization?

Seems you were quite close to the same recording location both days.
Center X/Y pair in PAS both days? (same approximate 50 degree angle between mics to PAS both days or are you saying you made it a bit tighter on Saturday than on Friday?)
^Just want to make sure before I draw conclusions.

BTW for folks reading, there is more discussion on these two recordings and photos of the setups used in this alternate thread- http://taperssection.com/index.php?topic=185887.msg2259795#msg2259795 (http://taperssection.com/index.php?topic=185887.msg2259795#msg2259795) And here's 'Suitcase's photo from that thread showing the 15' split omnis + PAS hyper center pair setup used to make this recording-

(http://taperssection.com/index.php?action=dlattach;topic=185887.0;attach=130434;image)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 29, 2018, 04:47:45 PM
The Pintle tow hitch system Moke found as an alternate and more heavy-duty telescopic mic bar for spacing the omnis looks very promising, and Moke is already made rapid progress in transforming into a working telescopic mic bar.  To bring folks reading this OMT thread up to speed, we've posted more discussion on that in another thread specifically adressing bars for spacing 4060s and the use of various shapped modifier attachements for them- http://taperssection.com/index.php?topic=185872.msg2259701#msg2259701 (http://taperssection.com/index.php?topic=185872.msg2259701#msg2259701)  I won't duplicate that info here at this point since whats' been posted thus far is pretty much covered in the original OMT thread, other than linking a couple photos of his posted over there showing what he's done and a comparison with TV antenna arms.  Looks significantly beefier and capable of supporting mics larger than flyweight miniature omnis.

(http://taperssection.com/index.php?action=dlattach;topic=185872.0;attach=130449;image)  (http://taperssection.com/index.php?action=dlattach;topic=185872.0;attach=130451;image) (http://taperssection.com/index.php?action=dlattach;topic=185872.0;attach=130453;image) (http://taperssection.com/index.php?action=dlattach;topic=185872.0;attach=130455;image)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on March 29, 2018, 06:22:41 PM
For anyone lurking, or wondering what the OMT hubbub is all about,  Rocksuitcase and Kindms's recording of JGB with Melvin Seals last Sat is an excellent example of what this technique is capable of, and is in my opinion indeed quite kickass!

I gave a quick listen to the Friday GGW for comparison, and yes the difference in sound quality in PA optimization is apparent.  I can mentally "listen around" that when listening for other attributes of the recording which correspond the differences in your recording setup over the two days and I suspect others reading this can mentally do the same, as long as I know what variables didn't change.  With that in mind, can you clarify a bit on what was different other than the much wider omni spacing (15' verses 42"), the bands themselves, and the PA optimization?

Seems you were quite close to the same recording location both days.
Center X/Y pair in PAS both days? (same approximate 50 degree angle between mics to PAS both days or are you saying you made it a bit tighter on Saturday than on Friday?)
^Just want to make sure before I draw conclusions.
Answers to questions in edited clarified post above yours! Thanks so much for your inspiration- results such as these make it all worth learning and doing!
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kindms on March 29, 2018, 07:38:34 PM
For anyone lurking, or wondering what the OMT hubbub is all about,  Rocksuitcase and Kindms's recording of JGB with Melvin Seals last Sat is an excellent example of what this technique is capable of, and is in my opinion indeed quite kickass!  Its comparatively easier to make a recording of this quality from well FOB in the sweet spot, but not so easy from 50' back near the back of the room in an indoor hall.

Link to that recording (again)- https://archive.org/details/jgb2018-03-24.akgck3_ck22 (https://archive.org/details/jgb2018-03-24.akgck3_ck22)

Quote
What I noticed between the two days differing setups is the wide spread omnis certainly have more "uniqueness" to the signal with very little correlation between the two channels.

Yes, exactly.  Low correlation between the wide omnis providing the big open ambience, fat bottom, and a nicely diffuse representation of the audience + High correlation between the coincident PAS hyper center pair providing clear focus and imaging of the direct sound from the PA and stage.. with the right amount of blend between the them.  Two complementary pieces of the puzzle which go hand in hand and work especially well in combination partly because they are sufficiently different enough from each other.  This is the core essence from which the technique is constructed - each part contributes something different, and no part works optimally on its own without the other (which is the necessary leap of faith in really taking the technique to the next level and making the most of it), so that in combination the sum of the separate elements produces something greater than any of the individual parts.

That leap of faith thing is the tough part, yet is essential to really wring the most from OMT.  It's much more comfortable to build upon 2-channel stereo techniques we've a preference for from personal experience and general practice, which are certainly true for for 2-channel recording in general (things like near-spaced stereo pairs in the center, wider X/Y angles in the center, pointing all the mics toward the stage, not overly-wide omni spreads, etc).   It's really ingrained in us.  I still find myself convincing myself to push further outside the envelope of "known good" stereo practice sometimes with regards to advancing the technique further in pursuit of the sound, man, the sound!


I gave a quick listen to the Friday GGW for comparison, and yes the difference in sound quality in PA optimization is apparent.  I can mentally "listen around" that when listening for other attributes of the recording which correspond the differences in your recording setup over the two days and I suspect others reading this can mentally do the same, as long as I know what variables didn't change.  With that in mind, can you clarify a bit on what was different other than the much wider omni spacing (15' verses 42"), the bands themselves, and the PA optimization?

Seems you were quite close to the same recording location both days.
Center X/Y pair in PAS both days? (same approximate 50 degree angle between mics to PAS both days or are you saying you made it a bit tighter on Saturday than on Friday?)
^Just want to make sure before I draw conclusions.

BTW for folks reading, there is more discussion on these two recordings and photos of the setups used in this alternate thread- http://taperssection.com/index.php?topic=185887.msg2259795#msg2259795 (http://taperssection.com/index.php?topic=185887.msg2259795#msg2259795) And here's 'Suitcase's photo from that thread showing the 15' split omnis + PAS hyper center pair setup used to make this recording-

(http://taperssection.com/index.php?action=dlattach;topic=185887.0;attach=130434;image)

Hey thanks for the kind words. Always nice when it turns out well

considering we had all sorts of real and imagined issues  :o its amazing the v2 & v3 stayed powered on and we didnt create a problem

was really fun being able to contribute the 414s to the stream as well. we got to demo the mix during the JGB soundcheck. Matt said he had always wanted to mic the audience that way but never had the time / chance to do it

Also have to give a shout out to math and rocksuitcase. One of those classic moments. He walks off the distance from the video FOH to stage. yells back to set the delay 40ms, then says make 35ms. It was dead on
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on March 30, 2018, 05:20:36 PM
another OMT goodie:
http://taperssection.com/index.php?topic=185913.0
Kung Fu
The OMT setup:
Source: AKG ck3 (60deg) >Tascam DR680(24/48) + AKG ck22 split 42" (108cm) >V2 >Tascam DR680(24/48)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on April 02, 2018, 01:13:41 PM
Saturday night I broke out the TV antennas and ran some split omnis.  Specifically, I had a pair of AT4031s in the center in DIN config.  Flanking those were a pair of CA14 omnis, 70 inches apart, oriented 180 degrees from each other.  I've only listened to snippets of the recording, but I am very surprised at how decent the omnis sound on their own (this was indoors, by the way).  I hope to have something posted this week, but in the meantime I can say that it was a lot of fun to fly some mics at such a wide spacing.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on April 04, 2018, 09:47:11 AM
Here's my recording from 3/31 with the split omnis and AT4031 mix: http://taperssection.com/index.php?topic=185963.0

I really like the low end that the omnis add, and was initially concerned about them adding too much crowd noise.  Then I listened to just the ATs and, unfortunately, the crowd was just really loud that night...can't blame the omnis.  As I mentioned before, though, I was really impressed with the omnis by themselves.  I wonder if Chris adds a bit of a high end boost to his omnis since they'll generally be used far from the source in our concert recording situations (that's a topic for another thread, though).
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on April 04, 2018, 12:55:21 PM
^^^^^^^^^^^^^^^^^^^  downloading now. I love any Medeski project. I'll let you know my opinion on the recording. Thanks for sharing!

Wow, half way through- I like it. Very "wide" and spacious. I'm at work on small speakers but the AUD hasn't gotten in the way yet. Scofield has a very airy guitar tone which you captured pretty well here.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on April 04, 2018, 12:59:29 PM
I'll let you know my opinion on the recording.
Looking forward to it.  I still have a lot to learn.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on April 04, 2018, 02:59:13 PM
Heathen, any possibility of posting short (say minute long or so) samples of the omnis and cards on their own prior to mixing?  No worries if that's too much hassle.
MP3's uploaded directly to the thread would be perfectly fine.  The size limitation on each file in that case is 750KB.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on April 04, 2018, 03:15:24 PM
Heathen, any possibility of posting short (say minute long or so) samples of the omnis and cards on their own prior to mixing?  No worries if that's too much hassle.
MP3's uploaded directly to the thread would be perfectly fine.  The size limitation on each file in that case is 750KB.
No problem at all...I'll try to remember to do it tonight.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on April 04, 2018, 06:34:49 PM
Here's a clip of the raw CA14 and AT4031 files: https://we.tl/GGNxlvRxY6

All I did to these was to make each into a stereo file (you can split them back up into individual channels in you DAW, of course) and trim them down to the short clip size (I tried to find a passage that has loud and quiet parts).  They're both of the exact same passage of music.  Link should be good for seven days.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kindms on April 04, 2018, 07:10:07 PM
heathen. grooving the MSMW.

Curious about your thoughts as well as others. rocksuitcase and i were discussing this the other day. You mentioned talkers etc. We are sort of thinking that the OMT has a tendency to mitigate the crowd to some extent. we were thinking perhaps as its more "spread out"  vs. a more direct in a 2 channel scenario.

curious what you guys think about that

Im only about 15 minutes in on the recording and so far the crowd is there but I haven't found it distracting etc
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on April 04, 2018, 08:37:03 PM
heathen. grooving the MSMW.

Curious about your thoughts as well as others. rocksuitcase and i were discussing this the other day. You mentioned talkers etc. We are sort of thinking that the OMT has a tendency to mitigate the crowd to some extent. we were thinking perhaps as its more "spread out"  vs. a more direct in a 2 channel scenario.

curious what you guys think about that

Im only about 15 minutes in on the recording and so far the crowd is there but I haven't found it distracting etc
This is one of Greisenger's concepts which informs the OMT theory: decorrellation- the omnis are sufficiently spaced and separated from the center microphone(s), the more "unique" each signal is, time of arrival and pressure difference wise, the more decorrellated the signals are said to be. This is one reason why chatter seems less annoying when doing a 3 or more channel OMT using spaced omnis as the anchor. Correct my cite GB if wrong    ;)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on April 04, 2018, 08:57:50 PM
Forgive me for what may be stupid questions, but doesn't OMT still pick up the general din of the room?  Any particular yell or the like may be decorrollated, but that background constant level of noise will remain right?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on April 04, 2018, 09:16:08 PM
Forgive me for what may be stupid questions, but doesn't OMT still pick up the general din of the room?  Any particular yell or the like may be decorrollated, but that background constant level of noise will remain right?
Oh yeah, same as every/any mic. There is always the room chatter these days, I feel for you there, BUT, your recording is very good.
re decorrelation: I think what I hear is when I know a person was coughing or yelling to one side (i.e. I'm sitting next to them), it seems that cough or yell isn't as present on the recording. Of course, anything loud near any mic will be in the mix at one level or another.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on April 05, 2018, 12:08:45 PM
You've got it.  The audience sounds are still there and are not reduced in level, but the way in which that is portrayed and perceived during playback is different.  The audience sound pickup is directly related to the how room ambience is picked up and portrayed - both are more-diffuse, and open and "out there", perceptually separated to some degree from the music of interest which is more highly focused in the center front quadrant.  The wide omni spacing does this in an increasing way for direct sound which arrives further off the central axis and especially so for the diffuse sound which is effectively arriving from all directions (in this case that diffuse audience sound component is more murmur and general din, as opposed to any specifically identifiable audience sounds).

Acually, due to the omnis we're most likely picking up more audience and room sound from all directions than we would using a single pair of directional mics, yet that content (at least the room sound and the desirable audience reaction) is less in conflict with the music because of the OMT arrangement because it picks up the direct sound and the room/audience sound in different ways before we combine them.  Of course there remains a lot of overlap between them, and that's a good thing.  But the differentiation is important and useful.

To take best advantage of that differentiation, it helps to keep the central mic pair as focused on the direct sound pickup from stage and PA as possible, with the omnis less intentionally focused on that and more oriented on the diffuse sound arriving from all directions.  So more-directional PAS center pairs are helpful for maximizing direct sound pickup from stage and PA, and a coincident arrangement of the center pair is helpful in producing a tighter and highly-correlated type of stereo for that direct sound component (contrasting against the more-decorrelated and diffuse omni pickup of room/audience).  Omnis which don't especially favor the forward direction are helpful, achieved by using miniature omnis which have less directionality due to their small size, or omnis with diffuse grids like the AKGs rocksuitcase and kindms are using, or pointing more directional omnis sideways or backwards.  And spacing the omnis as far as practical helps decorrelate the diffuse pickup to a lower frequency, narrows the SRA angle of the omnis, meaning more of the off-axis audience direct sound pickup by them will image far-left or far-right leaving room for the center pair stereo stuff in the middle.

The other thing which spacing the omnis sufficiently helps with is audience sounds close by the recording position.  Close sources will tend to be considerably louder in one omni than the other and that will cause them to image further to one side or the other, leaving more perceptual separation between that and the music which is imaging more tightly in the center, allowing it to be more easily perceptually ignored even though its still there (cocktail party effect).  Again, the setup is actually more sensitive to close audience sounds due to the omnis, but the arrangement helps to make that seem less in conflict with the music.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on April 05, 2018, 01:04:17 PM
Heathen, thanks for the MSMW.  Sounds good (dig those guys).  And very cool that you were able to manage a 7' spacing on the omnis.

Here's a clip of the raw CA14 and AT4031 files: https://we.tl/GGNxlvRxY6

Thanks for that.  It's helpful to hear each part in isolation.  Here's something which I think will make things even better.

Are you one who does any EQ?  No problem if not.  This is a big topic in general, and even more so with regards to the potential application to OMT where each part can be EQ'd separately and/or the resulting combination can be EQ'd as well.  In general, its a good approach to EQ the center pair and omni pair separately to each sound as good as possible on their own prior to combining them.

But there is an important exception to that, which can be useful to do even if you don't really care to make the effort to EQ the two parts separately.   It's this- Often it helps to clean the sound up greatly by reducing the low frequency content of the center pair.  Let the omnis provide the majority of the low and upper bass content.  Its okay, even good, if the center pair is more-focused on the midrange (especially) and high frequency content.  Directional mics with weak bass response (like those more intended for speech pickup) can actually work well as center pair because of this, since their response is sort of pre-EQ'd that way already and fits the roll.  Otherwise it helps to use a gentle roll off from the below the upper mids to reduce any excess "thickness" and boom in the center pair.  And although I've not tried it, a high pass filter could work for this, especially if you can set the slope to first-order (-6dB per octave).

This represents another aspect of the "division of labor" sort of thing described in the previous post, letting the omnis do their thing down low without conflict.

And a midrange focus in the center pair plays nicely against the tendency of omnis to be less forward in that range.  Again, the mic patterns used sort of naturally do this for you, but you can emphasize the trend somewhat with EQ if you want to play with it, just keep the difference moderate.

At higher frequencies I find the interaction between the omnis and center pair to be productive.  No need to reduce one to let the other "breathe" sufficiently.  Probably partly because the signals are sufficiently decorrelated at high frequencies (short-wavelengths) so the content is different enough, and partly due to how we perceive phase differently at high frequencies, where  randomized phase tends to sound "airy" and "open".



TLDR- reduce any tendency toward "mud" or excess "thickness" in the center pair via mic selection or EQ, even erring toward what would be an "over-thin" bass-weak sound when the center pair is listened to in isolation.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on April 05, 2018, 01:25:45 PM
I'm not sure if you just made a typo, but my omni  spacing was 70 inches.

As for the EQ, I have EQ'd some recordings in the past but I still don't feel very comfortable with it.  While I'm not opposed to messing with it more and trying to get better, I'm leaning more towards mics that sound the way I like without need for EQ (hence my love of the AT4031...maybe not for everyone, but to me they sound damn near perfect).

If you tinker with that clip to the point you get something that sounds good, I'd love to hear what you come up with (and perhaps more importantly, how you got there).

I'll admit that for this show I was thinking of the AT pair as my primary focus, and OMT was a secondary thought.  That's why the ATs were DIN...if I were primarily focused on OMT then it seems from the recent comments that having the ATs PAS or XY would have been better.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on April 05, 2018, 01:26:05 PM
^^^^^^^^^^^^^^^^^^^^^^^^^^
Heathen- I find that unless conditions are ideal, often I like to EQ the omni channel usually taking out high end above 3kHz gradually to 20kHz (always depends on source material)
Then import the middle channels, and typically do not need to EQ our AKG ck61ULS or ck3's. but if I do I do it separately from the Omnis as GB mentions. THEN
I level the two stereo sources against each other, typically boosting the center 2-4 dB over the omnis, but it can go the other way as well. (often coming up with different rations of Omni to center even between sets)
THEN export to two tracks THEN re-level or do a light overall EQ if something seems it needs shaping. ( I like to NOT do EQ at this stage if it all sounds right)

IMO, the complete approach to OMT involves knowing there WILL be post processing involved and much more than with 2 channel recordings. For me, after all the years of running co-incident patterns this last 3 years has been much more FUN doing the various things involved to go multi-channel both equipment wise and in my interactions with FOH and musicians. I have had several musicians, producer types, ask about the mic technique and in fact have had a few of them reach out after the event to ask for their raw files. (which I eagerly provide)

I will post a wetransfer just for you of one of my best takes like this using 4 channel OMT plus 2 ch SBD. The band isn't "taper friendly" so it will be on the DL via PM to you.
Quote
I'll admit that for this show I was thinking of the AT pair as my primary focus, and OMT was a secondary thought.  That's why the ATs were DIN...if I were primarily focused on OMT then it seems from the recent comments that having the ATs PAS or XY would have been better.
If this is the case, then your recording is all that much "better". I hear a nice wide soundstage plus a relatively centered overall image.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on April 05, 2018, 01:29:29 PM
Thanks for the input, and for sharing the file!
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on April 05, 2018, 04:25:41 PM
My mistake, I meant to say 70 inches not 7 feet, yet the point stands - that's more spacing than most tapers are able manage from a single stand, and is in the enough for "good OMT spacing" IME.

No worries in considering your DIN pair primary, and that's the way I'd approach it if I was just getting into OMT.  Best to start from what you are comfortable with and what has worked well for you in the past, using that as a baseline of comparison for whatever changes you end up making, before changing things up too much.

Conceptually I work the opposite way, starting with the omnis alone and getting them balanced and sounding good by themselves, then embellishing on that with the other channels I have available.  I like starting from a well balanced, natural ambient sound, then adding presence, focus, imaging and depth through the addition of the center mic(s).  Either approach can work, this just works best for me, partly because I began taping with spaced omnis rather than near-spaced pairs so this approach comes naturally to me.  But I also think it's helpful to build the mix this way from the bottom up (from the ambience inwards).  And when the omnis are considered the primary pair, that sort of opens things up to more non-mainstream options for what one might do with the "additional" center mics in trying various things over time.

The omnis sound pretty good alone, don't they?  I bet a lot of tapers may be surprised by that.  Especially since they are facing to the sides and not forward.



Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on April 05, 2018, 04:37:40 PM
Don't worry about all this EQ stuff.  But do listen to each pair on its own, and I encourage you to listen carefully to identify the frequency balance thing I'm talking about in the center channel or center pair.  Not just with respect to this recording, but in general when using this technique.  Listen for any excessive energy or resonance in the lower mids and bass in the center pair which may tend to cloud the clarity of the mids in any way.  It also helps to compare what you hear in that below-mid frequency region with what the omnis are providing.

One way to test out this center pair frequency shaping aspect for yourself without using any EQ afterwards is to try switching in the low-cut on the mic bodies (if they have them) or on the recorder for the center pair, although that does sort of commit you to mixing with the omnis instead of keeping a fully independent center pair.  Besides making everything clearer in general and improving imaging, this can also allow you to use somewhat more center-pair level in the mix if appropriate, without cluttering things up.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on April 05, 2018, 04:40:36 PM
The omnis sound pretty good alone, don't they?  I bet a lot of tapers may be surprised by that.  Especially since they are facing to the sides and not forward.

Yes, I think I've commented before that I was surprised at how good the omnis sound by themselves since this was indoors.  I think I also made an off-hand comment wondering if Chris Church tunes his omnis for being used farther from a sound source, since most tapers are doing that (would that be diffuse field?  I can't keep it straight).  If that's the case, I would guess that's part of why they sound so good.

If nothing else, this is definitely going to make me more inclined to try this sort of thing in the future, even indoors.  I've got some indoor shows coming up in the next few months where I might be able to try more OMT stuff (of course, I've also got some indoor shows were the spacing of my mics will be limited to the dimensions of my stupid head  >:D ).  I'm already trying to think of ways I could mount these omnis at Red Rocks this summer.  (Summer?  Sheeeeeeit...I'm going to start seeing show there in a month!)

I think I'll also play with this recording a bit more, taking your approach of starting with the omnis.  That seems to be consistent with rocksuitcase's approach of EQ'ing his omnis first.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on April 05, 2018, 05:26:50 PM
I find that unless conditions are ideal, often I like to EQ the omni channel usually taking out high end above 3kHz gradually to 20kHz (always depends on source material)

I don't mean to turn this into too much of a discussion on tweaking EQ (keeping Heathen in mind at this point, but have been meaning to explore OMT EQ in depth, so definitely later).  And some of the difference in approach may be a result of the different omnis we are using.  But as a general trend, I don't like throwing away that high frequency omni ambience, for me much magic lies there.  It can open up the recording, and also provide sufficient high frequency energy in that region when that's needed without becoming strident, as can sometimes be the case when trying to add sufficient energy there by boosting that region in the center pair.  Again in general, I find a sort of loudness-curve shaped response tends to work well for the omnis (sort of the classic lopsided smile-shaped EQ, mostly emphasising the bottom, less mids, yet rising at the very top providing sufficient high frequency "air" so it doesn't sound dull or muffled, maybe somewhat distant but still retaining a nice live "sparkle" and naturalness.   And that loudness-curve trend thing sort of makes sense when you consider the lower level of the ambient sounds compared to the direct sound.

As for a generalization on EQing the center pair, it's mostly that smooth reduction in low frequency content as mentioned for less competition with the omnis down there.  If I want more clarity or presence (SBD like) I'll work the mid range and push up between 700 and 3kHz in the center mic or pair, which acts somewhat like a zoom control for vocals.  The part I find curious but seems to work well for blending the center seamlessly and allowing more center energy without the center over dominating the mix is a cut centered somewhere around 7-10kHz or there about. Keeps the center from getting "shouty" and calling attention to itself.  Perceptual HTRF stuff going on there for sure.*  I'm doing this monitoring through three front speakers (dedicated center speaker), but it seems to work the same (as far as I can tell, at least similarly) mixing to two channel stereo.



*BTW, I contacted David Greisinger recently and he kindly sent me his Personal Headphone Equalization App, which helps the user find a personal headphone equalization curve which matches the response of a speaker located directly in front of the listener.  The user adjusts frequency bands and balance controls to find the same apparent centered loudness level in each band.  The resulting curves can then be used for any stereo source listening by that user through those headphones.  This corrects for both the specific headphone's response as well as the listeners personal HRTF, producing much more natural headphone listening both in terms of frequency response and "out of head" spatial imaging.  I've not had a chance to do anything with it yet or go through the process yet, but am excited to do so.  I've asked his permission to discuss it on this board, which I plan to do in a separate thread at some point.  I suspect this is related to that lower treble center EQ cut I describe above.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on April 05, 2018, 06:08:30 PM
But to emphasize GB's commentary- don't sweat the EQ stuff much, It's truly all to taste. And ALWAYS be judicious, less is more is generally the case with tonal balance EQ.
One thing To add on a tangent- I like to listen to the two channel "rough mix" 3 different ways before I decide if/how to EQ- over computer monitors using both Audacity and foobar2000, headphones, and in my car. So silly, but my car audio system is the most revealing of the three.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on April 05, 2018, 06:32:34 PM
One thing To add on a tangent- I like to listen to the two channel "rough mix" 3 different ways before I decide if/how to EQ- over computer monitors using both Audacity and foobar2000, headphones, and in my car. So silly, but my car audio system is the most revealing of the three.
I try to do that as well.  My primary headphones (Beyer DT880 600 ohm) are on the bright side, so if I rely just on them the end result can sound dull on any other system.  So, in this case, I made some rough mixes and compared them through my main rig (Monitor Audio Silver 10s, Simaudio Moon 240i).  In this case I wasn't comparing different EQs, but different ratios of omnis to AT cards.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kindms on April 05, 2018, 06:42:55 PM
One thing To add on a tangent- I like to listen to the two channel "rough mix" 3 different ways before I decide if/how to EQ- over computer monitors using both Audacity and foobar2000, headphones, and in my car. So silly, but my car audio system is the most revealing of the three.
I try to do that as well.  My primary headphones (Beyer DT880 600 ohm) are on the bright side, so if I rely just on them the end result can sound dull on any other system.  So, in this case, I made some rough mixes and compared them through my main rig (Monitor Audio Silver 10s, Simaudio Moon 240i).  In this case I wasn't comparing different EQs, but different ratios of omnis to AT cards.

thats pretty much what i do. I fly by the seat of my pants if and i mean IF i do any EQ. I just go with what sounds right to me vs. any real concept or philosophy. You can tweak all day every day. I figure go with my gut and get it done.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on April 05, 2018, 07:32:22 PM
I fly by the seat of my pants if and i mean IF i do any EQ. I just go with what sounds right to me vs. any real concept or philosophy. You can tweak all day every day. I figure go with my gut and get it done.

I do that then rationalize it and make long posts justifying to myself here.  ;)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on May 15, 2018, 10:59:48 PM
Nothing really groundbreaking here compared to other setups in this thread, but I think this effort came out okay. 

Here's a link to the setup: http://taperssection.com/index.php?topic=151303.msg2264778#msg2264778

Here's a link to the recording: http://taperssection.com/index.php?topic=186458.0

As always, input is very much appreciated.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on May 17, 2018, 05:55:13 AM
Thank you for recording and photos. It is sounding very good, I like it a lot. Please, do you have recordings from others to compare (single pair mics)?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on May 17, 2018, 08:34:53 AM
Thank you for recording and photos. It is sounding very good, I like it a lot. Please, do you have recordings from others to compare (single pair mics)?
If you mean others from the same show, there's this: https://archive.org/details/GarajMahal2018-05-11
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on May 17, 2018, 09:17:22 AM
Thanks heathen, sounds good.  Interesting to compare the two recordings partly because they aren't a straight comp, made from quite different perspectives, one from out in the audience the other on stage, and also represent a quite different level of investment cost. The portrayal of the audience and room sound is quite different.  I don't have time to download and play with them today, but if I did it would be interesting to see how close I could get the two in terms of frequency response after some EQ adjustment.  That wouldn't effect differences in perspective, spatial balance, and mix balance, but is a good way to really understand the essence of the differences other than the spectral differences which strongly dominate any initial listening impression. 

Title: Re: Oddball microphone technique (OMT) - part 2
Post by: dactylus on May 17, 2018, 09:45:24 AM

^^
Thanks for sharing the links heathen!

I found the comparison of onstage DPA 4006a omnis vs onstage DPA 4015c wide-cards interesting too.  One recording was made on 5/10 and the other on 5/11.  Same band, same taper.  I was very surprised at how much more I liked the omni recording vs  the subcards.  It is a shame that for what we do the omnis often have to take the backseat to the directional mics to avoid all of the "extraneous noise" surrounding the performance.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on May 17, 2018, 12:00:08 PM
I found the comparison of onstage DPA 4006a omnis vs onstage DPA 4015c wide-cards interesting too.  One recording was made on 5/10 and the other on 5/11.  Same band, same taper.  I was very surprised at how much more I liked the omni recording vs  the subcards.

Can you describe what it is you like so much more about the omni recording?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on May 17, 2018, 12:35:25 PM
^ Thanks for pointing me to these recordings.  I don't have a strong preference for either of these two.  Both are nice - I find myself liking some things about one more than the other and vice-versa.  In general, I like the spatial depth, overall smoothness and solid bottom of the omnis, and like the more distinct imaging and up-front presentation of the subcards.  I say this from comparing the same numbers played both nights.  If forced to choose a favorite, I'd probably give the nod to the subcards.

It's exactly this kind of "wanting the best of both" that makes multi-microphone combinations like OMT attractive to me (among other reasons).  Sure, really good 2 channel stereo recordings can have a clean minimalist purity and beauty to them which cannot be matched via mic combination techniques, but will always be more of "take what you get, like it or not" kind of thing.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on May 17, 2018, 01:01:01 PM
FWIW I'm pretty sure Scott ran both omnis and subcards on 5/11.  I definitely remember seeing two pairs of mics on the stand.  I have no idea how to get in touch with him (met him for the first time that night), but maybe someone who does could cajole him into posting his other 5/11 recording for you guys...?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on May 18, 2018, 01:35:55 PM
Nothing really groundbreaking here compared to other setups in this thread, but I think this effort came out okay. 

Here's a link to the setup: http://taperssection.com/index.php?topic=151303.msg2264778#msg2264778

Here's a link to the recording: http://taperssection.com/index.php?topic=186458.0

As always, input is very much appreciated.
I listened to most of the LMA 5-11 recording this morning at work over cheap PC speakers. I liked the openness of tone and the balance of instruments seemed more distinct than I typically get out of these Logitechs.
Great job both recording and Post.
Thanks for sharing
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on May 18, 2018, 02:04:43 PM
Thanks, that means a lot to me.

To be honest, if I hadn't gone with XY on the center pair I might have scrapped the omnis entirely because of how much crowd noise the omnis picked up.  The XY pair on their own, though, was just too narrow of an image for my taste so I kept the omnis in the mix. 
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on May 18, 2018, 03:03:52 PM
The XY pair on their own, though, was just too narrow of an image for my taste so I kept the omnis in the mix.

That's a good indication that you are doing OMT right!  Sort of like the inherent balance of a three leg stool.

I didn't listen to the entire recordings, but of what I did I prefered the portrayal of the audience reaction in yours.  More open, natural, less muffled, more spatially correct to my ear.  That's not necessarily with respect to the level balance of the audience, but at least for what I listened to the balance was in no way unacceptable.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on May 18, 2018, 05:56:28 PM
The XY pair on their own, though, was just too narrow of an image for my taste so I kept the omnis in the mix.

That's a good indication that you are doing OMT right!  Sort of like the inherent balance of a three leg stool.

I didn't listen to the entire recordings, but of what I did I preferred the portrayal of the audience reaction in yours.  More open, natural, less muffled, more spatially correct to my ear.  That's not necessarily with respect to the level balance of the audience, but at least for what I listened to the balance was in no way unacceptable.
I keep marking this thread unread all day today as I wish to comment on that sentence heathen, but am moving so fast today- so briefly- the OMT mix uses the decorrelation aspect of the theory which makes the stereo illusion seem more natural. the psychoacoustic result, to my ears, is random audience noises such as talking or beer bottle drops are de-emphasized in an OMT mix when compared to the straight omni or straight center pair (all other things relative of course).
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: dactylus on May 19, 2018, 09:20:58 AM
I found the comparison of onstage DPA 4006a omnis vs onstage DPA 4015c wide-cards interesting too.  One recording was made on 5/10 and the other on 5/11.  Same band, same taper.  I was very surprised at how much more I liked the omni recording vs  the subcards.

Can you describe what it is you like so much more about the omni recording?

^ I enjoyed both of the recordings but I was sucked into the omni recording by the same strengths of this particular omni pull that you mentioned earlier.  The depth and fullness of the low end really grabbed me and I enjoyed the overall immersive feeling that the omni recording gave me.  The subcards were very powerful in their own right, crisp, clear and in your face, but in this case I enjoyed the total omni effect!




Title: Re: Oddball microphone technique (OMT) - part 2
Post by: scottsch3 on May 19, 2018, 05:37:39 PM
FWIW I'm pretty sure Scott ran both omnis and subcards on 5/11.  I definitely remember seeing two pairs of mics on the stand.  I have no idea how to get in touch with him (met him for the first time that night), but maybe someone who does could cajole him into posting his other 5/11 recording for you guys...?

https://archive.org/details/gm2018-05-11.dpa4015c.flac16

Here is the 4015 source if it helps to keep the conversation moving along. It’s not going to be an accurate comp since I used the Portico in front of the 788 but the relative soundstage of the recording shouldn't be affected.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: dactylus on May 20, 2018, 09:31:30 AM
^Thanks Scott.  Did you enable the "silk" option on the 5012 for the 4015 source linked to above??
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: goodcooker on May 21, 2018, 12:56:56 PM
^Thanks Scott.  Did you enable the "silk" option on the 5012 for the 4015 source linked to above??

mmmmmnh, Silk.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: djphrayz on June 26, 2018, 02:54:46 PM
From previous thread https://taperssection.com/index.php?topic=96009.msg2250985#msg2250985 (https://taperssection.com/index.php?topic=96009.msg2250985#msg2250985)


Quote from: Gutbucket
Here are a few tricks to maximize the spacing you can get with whatever bar you are using-
Point the omnis sideways, each facing away from the other.  You can probably gain a few inches additional spacing at minimum by using the length of the mic bodies and their position in the mounts to extend the capsules a bit further out to either side.

Would this omni configuration still be accurately documented as A-B?  Or is there another name for this configuration with the capsule ends pointed 180 degrees from one another?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on June 26, 2018, 03:48:17 PM
Yes. "A-B" describes the omni pair, regardless of the angular orientation of the microphones.  The direction they point is more of a detail.  Pointing them outwards can help get a bit more spacing than you could otherwise, as well as increase the highest frequency stereo difference a bit if the omnis are somewhat directional.  Pointing them upwards instead of forward can act as tone control and reduce the high-frequency pickup of the main sound a bit.  Pointing them backwards maximizes the ambient and audience high frequency cues rather than those of the main sound, and maximally differentiates pickup in comparison to the forward facing center mic(s).

Play around with different orientations to see what works best in the mix with your center mic(s).  This is probably where different mics behave differently enough that a taper may have different preferences for what direction the omnis are pointed based upon personal preference and the gear used.  It can be somewhat subtle.  With really tiny omnis the effect of angular orientation will be insignificant, unless some kind of attachment is used to intentionally make them not tiny.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on July 16, 2018, 01:48:31 PM
I've been thinking a bit about using a baffle with omnis in situations where really wide spacing isn't feasible.  One of the approaches I've been thinking about (and to be clear, I'm not claiming this is an original idea), is two small-ish circular baffles with some space between them and with the omnis mounted either flush or nearly flush with the surface of each baffle.  The general idea being something like this, but without the incorporated electronics and fake ears: https://3diosound.com/products/free-space-binaural-microphone

Right now my idea is a couple of these ( https://www.ikea.com/us/en/catalog/products/87077700/ ) with a dowel or some tubing between them.  The dowel/tubing could then be held in a Rycote INV-style shock mount.

So my first question is whether the cork of those hot pads would be sufficient to block sound and make an effective baffle?  If not, what could I do to make them better (or, what could fill that role better)?  Also, any ideas about attaching the baffles to the central connector, particularly in a way that they can be taken apart for easier storage in a bag?

Edit: Another idea for the baffles, which would be much smaller and thus easier to transport, is some wooden coasters.  Again, one on each end of the connecting dowel or tube of some sort.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: goodcooker on July 16, 2018, 02:59:41 PM
I've been thinking a bit about using a baffle with omnis in situations where really wide spacing isn't feasible.  One of the approaches I've been thinking about (and to be clear, I'm not claiming this is an original idea), is two small-ish circular baffles with some space between them and with the omnis mounted either flush or nearly flush with the surface of each baffle.  The general idea being something like this, but without the incorporated electronics and fake ears: https://3diosound.com/products/free-space-binaural-microphone

Right now my idea is a couple of these ( https://www.ikea.com/us/en/catalog/products/87077700/ ) with a dowel or some tubing between them.  The dowel/tubing could then be held in a Rycote INV-style shock mount.

So my first question is whether the cork of those hot pads would be sufficient to block sound and make an effective baffle?  If not, what could I do to make them better (or, what could fill that role better)?  Also, any ideas about attaching the baffles to the central connector, particularly in a way that they can be taken apart for easier storage in a bag?

Edit: Another idea for the baffles, which would be much smaller and thus easier to transport, is some wooden coasters.  Again, one on each end of the connecting dowel or tube of some sort.

I did something very similar to this for recording drum overheads with a pair of small omnis. I used two 45rpm singles with some camping pad foam glued to them threaded onto a piece of PVC. I tried a couple different ways but ended up using them spread about 5 inches apart with the mics around 1 inch from the barriers on the outside pointed slightly outward. I was looking to achieve a Jecklin disc type thing and it worked fairly well. I ended up using it on a lot of the percussion for the recording - there was a lot of percussion and once we got the drums to have that good stereo spread we found that miking the congas, bongos and other stuff the same way made the mix sit nice without too much panning.

I would suggest adding some foam or hairy fabric to the side of the disc to minimize reflections. If you use a single disc like a Jecklin it should be around 12" (people have done smaller with good results). If you use two discs and separate them they should get smaller the farther away they are.

The stereo separation happens largely in the high frequencies since the lower (longer) waveforms can get around the baffle.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on July 16, 2018, 03:09:41 PM
I've been thinking a bit about using a baffle with omnis in situations where really wide spacing isn't feasible.  One of the approaches I've been thinking about (and to be clear, I'm not claiming this is an original idea), is two small-ish circular baffles with some space between them and with the omnis mounted either flush or nearly flush with the surface of each baffle.  The general idea being something like this, but without the incorporated electronics and fake ears: https://3diosound.com/products/free-space-binaural-microphone

Right now my idea is a couple of these ( https://www.ikea.com/us/en/catalog/products/87077700/ ) with a dowel or some tubing between them.  The dowel/tubing could then be held in a Rycote INV-style shock mount.

So my first question is whether the cork of those hot pads would be sufficient to block sound and make an effective baffle?  If not, what could I do to make them better (or, what could fill that role better)?  Also, any ideas about attaching the baffles to the central connector, particularly in a way that they can be taken apart for easier storage in a bag?

Edit: Another idea for the baffles, which would be much smaller and thus easier to transport, is some wooden coasters.  Again, one on each end of the connecting dowel or tube of some sort.
I like the general idea. From a pure acoustics pov I would think the ikea 7" hot pads are as small as you would want to go. Don't forget all you are influencing at 7" or less (or any baffle small enough to hold in one hand) is high frequencies and going any smaller (less than 5" IMO) would not be worth it (i.e. your coaster idea)
Although, I've read maybe on TS where folks have used coasters on a tabletop as a sort of stereo separator.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on July 16, 2018, 03:18:48 PM
Do you think the cork would be fine on its own, or should I layer some other material with it?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on July 16, 2018, 05:31:54 PM
We've talked about split-baffle ideas variations and in the past, both in the Oddball Mic Technique part 1 tread and in various Jecklin-disk threads.  I can't recall where specifically so you'd have to search them out.  The discussion in the OMT part 1 thread is probably somewhere close to the beginning, as I was messing around with Jecklin disks back in 2007 or so and strongly considered the idea of split small disks (I considered using clear CDR dummy discs) before going with the DIY spherical attachments instead.
 
I'll summarize a few issues which come to mind-

> Size of the baffle (and microphone distance from the baffle) determines the low frequency cut-off above which the baffle becomes effective.  Smaller = higher cut-off frequency.

> If mounting the mics right up against the baffle or flush-mounted in the baffle surface, it can be advantageous to use a hard, sonically-reflective baffle instead of a damped sonically-absorbent surface.  That creates a small boundary mount situation above the cutoff frequency.  That makes it unnecessary to try and evenly-damp the surface with respect to frequency, making the setup simpler and lighter-weight.  Mounting the mic on the baffle surface also maximizes the geometric "occlusion angle" - that is, how much the mic "sees" around the edge of the baffle, making a small baffle somewhat more geometrically effective above the cutoff frequency (the baffle "appears bigger" from the microphone's perspective, compared to spacing the mic away from the baffle, where it can "see further around the edges").

> If not mounting the mic directly to the baffle, use felt, foam, wool or a combination of materials to damp the reflection off the baffle.  To check effectiveness of the materials, hold the material against the baffle and place it close to your ear at an angle similar to cupping your hand to hear.  Play some music on the stereo and get up close to one of the tweeters.  Orient yourself so that the baffle is angled like a mirror reflecting the tweeter output into one ear.  Play with the baffle angle and listen for significant change in timbre of the reflected sound.  If it sounds brighter with the baffle reflecting the sound directly in, and less bright at other non-aligned angles, the damping material stands to be improved.

Raw cork will be quite reflective at these higher frequencies. It can work as a support disk, but think felt, wool blanket, or a couple layers of stuff like that glued to the cork disk.  Fur as used for wind protection isn't particularly good except maybe as a top cover layer, as the intent of wind protection fur is to not attenuate the high frequencies as much as practical.  You wan't the exact opposite for this- maximal attenuation within the frequency range in which the baffle is effective.

> Figure a way of adjusting the angle of the baffles on the bar, so you can play around with pointing them more forward rather than always facing directly to each side.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: mjwin on July 16, 2018, 06:08:47 PM
I've been thinking a bit about using a baffle with omnis in situations where really wide spacing isn't feasible.  One of the approaches I've been thinking about (and to be clear, I'm not claiming this is an original idea), is two small-ish circular baffles with some space between them and with the omnis mounted either flush or nearly flush with the surface of each baffle.
Some years back I made up a similar arrangement to that which you're suggesting.  To get close to head-spacing, I used 2 omni mics strapped together side to side but facing opposite directions, each with a right-angle xlr connector. Each mic protruded just far enough beyond its partner's rear XLR  connector to enable me to slip on a small baffle so that the mic diaphragm was flush with the surface.   In my case I wanted the whole thing to slide inside (an original) Rode blimp, so  the baffles were only 120mm diameter, and the holes offset in order for it all to align correctly.  I cut each baffle from rigid foam-core (art mount) board then glued a layer of softer foam to the outer surfaces.

The arrangement worked quite well for & wide ambiance & birdsong in the woods.  It also gave a much more realistic image with headphones than with speakers, which is what you tend to get with this kind of binaural arrangement.  The biggest problem for me was that the mics were too high-frequency directional left-right, so I couldn't actually point the array at anything!  I was using AT 3032 omni mics which are fairly typical for pencil omnis in being already quite directional above a couple of kHz. With the baffles in place I really did feel that there was a hole in the middle. 

It's interesting to experiment with baffle materials, though.  If you use a hard surface such as cork, you'll get more of a boundary effect at high frequencies, which will boost the top end up to 6dB or so. The larger the baffle/boundary, the lower will be the frequency at which this effect cuts in. Soft foam or felt will tend to act simply as a shield.  I think you'll need to make the discs out of something fairly rigid which can be slipped on/off at ease (wooden coasters sound ok),  then you can try different surface coatings, or even different materials each side so that you can swap around.  It doesn't seem to make much difference what, if anything, is between the baffles (as in that slightly wacky fake-ear contraption you linked to!)
 
I use the Rycote INV-7 shockmounts which are quite rigid, and one of these will easily hold your pair of mics in a fairly compact arrangement, then the baffles of choice can be slipped into place when you set up.  Thinking out aloud here, once you have the mics mounted you could also drop over a  single large (12") foam covered central baffle with a slit in it to get an approximation of a Jecklin disk. This will give a bit less shadowing to the front / rear, so might be better for capturing a performance of some sort.  But then, if you want a small rig, it might not be ideal.

There are a lot of subtle variations possible with this kind of arrangement and few hard & fast rules.  I always say:  if it sounds good, it is good:)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on July 17, 2018, 09:58:01 AM
Welcome to the thread mjwin.  Seems you'll be right at home here with these often DIY focused approaches.

The biggest problem for me was that the mics were too high-frequency directional left-right, so I couldn't actually point the array at anything!  I was using AT 3032 omni mics which are fairly typical for pencil omnis in being already quite directional above a couple of kHz. With the baffles in place I really did feel that there was a hole in the middle.
^
If using these split-baffled A-B omnis as part of a 3 or more channel OMT array, "hole-in-the-middle-ness" becomes a feature rather than a bug, and is filled by the forward-facing directional center microphone without excessive interference, but with just the right amount of overlap or with the omni pair.   And this is partly why I recommend figuring a way of adjusting the angle of the baffles as a way to experiment with facing them somewhat forward, say +/- 45 degrees rather than directly to the sides, which is likely to be more important if using the split-baffled omni pair on their own without a forward-facing mic or mic array in the center.

In my 6 channel setup, where I'm using sideways and forward-facing near-spaced supercards as the primary Left/Center/Right array for mid and high frequencies, I'd choose to angle the baffles backwards rather than forwards in many situations, to more strongly differentiate the diffuse ambience/audience reaction picked up by the baffled omnis from the front direct-arriving sound dominant in the L/C/R array.  The front direct-arriving and ambient diffuse-arriving lower frequencies which the omnis provide below the rolloff of the directional supercardioids are of a long enough wavelength that they will not be affected by the orientation of the baffles.  The only parameter which strongly affects the quality of the low frequency pickup is the actual spacing distance between the omnis, regardless of baffles or attachments.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on August 01, 2018, 01:16:43 PM
Transfering a few posts to follow from another thread as they are OT there and really belong in this one instead.
 
These are near-spaced stereo setups which allow for varying pickup-pattern and in the second case the angle between microphones in combination with pickup-pattern, after the recording has been made.  Both require one to choose the desired spacing between microphones prior to recording, which is not adjustable afterwards.

They are indeed oddball in how they are set up, what they can do and the flexibility they can provide, yet are essentially standard near-spaced stereo pair arrangements otherwise.

Original thread is here- Unusual Schoeps MK8 (eBay Germany) (https://taperssection.com/index.php?topic=187213.msg2271527#msg2271527)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on August 01, 2018, 01:26:02 PM
Near-spaced Straus-packet pair-

Here's a suggestion for a practical implementation for tapers who like using standard near-spaced stereo pair arrangements, which provides the capability to go back after the recording has been made and vary the pickup patterns of the microphones.

One needs two pairs of microphones with different pickup patterns and the ability to record all four channels. For maximum pattern flexibility use pair of omnis and a pair figure-8s.  Don't have omnis and eights?  This works for varying pattern seamlessly between whatever pairs of decently-matched microphones one has available - say between subcardioid and supercardioid, or between omni and supercardioid, providing the option of choosing any pattern in between the two afterward.   The setup will be cleaner and more easily managed if using all end-address microphones, or all side-address microphones.

Arrange the mics in two pairs such that in each pair the two different-pattern microphones form a coincident pair, with one directly above the other and both facing the same direction.   Do the same on both sides of your favorite near-spaced stereo pair arrangement.  Use standard over/under-style Mid/Side mounts and windscreens (with each omni/supercard pair in this example facing the same direction).  Record all four channels.  Afterwards, cross-fade between the omnis and supercards to derive whatever pattern you wish between the two. 

Can use a standard Mid/Side decoder to do the cross fading if you like, by feeding the omni into the Mid input and supercard into the Side input, and using only the Left channel output.  100% Mid = omni, 100% Side = supercard, 50/50 ratio = subcardioid, choose any pattern you wish in between.  Do that for both sides of the near-spaced stereo pair. 

Otherwise just mix the two to find what combination works best, and don't worry about what patterns you actually end up with

 

If needing even more control, one can use this method to choose slightly different patterns for Left and Right, and/or apply differential EQ to vary pickup pattern by frequency and do so independently for each side.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on August 01, 2018, 01:31:08 PM
Two Mid/Side pairs as near-spaced stereo array providing variable pattern/microphone-angle-

This is a very interesting setup possibility for a near-spaced stereo pair.  The more I think about it, the more I like it.  Near-spacing distance between microphones remains constant, yet this allows one to vary both pickup-pattern and microphone angle.  Choice of pattern and angle is linked, just as with standard Mid/Side.  First thought and most straightforward would be to set this up with both Mid/Side pairs parallel to each other and pointing directly forward.  However, pointing the two Mid/Side pairs such that they face directly to either side instead of forward offers a far more useful range of pattern/angle combinations. In which case, adjustment of the Mid/Side ratios allows one to vary pattern/angle between forward-facing parallel figure-8's (Sometimes described as a Faulkner phased array) through cardioids with a 180 degree angle between them.  At Mid/Side ratios in between those extremes one will derive supercardioids with an angle somewhat wider than 90 degrees and hypercardioids at a somewhat narrower angle.  Pattern and angle can be varied seamlessly across this spectrum after the recording has been made, with the decision of what sounds best made by ear.


Setup for two near-spaced M/S pairs-

Use two Mid/Side pairs with cardioid Mids.  Space the two pairs 17cm apart (or 20, 25, 30cm or whatever near-spacing you want), and angle them such that the Cardioid Mids are facing directly to the sides (180 degrees away from each other). Both Side microphones should have their positive polarity lobe facing forward, so flip the Side figure-8 of the Left pair so that it's positive polarity lobe is facing forward instead of rearward. 

Record both raw M/S stereo pairs (4 channels total).  Let's call the Left-side M/S pair- pair 1, and the Right M/S pair- pair 2.
After recording, you run both raw Mid/Side pairs through Mid/SIde to Left/Right decoders.  The Left output of Pair 1 is routed to Stereo Left.  The Left output of Pair 2 is routed to Stereo Right. Set the ratio to determine the pattern and angle (both remaining linked, as it always does with standard Mid/Side) from forward-facing figure-8 through sideways facing cardioid.  Typically one would use the same ratio for both Mid/Side pairs, but one could use different ratios on each side to choose different patterns and angles for Left versus Right.

Cool multichannel surround / ambience channels option-

The Right channel outputs from both Mid/Side decoders provide rear-facing virtual microphones with a pattern and angle that mirrors the forward-facing microphones on either side.  If you understand how to dial in a different Mid/Side ratio for Left versus Right in a typical stereo Mid/Side setup, you'll see how you are able to choose a different combination of pattern and angle for the rear-facing ambience channels.


A few thoughts-

While going through this, after realizing that it makes more sense to point the Mid/Side pairs sideways instead of forward and makign the drawings, I realized that there is nothing new under the sun.  Kudos to Jerry Bruck and Schoepes for basically pioneering this approach already with their KFM 360. This is basically the KFM 360 arrangement except substituting cardioids for the flush-mounted sphere baffled omnis.

Over a decade back, I schemed about of ways of emulating the KFM360 as a lower-cost, headworn HTRF setup.  I ended up going with an alternate 4-channel setup which did not use Mid/Side pairs. Still these ideas have been been in the back of my mind since then, and this seems a setup that seems far more practical actual real taper use.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: EmRR on August 01, 2018, 05:02:29 PM
I applaud the use of MS with spaced pairs.   Seems like best of both worlds. 

I've been playing a bit with DMS to change the M pattern.  I suppose you could do a pseudo-spaced variant with the use of delays on both the DM signals and duplicated S signals.  Clearly not the same, but may have possibilities for front to back depth perception, and once enough delay is introduced polarity flips on the duplicated S might get useful.  You could make a huge mess too.  So far I've only tried delaying one of the M elements to good effect. 

Down that tangent, a good head stretching exercise, it was pointed out that a mic like the Sennheiser MKH800 Twin or Lewitt LCT-640-TS can be used as a stereo mic, and the pattern is really the 'same-as' MS with an omni M.  To check it out, I duplicated the source, converted one to omni and the other to figure 8, then ran those through MS processing.  I really couldn't detect an obvious difference comparing direct result with matrixed result.  Anyway, a nice head game to make you think about possibilities and realities.  I expect doing 'proper' MS with omni M would have a very different sonic tilt due to the differences in proper pressure omni versus constructed pressure gradient omni, along with the high frequency directivity differences between the two approaches (90º difference in this example). 


Carry on....
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on August 01, 2018, 06:39:17 PM
Yeah, Mid/Side stuff is fun to think through.

The next logical step with the near-spaced Mid/Side pair setup described above would be to replace the two standard Mid/Side pairs with Double-Mid/Side setups.  One could then adjust the pickup pattern and microphone angle independently. And because of that, one could set it up with both Double-Mid/Side setups pointing directly forward.  Cool thing is that would only require 6 recording channels in total to make that work.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on August 01, 2018, 06:39:52 PM
I really couldn't detect an obvious difference comparing direct result with matrixed result.

I've noticed playing around with Ambisonics (basically the same as Double-M/S in the horizontal plane) that it can be very difficult to discern changes of pattern when listened to in isolation (mono), especially with recordings made out in the diffuse field at a significant distance from the source, except for listening for low-frequency response differences (omni providing the most low bass, figure-8 the least).  It's really only when two or more channels interact with each other (electronically or in air) that the differences come to the perceptual fore.  For instance, except for the low bass response, an omni and a figure-8, both placed out in a diffuse environment sound about the same, while a pair of coincident omnis verses a pair of coincident crossed fig-8's sound obviously and completely different when listened to in stereo.

Yesterday when thinking about and writing up my posts on PolarFlex in the other thread, I found a sample player embedded at the bottom of the Schoeps PolarFlex plugin web page.  It allows one to listen to two different recordings using a stereo pair of PolarFlex'd microphones.  One is a main microphone pair (diffuse field) and the other a pair of stereo piano spots (much closer).  For each source, one can choose between listening to the stereo omnis in isolation, the stereo figure-8s in isolation, and between two different PolarFlex combinations of those mics.  The two combinations are polar opposites (pun) in terms of their polar response's varying by frequency. One is omni directional at low frequencies morphing to bi-directional at high-frequencies, and the other more or less the inverse.

What is interesting is using the sample player to listen for what I describe above.  Start by putting only one headphone ear cup on (or otherwise selecting only the Left or Right channel to monitor).  With the more distantly mic'd main-pair sample, switching between the solo-pre omni and solo-pre fig-8 sounds more-or-less identical.  Yet when listened to in stereo the difference is easily discernible.   Likewise with the two PolarFlex settings- listening the a single channel they sound more or less the same except for a somewhat larger frequency balance difference than the omni and fig-8 solo'd.  Yet when listened to in stereo the difference is immediately obvious.

With the stereo piano spots recording the differences between the solo-pre omni and fig-8 are greater due to the closer "free-field" mic positioning, yet the same basic trend holds- the differences are far more discernable in stereo than as a mono feed of either channel.

Link to the page- https://schoeps.de/en/products/spezialmikrofone/polarflex/polarflex-plug-in.html
Sample player in at the very bottom on the right side of the page.


[Edit]- I also notice the same with the my OMT setups. On more distant diffuse-field recordings, the individual channels often sound almost identical to each other when listened to in isolation, other than the basic frequency response differences of the microphones themselves.  It's only upon combination that various spatial qualities and properties emerge.  That aspect is rather analogous to holography in this way (holophony?).  Where as for small room and closer-perspective recordings, I'm more often able to easily hear the differences between channels in isolation.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rigpimp on August 02, 2018, 11:32:02 AM
OK, I'm on board the oddball train.  I've run fixed ORTF and MS for a while now and I really enjoy MS for being able to dial it in different directions in post.  I now want to goof around with the Schoeps Polarflex plugin.  While I do not have MK2's I do have matched pair of MK5's and with a matched pair of MK8's so it seems silly not to try something weird. 

With that said I have reached out to Scott at SRS so see if he can make the mounts.  I have sent him gutbucket's sketch and the Schoeps brochure showing the Polarflex mount.  I'll report back with any progress as it has been made.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on August 02, 2018, 11:55:21 AM
Cool. Will be interested to hear how it works out.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: noahbickart on August 02, 2018, 01:02:21 PM
This is all very intriguing. With 2x MK4v + mk8 I can do double m/s and still have from on the mixpre6 for a
Pair of spaced mk2xs omnis. Hmmmm.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on August 02, 2018, 03:29:43 PM
Had you in the back of my mind thinking about this Noah, as I know you have both the mics and the predilection to pull it off.

You probably want to keep your wide-cardioid MK22s in your standard reference setup, but it may be useful to try them as Mids in place of the cardioid MK4Vs.  Doing so would shift the virtual cardioid pattern of the Mid/Side adjustment range somewhat forward rather than pointing directly to either side, and open up the other virtual patterns slightly for the same virtual angle.  It's likely that using the MK22s as Mids you'll just want a bit more spacing between pairs, same as with standard near-spaced setups using various pickup patterns.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on August 02, 2018, 04:26:32 PM
Thanks a lot for interesting posts, I will read it more times. And thanks for nice sketch which makes it clear.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on August 02, 2018, 06:01:55 PM
To add: kindms and I have done single M/S inside of split omnis (100cm). It can be very yummy and also provides you with a solo 2 channel mix if you just want a "backup" in case you don't prefer the spaced omni contribution. I wholeheartedly endorse this double MS configuration. We don't have the proper combination of mics to do this however. lol
We have the 414's and any number of cardiods though to do a rough version.

rigpimp and noah I really think that each of your combos of Schoeps would result in a great recording.
Thanks GB
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: EmRR on August 02, 2018, 10:49:48 PM
it can be very difficult to discern changes of pattern when listened to in isolation (mono), especially with recordings made out in the diffuse field at a significant distance from the source, except for listening for low-frequency response differences (omni providing the most low bass, figure-8 the least).  It's really only when two or more channels interact with each other (electronically or in air) that the differences come to the perceptual fore.

Very true. 

I neglected to say the sample I experimented with was a stereo drum kit recording at about 6 feet out, so very definite spread in the free field. 
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on August 03, 2018, 11:45:48 AM
I've thought about incorporating these kinds of sideways-facing Mid/Side pair arrangements in multichannel OMT setups.  Several are mentioned in the latter pages of the OMT illustrated PDF booklet I uploaded near the end of the OMT part 1 thread last year.  What is different in the recent posts above is simply applying the same concept to more typical near-spaced stereo pair setups.

Attached is a PDF showing a few OMT variants using sideways-facing Mid/Side pairs-
The first is a 6-channel setup consisting of 3 Mid/Side pairs:  It starts with a standard Mid/Side forward-facing pair in the center between two wide spaced omnis - the setup rocksuitcase just posted about above.  It takes that and adds front/back facing fig-8s coincident with the wide-spaced omnis, turning them into Mid/Side pairs with control over front/back directivity.  That provides full-range pattern control (omni>subcard>cardioid>supercardioid>figure-8) over the wide-spaced omnis with the ability to choose if those virtual patterns face forward or backward.

The second two are 8-channel OMT setups which I hope to experiment with next, both variations on the 6-channel arrangement I'm currently using, with the near-spaced front/back OCT setup (Double-OCT?) in the center rather than a Mid/Side pair in the center.   

In the first of these I plan to place figure-8s with the omnis to form front/back Mid/Side pairs just like the 6-channel version above, but using the OCT arrangement in the center.  I suspect this will be advantageous in good acoustics and outdoors, by providing the ability to reduce the sensitivity of the wide omnis to direct sound arriving from the front, providing the ability to use more ambience, audience and room-sound from the wide omnis without getting excessive direct sound through those channels.

The second 8-channel variation places the two figure-8s coincident with the sideways facing Left/Right OCT supercardioids instead of the omnis, providing the ability to dial in forward angle for those channels which may prove helpful in smaller rooms and difficult acoustics.   This is very similar to the near-spaced Mid/Side pairs setup outlined above, except with the addition of the front/rear-facing center mics and wide omnis.

[Edited to update PDF with 3rd array, and update description above]
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on August 03, 2018, 12:18:59 PM
Sorry to veer off course a bit here, but I've been thinking about four channel setups like a pair of spread omnis with a pair of directional mics in the middle.  What I'm wondering about is the relationship between the SRA of each pair to the other.  So, using that Sengpiel Audio visualizer tool, if I have a pair of omnis 60 cm apart then that gives me a SRA of 118.1 degrees.  Assuming that's the right SRA for the specific location/circumstances, should the directional pair's SRA ideally be the same as that of the omni pair (assuming something like mid/side that can be adjusted in post isn't being used)?  If the SRAs are significantly different, won't the blend of mics result in a weird stereo image?

(I should add that the end goal here is stereo playback.  I imagine that surround/multi-channel playback as the end goal would have a different impact.)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on August 03, 2018, 12:23:59 PM


[Edited to update PDF with 3rd array, and update description above]
I grabbed it and added to the others. THANKS so much Lee!
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on August 03, 2018, 12:58:03 PM
Hey Kyle, I basically pulled a few setups out of the previous illustrated OMT booklet to make the PDF I just posted above.  I did simplify the images and change the wording a bit, but in essence the info there isn't really any different than what I'd already posted.   It mostly puts these setups using sideways-facing Mid/Side arrangements together and identifies that as a category. 

And as always, thanks for your interest and insights!
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on August 03, 2018, 02:23:32 PM
Sorry to veer off course a bit here, but I've been thinking about four channel setups like a pair of spread omnis with a pair of directional mics in the middle.  What I'm wondering about is the relationship between the SRA of each pair to the other.  So, using that Sengpiel Audio visualizer tool, if I have a pair of omnis 60 cm apart then that gives me a SRA of 118.1 degrees.  Assuming that's the right SRA for the specific location/circumstances, should the directional pair's SRA ideally be the same as that of the omni pair (assuming something like mid/side that can be adjusted in post isn't being used)?  If the SRAs are significantly different, won't the blend of mics result in a weird stereo image?

That's one way of approaching it, and partly informed my thought process along with other ideas when working up these setups initially.  But I now don't think it applies in any straightforward way.  And think the opposite is what actually works best-  very different SRAs from the omni and center pairs

The SRA curves are empirically derived from listeners with 2-channel recordings made using various combinations of microphone spacing and angle.  It's an attempt to derive objective conclusions from subjective psychoacoustics, addressing situations where only a single pair of microphones is used rather than more than one pair.  Even in Michael William's extension of this approach to multi-channel surround recording, each sector around the playback array is always covered by no more than a single microphone pair, the intent being to have each sector line up with the adjacent sectors on either side without a gap or excessive overlap. It specifically does not address content outside the SRA or "cross-talk" from the microphones of non-adjacent sectors, which is related to what you are asking about. 

OMT differs by relying on the overlap and intentionally managing it.  It pushes the omnis wider than one would probably want without the center mic or pair to intentionally tend toward a hole-in-the-middle which the center mic or pair then fills with partial overlap. Yes that omni spacing may or may not produce a seemingly appropriate SRA angle by charts, yet SRA imaging only weakly applies to non-uniformly distributed omni pair imaging (hence the middle-hole thing), and the center pair is typically dialed in such that it provides less overall width than one would want without combination with the omnis.

I think that explains the essence of what's going on, but stated another way from experience..

With wide-spaced omnis + a center Mid/Side pair, I always end up dialing in far less stereo width from the center pair than I would without the omnis.  Say I'd choose a 50/50 Mid/Side ratio as being best when just using center Mid/Side pair on its own.  When combining with the wide omnis I'm likely to dial that back to something like a 80/20 or 90/10 ratio of Mid/Side.  If the same SRA was desirable with the omni pair and center pair, there would be no reason dial back the center pair with a more Mid-heavy ratio when combined with the omnis.

If you go to the Sengpiel Audio visualizer and choose a 60cm omni spacing the SRA is 118 degrees.  Switching to X/Y supercards it takes a 107 degree angle between microphones to produce an equivalent 118 degree SRA.   That's a combination I'm quite likely to use for an X/Y pair on its own, but not one I'd be likely to decide is best in combination with the omnis.

By contrast, here is a combination I'd be likely to use- A pair of 1.5m spaced omnis (around the spacing I typically use for OMT) has an SRA of around 40 degrees total.  A pair of X/Y supercards with a narrow 20-degree angle between them produces a super-wide SRA of 220 degrees or so.   

Empirically I've found it works best when the SRAs of the omnis and center pair are sort of tending towards opposite opposite extremes rather than close to the same.  It's probably another case of achieving good differentiation between pairs so they do not "step on each others toes", rather than trying to achieve similar SRAs across both pairs. The imaging of the omnis positioning discernable sources widely near or outside the speaker locations, while the imaging from the X/Y pair positions discernable sources more narrowly across the center between the speakers.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on August 03, 2018, 02:40:48 PM
Thanks for the explanation.  I may be revising my plans for the show I'm going to tonight based on this information.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on August 04, 2018, 04:17:26 PM
Nothing terribly innovative here, but I'd like to share my reasoning for the setup (and find out how wrong my thinking may have been): http://taperssection.com/index.php?topic=187418.0

I've got DPA 4061s on a TV antenna, spread about five feet.  Nothing much to say about that, other than that it was heavily influenced by Gutbucket's recent comments about my SRA question.

Roughly in the middle I've got the pair of Audio-Technica AE5100s.  I've tried XY from this same location, between split omnis (for reference: https://archive.org/details/garajmahal2018-05-11.AT4031.CA14), so I wanted to try something different.  I've got a DIN/ORTF combo mount for the AT4031s that I can squeeze the AE5100s into, but I wanted to configure the AE5100s in a way that would maximize sound from the stage hitting the mics on axis.  Playing around with the Sengpiel visualizer, I ballparked that if I had the AE5100s AB about 20 cm apart, and at around a 75* angle between them, I could get an SRA that should nicely cover the stage from that distance.  My thinking was that this would give me a pretty solid center "image" to compliment the wide split of the omnis, without making the center too smooshed like XY might.  My goal was basically keeping a fairly wide soundstage once it's all mixed together.  The Rode bar I used allowed me to get the mic spacing pretty much dead on, but I had to eyeball the angle.

I haven't mixed it all together yet, but on an initial listen I think it sounds pretty good.  The DPAs will likely need some EQ to keep the bass from getting too flabby when both sources are combined, but even without EQ I'm happy with the sound.  One thing that's particularly gratifying is that both sources sound good on their own, but mixing them together is definitely an improvement.

To be clear, I'm not trying to say that I've done anything new here.  Nor am I trying to say that this was the ideal setup for this spot.  It will be interesting to compare the Garaj Mahal show with this one, though, mostly to compare the results in terms of soundstage.  As always, I appreciate any comments and criticisms (though I'm sure it will be much more helpful once I actually post the recording!).

Is there any interest in me posting a raw sample of each source so people can do their own mixing/EQ?  I'm happy to do so if anyone wants.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on August 06, 2018, 06:33:42 PM
Should be interesting comparing your recordings made with these two similar setups using the same microphones- the first with an relatively-wide angled X/Y directional center pair and the second with a near-spaced PAS directional center pair.  Are all other variables other than the band and date generally the same?  (Venue, recording location, omnis used and their spacing, etc?)


..I wanted to configure the AE5100s in a way that would maximize sound from the stage hitting the mics on axis

That is a very appropriate fundamental goal for the center pair IMO, and there are several ways of achieving it.  Each presents different implications-

Your method of playing around with the Sengpiel visualizer variables to find a near-spaced combination of pattern/angle/spacing that points the microphones directly at the PA, is one of them.  This is the essence behind the Improved PAS technique (https://taperssection.com/index.php?topic=167549.msg2087409#msg2087409) of which you are aware, which consists of a table indicating the most appropriate spacing between microphones based on the Point-At-Stacks angle between them, such that the resulting SRA angle equals the PAS angle.  The table simplifies the process by not requiring online access to the visualizer and not requiring playing with the variables to find the solution each time.   The Improved PAS technique and Sengpiel visualizer data upon which it is based assumes we want an SRA which is equal to the orchestra angle / PAS angle.  As I mentioned in my previous post above , that's almost always appropriate for a two channel stereo microphone arrangement, yet may or may not be optimal for a stereo main microphone arrangement built upon the combination of of more than two pairs..

Another is to run the center pair as a coincident X/Y arrangement, except using a narrower mic angle than you'd typically want if the X/Y stereo recording was intended to be used on its own.  In that case the X/Y angle is equal to the PAS angle and the microphones are pointed directly at each PA.  SRA will be much wider and discrete imaging across the center will be tight and more compact.  I'd suggest trying this arrangement for your next recording at this same venue, keeping the other variables unchanged.  You'll then have all three setups to compare against one another.

Wide-angled X/Y center pair (appropriate microphone angle and SRA for an X/Y pair alone) with mics not pointed directly at the PA.
Near-spaced PAS center pair (appropriate spacing/angle and SRA for a spaced-pair alone) with the mic pointed directly at the PA.
Narrow-angled X/Y center pair (less appropriate microphone angle and SRA for an X/Y pair alone, but likely good with the omnis) with the mic pointed directly at the PA.

At that point you can try something interesting while comparing the three recordings.  Besides comparing each as mixed in a straightforward fashion, try inserting a stereo-width adjustment tool in the signal path of the center pair.  You can then play with making the center pair contribution wider or narrower (all the way down to a monophonic center) while listening in combination with the wide omnis.  Although this kind of stereo-width adjustment is intended for coincident-pair arrangements such as Mid/Side and X/Y, it can also be applied to your near-spaced pair.  The range of adjustment before comb filtering problems become audible will be more limited with the near-spaced pair (listen for it by muting the omnis and dialing the width of the near-spaced pair all the way down to mono). 

We've discussed in the past how to do this using two back-to-back Mid/Side matricies (L/R>M/S>[ratio adjustment]>L/R) and how its easier to use a single instance of a stereo width adjustment in the DAW software (most typically accessed through the panning control for a stereo channel) or a Mid/Side based stereo-width plugin, both of which do the same thing.  I can explain that in more detail again if you like.  Here's good free VST plugin with this capability - https://www.voxengo.com/product/msed/ (https://www.voxengo.com/product/msed/)

A comparison made along with center width-adjustment will be illustrative in a couple ways- First, you are quite likely to find in an altered-width setting that works better than a straight mix of the two pairs, and this will be a good starting point setting for other recordings made using the same setup.  Second, you can better compare the different center mic-pair arrangements against each other after each has been tweaked to achieve its own optimal center width and blend with the omnis.  And third, you can mute the omnis to find how non-optimal that setting is for the center pair on its own without the omnis.

Quote
My thinking was that this would give me a pretty solid center "image" to compliment the wide split of the omnis, without making the center too smooshed like XY might.  My goal was basically keeping a fairly wide soundstage once it's all mixed together.

How smooshed or stretched is best is a large part of what you will be determining with this.  In my experience, it's much better to have the center pair contribution smooshed rather than stretched or even optimally-wide (for use on its own), since the omnis will be stretching out the center and usually don't need help in conveying additional width.  Consider the simplified setup of a single forward-facing center microphone between the two wide omnis, in which there is no stereo width provided by the center microphone at all.  It works, quite often far better than a pair of omnis alone, but can usually be improved by introducing some stereo width to the center.  The question is how much center width is most appropriate?  The answer IME is always "somewhere in between a single mono center microphone and an X/Y pair optimized for good stereo width on its own.  Mono is too narrow, optimized X/Y on its own, too wide.  The same applies to near-spaced center configs.

The bummer is not having either the omnis nor center pair fully optimized for use on their own, but that's the price to pay for achieving something superior than could be achieved without both pairs in combination.  That said, there is nothing wrong with preferring to optimize each pair on its own, which provides better redundancy should one pair fail, rather than pursuing the most optimized combination which relies on both working.

Quote
One thing that's particularly gratifying is that both sources sound good on their own, but mixing them together is definitely an improvement.


That's a good indication of being on the right track.  The trade-off I mention above is between how much of an improvement that represents, when weighed against further improvements that push each source towards not being as good on its own without the other. 

My current thinking on this is to always have a the directional center microphone or pair pointed directly at the source, to use a coincident center arrangement for that pair to minimize phase interaction problems, and to adjust the stereo width of the center contribution afterwards as appropriate.   It may seem contradictory that I'm using a near-spaced 3-microphone arrangement in the center of my 6-channel OMT setup, but the difference is that even though this 3-mic arrangement is near-spaced, it provides a direct source-pointed hard-center channel and is specifically designed to minimize phase interaction problems between the 3 channels.

Quote
Is there any interest in me posting a raw sample of each source so people can do their own mixing/EQ?  I'm happy to do so if anyone wants.

I'd like to play with samples of these two recordings (or three if you decide to try the suggested PAS X/Y variation as well) to help check my thinking on all this using someone else's recordings other than my own.  It makes for a nice opportunity when the there is only one significant variable which changes between recordings (other than the band).
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on August 06, 2018, 08:08:20 PM
Should be interesting comparing your recordings made with these two similar setups using the same microphones- the first with an relatively-wide angled X/Y directional center pair and the second with a near-spaced PAS directional center pair.  Are all other variables other than the band and date generally the same?  (Venue, recording location, omnis used and their spacing, etc?)

The venue and recording location are the same, but the mics are different.  The Garaj Mahal show was the XY AT4031s with split CA14 omnis, whereas this Breakfast show was AB AT AE5100s with split DPA 4061s.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on August 06, 2018, 09:21:55 PM
Quote
Is there any interest in me posting a raw sample of each source so people can do their own mixing/EQ?  I'm happy to do so if anyone wants.

I'd like to play with samples of these two recordings (or three if you decide to try the suggested PAS X/Y variation as well) to help check my thinking on all this using someone else's recordings other than my own.  It makes for a nice opportunity when the there is only one significant variable which changes between recordings (other than the band).

You've given me a lot to think about, as usual.  In the meantime, here's a link to download a sample of the raw sources on their own (link good for seven days): https://we.tl/89Rd74EsX5

I'll confess that part of my desire to make sure each source sounds good on its own is to continue my evaluation of the AE5100 because there aren't a lot of tapers out there using it.  I may even post the AE5100 source separate from the final four-mic mix.  I think this was only my second outing with the AE5100s, and so far I continue to think they have a lot of promise.

I would love to hear what anyone does with the samples!
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on August 07, 2018, 10:03:21 AM
Thanks, I may have some time in the evenings this week before I head out of town.

I'll also say that my listening preference has shifted somewhat over the years, which is inevitably influencing my comments above.  I've always loved detail, clarity, stereo width and immersion.  These days I find I also really value a strong, solid, well-anchored center as a vital foundational element that conveys realism and naturalness.  Sort of the kernel from which everything extends and emerges except for ambience and audience reaction - best when not obviously identifiable in itself, except upon its absence or when contrasted against recordings which do not have that quality.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on September 04, 2018, 01:18:07 PM
After a cursory search I don't think this link has been posted here before: https://www.merging.com/news/use-cases/morten-linderg-2l-norway

While I doubt anyone here is going to try to duplicate that rig for some random jamband show, it's interesting at the very least.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on September 04, 2018, 01:55:48 PM
After a cursory search I don't think this link has been posted here before: https://www.merging.com/news/use-cases/morten-linderg-2l-norway

While I doubt anyone here is going to try to duplicate that rig for some random jamband show, it's interesting at the very least.
Wow! All DPA full bodies and with z axis stuff in the arrays. I counted 11 mics in the one array titled "Remote galaxy mic array"
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on September 04, 2018, 03:53:26 PM
^The horizontal-plan portion of that microphone setup looks to be based upon Michael William's Multichannel Microphone Array Design (MMAD), an extension of his two-channel Stereo Zoom technique to multichannel surround which followers of this thread will recall me referencing regularly.  In addition, the 2L approach adds the four "Z-axis" microphone channels spaced above the horizontal-plan portion of the array for compatibility with contemporary film-surround playback schemes that aim to add a height dimension via an additional array of speakers located above the horizontal plane.

I'd like to hear the recordings.  This array, used on its own without spot-mics (which is not to say there is anything wrong with tastefully employed spot mics), represents something of a "purist location surround recording technique" based upon a combination of time-of-arrival differences as well as level-difference between channels.  It is in some ways the decadent descendant of Decca tree and other spaced-microphone-array techniques.

I suggest use of these complicated looking arrays by audiophile-quality-oriented recording labels can be interpreted as indirect proof that coincident or near-single-point microphone surround recording techniques (ambisonics, double Mid/Side, and whatever) do not work as well as dedicated spaced arrays for quality surround recording of music.  If they did no one would have to go to the trouble to rig up these kinds of jungle-gym-like spaced arrays.  Regardless of the marketing claims of the single-point multichannel microphone purveyors, those systems are really mostly about compactness, simplification and ease of use, rather than about achieving the most robust and highest quality musical results.

That said, I'm suspicious of the true value of using four separate elevation microphones in most recording situations.  I don't doubt that playback through a system using height speakers can be more immersive and convincing, only that such content cannot be essentially "ambience extracted" from the horizontal portion of the microphone array without much of an impact on perceived quality.  Consider that extraction and upmixing of ambient surround content from 2-channel recordings has gotten very good, and that's across the horizontal plane where there are a lot more differentiated sounds to deal with, as well as being the plane in which we are able to discern directionality far more accurately than in across the height dimension.  As some point the question becomes, "what is more fruitful- recording additional ambience channels or extracting/synthesizing them?"

If the 2L outfit has the mics, the channels, the setup time, and content for which true-recorded height info may be useful beyond simply providing a more seamless diffuse reverberant playback ambience, then they might as well go ahead and run them.

Smoke 'em if you got 'em!
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on September 04, 2018, 04:03:28 PM
BTW, the irony of my questioning the dedication of 4 discrete channels to vertical ambience is not lost on me!  After all, any number of tapers have either looked at me in bewildered disbelief or simply shook their heads as I pointed a single microphone directly rear-wards away from the stage, two more side-on, and my wide omnis towards the rear-corners of the venue.  One even became partly belligerent at one point!  It made him angry that I was doing it all wrong, pointing the mics in stupid directions that made no sense to him at all!

Title: Re: Oddball microphone technique (OMT) - part 2
Post by: EmRR on September 04, 2018, 05:41:36 PM
I'd like to hear the recordings.
indeed
I suggest use of these complicated looking arrays by audiophile-quality-oriented recording labels can be interpreted as indirect proof that coincident or near-single-point microphone surround recording techniques (ambisonics, double Mid/Side, and whatever) do not work as well as dedicated spaced arrays for quality surround recording of music.  If they did no one would have to go to the trouble to rig up these kinds of jungle-gym-like spaced arrays.  Regardless of the marketing claims of the single-point multichannel microphone purveyors, those systems are really mostly about compactness, simplification and ease of use, rather than about achieving the most robust and highest quality musical results.
Here I'll temper that thought with contrast on the intended capture.  I believe that to be true with ambiently experienced music, but I find with studio recording, especially pop or rock, one gets a much more satisfactory result with the 'strong mono' of single point stereo systems.  Or a combo of closer single point stereo capture mixed with spaced ambient arrays.
Smoke 'em if you got 'em!

fo' sho'!
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on September 05, 2018, 09:45:34 AM
I suggest use of these complicated looking arrays by audiophile-quality-oriented recording labels can be interpreted as indirect proof that coincident or near-single-point microphone surround recording techniques (ambisonics, double Mid/Side, and whatever) do not work as well as dedicated spaced arrays for quality surround recording of music.  If they did no one would have to go to the trouble to rig up these kinds of jungle-gym-like spaced arrays.  Regardless of the marketing claims of the single-point multichannel microphone purveyors, those systems are really mostly about compactness, simplification and ease of use, rather than about achieving the most robust and highest quality musical results.
Here I'll temper that thought with contrast on the intended capture.  I believe that to be true with ambiently experienced music, but I find with studio recording, especially pop or rock, one gets a much more satisfactory result with the 'strong mono' of single point stereo systems.  Or a combo of closer single point stereo capture mixed with spaced ambient arrays.

Absolutely.  I agree completely.   In my experience, a strong solid center as anchor out of which which everything sort of extends peripherally is always more convincing and more satisfying even with very ambient recorded material. That's one reason I'm a strong proponent of using a center channel in multichannel microphone arrays even when the recording is only intended for 2-channel stereo.  The two general approaches - spaced ambient arrays verses focused coincident mic'ing, needn't be exclusive of each other. We can combine the advantages of both in clever ways which support each other and avoid conflicts.

The center microphone position is an excellent place for a single-point stereo pair or ambisonic microphone.  In addition to a solidly-anchored center, that provides the option of dialing in as much level-based, coincident-type stereo as we want, with tight, phase-locked, pin-point imaging extending outwards from the center of the playback image, balancing nicely against the randomized-phase stereo ambience and wide, diffuse directionality provided by the spaced array.  And that can make for a more optimized portrayal consisting of both a big overall picture with enveloping ambience as well as a solid, tightly-focused "strong-mono" center anchoring it all.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on September 05, 2018, 10:30:20 PM
Playing around with a Phish recording that I did this summer with my Tetramic, I decided to decode it to Blumlein and then also decode a forward-facing cardioid.  I blended the mono cardioid with the Blumlein and I have to say I like how it solidifies the center, without really needing to add much of it.  That said, I don't know that my ears are good enough to tell if I'm causing phase problems or the like.  Anyway, Blumlein with a coincident forward-facing cardioid seems like it might qualify as oddball.  Here's some quick and dirty samples to compare....

Blumlein only: https://we.tl/t-Y1Zh2cfiuC
Blumlein with the addition of the forward cardioid: https://we.tl/t-u12aG1io2p

As ever, I'm interested to hear what others have to say about these.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: EmRR on September 05, 2018, 10:33:42 PM
I've used Blumlein with a center omni for close studio work and been very happy with the addition. 
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: noahbickart on September 05, 2018, 11:16:42 PM
Not exactly OMT.

But this thread may be of interest to folks here:

http://taperssection.com/index.php?topic=187767.0

Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on September 06, 2018, 12:34:16 PM
Playing around with a Phish recording that I did this summer with my Tetramic, I decided to decode it to Blumlein and then also decode a forward-facing cardioid.  I blended the mono cardioid with the Blumlein and I have to say I like how it solidifies the center, without really needing to add much of it.  That said, I don't know that my ears are good enough to tell if I'm causing phase problems or the like.  Anyway, Blumlein with a coincident forward-facing cardioid seems like it might qualify as oddball.  Here's some quick and dirty samples to compare....

Blumlein only: https://we.tl/t-Y1Zh2cfiuC
Blumlein with the addition of the forward cardioid: https://we.tl/t-u12aG1io2p

As ever, I'm interested to hear what others have to say about these.

I'll try and give a listen tonight.

I can see how mixing in some forward facing cardioid with the straight 90-degree angle Blumlein pair would be useful in many cases.  And it's interesting to think about what the addition of the forward-facing cardioid is doing.  In some ways it's similar to  narrowing of the angle between the 8's to something less than 90 degrees, but not exactly.  Narrowing the angle between 8's is equivalent to increasing the ratio of Mid to Side.  It is the same as adding more forward facing figure-8.. similar but not exactly the same as adding more forward facing cardioid.  But I'm getting ahead of myself, let me back up for a moment-

I found that when I was recording from out in the audience using either a pair of ADK TLs or a Peluso P-Stereo in Blumlein that I often liked tightening up the angle between the microphones from the standard 90 degrees to something a bit less.  That helped in solidifying center focus and made for a more-even power-response across the front playback stage.  Otherwise there tended to be a bit too much separation between channels with the microphones angled a full 90 degrees apart.   

When I started using the TetraMic and was able to more easily play around with incremental adjustments to both pattern and angle afterwards while seeing both a graphical and numerical indication of what those actual angles and patterns were, I gravitated towards the same preference, typically preferring an inclusive angle of somewhere between 70 to 80 degrees for a pair of crossed 8's.  However, the pattern/angle combination I most often like best is a crossed pair of super/hypercardioids, using a slightly wider angle between microphones than I'd gravitate to with 8's.  That combination seems to achieve a nice balance of Blumlein-like qualities with more forward-bias that brings the important stuff in front (band and PA) into better focus with increase clarity.

I think what the addition of the forward facing cardioid does is similarly push the virtual patterns towards super/hypercardioid rather than 8s, except narrowing the virtual angle somewhat. 

Obviously each of these variations are similar yet also vary slightly, which IMO is significant.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on September 06, 2018, 12:34:53 PM
Lucas, If you want to mess around with this a bit more simply as a way to get a good mental handle on how all this stuff works, here is what I'd recommend-

Based on my analysis here of what your addition of the cardioid is doing, try adding some forward facing carioid to the crossed fig-8's as before, except try using an angle wider than 90 degrees between the 8's.  The addition of the forward-facing cardioid essentially narrows the virtual angle, so using more angle on the 8's to start with will help retain ambient stereo width while still getting the advantage the forward-facing sensitivity bias and center focus provided by the cardioid.  It should let you use more cardioid if desired, before things get overly narrow sounding.  How much wider is going to be subjective, it's assessing the general trend in that direction which should be most informative.

All of this is illustrative of the many balancing acts between center-focus/solidity and ambient-width/stereo-openness.  The same balancing act is "baked in" to standard stereo microphone configuration pattern/spacing/angle combinations (which to a limited extent we can tweak afterwards using Mid/Side readjustments).  With these ambisonic recordings you gain more control over finding the most appropriate balance point by ear.  The additional step of introducing a 3rd virtual microphone facing forward can potentially take that to another level..  which I don't think is happening here exactly yet unless you are applying different processing to the 3rd channel in comparison to the other two, such as EQ'ing it differently.  Rather, I think the addition of the forward facing cardioid (or omni or whatever) can be fully explained in terms of Mid/Side and the resulting change of virtual patterns.

Ambisonics is essentially advanced Mid/Side. The addition of a forward facing cardioid (or omni as EmRR mentioned for close studio work) coincident with the Blumlein pair is really no different than changing the virtual pattern/angle.  Assuming the level of both are identical, mixing an omni with the 8's turns the Blumlein pair into a virtual pair of 90 degree X/Y cardioids.  If somewhat less omni is used, that becomes equivalent to a pair of supers or hypers with the same 90 degree inclusive angle.

Mixing in forward-facing cardioid instead of an omni does essentially the same, except it also narrows the virtual angle somewhat, due to the presence of the forward facing bi-directional component of the cardioid in addition to its omni component.

The suggestion of making the angle between crossed 8's wider before adding the forward-facing cardioid, serves to at least retain the 90 degree angle between the resulting super/hyper-ish virtual pair, if not increase it somewhat.  The only real difference between doing this and dialing in a wider angled pair of super/hypers to begin with is the process one goes through in arriving at the end result.  Don't disregard the difference in process even if you can end up achieving the same end result either way.  Different working processes definitely affect our preference as we work toward and settle upon what sounds best.

What would leverage this to the next level and move it beyond an alternate way of making the same Ambisonic Mid/Side readjustment would be EQing the forward-facing cardioid differently from the fig-8 pair prior to mixing them.  Say you EQ the cardioid to achieve best clarity and presence of the direct sound from the PA and stage, while EQing the crossed 8 pair for best ambient correctness.  In addition, to get things correct in an overall global EQ sense,  you'd can compensate for whatever specific EQ works best on the cardioid in your EQing setting for the 8s.  As an example, if you start from an overall well-balanced point of reference with regards to frequency, and then boost midrange/treble in the cardioid for improved clarity and articulation of the sound from the stage and PA, you might want to boost the bass of the 8's even if they didn't need that on their own, in order to compensate "globally" for a better frequency-balance of the overall combination of the forward-direct and diffuse-ambient portions.

That's still essentially making Mid/Side type manipulations, but more advanced ones which equalize the sound arriving from the foreword quadrant differently than than arriving from all other directions.   One of the cool things about single-point in space Ambisonics is that it is all level/polarity based. That means we can potentially split things up into as many virtual microphones as we want and recombine them without phase interaction problems.  One just has to be careful that the processing done to each part does not introduce significant phase differences, so this sort of thing is probably a good place for linear-phase EQ's.  Of course coincidence and lack of time-difference is also ambisonic's biggest constraint, and why spaced arrays which do introduce phase differences become advantageous.


Brief ambisonic aside- Excepting the EQ part, all this is getting close to the first-order Ambisonic control oddity of the "zoom" function, but not quite.  I don't understand the zoom function well, but in my limited understanding, it essentially modifies the W component by shifting it from omni towards a more forward-directional pattern prior to doing the Ambisonic matrixing that derives the virtual mic-patterns.  Don't sweat it if you don't follow that.  It's pretty much above my head too, and I'm likely grossly oversimplifying it.  It's a fun control to mess around with within a rather limited range though.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on September 06, 2018, 12:35:30 PM
Following up on the above two posts-
Lucas was kind enough to provide the raw A-format TetraMic files of one of these Phish shows to me a few weeks ago (not sure if it was the one he posted links to above or not) for me to assess for him and mess around with a bit.  It's been a while since I used my TetraMic, which is due for a recalibration, and it was fun to dive back into messing around with the virtual microphone settings, homing in on a few good 2-channel decode options.  Below is a portion of my PM to him talking about that, which I'll copy here because it's relevant to this discussion of the most appropriate angle between microphones based on the pickup pattern.  I posted essentially this same information way back when I was first messing with the TetraMic, and it was good to confirm again that it still holds true for me now. 

Essentially, the trend outlined below represents one of the most useful things I found using TetraMic, which has informed my general thinking on coincident 2-channel stereo ever since-

-------------------------------------
For good sounding material, I typically end up somewhere around this trend line of settings:
pattern = 2.0 (fig-8s) / width = 70-80 degrees
pattern = 1.8-9 (hypercardioid) / width = 90ish
pattern = 1.7 / width = 105-115ish
pattern = 1.6 (supercardioid) / width = 120ish
...etc..
pattern = 1.0 (cardioid) / width = 130-140ish
pattern = 0.5-0.8 (subcardioid) / width = 140-150ish

Often several different settings along that trend line work well and it comes down to choosing which is most prefered.

Of course that's just a very generic trend.  I may end up with something significantly different, especially if the recording environment is less than ideal, or the recording is otherwise wonky.
-------------------------------------

^
I'd love to be able to combine several of those options, each targeting a different frequency range.  For example one could have very wide angled subcards for the lowest frequencies and narrower angled more directional patterns higher in frequency.  This would essentially be like the Schoeps Polar Flex system extended to Ambisonic stereo.  It's possible to do so via a lot of manipulation and recombination in a editor, but far more work than I want to do.  What would be great is if that functionality was included in the B-format to virtual-microphone decoding application, where it would be simple and easy to apply with visual confirmation.

[Edit- Another more-basic function which would be very useful in VVM or any ambisonic virtual-microphone decoding application is a single control which would allow one to sweep between the various pattern/angle settings I've listed above, without having to rapidly readjust both pattern and angle separately each time.  One could then simply manipulate that single parameter while listening even with one's eyes closed, and really get a good feel for the incremental variations between them without having to do so in a much slower, clumsier, iterative way.]
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on September 06, 2018, 12:36:40 PM
Not exactly OMT.

But this thread may be of interest to folks here:

http://taperssection.com/index.php?topic=187767.0

Thanks Noah!  I grabbed your files yesterday but haven't had time to listen yet.  Looking forward to doing so.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on September 06, 2018, 12:46:07 PM
Lucas, If you want to mess around with this a bit more simply as a way to get a good mental handle on how all this stuff works, here is what I'd recommend-

Based on the analysis above, try adding some forward facing carioid to the crossed fig-8's as before, except try an angle wider than 90 degrees between the 8's. 

This hadn't really occurred to me but I'll definitely play around with it.  Thanks!

Quote
I think what the addition of the forward facing cardioid does is similarly push the virtual patterns towards super/hypercardioid rather than 8s, except narrowing the virtual angle somewhat. 

(Here's where I'll probably mess up the technical side of things...)  Does adding the forward-facing card impact the rear lobes of the Blumlein pair, though?  I definitely see how it impacts the pattern in the front, but aren't the full figure 8 rear lobes still picking up as much as the unaltered Blumlein pair?

Quote
Lucas was kind enough to provide the raw A-format TetraMic files of one of these Phish shows to me a few weeks ago (not sure if it was the one he posted links to above or not) for me to assess for him and mess around with a bit.

The samples above are from the same venue, but a different night (IIRC from what I previously sent you).

Also, if anyone is at all interested in messing with this stuff, the VVMic program is free to download and I'd be happy to share any of my raw A format files.  You could then try all of this out yourself.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on September 06, 2018, 01:18:40 PM
Does adding the forward-facing card impact the rear lobes of the Blumlein pair, though?  I definitely see how it impacts the pattern in the front, but aren't the full figure 8 rear lobes still picking up as much as the unaltered Blumlein pair?

Increasing sensitivity to the front is essentially the same as decreasing it to the rear in an overall sense.

Consider the cardioid in terms of its basic polar components- an equal sum of a forward-facing figure-8 and an omni.  In that case the figure-8 and omni components combine to produce twice the sensitivity of either alone in the forward direction, the same sensitivity as the omni alone 90-degrees off to either  side, and destructively interfere to create reduced rear sensitivity culminating in a central rear-facing null (or near null).

The same essentially applies to adding the forward facing cardioid to the Blumlein pair.  The main difference is that we're now thinking in terms of combined stereo pattern sensitivity, rather than a single channel polar pattern.

In that overall combined-pattern sense, a Blumlein pair on its own has equal sensitivity in all horizontal directions, making it omnidirectional in terms of stereo sensitivity.

Adding forward cardioid to that shifts the sensitivity bias forward, so the overall combined stereo sensitivity pattern is more subcardioid-like in shape.  Similarly if you overlay a crossed pair of hypercardioids and trace the combined outline of them (ignoring polarity) the overall combined stereo pattern sensitivity is likewise subcardioid shaped.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on September 06, 2018, 01:22:39 PM
Also, if anyone is at all interested in messing with this stuff, the VVMic program is free to download and I'd be happy to share any of my raw A format files.  You could then try all of this out yourself.

I encourage anyone interested to take him up on this offer!  It's very enlightening to play around with.  I've been meaning for years to make some of my raw TetraMic files available here but for numerous reasons have never gotten around to doing so.  And I'm happy to discuss the particulars with anyone who does.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on September 19, 2018, 09:24:16 AM
Copying a couple posts from another TS thread (https://taperssection.com/index.php?topic=186823.0) to here, because I feel they do a good job of conveying the philosophy driving the development of OMT and what it is designed to achieve-

Hi. A couple of thoughts:

- If you're coming from a background of recording with spaced omni microphones, I think you'll find that recording with two coincident or closely-spaced supercardioids gives a fundamentally different overall impression. It's not just a variation by degree from what you're used to. The listener's brain goes into a different mode of listening, because the sense of space and the ability to localize direct sound sources are so different between the two kinds of recording. They're both called "stereo" but they're so different in their effect that I sometimes think there should be different terms for the two approaches. (A/B vs. X/Y comes close; "intensity" vs. "arrival time" differences are involved, but those are ugly terms and anyway, those two principles of operation aren't mutually exclusive in most cases.)

With spaced omnis, if the live environment in which you made your recording was rich and spacious, a similar feeling can be manifest when your recording is played back. It's like bringing that _environment_ into the room where the playback occurs; you may feel as if you are wrapped or "enveloped" by that environment, even with only two channels and two loudspeakers. This encourages a mode of listening in which sensuousness and the color of sound are the main offerings. It invites you to turn off certain critical tendencies, and just take a bath in the sound. If the material being recorded is highly complex, it will be blended and softened and the edges rounded off by this type of recording. That can make it more palatable and atmospheric--sometimes primitive and mystical, even--at the cost of some clarity and specificity. That's where judgment and experience come in, since you may not always want that particular tradeoff.

With directional microphones, particularly coincident supercardioids or crossed figure-8s, you can get a very clear "stereo image"--a representation of the direct sound sources that's consistent over space and time, and that involves your knowing (on some level in your brain) where the direct sound sources were relative to the microphones. This offers much better support if you're consciously trying to grasp the specifics of the content that's being delivered. But esthetically it is a very different type of experience. The emphasis is more on the direct sound sources and where they are and what they're doing; the "atmosphere" is reproduced more quantitatively than qualitatively. Its tradeoff is that it puts more of a cognitive burden on the listener, but with a greater payoff in specific information if the listener chooses to engage that way. But it's not usually as intuitively persuasive as a good spaced-omni recording.

There are crossover and compromise approaches. I like certain aspects of both typological extremes, so I'm very drawn to those crossover approaches in many recording situations. Those include the use of "subcardioid" microphones (in the Schoeps line, that would be the MK 21 and MK 22--the so-called "wide cardioid" and "open cardioid" patterns respectively) with an approach to angling and spacing that's derived from ORTF stereo recording.

- "Reach" is a problematic concept, especially where stereo recording is concerned. A fact of physics that surprises a lot of people is that the highest directivity you can get from a "first-order" microphone (with a single capsule and no special signal processing) only gets you a 2:1 "distance factor" relative to an omni. In other words, if you find that the optimal balance of direct to reverberant sound is obtained when an omni mike is 3 feet from something, then a hypercardioid would give you that same quantitative balance of direct and reverberant sound at 6 feet. No first-order microphone pattern can ever give you that same "3-foot balance" at any greater distance; no microphone can "zoom in on" a more distant sound source and make it seem that close.

For a number of technical reasons, a pair of good supercardioids may well be your best choice when you are forced to record in stereo from all the way into the reverberant sound field. Certainly NOT shotgun microphones, which have highly irregular off-axis response at high frequencies, and no better than supercardioid directivity at low and mid frequencies (i.e. they're useful only when they're close enough to the sound source to pick up enough direct sound on axis so that you don't care about the residue of off-axis sound). But even good supercardioids can't compensate for excessive recording distance. Directional microphones are, if anything, more sensitive to their exact placement than omnis are.

- All that said, there's an interesting variant on omnis that can produce surprisingly good results sometimes, and that is to embed the membranes of each microphone in the surface of a sphere (see attached photo). I wonder whether you've tried this technique with your omnis. (Add-on sphere accessories are available for various microphone diameters.) It's another one of those adaptations or compromises that I spoke of, but this one completely preserves the spaciousness and "envelopment" aspects of spaced-omni recording, while increasing the clarity and directness of the direct sound sources.

Just as food for thought.

--best regards

P.S.: The attached photo shows a Schoeps omni capsule mounted on a Colette active cable and surrounded by a sphere accessory. But such spheres can also slide over the capsule when the capsule is mounted directly on the microphone body (amplifier). The important thing is for the surface of the sphere to be "flush with" the front edge of the capsule. -- This technique works only for omni (pressure) transducers. It would block the rear sound inlet of a pressure-gradient (directional) capsule and mess up both its polar response and its frequency response.

P.P.S: I meant to point out--when you're looking in Williams' charts or on Sengpiel's site or on http://www.hauptmikrofon.de/, be aware that supercardioid and hypercardioid have dictionary definitions which any given microphone probably won't fit exactly. The Schoeps MK 41 isn't exactly a supercardioid; it's like 2/3 supercardioid and 1/3 hypercardioid. Neumann calls their small hybrid a hypercardioid, but it's also in between hyper- and super- (with a slightly different recipe from Schoeps). Similarly, Sennheiser calls theirs a supercardioid, but it has about the same pattern as Neumann's hypercardioid, etc., etc.

What I mostly wish to contribute to the thread is to echo DSatz's comments on the fundamental difference in overall listening impression between A/B and X/Y microphone techniques - an excellent observation, well stated.  I especially perked up at the mention of "The listener's brain goes into a different mode of listening, because the sense of space and the ability to localize direct sound sources are so different between the two kinds of recording. They're both called "stereo" but they're so different in their effect that I sometimes think there should be different terms for the two approaches."

The bit below may seem OT at first, but I'll explain further down why I think it applies.

I consider near-spaced microphone techniques commonly used around here as attempts at finding optimized middle-ground solutions which effectively bridge the gap between these two very different modes of recording and listening, without moving beyond the constraint of two microphones and two recorded channels.  This can work very well for live music, where we can achieve a respectable balance between immersive ambience, good clarity and sharp imaging using well considered arrangements of two microphones.  Yet I'm rarely completely satisfied with the results given the necessary compromises.  Once I became aware of how well each aspect can be addressed on their own, albeit at the detriment of the other, those compromise solutions all to often no longer satisfy either listening mode for me sufficiently.  Of course there are plenty of exceptions, but the general trend holds.

I want to try and better optimize for both modes of listening at the same time, so I break the listening experience down further and essentially use separate pairs of microphones optimized to more ideally capture these different aspects, then combine them afterwards.  I feel this results in a better overall result than trying to find a good "middle of the road" optimization using a single pair of microphones.  The trick is that this must be done in such a way that the separate pairs support rather than fight each other, and the devil is most definitely in the details with respect to achieving that.  It's easy to make a mess of it and just complicate things without really improving the end result.  Still, I commonly argue for this somewhat unusual approach here at TS.  That's partly because I feel audience-perspective music recording is a unique recording endeavor compared to other forms of recording- For one thing, audience perspective recording is typically done from a considerable distance from the source.  It represents a very ambient recording situation regardless of whether we like that or not. In addition, we have far less control over the situation and the techniques I'm suggesting provide some additional control and flexibility;  And lastly because I find the presentation more convincing for both "modes of listening" - I can mentally switch back and forth and get a better feel for both than I can with straight 2-channel near-spaced microphone techniques. 

I see these things as possibly being applicable to your nature and ambience recordings as well.

Consider what you are recording and what you want to convey to the listener.  Then consider recording approaches which are optimized for what you want to convey.  If it's relaying a feeling being there in that place with a convincing immersive ambience, a spaced A/B technique with open pattern mics such as omnis is hard to beat.  If its a clear and precise focus on a particular sound within a particular soundscape, a single microphone or a coincident (X/Y, Mid/Side) technique using highly directional mics like the Schoeps MK41's can achieve that.  If you want both at the same time, you may be able to find a "middle ground" near-spaced approach which works for both aspects without compromising either too much. Or you can optimize separately for each aspect, and make a composite recording which better portrays both of them.  All depends on what you want to achieve, and how much effort you want to put into it.

For what you are doing the composite approach would probably mean setting up a spaced A/B omni recording to capture the ambience, and focusing a single MK41 directly on the subject of interest from a not overly distant location.  If the direct sound from subject of interest has stereo qualities to it which you'd like to convey in addition to the atmospheric stereo ambience from the A/B pair, you might consider using both MK41 in a narrow X/Y configuration (or better, a Mid/Side setup using one MK41 plus a figure-8 such as the MK8). Narrow so that neither mic of the pair is very far off-axis from a direct line to the source (which is why a Mid/Side setup works well for this - the Mid microphone is always pointed directly at your source), thus retaining good direct focus on the subject while still getting sufficient direct imaging type stereo-ness. And also narrow because the A/B omni pair will be contributing plenty of the other kind of stereo-ness, meaning less stereo-ness is required from the "direct sound" focused pair for a good overall listening impression.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kindms on September 23, 2018, 07:52:16 PM
ok Gut etc

thinking of my new 426 as center front and rear (can be run 180)

so what are your thoughts with front rear card or whatever with flanking mics ?

Was wondering if say front and rear cards with say either 414 omni or ck22 omni in either A/B or perhaps Healy ? Constrained to the circumfrence of a human head or maybe 12" split ? (can be adjusted 12" increments up to 4 ft)

Omni----c4+26-----Omni ??

oh and this is 4ft split AKG ck22 with the 426 run hypers at like 65deg

http://taperssection.com/index.php?topic=187967.0

Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on September 24, 2018, 10:19:18 AM
Looks like a cool venue.. As Sam would say- "You look marvelous, dahling".

With any L/C/R microphone setup, I like spacing the L/R pair twice as far or more than I might without using center mic, as long as that's practical.  I'd probably shoot for 2' minimum or as wide as you dare.  If you can't space them as widely as you like for whatever reason, you might try the 414's in subcard instead of omni, pointed out to the sides.  A relatively wide spacing is what produces that nice open and spacious decorrelated ambience, and helps keep the audience sound from competing as much with music in the center of the image.

Using a single forward-facing center channel rather than a stereo-pair (like your 65 degree X/Y hyper pair), I might not go quite as wide as I otherwise would, because the single microphone in the center is more of a point source and I don't want that to come across as a separate "island of sound" in the middle.  A stereo pair in the center sort of helps feather the center in with the omnis, smoothly blending the imaging across the front.

With regards to using the 426 angled 180 degrees apart and facing front/rear- I've never clearly determined the importance of center front/rear microphone spacing, except that I don't want too much (don't want the rear facing mic so far back that there is an obvious delay) and that front/back spacing it is less important than left/right spacing.  I think it might work well dialing in a forward facing supercard and a rear facing cardioid.  That way you get maximum focus on the direct sound in the front facing channel and maximum exclusion of the direct sound from the rear facing channel.

Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on September 24, 2018, 10:58:56 AM
Using a single forward-facing center channel rather than a stereo-pair (like your 65 degree X/Y hyper pair), I might not go quite as wide as I otherwise would, because the single microphone in the center is more of a point source and I don't want that to come across as a separate "island of sound" in the middle.  A stereo pair in the center sort of helps feather the center in with the omnis, smoothly blending the imaging across the front.

Expanding a bit on that-
With the mics you now have, I encourage you to try a setup close to what I'm doing.  I really like what it does. This would be six channels total into the DR-680:

Space the ck22 omnis as wide as you can get them, put the 426 in the center facing front/rear, and place your 414's about halfway out between the center and omnis (say at least 12" but less than 24" out from center) as supercardioids facing directly to the sides.

This will give you a different type of directional stereo across the center- not a coincident center L/R pair, but a near-spaced L/C/R stereo triplet.  You'll retain the center forward focus and get some near-spaced goodness. 

When mixing it, try this-
First bring up the 414's in isolation and balance them against each other to center their stereo image. Then mute them.

Next bring up the omnis in isolation and balance them against each other.  Leave them up and bring up the center channel until you get a good balance between the omnis and center mic.

At that point slowly bring up the Left/Right facing supercardioids.  This feels sort of like dialing in more Side to a Mid/Side pair to widen the stereo image, but without loosing center detail and focus.  Sometimes it's seems  like a sort of acoustic zoom control, bringing presence, excitement and "up-frontness".

Then bring up the rear-facing mic to taste.


After you get that sounding good, start over and try the mix a different way-
Get a good balance of the center + sideways supercards first, then bring up the omnis, and finally the rear facing channel. 

The first approach treats the omnis + front-facing center microphone as the primary L/C/R part, sweetening that with the addition of the sideways-facing supercards. The second approach starts with the near-spaced directional triplet as primary L/C/R, and sweetens that with the addition of the omnis and rear facing channel.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kindms on October 07, 2018, 11:40:24 AM
so friday night for Warren, Porter, Medeski and RUsso

we had intended to run 4ft split but as we were setting up they gave the 7ft height limit. So figuring that the spit would be an issue at that height we opted for

12" split ck22 Healy > V2
8" forward / rear ck61s
center c426 hyper (again :) ) pointed at the stacks. so fairly wide probably like 100

I mixed it with the ck22 down slightly (signal was hottest), bumped the c426 slightly. left the center forward ck61 alone and dropped the rear 10db. Was gonna ditch the rear in the mix but figured i would leave it in even if just barely noticable

http://bt.etree.org/details.php?torrentId=601986

I think it sounds better over cans vs speakers but probably due to the proximity of the omnis
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on October 08, 2018, 05:06:11 PM
Kindms, thanks to you and Rocksuit for your recording. I am listening it via speakers now. It has something that it makes me feel like I am right there. It sounded very pleasant because this.

I also tried to mix near spaced omnis (because it was stealth) with a center microphone. I was afraid of the comb filter. In the end, I mixed very little of center mic. I'm not sensitive for comb filtering, so I was rather careful. Still, the small addition of the center has improved the recording.

I was playing with my old oddball recording. Here is my little observation. Gutbucket advised us to try more methods to mix rear channel. One was just to mix it in. Another was to stereoise the rear channel by M/S with forward mic. Or we can stereoise the rear channel by some other artificial effect (eg.reverberation). I was trying M/S and it was not working well in my recording. It sounded somehow sharp, unpleasant. I remembered that Gutbucket also mentioned that we can try to make artificial stereo of rear channel by plugin for phase shift. I found this plugin. This plugin shifts phase of all frequencies by constant angle. The rear channel is mixed in M/S by phase shift of +-180°  180° . But we can set lower shift by this plugin.
http://www.pcjv.de/vst-plugins/betabugs-plugins/ (http://www.pcjv.de/vst-plugins/betabugs-plugins/)

I think I used +-55°. It sounded better than M/S. It was not so aggressive. I mixed the rear mic into the right channel with positive phase shift and into the left channel with the opposite phase shift. There are two variables for setting - level of rear channel and phase shift. I set up the level as in the previous methods. Phase shift, I set first +-180 ° 180 ° as in M/S, and then I was lowering it than it sounded pleasantly.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kindms on October 08, 2018, 06:58:00 PM
Kindms, thanks to you and Rocksuit for your recording. I am listening it via speakers now. It has something that it makes me feel like I am right there. It sounded very pleasant because this.

I also tried to mix near spaced omnis (because it was stealth) with a center microphone. I was afraid of the comb filter. In the end, I mixed very little of center mic. I'm not sensitive for comb filtering, so I was rather careful. Still, the small addition of the center has improved the recording.

I was playing with my old oddball recording. Here is my little observation. Gutbucket advised us to try more methods to mix rear channel. One was just to mix it in. Another was to stereoise the rear channel by M/S with forward mic. Or we can stereoise the rear channel by some other artificial effect (eg.reverberation). I was trying M/S and it was not working well in my recording. It sounded somehow sharp, unpleasant. I remembered that Gutbucket also mentioned that we can try to make artificial stereo of rear channel by plugin for phase shift. I found this plugin. This plugin shifts phase of all frequencies by constant angle. The rear channel is mixed in M/S by phase shift of +-180° . But we can set lower shift by this plugin.
https://www.kvraudio.com/product/phasebug_by_betabugsaudio (https://www.kvraudio.com/product/phasebug_by_betabugsaudio)

I think I used +-55°. It sounded better than M/S. It was not so aggressive. I mixed the rear mic into the right channel with positive phase shift and into the left channel with the opposite phase shift. There are two variables for setting - level of rear channel and phase shift. I set up the level as in the previous methods. Phase shift, I set first +-180 ° as in M/S, and then I was lowering it than it sounded pleasantly.

Interesting. And Im glad you dig the recording. I think the proximity of the omnis makes the recording sort of "shine" in headphone playback. We kind of envisioned the human head when setting up the array if you can call it that.  So Omnis as the ears c426 as the eyes, the ck61s as the 3rd eye

(http://www.chakras.info/wp-content/uploads/third-eye-opening.jpg)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: ycoop on October 08, 2018, 08:06:10 PM
^ Talk about oddball  ;)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on October 09, 2018, 06:49:20 AM
^ Talk about oddball  ;)

Great, this picture should be the title page of Gutbucket's oddball pdf.

I think the proximity of the omnis makes the recording sort of "shine" in headphone playback. We kind of envisioned the human head when setting up the array if you can call it that.  So Omnis as the ears c426 as the eyes, the ck61s as the 3rd eye

Yes, it sounds great in headphones.

I downloaded for comparison second recording of the same show made by Michael - pair of Schoeps, supercardiod . It is excellent recording. It has very nice stereo separation and everything is sounding clear and upfront. But for some unknown reason the omt recording sounds little more pleasant to me. Maybe it is because openness or just different sound color (eq).
http://bt.etree.org/details.php?torrentId=601963 (http://bt.etree.org/details.php?torrentId=601963)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 09, 2018, 10:54:16 AM
We kind of envisioned the human head when setting up the array if you can call it that.  So Omnis as the ears c426 as the eyes, the ck61s as the 3rd eye

Love it!

I was playing with my old oddball recording. Here is my little observation. Gutbucket advised us to try more methods to mix rear channel. One was just to mix it in. Another was to stereoise the rear channel by M/S with forward mic. Or we can stereoise the rear channel by some other artificial effect (eg.reverberation). I was trying M/S and it was not working well in my recording. It sounded somehow sharp, unpleasant. I remembered that Gutbucket also mentioned that we can try to make artificial stereo of rear channel by plugin for phase shift. I found this plugin. This plugin shifts phase of all frequencies by constant angle. The rear channel is mixed in M/S by phase shift of +-180° . But we can set lower shift by this plugin.
https://www.kvraudio.com/product/phasebug_by_betabugsaudio (https://www.kvraudio.com/product/phasebug_by_betabugsaudio)

I think I used +-55°. It sounded better than M/S. It was not so aggressive. I mixed the rear mic into the right channel with positive phase shift and into the left channel with the opposite phase shift. There are two variables for setting - level of rear channel and phase shift. I set up the level as in the previous methods. Phase shift, I set first +-180 ° as in M/S, and then I was lowering it than it sounded pleasantly.
^
Great that you've tried this!  Thanks for your report.  This is one of the things I've wanted to explore for years- constant-angle opposite phase-shifts routed Left and Right (guessing a shift of somewhere between 40° and 90° will be most appropriate).  I'll have to check out that kvraudio plugin.  Most of the others I came across did other stuff than simply shifting phase by a constant amount across all frequencies- and those intended as "pseudo-strereoizing" mono-to-stereo plugins are mostly crap.  The one I do know can do the constant phase shifting without other unwanted tricks is Voxengo PHA-979.

A few reasons this approach is conceptually attractive for me-
It doesn't change the timbre of the rear-facing channel content.  The solo'd rear facing channel(s) sound the same before and after this phase-shifting treatment.  It only changes the how the separate channels interact with each other. 

When summed to mono, all opposite polarity content cancels out.  So with a standard Mid/Side 180° phase shift of the Side channel (in this case Rear channel), the Side/Rear content goes away entirely and only the Mid + omni sum content remains.  But with less than a 180° shift, only some of that content is cancelled, so by gaining control over the degree of phase shift, we gain control over how much rear-ambience remains in the mono sum.. which is also how much rear-ambience is present across the center portion of the 2-channel stereo image.  In other words, we gain control over rear ambient stereo width without effectively reducing the center channel level at the same time.

This is the primary principle upon which old-school matrix surround is based.  Content with a total phase shift of 180 degrees between Left and Right channels is routed to the back center.  Content with no phase-shift is routed to the front center.  Content with a phase shift somewhere between those two extremes is steered somewhere between front and rear with the degree of phase shift determining how far front/rear and the polarity of the shift determining if that is sent towards the Left or Right sides.  So in addition to making better sounding 2-channel stereo output, this is also effectively modifying the defacto matrix surround encode created by your mix.  Anyone playing your 2-channel stereo file back through a surround matrix decoder will hear the rear ambience spread around the back between the Left/Right and surround channels.

A +/-90° Left/Right phase shift = 180° total (rear ambience routed to the back in surround, to the far sides in stereo, and cancels out entirely in mono).
A +/-45° Left/Right phase shift = 90° total (rear ambience routed to the sides in surround, halfway between the far sides in stereo (less out-of phase stereoness), and is reduced by 6dB in the mono sum rather than canceling out entirely).
No Left/Right phase shift = 0° total (rear ambience routed to center in surround, to the middle of the image in stereo (Mid), and is not reduced in level at all in the mono sum.

Your +/-55° Left/Right phase shift = 110° total, which likely represents the most appropriate mid-way point between +/-90° and +/-45° for that particular recording.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 09, 2018, 11:21:20 AM
I'm also interested in other ways of decorrelating the Left/Right routing of the single rear-facing ambience channel which may be more effective than phase-rotation.  In my discussions with wforwumbo (who just completed a doctorate in acoustics), IIRC he suggests trying a plate-style reverb with zero (would that work?, maybe an especially short) reverb time.  Not sure of the specific settings, but the intent is not adding 'verb which extends the time envelope of the sound, even if very short, but rather sufficiently "different-izes" the Left/Right feeds from the single channel without adding any specific sound character other than increased spatialization.  Perhaps he'll chime in here.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on October 10, 2018, 06:30:25 PM
When summed to mono, all opposite polarity content cancels out.  So with a standard Mid/Side 180° phase shift of the Side channel (in this case Rear channel), the Side/Rear content goes away entirely and only the Mid + omni sum content remains.  But with less than a 180° shift, only some of that content is cancelled, so by gaining control over the degree of phase shift, we gain control over how much rear-ambience remains in the mono sum.. which is also how much rear-ambience is present across the center portion of the 2-channel stereo image.  In other words, we gain control over rear ambient stereo width without effectively reducing the center channel level at the same time.

Thanks for this explanation. It's good to look at this issue from perspective of mono and stereo. I like the idea of mixing Mid/Rear. It is bringing something special to the recording. When I mix the rear channel just as mono, the effect is less significant. I recorded only couple of recordings by omt. Maybe it's just a coincidence and the next recordings will sound better with mono rear channel. I am curious how would compare the Mid/Rear and a pair of rear mics in XY. Also, I am curious about wforwumbo reverb effect too. Thanks for the basic surround matrix theory too.

I update the link for phase plugin. I don't know if the plugin is high quality. But I tested it on the sum of mono. It is working very well. When decreasing the phase, the mono signal increases. And all is canceled for 180°. I do not have a good listening skills. Maybe it is creating some unwanted artifact. But it should be negligible for our rear mic.
http://www.pcjv.de/vst-plugins/betabugs-plugins/ (http://www.pcjv.de/vst-plugins/betabugs-plugins/)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 11, 2018, 12:44:26 PM
Yeah I really dig the rear-facing channel.  I've said it here many times, but almost every time I'm tempted to leave it out, I find that things are just not quite as good without it.  I keep meaning to experiment more with an additional rear-facing channel, but I value what the addition of other microphone channels do more, so tricks such as we are discussing which "de-monoize" a single rear-facing channel will remain attractive unless I move to recording more than 6 channels. 

"De-monoizing" the rear ambient material, either by manipulating the single recorded channel or by recording more than one rear channel seems to help with a couple things- It keeps that material from imaging strongly in the middle and thus directly competing with the forward-facing channel intended to monopolize the monophonic center-portion of the image; and it conveys that material in a more more diffuse, wide and enveloping way, which is appropriate as it ideally consists of all reverb, reflections, and audience reaction, with as little direct sound leakage from the front in it as possible..

I am curious how would compare the Mid/Rear and a pair of rear mics in XY.

Stick with me here and I'll get to that..
TLDR- Other than one test mentioned below, I've yet to move beyond a single rear-facing channel mainly because any additional recording channels have proven more valuable to me when pointed elsewhere, at least when recording up to 6 channels total. 

IME, the primary requirement of the rear-facing channel is minimizing pickup of direct sound arriving from the front.  Next is appropriate time-alignment, such that the direct sound from the front which "leaks in" to that channel will not be smear the imaging provided by the the primary microphones when everything is mixed together.  That happens automatically if all the microphones are on the same stand and the rear-facing microphones aren't distant from the others.  It doesn't have to be perfectly aligned though, as it does for a typical matrix of multiple forward-facing mics- and I suspect a few milliseconds (corresponding to a foot or two between the front/rear pair) is helpful for differentiating the front from back, "keeping the front sound in front" via that slight time of arrival difference.

^That's most definitely the case for discrete surround playback where the rear channel is routed to speakers behind the listening position.  In that case the front-bleed into the rear channel, combined with insufficient front/back spacing perceptually pulls too much of the front direct sound into the rear surround speakers.   A little spacing provides time-of-arrival cues which helps keep the direct sound from the front sounding like its coming from the front, such that more rear facing channel ambience can be used before the front imaging shifts rearwards.  And for quieter sections where the front sound isn't considerably louder than the sound from the rear, it also helps keep the "rear sound in back", and better differentiated from the front. 

However, I'm not as certain about the front/back microphone spacing when mixing to 2-channel L/R stereo.  I know that the spacing I am using works nicely in my 2-channel mix, so I stick with it because it works well for both surround and stereo, but I'm not certain if less spacing might be better or not for 2-channel stereo alone.  It could be that having only level differences between the front/rear channels and no time of arrival differences will make for cleaner, less smeared front imaging.  It's probably a trade off depending on how much front/back level isolation can actually be achieved, because in a practical sense, the greater the front/back level difference there is, the less time-of-arrival difference should be required.  Varying the front/rear microphone spacing is something I encourage those of you trying these OMT setups to experiment with, including trying a coincident front/rear arrangement.  If you do so, please let me know.  From a practical point of view, reduced front/rear spacing will make for a more compact and potentially less visually intrusive setup.


After minimizing pickup of direct sound arriving from the front and achieving appropriate time-alignment, the third most important thing is the "de-mono-ization" of the rear-ambient pickup we've been talking about.  I'd probably not choose a rear-facing X/Y pair for "de-mono-izing" the rear ambience because X/Y with cardioids is center mono-heavy unless you use a very wide inclusive angle, and then you are going to get lots of front leakage into the sides of the cardioids.  X/Y supercards would be better, angled such that their shared null-axis points directly forward, but if using a pair of cardioids or supercards, I'd rather just space them out on the same bar which is supporting the omnis and point them directly rearward or maybe with a slight outward angle, keeping their minimum sensitivity axis facing towards the front.

I make a practical exception for a Mid/Side rear-facing pair (by the addition of a coincident Side fig-8 to the rear-facing cardioid/supercard), partly because it means the simple addition of the figure-8 to the already existing rear-facing microphone without otherwise changing it.  If the rear-microphone is a cardioid, the pattern nulls of both the cardioid and the 8 face directly forward and regardless of the Mid/Side output ratio all virtual output pair combinations will likewise feature a forward facing null, helping to limit pickup of direct sound from the front.  This is essentially the same as rear-facing X/Y supercards/hypercards angled such that their shared null angle faces forward.

^ I made some test recordings at Wanee year before last to experiment with front and rear facing Mid/Side pairs, but have yet to do anything with the rear facing pair.  In that case I placed Naiant X-8S fig-8's coincident with my standard front-facing supercardioid and rear-facing supercardioid, in order to turn them into front and rear facing Mid/Side pairs.  I recorded the rear-facing pair to the stereo channel of the DR-680 through a V3 feeding the digital input of the DR-680 so as to be able to record all 8 channels time-aligned on the same machine, and only messed around with comparison between the split omnis + a coincident Mid/Side stereo center, versus split omnis + a near-spaced 3-channel L/C/R center setup, as well as various combinations of the two.  I did so via a 2-channel mix directly out of the recorder using its Mid/Side playback function option.  The conclusion was that either center setup works well in 2-channel mix, they sound different from each other, both represent a significant improvement over a single center channel, and both together in a 2-channel mix is not necessary.  Also that the 3-channel near-spaced L/C/R center setup is superior for playback over 3 front speakers, which is not surprising.

In doing that comparison, I was struck by the absence of the rear-facing ambience channel, since in the direct-off-the-DR-680 monitor mix the stereo channel cannot be played back simultaneously along with the other 6 channels. I missed it!  And I've yet to get around to playing around with all 8 channels in the DAW including the rear-facing Mid/Side pair.

Quote
I update the link for phase plugin. I don't know if the plugin is high quality. But I tested it on the sum of mono. It is working very well. When decreasing the phase, the mono signal increases. And all is canceled for 180°.

Good test, which seems to confirm it is working correctly.

wfowumbo reminds me that this kind of equal phase rotation by frequency manipulation is called a Hilbert filter.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on October 13, 2018, 04:21:36 PM
OK,... Impr0v Oddball,...
Acoustic music, string quartet, w/ amplified vocal.  6' out from stage.
Binaural + Line Audio CM3 as 0º forward and 180º rearward.  The 0º forward mic is synched with the binaural. The ambient 180º mic is slightly rearward of the main three.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on October 14, 2018, 06:11:13 AM
Mike, you have started to use rear mics too! I am looking forward to hear from you how the rear channel complements Gude's head. Is it an improvement or is the rear channel negligible? I am curious too what you will say about using the rear mic for acoustic music. I don't tape a lot now. But if I have chance I always use OMT with rear channel for audience recording. Big thanks to Gutbucket.

Mike's setup brought me a question. Have somebody tried rear channel for onstage or stage lip? It can revive the recording, bring more audiences. But does it have any plus for music?

Gutbucket, thanks for your great explanation. I'm already infected like Moke, Kindms, Rocksuit, Heathen ... I'm thinking that I will try 6 channels next occasion.

Varying the front/rear microphone spacing is something I encourage those of you trying these OMT setups to experiment with, including trying a coincident front/rear arrangement.  If you do so, please let me know.  From a practical point of view, reduced front/rear spacing will make for a more compact and potentially less visually intrusive setup.[/i]

How we can setup coincidence arrangement? It is easy with vertical capsules. But the mic's bodies should influence sound for horizontal capsules.

wfowumbo reminds me that this kind of equal phase rotation by frequency manipulation is called a Hilbert filter.

I google it. Some very complicated math behind this (probably behind most of plugins we are using). Kudos to programmers.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on October 14, 2018, 10:20:01 AM
In a quick throwdown mix, I like it.
The 0º CM3 brought the vocal amplifier from its natural 1 o'clock position in the sound field, and, dragged it to the center at 12.  That was actually kind of a nice bend.  The binaural stereo aspect remained strong in headphone listening; rightfully. I've only listened to a few songs, and via headphones. But I have had a chance to compare binaural and bino-mix that way.  The binaural stereo is a bit softer presentation; the Mix is more dynamic, especially in vocal presentation.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 15, 2018, 09:20:11 AM
Cool setup Mike.  Thanks for sharing it here.  Let me know what you think about the rear facing channel in that setup.  Its usefulness may depend on how ambient the binaural recording is to begin with.  Try it simply panned center, and you might alternatively try it as Side channel matrixed with the Front as Mid.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 15, 2018, 09:42:07 AM
I am curious too what you will say about using the rear mic for acoustic music.

Have somebody tried rear channel for onstage or stage lip?

How we can setup coincidence arrangement? It is easy with vertical capsules. But the mic's bodies should influence sound for horizontal capsules.

Works great for acoustic music.  I pretty much always use the rear facing channel(s) when recording both onstage and out in the audience.  At the lip I take advantage of the stage edge itself as an acoustic barrier, mounting either a directional pair below the lip facing out into the room, or a wide spaced pair of omnis boundary-mounted onto the front edge of the stage facing out into the room.  That way the stage edge helps limit how much direct sound radiating from the stage sources reaches those microphones, yet the direct sound which does refract around the edge and leak in remains closely enough time-aligned that smear or echo isn't a problem.

To make the front/rear facing mics coincident just mount them side by side or one over the other, such that the capsules are aligned with each other in the fore/aft plane.  I posted photos of the side by side arrangement in the previous OMT thread.  In that case the microphones were not coincident, but tight enough to be able to fit under a single umbrella.  I'd shift them further forward/backward in the mounts to increase the spacing as long as the weather was good.

Here are a couple of those photos again-

(http://farm9.staticflickr.com/8486/8161220094_4880b2cea7_c.jpg)

(http://farm9.staticflickr.com/8477/8161220180_f1d3fa81b9_c.jpg)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on October 15, 2018, 09:47:30 AM
there are two Axis-Reference stereo bars on this page.
First time ever for two in the same thread/page?
heart swells with pride.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 15, 2018, 10:00:10 AM
Axis-reference, nice. Is that what you call your DIY mic-bars with the angle markings?

For those following, Moke made the bar supporting the microphones in the photos I just posted above, which features easy to read 90-degree inclusive markings at each mount point.  I've gotten a lot of good use out of that bar.  Thanks Mike!
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on October 15, 2018, 10:27:04 AM
I've built three or four of them.  SCB has one I made for DPA4028 pair.  Yours. and the one I'm presently using. 
I threw the one I'm using together on a rush, and then never followed up with the white markings. Its all scribed in, just not painted lines.
makes note to self,....
If Scott posts his in this thread, world balance might just change.

regarding the rear mic, and the binaural rig.
Yeah, probably not a necessary addition.  It did add something to the sound, didn't seem to detract, so I left it. 
The library did all of these upgrades to the room over the summer, since the last time we were in there. but, they still have an HVAC whoosh going on.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 15, 2018, 10:46:12 AM
Fun times!

I've had a Roland R-88 on loan from Spyder9's for the past couple months, and finally employed all 8 channels this past Saturday recording Ween at the Fillmore in Miami Beach.  It's a quite nice recorder, although almost comically large in comparison to the more contemporary compact Zoom F8.

I used the extra two channels to record a second rear-facing channel and a fig-8 Side channel coincident with the front-facing center.  I've been wanting to record a stereo pair of rear-facing channels for a long time, and the 8 inputs of the R-88 make doing that easy without needing to use the V3 to get more than 6 channels into the DR-680.  It also makes it possible to play back a stereo mix of all 8 channels directly from the recorder, including Mid/Side matrixing of the center pair.

If I move to recording 8 channels regularly, I think this arrangement is most likely to end up as my standard 8 ch OMT setup.  The other 8 ch option I'd like to try is placing front/back-facing figure-8's coincident with the wide-spaced omnis, allowing me to dial in front/back facing wide pairs of any pattern, but I can't currently support the weight of the 8's and their cables at the ends of the telescopic antennas.

Total channel count was as follows:
ch 1/2 = 4061 omnis in APE spheres (widely spaced, facing the rear corners of room)
ch 3 = 4098 supercard- 0º forward-facing center (Mid); ch 4 = Naiant X-8S fig-8- 90º sideway-facing (Side)
ch 5/6 = 4098 supercard Left/Right forward-facing pair- angled ~ +/-35º towards outside edge of stage/PA (forming near-spaced L/C/R triplet with center mic)
ch 7/8 = 4098 supercard Left/Right rear facing pair (angled/spaced such that their null angles more or less face directly forward, and such that the 5 supercard array has appropriate angle/spacing relationships all the way around.

A couple photos-
The 5 microphones in the center are the DPA 4098 supercards.  The center is in the big Shure windscreen along with a Naiant X-8S fig-8 forming the Mid/Side pair.  Zac, the other taper from California, was running Octava cardioids>FRLE2 and doing the entire tour.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 15, 2018, 11:18:59 AM
A few photos of the 6ch OMT rig about a month ago at a gig in a cool basement club, effectively "on-stage".  This was a tight spot for it, and I pretty much wedged it in next to the keyboard player.  This is my standard 6ch OMT setup featuring a single rear-channel, with big Shure windscreens on all 4 of the supercards.  This was also recorded into the R-88, serving as my first real test of that recorder.

Fantastic band featuring a couple local Joe Zawinul Syndicate members, doing Weather Report material.

Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 15, 2018, 11:49:06 AM
While I'm at it, below are a couple shots from my initial trial run of the R-88.  Same recording setup and same guitar player as above (Randy Bernsen) in a trio format with a couple different outstanding local musicians.  This was an anniversary party for the bar/brewery, at which I had not planned to record, but had the rig in the car just in case.  Sure enough, as expected the scene was not conducive to recording with no good place to make the effort to place the rig..  Yet upon walking around the back of the pop-up canopy forming the stage, I found the sound was not too bad behind the acoustically transparent backdrop immediately behind the drummer.  So I set up the rig back there simply to do a trial run.  Worked out better than expected, if nothing spectacular with the guitar and bass amps facing forward and the drummer's body occluding portions of the kit.  As you can tell from the photos, I actually shifted the rig off center towards the  bass-player's side in order to get a clearer path to the snare-drum around the drummer's back.

Title: Re: Oddball microphone technique (OMT) - part 2
Post by: jcable77 on October 15, 2018, 08:31:18 PM
A few photos of the 6ch OMT rig about a month ago at a gig in a cool basement club, effectively "on-stage".  This was a tight spot for it, and I pretty much wedged it in next to the keyboard player.  This is my standard 6ch OMT setup featuring a single rear-channel, with big Shure windscreens on all 4 of the supercards.  This was also recorded into the R-88, serving as my first real test of that recorder.

Fantastic band featuring a couple local Joe Zawinul Syndicate members, doing Weather Report material.
Nice GB. What was the lineup for this? Doesnt look like Scott Kinsey on keys but I cant tell? Love that stuff. Any chance of hearing it?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: EmRR on October 15, 2018, 10:34:20 PM
I always like seeing these rigs, food for thought.....
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on October 16, 2018, 07:43:03 AM
In a quick throwdown mix, I like it.
The 0º CM3 brought the vocal amplifier from its natural 1 o'clock position in the sound field, and, dragged it to the center at 12.  That was actually kind of a nice bend.  The binaural stereo aspect remained strong in headphone listening; rightfully. I've only listened to a few songs, and via headphones. But I have had a chance to compare binaural and bino-mix that way.  The binaural stereo is a bit softer presentation; the Mix is more dynamic, especially in vocal presentation.

Mike, it is good that bino-mix is sounding well. It is difficult for me to compare different variation and decide which is better. But I noticed that the more time I spent by listening and remixing the decision is easier. By the way you made nice stereo bar. I have one very similar but without angle lines. I will paint them too.

Gutbucket, many thanks for your posts and detailed explanation with photos. I appreciate it. It is great new that I can try omt for stage-lip and onstage. I like these setups a lot. The rig for Ween in FOB looks impressive.

Fantastic band featuring a couple local Joe Zawinul Syndicate members, doing Weather Report material.

The bass player of Weather Report Miroslav Vitous is living in my town. Unfortunately I can only use stealth setup at his little common gigs. By the way, I remember that you mentioned about basic omt for stealth setup for fun. I like this idea. I tried it once with two omnis and forward and rear cards. I put a lot of cables and I did not feel comfortable. But it was fun in the end.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 16, 2018, 10:23:05 AM
A few photos of the 6ch OMT rig about a month ago at a gig in a cool basement club, effectively "on-stage".  This was a tight spot for it, and I pretty much wedged it in next to the keyboard player.  This is my standard 6ch OMT setup featuring a single rear-channel, with big Shure windscreens on all 4 of the supercards.  This was also recorded into the R-88, serving as my first real test of that recorder.

Fantastic band featuring a couple local Joe Zawinul Syndicate members, doing Weather Report material.
Nice GB. What was the lineup for this? Doesnt look like Scott Kinsey on keys but I cant tell? Love that stuff. Any chance of hearing it?

Johnathan Joseph- drums
Randy Bernsen- guitar/midi-guitar
Jose Gola- bass
Abel Pabon- keys

They are playing gigs as WeatherUnderground

The above date was essentially a warm up down gig here prior to hitting the Iridium in NYC the following weekend. I need to mix it properly and hand it off to Joseph and Bernsen first, but I don't foresee any reason I shouldn't be able to share it.  Hang tight and I'll get to it.  It's the recording I've been most excited about recently and well worth the wait IMHO. I did make a slap-dash real-time stereo mix (R88>R44) the following day using headphones just to have something to listen to more easily, and because I might let the R-88 go. Also recorded a portion of their pre-show run-through as well (although cut short to save on limited card space), and it's real treat to hear everything snap into place as they work through a few of the more complex sections.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 16, 2018, 10:57:40 AM
The rig for Ween in FOB looks impressive.

The photo from below up toward the ceiling made me laugh out loud when going through them the next day.  Looks like some psychedelic taloned Ween bird Ween character / Klingon bird-of-prey swooping in to snatch a baby bunny or something.  Fortunately setup wasn't nearly as visually domineering viewed from audience level where the center array mics are all in the same plane.. except for the overall width at 6'.

Quote
The bass player of Weather Report Miroslav Vitous is living in my town.

Jose Gola is from Cuba (plays frequency with Gonzalo Rubalcaba).  He's an amazing player with monster tone.  The wide omnis really helped to capture his sound with an uncommon immensity, depth and envelopment.  Big shoes to fill as Jaco Pastorius was a South Florida native and he and Randy Bernsen grew up together here in Ft Lauderdale.

Let's keep the stealth discussions in PMs, thanks! Glad to hear you're enjoying this stuff and it's working well for you.  A critical aspect for sure is making these setups as easily manageable as possible/practical.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 16, 2018, 11:40:00 AM
Did some photo analysis to better determine the approximate microphone spacings and angles I used at the Ween show.  Mostly documented this for my own records so I can remember what I did moving forward.  Anyway, I submit the following for consideration in the "more information than anyone here is likely to want" category-
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: jcable77 on October 16, 2018, 07:46:27 PM
A few photos of the 6ch OMT rig about a month ago at a gig in a cool basement club, effectively "on-stage".  This was a tight spot for it, and I pretty much wedged it in next to the keyboard player.  This is my standard 6ch OMT setup featuring a single rear-channel, with big Shure windscreens on all 4 of the supercards.  This was also recorded into the R-88, serving as my first real test of that recorder.

Fantastic band featuring a couple local Joe Zawinul Syndicate members, doing Weather Report material.
Nice GB. What was the lineup for this? Doesnt look like Scott Kinsey on keys but I cant tell? Love that stuff. Any chance of hearing it?

Johnathan Joseph- drums
Randy Bernsen- guitar/midi-guitar
Jose Gola- bass
Abel Pabon- keys

They are playing gigs as WeatherUnderground

The above date was essentially a warm up down gig here prior to hitting the Iridium in NYC the following weekend. I need to mix it properly and hand it off to Joseph and Bernsen first, but I don't foresee any reason I shouldn't be able to share it.  Hang tight and I'll get to it.  It's the recording I've been most excited about recently and well worth the wait IMHO. I did make a slap-dash real-time stereo mix (R88>R44) the following day using headphones just to have something to listen to more easily, and because I might let the R-88 go. Also recorded a portion of their pre-show run-through as well (although cut short to save on limited card space), and it's real treat to hear everything snap into place as they work through a few of the more complex sections.
Thank GB. Psyched to hear it!!!!
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: aaronji on October 17, 2018, 08:52:07 AM
A few photos

I love that last photo ("listen and silent are spelled with the same letters")!  I wish more venues had that sort of thing, especially for quieter music, such as jazz or bluegrass...
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 22, 2018, 03:59:24 PM
I just posted the content below in another thread were we had been discussing sphere attachments for omnis, yet had been unable to find it since the title of the thread is Stereo Technique with MK41 or other super-cardioid Microphones (http://taperssection.com/index.php?topic=186823.msg2268485#msg2268485).  Anyway, I'm pretty much duplicating the same content here, where we've been talking more specifically and in depth about these things-


I recently came across a website specializing in classical recording, which has generously made available various comparative sample recordings for download.  The methodology seems very well-controlled in comparison to many taper comps, making these comparisons especially useful

   The Research on Classical Music Recording - for the future of music production and recording
   Nagoya University of the Arts, Kazuya Nagae
   http://kazuyanagae.com/ (http://kazuyanagae.com/)


Of the numerous comparisons linked there, one is of pairs of 60cm spaced DPA 4006 omnis with and without the DPA 50mm diameter APE sphere attachments installed. Listen for yourself and hear the somewhat subtle but certainly audible effect imparted by the spheres here- http://kazuyanagae.com/20110930windorch/index.html (http://kazuyanagae.com/20110930windorch/index.html)[/b]

Also hear the comparison of 30cm, 60cm, and 100cm omni spacing (without the sphere attachments)- http://kazuyanagae.com/20110420orch/index.html (http://kazuyanagae.com/20110420orch/index.html)

I've yet to explore the other comparisons available there.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on October 24, 2018, 10:05:37 PM
Apologies if this has been brought up and discussed already, but has anyone tried incorporating a vertically-oriented mic in the OMT setups?  I know this can be done with ambisonics, but I don't think there are many here incorporating an ambisonic mic in an OMT setup (other than Gutbucket).
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 25, 2018, 10:49:24 AM
I've not. Not saying upward facing microphones wouldn't ever be useful, it's just that there are so many other things I'd use an additional channel for that take precedent, except in special cases*.. and I see a fundamental problem with upward facing microphones that I'll explain below.  Other than a few test recordings at Wanee a few years ago that I never really got around to messing with, it wasn't until just recently that I ran a pair of rear facing microphones instead of a single rear-facing channel, which I suspect is more important than an upward facing one.  And I didn't do either until moving to recording 8 channels rather than 6.

*A special case- I've pointed the single rear-facing channel upwards (sort of diagonally up and back) when there was some obstruction like a wall immediately behind the recording position to avoid a strong reflection off of it.  Rocksuitcase and Kindms have done the same and posted a photo of it in this thread, but I'd have to go back to look for it.  In those cases the upward-facing channel proved useful in lieu of a rear-facing one. 

More thoughts on this in a following post..
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on October 25, 2018, 12:25:54 PM
Apologies if this has been brought up and discussed already, but has anyone tried incorporating a vertically-oriented mic in the OMT setups?  I know this can be done with ambisonics, but I don't think there are many here incorporating an ambisonic mic in an OMT setup (other than Gutbucket).
At least once we oriented the ck22's (omnis) up as opposed to pointed forward, but that shouldn't matter much to the overall blend of the 4 or 6 channels. I think you are asking about the center mic(s) being oriented vertically? As gut mentioned, we did that to compensate for a close wall to the rear mic once. Pic is in this thread or in rig pics- fall 2017 or so timeframe.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 25, 2018, 12:43:28 PM
If you mean the forward-facing center mic, I point that towards wherever the cleanest direct sound is coming from, and if that's a hanging PA at an elevated angle, I point the front-center mic more upwards to focus on that to the exclusion of everything else.  That scenario can actually help reduce the pickup of the audience directly in front of the recording position in that channel.  And I basically want any rear-facing channel(s) pointed as far away from that as possible.  Again, the exception being that if that rear-facing microphone is going to pickup a strong reflection of the direct-sound of the back wall or whatever.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 25, 2018, 01:08:23 PM
More and more I find it important to differentiate as much as possible the direct-front-arriving-sound from the diffuse sound which arrives from all directions essentially equally.  I increasingly see this as one of the more fundamental aspects which OMT exploits.  Even though the diffuse sound arrives from all directions equally, if we are to try to pick it up to the exclusion of the front-arriving direct-sound, we need to point the microphones further away from the front in order to skew the balance as far as possible toward the diffuse stuff.   Not because the diffuse sound is any stronger from that direction, but because the front-arriving direct sound is sufficiently less strong there. And that strong front-arriving direct-sound is not just coming from directly forward at 0-degrees, it is actually arriving from a pretty wide angle across the entire front quadrant.

The fundamental problem I see with upward facing microphones is that regardless of the microphone pattern used, they will simply pick up too much front direct-sound.  The sideways-facing supercards I use as my primary Left/Right channels have a loads of front-direct-sound in them.. much more than most folks realize.  They need to, because with surround playback they are directly feeding the Left and Right front speakers.  Similarly, just like my sideways facing L/R pair, an upward facing supercard would also be 90-degrees off-axis and pickup about the same amount of frontal-direct-sound.

Sure, direct-sound arriving from straight ahead is about 9dB down in a 90-degree off-axis supercard (which isn't really that much), yet the direct-sound from in front isn't arriving from just dead-ahead.  It is actually spread out across the front quadrant.  So what we should really consider is something more like the the average sensitivity across the front quadrant for any microphone facing 90-degrees off-axis.  Sound arriving 45 degrees off-axis to a supercard is only 2 dB down.  Even with an figure 8 the sound arriving from 45 degrees off-axis is only -3dB down.  A figure-8 has a nice deep null at 90-degrees off-axis, but it's simply not wide enough to be effective at this.

If you ever use a center Mid-Side pair in combination with a rear-facing cardioid or supercard channel, you can hear this for yourself by soloing just the Side channel, then the rear-facing cardioid channel, and comparing the two.  Listen to how much front-direct-sound is in the Side channel in comparison to the rear facing channel.

Because of that, I think any microphone intended to exclude the front direct sound as much as possible needs to be a supercardioid pointing at least 130 degrees away from the front, or a cardioid pointing even further away from the front.   And I feel this is just as important when the intent is mixing to 2-channel stereo as it is for surround.


Although I see getting sufficient direct/diffuse differentiation as most important, there are other less important things the rear-facing microphones can provide.
Picking up the direct-sound components of audience reaction and room reflections arriving from behind is very nice for both 2-channel and surround (more so for surround where it anchors things with discrete sounds from directions other than the front), but is a far second to getting good diffuse sound with minimal frontal-direct sound in it.  And many times there may not be much if any good direct audience reaction stuff or good room reflections back there anyway, depending on the venue and recording position.

So somewhat upward-facing when backwards-facing isn't practical.  Otherwise I see it as an unnecessary extravagance, even if one was actually recording for surround playback that includes overhead speaker channels, where I suspect it would be more fruitful to use ambience-extraction/decorrelation techniques to generate those extra channels from the existing surround channels.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on October 27, 2018, 03:27:49 PM
Thanks for your posts about the microphones in vertical direction in OMT.  Thanks too for the photo analysis to determine spacings and angles of your rig at the Ween show. It will be useful and it is good to see it in real photo with all dimensions. I can imagine it better now.

Jose Gola is from Cuba (plays frequency with Gonzalo Rubalcaba).  He's an amazing player with monster tone.  The wide omnis really helped to capture his sound with an uncommon immensity, depth and envelopment.  Big shoes to fill as Jaco Pastorius was a South Florida native and he and Randy Bernsen grew up together here in Ft Lauderdale.

I didn't know that Jaco was a Florida native. I listened to a few music with Jose Gola on the internet. You are right, he is playing great. You have a good substitute for Jaco. I hope Jose is travelling often to Europe.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 28, 2018, 06:06:50 PM
All those guys have immense talent.  Its a real privilege to be able to record them.

The Ween recording setup will sort of serve as a baseline for me as I begin to play around with the rear facing pair configuration.  I plan to do some testing of variations on the setup in our warehouse after hours, which is a large reverberant space.  I test by walking around the array at various distances, calling out the number of the clock and clicking a dog-clicker (a test I sometimes do while still setup after some events as other tapers at the Spirit of the Suwannee Music Park may recall).  In this more-casual controlled situation I'll probably also use other signals like carrying around a little speaker producing pink-noise, or dragging a piece of chain or scrap metal on the concrete floor, etc.  It's informative to listen to how that translates in terms of source-location imaging, the distribution of reverberation, and the general feel of the ambience.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on October 29, 2018, 05:44:32 PM
All those guys have immense talent.  Its a real privilege to be able to record them.

I understand that very well. And the cherry on the cake is that you used the omt setup.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: noahbickart on October 29, 2018, 05:52:54 PM
Is a recording with a m/s pair and a spaced omni pair OMT?

If so, check this out:

http://bt.etree.org/details.php?torrentId=602481

Phish
October 28, 2018
Allstate Arena; Rosemont, IL

Show Time: 7:30 pm
Doors Open: 6:00 pm

Location: FOB, DFC
Source 1: Schoeps mk3 [aka mk2xs] (A-B @ 50cm )> Nbob actives> Naiant PFA> Sound Devides Mixpre6 (Mic in Channels 1/2 @ 24bit, 48kHz)
+
Source 2: Schoeps mk21/mk8 (MS)> Nbob KCY> Naiant PFA> Sound Devides Mixpre6 (Mic in Channels 3/4, onboard M/S Encode @ 24bit, 48kHz)

Transfer: Sound Devides Mixpre6> USB-C> Macbook Pro> Reaper (Mixing, DSP if applicable)> Sound Studio (Tracking & Fades)> izotope SRC & Dither (if applicable)> xAct (Flacing and Tags)

16bit file sets have DSP (dynamics and eq processing)
24bit file sets are normalized raw files only

Recorded and Transferred by Phishrabbi (noahbickart@gmail.com)

Set One:

Everything's Right
Destiny Unbound
Heavy Things
Miss You
Tube
Petrichor
I Always Wanted It This Way
Grind

Set Two:
Carini>
No Quarter>
Cities
Gotta Jibboo
Twist>
What's The Use?>
Twist
Shade
Plasma
Character Zero

E: Fluffhead
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: ycoop on October 29, 2018, 06:32:36 PM
^yep. it has a diagram in Gutbucket’s OMT PDF.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 29, 2018, 10:23:33 PM
Thanks Nick!  On the torrent now and I'll check it out when I get back from a trade show which is about to start. 

Yes, I think M/S between omnis makes for a quite attractively simple yet well-reasoned 4-channel OMT setup, combining directional coincident and spaced omni stereo techniques. with sharp imaging level-based stereo across the center plus lush, ambient time-of-arrival based stereo from the omis.  I'll be interested to hear this.  How do you like it compared to the near-spaced pairs you typically run? 

I also still need to give a serious listen the previous set of 3 pairs you made available which I grabbed but haven't had time to review yet.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 29, 2018, 10:29:52 PM
Did you play around with the Mid/Side ratio of the center pair when dialing in the mix with the omnis?  If so what ratio did you end up gravitating towards?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on October 29, 2018, 10:42:38 PM
Working late getting ready, and decided to listen to the Fluffhead encore before heading out the door.

Sounds really good to me Nick!  It has the OMT essence I like and aim for- clear center image with wide enveloping audience and ambient big-ness!  Sounds like I'm there, and has me smiling after a long, grueling day.  Thanks for that.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on October 30, 2018, 05:40:29 AM
Noah, it sounds superb. Thanks for the recording and sharing it here. I'm also curious about what do you think about changing M/S ratio when mixing it with spaced omni.

Source 1: Schoeps mk3 [aka mk2xs] (A-B @ 50cm )> Nbob actives> Naiant PFA> Sound Devides Mixpre6 (Mic in Channels 1/2 @ 24bit, 48kHz)

I thought you had only inches and feets in States. That's good, next time I do not have to recalculate spacing, I will leave it in centimeters.

Edit: I just noticed that you recorded multiple sources and put all on bt.etree.org. So we all can play with the mix of M/S and omni. Many thanks for your big effort! Great opportunity for comparing individual configurations and microphones patterns of top quality mics as well as omt mix. That is very helpful. Maybe it would be worthwhile to keep it all together somewhere for others tapers. Please, what config did you setup for MK21 and MK22 source?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: noahbickart on October 30, 2018, 10:23:50 AM
Here's my 24bit mix:

https://drive.google.com/open?id=1g6P51snmiYj4XN2CXz0WMMGnaoYcirIG

-Noah
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: ycoop on October 30, 2018, 02:10:18 PM
Working late getting ready, and decided to listen to the Fluffhead encore before heading out the door.

Sounds really good to me Nick!  It has the OMT essence I like and aim for- clear center image with wide enveloping audience and ambient big-ness!  Sounds like I'm there, and has me smiling after a long, grueling day.  Thanks for that.

I concur with Gutbucket. It sounds like I’m there. Solid listen on both my over-ears and earbuds.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on October 30, 2018, 11:20:41 PM
Nothing too wild here.  AT4031s at approximately 110* and 13" apart.  In the center are forward and backward facing AT853 subcards.  The forward-facing AT853 is either lined up with the AT4031s horizontally or slightly in front of them.  I used this for a show last weekend (Spafford and Cycles) but couldn't get a good photo at the venue so I set it up again at home.

I know what you're thinking.  "My god, the beauty of that old world craftsmanship on display in the AT853 mount."  That is a cardboard and gaffer tape concoction passed down through the generations.  Rycote, eat your heart out.

So far I've only processed the Cycles set.  For that one I left out the backward-facing AT853.  I may use it for the Spafford set...whenever I get around to processing that.  The Cycles set can be heard here: http://taperssection.com/index.php?topic=188428.0
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kingdong on November 07, 2018, 10:47:50 AM
Maybe a little off topic, but I noticed a photo of "Professor Fellgett with his ambisonic equipment" on Ebay today and thought others might want to see it...
https://www.ebay.com/itm/Professor-Fellgett-with-his-ambisonic-equipment-Vintage-photo/143001097985?hash=item214b879701:g:D7gAAOSwiJhbq-LR:rk:14:pf:0
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: goodcooker on November 08, 2018, 09:13:29 PM

There was a messy desk thread way back when...I think we need to revive it.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on November 09, 2018, 09:49:14 AM
Ugh, you don't want to see my desk!

[edit- kingdong that's a cool photo.  I've never come across Professor Fellgett in researching ambisonics, do you know anything about him? Too bad it does not show the ambisonic equipment in more detail. That was really specialized stuff back in the day.  What we can now do easily digitally on the computer was much more challenging to pull off successfully with analog equipment, due to the precise calibration and balancing required to make all the the matrixing work correctly without level and phase mismatches skewing everything.  We have it so easy by comparison.  It amazes me that we are now recording 6 or 8 channels regularly as tapers and how just that, much less recording ambisonicly, would have blown the minds of those folks doing it 4 decades ago]
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on November 13, 2018, 01:01:24 PM
Kickdown link to Kyle and Mike's most-recent OMT recordings-  https://taperssection.com/index.php?topic=188578.0

Thanks for posting this guys!  This is interesting here for providing a comparison of two OMT setup variants made at the same show, using the same common microphones and signal path.  The difference between the two represents a choice of which microphone feeds were used, and the mix itself.  It's quite helpful to hear these two mixes using different microphone combinations with the other variables held constant.

Kindms' OMT4 mix (4 microphone channels total) uses a front/back facing pair of AKGck61 between 3'/90cm spaced omnis.  This pretty much makes for a baseline OMT4 recording in the way Mike and Kyle have been realizing the OMT setup up to this point (although sometimes using the ck61s in X/Y instead of front/back, IIRC)

Rocksuitcase' OMT5 mix (5 microphone channels total) builds upon Mike's newly acquired AKG426 LD stereo microphone, set to crossed hypercardioids with a 55-degree inclusive angle (I presume Pointed At Stacks or pointed just outside of them).  Starting from that, the 3'/90cm spaced omnis are added, as well as the forward facing ck61.  The rear-facing ck61 channel is unused in this mix.

[Edit- I've make some assumptions in this post and the one which follows.  If I've assumed incorrectly, please correct me]
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on November 13, 2018, 01:01:37 PM
My thoughts-
The clarity and stereo image in the OMT5 mix really grabs me.  I have a soft spot for crossed hypercardioids, as they often get a lot of things right to my way of thinking, sounding really good to me in a number of important ways, and I think this particular set up choice of angle and pattern is well chosen.  In addition to the stereo imaging aspects, there is a very nice clarity, heard especially in the vocals and percussion transients, and the stereo ambient pickup to the rear is nicely balanced against the direct sound arriving from the front.

Part of that is related to the high-quality 426>V3>(SPDIF maybe?)>DR680 signal chain, but a lot of it reflects aspects of the microphone configuration itself.  I've posted previously about how I consider crossed hypers as being something akin to improved Blumlein crossed 8's for real-world taper situations, in that it provides similar imaging and ambient qualities, but with an increased forward-sensitivity bias which makes the perfect placement in a perfect room which Blumlein requires far less critical.

Similar to Blumlein, crossed hypercardioids is sort of like using four center microphones (a forward facing pair + a rear facing pair) instead of two, but with the mix of the four being fixed.  The crossed rear lobes of the hypercard pattern serve a similar role as dedicated rear-facing microphone channel(s).  The difference is that the front/back reverberant balance is fixed, or rather adjusted beforehand by choice of the pickup pattern and the angle between microphones, rather than via mix level of a separate rear-facing microphone (or rear-facing pair).  For those unfamiliar with the microphone, the single-point-stereo AKG426 provides a choice between 9 (IIRC) electronically switchable pickup patterns ranging from omni to figure-8, which may be set separately for either channel, as well as variable angle between the microphone capsules.

In an OMT setup, the narrow included angle of the central X/Y pair works well for a couple reasons: It points this coincident center pair of microphones so that they are more-or-less on-axis with the primary sound radiators (the PA stacks), providing good direct sound clarity; and it solidifies the center without concerns about loss of spaciousness or stereo width carried by the omnis.  Addition of the forward-facing AKGck61 further increases forward bias and center solidity.  And in a practical sense it provides an additional degree of freedom in the mix.

Kyle, I'm most curious about your thoughts while mixing this concerning the included angle of the 426 in combination with the center ck61:

Do you think you would have used as much ck61 in the mix if the 426 had been set to a slightly more forward directional supercardioid pattern?
Similarity, do you think you would have used as much ck61 in the mix if the 426 had been set to a slightly narrower inclusive angle?
^Those questions hint at the possibility of OMT4 incorporating just the 426 + omnis.  Curious if you speculate that if the most-appropriate pattern/angle combination for the 426 could be determined beforehand (a big if), no forward facing ck61 would be needed.

Alternately, going the opposite way:
Assuming the center ck61 is not "optional" but included as a necessary addition in the microphone setup and mix (with or without a rear facing mic), I wonder about a wider inclusive angle with the 426.  I could see an "over wide" angle of greater than 90 degrees working well as long as the center ck61 is there to hold the center in place.  That would have the front/back facing center pair playing a bigger role as necessary additions to the directional stereo imaging and stereo ambience provided by the 426.  The 426 would no longer be PAS or near PAS, which may be less appropriate in term of direct clarity from a relatively distant recording position in a reverberant room, but it would reduce interaction between 3 the similarly pointed, close-to-coincident channels channels (L/C/R).  The question then becomes- "how wide" and secondarily -"which pattern", both of which get me thinking about how the nulls of super/hyper/fig-8 patterns are oriented and what influence that would have.  Here's a hypothetical- should we use crossed fig-8's and point the nulls just outside the PA stack on the opposite side?  Anglewise with the 426, that would be pretty much the opposite of what you have here (at 55 degrees inclusive), definitely requiring the forward facing supercardioid to compensate.

Or perhaps best to split the difference between those two, using a traditional 90-degree inclusive angle for the 426 in hypercard, supported with the center-front (and possibly rear) facing microphones, which also provides redundancy of the 426 on its own as purist coincident stereo.  Fun to think about the possible variants to toy around with.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on November 13, 2018, 02:46:21 PM
I also prefer the mix that adds the C426.  I like the strong center image and direct sound...and all the benefits that come with that.

Did you guys try a mix with just C426 and omnis, without the 61s?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kingdong on November 13, 2018, 03:11:14 PM
[edit- kingdong that's a cool photo.  I've never come across Professor Fellgett in researching ambisonics, do you know anything about him? ...]

I hadn't heard of him before I saw that ebay listing which came up when searching 'ambisonics' which of course sent me down a little rabbit hole.  He gets mentioned in the wikipedia ambisonics entry, but there were some more cool photos and info here:
https://www.michaelgerzonphotos.org.uk/ambisonics.html
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on November 13, 2018, 03:21:24 PM
My thoughts-
 I've posted previously about how I consider crossed hypers as being something akin to improved Blumlein crossed 8's for real-world taper situations, in that it provides similar imaging and ambient qualities, but with an increased forward-sensitivity bias which makes the perfect placement in a perfect room which Blumlein requires far less critical.

Similar to Blumlein, crossed hypercardioids is sort of like using four center microphones (a forward facing pair + a rear facing pair) instead of two, but with the mix of the four being fixed.  The crossed rear lobes of the hypercard pattern serve a similar role as dedicated rear-facing microphone channel(s).    Response to this below in red

Kyle, I'm most curious about your thoughts while mixing this concerning the included angle of the 426 in combination with the center ck61:

Do you think you would have used as much ck61 in the mix if the 426 had been set to a slightly more forward directional supercardioid pattern?   responses in green
Similarity, do you think you would have used as much ck61 in the mix if the 426 had been set to a slightly narrower inclusive angle?                       responses in green
^Those questions hint at the possibility of OMT4 incorporating just the 426 + omnis.  Curious if you speculate that if the most-appropriate pattern/angle combination for the 426 could be determined beforehand (a big if), no forward facing ck61 would be needed.           response in blue

Alternately, going the opposite way:
Assuming the center ck61 is not "optional" but included as a necessary addition in the microphone setup and mix (with or without a rear facing mic), I wonder about a wider inclusive angle with the 426.  I could see an "over wide" angle of greater than 90 degrees working well as long as the center ck61 is there to hold the center in place.  That would have the front/back facing center pair playing a bigger role as necessary additions to the directional stereo imaging and stereo ambience provided by the 426.  The 426 would no longer be PAS or near PAS, which may be less appropriate in term of direct clarity from a relatively distant recording position in a reverberant room, but it would reduce interaction between 3 the similarly pointed, close-to-coincident channels channels (L/C/R).  The question then becomes- "how wide" and secondarily -"which pattern", both of which get me thinking about how the nulls of super/hyper/fig-8 patterns are oriented and what influence that would have.  Here's a hypothetical- should we use crossed fig-8's and point the nulls just outside the PA stack on the opposite side?  Anglewise with the 426, that would be pretty much the opposite of what you have here (at 55 degrees inclusive), definitely requiring the forward facing supercardioid to compensate.

Or perhaps best to split the difference between those two, using a traditional 90-degree inclusive angle for the 426 in hypercard, supported with the center-front (and possibly rear) facing microphones, which also provides redundancy of the 426 on its own as purist coincident stereo.  Fun to think about the possible variants to toy around with.
Re Hypercardiods: I used crossed Hypercards for most of the first 20 years I was taping. My early mentor at SU, Mark Fitzgerald, took the spec sheet of the Sony TCD5M and compared the input output sensitivities and "matched" them to the microphone he thought would best do the job of making a decent recording from a diffuse field. Hence we wound up with Beyer Dynamic M201c's. We all had the textbook of the era, David Miles Huber's "Modern Recording Techniques" which led us to the Hypercardiods crossed in XY, which we ran typically at 90" but occasionally at 110'. He explained it exactly as Lee does above, properly aligned, you actually can get the rear "quadrant" picked up as a result of the math.

I do feel that the 55' angle of the crossed Hypers allowed for a "smooth" addition of the CK61 cardiod to the center of the mix. If we had gone with "supercards" at 55' it may have required less ck61 in the mix for the reasons you mention; the supercard would have brought out more of the center vocals and imaging wise (IMO).

As for the choice of angle pre show, since we record in this venue often, I did tell Mike it would probably wind up being 55 or 60'; and yes, the 55' was essentially PAS as the Cap's PA is set a bit wide. Additonally to your point, while mixing I turned off the center ck61 many times to hear what just the 4 channel (426 hypers plus ck22 spaced omnis) would sound like. There was just enough centering and vocal clarity added which made me keep it in the mix; but as anyone who mixes OMT knows, you are making trade offs at every turn! For this OMT5 choice, I am happy with the tone and overall sound quality.
OTH- I am not 100% sure as to why kindms used the OMT4 with no 426 in the mix, but my ears told me this was a possibility as well. One variable which skews against typical OMT results IS the superior quality of this AKG C426 microphone and signal chain (V3 -> 680) which does appear to blend well with the AKG ck22 omnis.

I'll come back in and address the final thoughts here later (running 426 and spaced omni only):
Going the other direction, I DO feel running the 426 at 90 or 110 degrees would allow for a great stereo image then adding a cardiod in the middle would be just right. Of course, all this discussion implies running spaced omnis as well. So either an OMT5 or OMT6 with a rear channel added would make for a solid recording using the 426 this way.

Secondly, but equally as important, is the decision as to what capsule pattern(s) to use. Riffing off your idea Lee:
426 at 55' or 60' in Hypercards + ck61 (cardiod) front + ck22 (Omnis) spread at least 90cm is what we have run 2-3 times so far. The 426 in Hypers is very nice sounding BUT the narrow angle probably prevents the pair from being an ideal "safety" pair (to obtain a 2 ch recording no matter what else).

426 at 90' or 110' (Cards or subcards or fig 8) +ck61 cardiod + omnis pair would allow for a safety pair plus allow flexibility in mixing just as you mention, I suspect. I would try this in an outdoor venue or an acoustically perfect setting such as the Egg, but not in a reverberant large room such as MSG.  I am thinking what Lee is, that the combination would allow for a nice wide stereo image from the 426 plus a solid center via ck61 using the 426 in subcards or cards. Using it in fig 8 would be a different sort of mix but also something I would try.

To wrap this up, we did try the AKG C426 in "subcards" (#7 on the 9 ch box (AKG A26?)) at 90' by with zero other channels at Bob + Wolf bros 11-09 just because the HEAVY rain prevented us from slinging all the gear for 6 channels. The result was VERY good. (as kindms mentioned, the house was full for Bob but half full for New Bohemians- which obviously does influence the direct to reverberant ratio.)

Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kindms on November 13, 2018, 07:12:33 PM
RE: Why I mixed ck22 + ck61 vs. ck22 + ck61 + c426

I will admit to being a know nothing when it comes to mixing etc. I just know what i like. So I mixed for that. I tend to load them all in audacity and then feel it. I found I was able to get something smooth with the 4 mics I chose to use, I honestly didnt have any real philosophical reason for doing so.

I also rolled the bass quite a bit in my mix which i almost never do. To get an idea the bob weir recording we made the night after is almost in the same spot of the room with the 426. The difference is pretty striking. The room was of course at max for Bobby so we think most of that boom was the open room. which is why i dropped the rear ALOT but left it in.

To speak to crossed hypers on the c426. I wqas listening to the Bobby in the car and definitely on several occasions the crowd source was behind me. Put a nice smile on my face.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on November 14, 2018, 09:54:17 AM
I tend to load them all in audacity and then feel it.
A totally appropriate philosophy!

Yeah, a full house usually means a shorter reverb decay time / tighter sound.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on November 14, 2018, 01:10:14 PM
I tend to load them all in audacity and then feel it.
A totally appropriate philosophy!

Yeah, a full house usually means a shorter reverb decay time / tighter sound.
Updated my post above responding to the alternative configurations gutbucket mentions.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on November 14, 2018, 03:52:10 PM
Going the other direction, I DO feel running the 426 at 90 or 110 degrees would allow for a great stereo image then adding a cardiod in the middle would be just right. Of course, all this discussion implies running spaced omnis as well. So either an OMT5 or OMT6 with a rear channel added would make for a solid recording using the 426 this way.

Secondly, but equally as important, is the decision as to what capsule pattern(s) to use. Riffing off your idea Lee:
426 at 55' or 60' in Hypercards + ck61 (cardiod) front + ck22 (Omnis) spread at least 90cm is what we have run 2-3 times so far. The 426 in Hypers is very nice sounding BUT the narrow angle probably prevents the pair from being an ideal "safety" pair (to obtain a 2 ch recording no matter what else).

Since folks doing OMT generally aren't averse to tweaking stuff, it might be useful to consider a Mid/Side adjustment done afterwards as an intended part of the arrangement.  So if coincident 60 degree hypers on their own produce an image which is a bit overly narrow, yet achieves the desired clarity by being appropriately on-axis to the stacks, perhaps the best course will be to widen that afterwards to taste to produce the a 2-channel purist "safety pair" output that has both sufficient clarity and good image-width.

Likewise, tweaking that could be useful in an OMT mix as well.  And doing so takes advantage of the phase-difference-free nature of the 426 coincident-pair
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on November 14, 2018, 04:03:29 PM
Going the other direction, I DO feel running the 426 at 90 or 110 degrees would allow for a great stereo image then adding a cardiod in the middle would be just right. Of course, all this discussion implies running spaced omnis as well. So either an OMT5 or OMT6 with a rear channel added would make for a solid recording using the 426 this way.

Secondly, but equally as important, is the decision as to what capsule pattern(s) to use. Riffing off your idea Lee:
426 at 55' or 60' in Hypercards + ck61 (cardiod) front + ck22 (Omnis) spread at least 90cm is what we have run 2-3 times so far. The 426 in Hypers is very nice sounding BUT the narrow angle probably prevents the pair from being an ideal "safety" pair (to obtain a 2 ch recording no matter what else).

Since folks doing OMT generally aren't averse to tweaking stuff, it might be useful to consider a Mid/Side adjustment done afterwards as an intended part of the arrangement.  So if coincident 60 degree hypers on their own produce an image which is a bit overly narrow, yet achieves the desired clarity by being appropriately on-axis to the stacks, perhaps the best course will be to widen that afterwards to taste to produce the a 2-channel purist "safety pair" output that has both sufficient clarity and good image-width.

Likewise, tweaking that could be useful in an OMT mix as well.  And doing so takes advantage of the phase-difference-free nature of the 426 coincident-pair
I like this idea. One thing which slows me down at this point is lack of skill doing the M/S adjustments. kindms has done our MS decoding in the past by doing the simple technique(s) but we've not extensively used the M/S adjustment tool(s).
OTH- you've written recently about fig 8's crossed or M/S in the center (fwd, rear or both) and I feel with the 426 we could easily do some of these configs.
Also, you have a point about the yumminess of EXACT coincidence at the capsule end. This microphone is proving to be an excellent pick-up and truly allows us flexibility one could never have with just stereo pairs.
For instance, we have already run the 426 in: [1] Hypers at 55',60',90 ; [2] cardiods at 60 [3] "supercard" at 90 [4] one cap at 0' and the other at 180' cardiod to be a"classic" center for an OMT6 we did at Phish (2018-11-17)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on November 16, 2018, 03:31:40 PM
Kyle, what Gutbucket is saying is not a bad idea. You can save the center microphone and quite similar result you can achieve with akg426 and M/S manipulation. Then you can use the center microphone for something else (for example, to make a stereo side or rear facing pair).
On the other hand, I understand you. You use Audacity, and the possibilities of mixing are very limited there. Then the center microphone with akg426 makes sense.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on November 16, 2018, 03:54:29 PM
Kyle, what Gutbucket is saying is not a bad idea. You can save the center microphone and quite similar result you can achieve with akg426 and M/S manipulation. Then you can use the center microphone for something else (for example, to make a stereo side or rear facing pair).
On the other hand, I understand you. You use Audacity, and the possibilities of mixing are very limited there. Then the center microphone with akg426 makes sense.
kuba- I feel you are correct. There is a way to do rudimentary MS via Audacity. Not to mention I truly need to go up to izotoope or some other software with ability to do good plug ins. You get what you pay for and Audacity is free.
As for the mic config then we would running only the 426 for the center/rear + Omni spread, thus could use the other two channels for a side facing card midway between center and omni like gutbucket does with the subcards.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on November 18, 2018, 10:52:25 PM
Trying again, with another impromptu rigging.

Poway Symphony Orchestra
2018-11-18 sunday

DPA4060 pair as 16' spaced pair, with APE response balls, and mics forward @0º just emerging from the balls, with grids only exposed.
Line Audio CM3 pair as 0º forward and 180º rearward, from the stage lip, center.
Mics arranged along the stage lip edge.
Tas. DR70D 24.96

And, also Gude Head binaural stream_ R09HR 24.96 from 1st row DFC

these are shareable, and will be going to LMA
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: down2earthlandscaper on November 19, 2018, 11:43:44 AM
Trying again, with another impromptu rigging.

Poway Symphony Orchestra
2018-11-18 sunday

DPA4060 pair as 16' spaced pair, with APE response balls, and mics forward @0º just emerging from the balls, with grids only exposed.
Line Audio CM3 pair as 0º forward and 180º rearward, from the stage lip, center.
Mics arranged along the stage lip edge.
Tas. DR70D 24.96

And, also Gude Head binaural stream_ R09HR 24.96 from 1st row DFC

these are shareable, and will be going to LMA

This looks really interesting. Looking forward to checking it out when you post it. Thanks!
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on November 19, 2018, 09:42:21 PM
just posted this 1644 version (and missed properly id'ing it in the title. doh!)
don't use this link: https://archive.org/details/pso2018-11-182018-11-18.omt-mix_16
the retarded link, for now, ^^

and, the fixed link:
https://archive.org/details/pso2018-11-18.omt-mix_1644
https://archive.org/details/pso2018-11-18.omt-mix_2496
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on November 19, 2018, 09:56:42 PM
just posted this 1644 version (and missed properly id'ing it in the title. doh!)
https://archive.org/details/pso2018-11-182018-11-18.omt-mix_16 
the retarded link, for now, ^^

This is great!
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on November 20, 2018, 05:13:07 PM
just posted this 1644 version (and missed properly id'ing it in the title. doh!)
https://archive.org/details/pso2018-11-182018-11-18.omt-mix_16 
the retarded link, for now, ^^

This is great!

Yes, It's sounds excellent. Beautiful recording and music. Mike, thank you and orchestra for taping and sharing. 

How much did you add rear mic to the mix? What do you think is better -  to have the center mics forward and rear or to have both center mics forward in xy? I know, Gutbucket and you have an experience with acoustic music. I will make a recording of acoustic music, much smaller ensemble, voices and 2 or 3 instruments. I'll use a rig with four microphones, probably near the podium. Center pair are cardiods, spaced pair are omnis. And I do not know how to set the center pair. I'm tempted to do like you - let go the stereo created by xy and instead use front and rear mics.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on November 20, 2018, 05:32:19 PM
Thanks much, gents!

Kuba,
I used the rear mic as it was in the master, and mixed it in at that amplitude, and mixed to center.  I had the level of that mic set to where it balanced with the other three mics, but only during the applause. other than that, during the music, I so desperately wanted to "turn it up". 
The rear mic, in my use, is mostly redundant for what it offers. The omnis had explosive ovation response, and needed to be tamed a bit, so that everything else could be brought up. So, the rear mic is mostly what offers the audience ovation response, as the omnis were compressed through the ovations. The ovations were easily +12dBfs over the music, and into the peaking red zone via the 4060 pair. Limiter? yeah probably should have used it, but, haven't done so in decades.

the links above were updated to include the 2496 file set.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on November 20, 2018, 06:36:27 PM
Thanks for the reply. Yes I understand, the audience should be very loud in acoustic recordings. Sometimes I lower audience applause in master track manually. It is extra work to mark the segments of the applause. But when those segments are correctly selected, the jump in volume is not heard.

I tried the rear microphone on just two recordings and it was always interesting. Next time I will not record myself, but I will lend rig to my friends. They are doing amateur classical music. I will tell them to set it up with the rear microphone.  ;D
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: ycoop on November 27, 2018, 04:51:39 AM
https://archive.org/details/cats2018-11-21.avantCA14mix

This is my first attempt at more than 2 channels, though I’m not sure it qualifies as OMT exactly, due to not going XY in the center.  Listening back to either stereo pair in isolation gives me a good idea of the benefits/detriments of spaces omnis vs near coincident and also how the combination of the two can sound *much* better. I feel confident saying this is my best recording to date.

I ran the CK1 cards in DIN to try out a different configuration in a venue I’ve run the hypers in DINa. Listening back there’s still a somewhat noticeable hole in the middle, though not as wide of one as with the spaces omnis alone. I may try an XY configuration for the CK1s next time in hopes of addressing that more fully. As it turns out the hypers in DINa sounded better then the cards in DIN, though I wasn’t running in the exact same spot and the few foot difference also placed my center mics right up against a sound deadening pad on the wall, whereas last time I was 1-2” off the wall.

Sadly I didn’t take a picture of the rig in the wild, but I ran the CA14s spread about a meter on this antenna apparatus that I found at the local salvage yard (Urban Ore in Berkeley for any of you Bay Area folks). It seems to be designed to be placed into a socket of an analog TV. There was a ribbon attached which I snipped off. I just taped the contraption to my stand with gaff tape. I need to find a more elegant solution, as this was a major hassle to take apart.

Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on November 27, 2018, 09:06:48 AM
https://archive.org/details/cats2018-11-21.avantCA14mix

This is my first attempt at more than 2 channels, though I’m not sure it qualifies as OMT exactly, due to not going XY in the center.  Listening back to either stereo pair in isolation gives me a good idea of the benefits/detriments of spaces omnis vs near coincident and also how the combination of the two can sound *much* better. I feel confident saying this is my best recording to date.

I ran the CK1 cards in DIN to try out a different configuration in a venue I’ve run the hypers in DINa. Listening back there’s still a somewhat noticeable hole in the middle, though not as wide of one as with the spaces omnis alone. I may try an XY configuration for the CK1s next time in hopes of addressing that more fully. As it turns out the hypers in DINa sounded better then the cards in DIN, though I wasn’t running in the exact same spot and the few foot difference also placed my center mics right up against a sound deadening pad on the wall, whereas last time I was 1-2” off the wall.

Sadly I didn’t take a picture of the rig in the wild, but I ran the CA14s spread about a meter on this antenna apparatus that I found at the local salvage yard (Urban Ore in Berkeley for any of you Bay Area folks). It seems to be designed to be placed into a socket of an analog TV. There was a ribbon attached which I snipped off. I just taped the contraption to my stand with gaff tape. I need to find a more elegant solution, as this was a major hassle to take apart.
+T              running a crossed pair in the middle affords you a "safety pair" as well as gives some center imaging. When we run the hypers in the middle we have been going at about 50-60 degrees as opposed to a 90 or 110 (As recommended by Lee).
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: capnhook on November 27, 2018, 12:17:57 PM
The problem you can have if you don't have your XY center pair at 90 degrees is that the more you deviate from 90 degrees, the more you kind of lose your "safety pair".

It will be more difficult to make rational mid-side adjustments (with MSED or other software) if you aren't at 90 degrees.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on November 27, 2018, 01:13:46 PM
https://archive.org/details/cats2018-11-21.avantCA14mix

This is my first attempt at more than 2 channels, though I’m not sure it qualifies as OMT exactly, due to not going XY in the center.  Listening back to either stereo pair in isolation gives me a good idea of the benefits/detriments of spaces omnis vs near coincident and also how the combination of the two can sound *much* better. I feel confident saying this is my best recording to date.

I ran the CK1 cards in DIN to try out a different configuration in a venue I’ve run the hypers in DINa. Listening back there’s still a somewhat noticeable hole in the middle, though not as wide of one as with the spaces omnis alone. I may try an XY configuration for the CK1s next time in hopes of addressing that more fully. As it turns out the hypers in DINa sounded better then the cards in DIN, though I wasn’t running in the exact same spot and the few foot difference also placed my center mics right up against a sound deadening pad on the wall, whereas last time I was 1-2” off the wall.

Sadly I didn’t take a picture of the rig in the wild, but I ran the CA14s spread about a meter on this antenna apparatus that I found at the local salvage yard (Urban Ore in Berkeley for any of you Bay Area folks). It seems to be designed to be placed into a socket of an analog TV. There was a ribbon attached which I snipped off. I just taped the contraption to my stand with gaff tape. I need to find a more elegant solution, as this was a major hassle to take apart.

Your recording sounds very good to me. I don't hear hole in the middle. Perhaps you will not use safety track often. If it's not a bad sounding room, adding spaced omni has always been a benefit for me. Center coincident pair is giving you possibility for M/S adjustment when mixing with omni. But you can try M/S on non coincident pair too, here is more about it http://taperssection.com/index.php?topic=188238.0 (http://taperssection.com/index.php?topic=188238.0).

Also, when you mix coincident pair with spaced pair, there is less chance of phase cancellation in the resulting track. I use a coincident pair in the center, because it is more safe for me due to the already mentioned phase cancellation. On the other hand, others use up to eight microphones at a time and have no problem with phase cancellation, so my concerns are perhaps unnecessary.

To compare how sound different configurations go to bt.etree.org and find Phish 10/28/2018. Noah made beautiful recordings from tha same spot with different mic's patterns and configurations. There is also recording with fig. 8 and cardiod. You can try M/S manipulation on the true Mid / Side source.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on November 27, 2018, 02:03:15 PM
The problem you can have if you don't have your XY center pair at 90 degrees is that the more you deviate from 90 degrees, the more you kind of lose your "safety pair".

It will be more difficult to make rational mid-side adjustments (with MSED or other software) if you aren't at 90 degrees.
This is the nature of OMT, at some point you make trade offs unless you have unlimited channels. Lately, we have given up on the "safety pair" concept for two reasons:
1] We know what OMT will do for us and have determined the center channels, if coincident, at 50-60 degrees works best for the OMT mix but is NOT a safety pair at that point.
2] We typically run another set of mics and/or deck so that becomes our "safety recording".
That said, we have run 90' coincident crossed cards and hypers (AKG ck61, or ck3) several times as the middle pair of a 4chOMT setup and IMO this works a bit "better" mixing wise than the front/rear facing cards.
THAT said, I still prefer a "standard 4chOMT consisting of spaced omnis with front|rear cards or hypers. (Lately we have been doing the front mic a hyper (ck3) and rear a cardiod (ck61)
Finally, I have done exactly ZERO attempts at MS adjusting of any of our center channels; it's just not my thing.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: capnhook on November 27, 2018, 02:17:04 PM

That said, we have run 90' coincident crossed cards and hypers (AKG ck61, or ck3) several times as the middle pair of a 4chOMT setup and IMO this works a bit "better" mixing wise than the front/rear facing cards.


Exactly why I use coincident XY for the center.  With all these channels, I've been experimenting with including wide PAS cards lately, to get the "sizzle" I sometimes need.

Quote

THAT said, I still prefer a "standard chOMT consisting of spaced omnis with front|rear cards or hypers. (Lately we have been doing the front mic a hyper (ck3) and rear a cardiod (ck61)


Good to know what you prefer.  Thanks.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on November 27, 2018, 02:19:43 PM

Quote

THAT said, I still prefer a "standard 4chOMT consisting of spaced omnis with front|rear cards or hypers. (Lately we have been doing the front mic a hyper (ck3) and rear a cardiod (ck61)


Good to know what you prefer.  Thanks.

Yeah, I had to correct my post as I forgot the "4" in 4chOMT".
And yes, what I meant by preferring the front/rear mics as opposed to the crossed pair is for ease of mixing. (My mixing, not necessarily anyone elses) I just feel, for what we record (Rock n roll from indoor/outdoor PA's) it is simpler to my ears to have a solid center and the rear is optional depending on venue/acoustics/crowd
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on November 28, 2018, 09:14:55 AM
Hi guys, I just got back after 10 days away, most of it offline.  Good to see such activity in this thread, I'll make some comments as I can while catching back up at work today.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: ycoop on November 28, 2018, 11:48:54 AM
https://archive.org/details/cats2018-11-21.avantCA14mix

This is my first attempt at more than 2 channels, though I’m not sure it qualifies as OMT exactly, due to not going XY in the center.  Listening back to either stereo pair in isolation gives me a good idea of the benefits/detriments of spaces omnis vs near coincident and also how the combination of the two can sound *much* better. I feel confident saying this is my best recording to date.

I ran the CK1 cards in DIN to try out a different configuration in a venue I’ve run the hypers in DINa. Listening back there’s still a somewhat noticeable hole in the middle, though not as wide of one as with the spaces omnis alone. I may try an XY configuration for the CK1s next time in hopes of addressing that more fully. As it turns out the hypers in DINa sounded better then the cards in DIN, though I wasn’t running in the exact same spot and the few foot difference also placed my center mics right up against a sound deadening pad on the wall, whereas last time I was 1-2” off the wall.

Sadly I didn’t take a picture of the rig in the wild, but I ran the CA14s spread about a meter on this antenna apparatus that I found at the local salvage yard (Urban Ore in Berkeley for any of you Bay Area folks). It seems to be designed to be placed into a socket of an analog TV. There was a ribbon attached which I snipped off. I just taped the contraption to my stand with gaff tape. I need to find a more elegant solution, as this was a major hassle to take apart.

Your recording sounds very good to me. I don't hear hole in the middle. Perhaps you will not use safety track often. If it's not a bad sounding room, adding spaced omni has always been a benefit for me. Center coincident pair is giving you possibility for M/S adjustment when mixing with omni. But you can try M/S on non coincident pair too, here is more about it http://taperssection.com/index.php?topic=188238.0 (http://taperssection.com/index.php?topic=188238.0).

Also, when you mix coincident pair with spaced pair, there is less chance of phase cancellation in the resulting track. I use a coincident pair in the center, because it is more safe for me due to the already mentioned phase cancellation. On the other hand, others use up to eight microphones at a time and have no problem with phase cancellation, so my concerns are perhaps unnecessary.

To compare how sound different configurations go to bt.etree.org and find Phish 10/28/2018. Noah made beautiful recordings from tha same spot with different mic's patterns and configurations. There is also recording with fig. 8 and cardiod. You can try M/S manipulation on the true Mid / Side source.

I noticed the hole when switching between omnis alone and both pairs. The hole narrows, but I can still hear it with the center pair included.

Can someone explain the exact idea of a “safety pair”?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on November 28, 2018, 11:49:45 AM
https://archive.org/details/cats2018-11-21.avantCA14mix

This is my first attempt at more than 2 channels, though I’m not sure it qualifies as OMT exactly, due to not going XY in the center.  Listening back to either stereo pair in isolation gives me a good idea of the benefits/detriments of spaces omnis vs near coincident and also how the combination of the two can sound *much* better. I feel confident saying this is my best recording to date.

I ran the CK1 cards in DIN to try out a different configuration in a venue I’ve run the hypers in DINa. Listening back there’s still a somewhat noticeable hole in the middle, though not as wide of one as with the spaces omnis alone. I may try an XY configuration for the CK1s next time in hopes of addressing that more fully. As it turns out the hypers in DINa sounded better then the cards in DIN, though I wasn’t running in the exact same spot and the few foot difference also placed my center mics right up against a sound deadening pad on the wall, whereas last time I was 1-2” off the wall.

Sadly I didn’t take a picture of the rig in the wild, but I ran the CA14s spread about a meter on this antenna apparatus that I found at the local salvage yard (Urban Ore in Berkeley for any of you Bay Area folks). It seems to be designed to be placed into a socket of an analog TV. There was a ribbon attached which I snipped off. I just taped the contraption to my stand with gaff tape. I need to find a more elegant solution, as this was a major hassle to take apart.
+T              running a crossed pair in the middle affords you a "safety pair" as well as gives some center imaging. When we run the hypers in the middle we have been going at about 50-60 degrees as opposed to a 90 or 110 (As recommended by Lee).
I listened to most of this recording at work on cheap speakers yesterday. It sounded very fine to my ears. Very "open" and crisp in the high end and not too much bass. good job and thanks for sharing!

quote from: ycoop
Quote
Can someone explain the exact idea of a “safety pair”?
It is covered in some of the detailed descriptions gutbucket has in these OMT threads; however, I use the term to mean having a "standard" coincident configuration of 90 or 110 degrees (typically in cardiod or hypercardiod) in the middle of a 4/6/8 channel OMT with spaced omnis on the outside. This way, you have a "safety" pair of mics to use/listen to in case you do not wish to add the omnis in the mix. Once you use a coincident configuration of less than 90 (in our case it's been 50-60 degrees) then when processing/ listening to the coincident pair by itself does not supply the typical/expected stereo imaging OR to do MS processing on the center pair.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on November 28, 2018, 11:55:17 AM
Can someone explain the exact idea of a “safety pair”?

Let's say your split omnis don't come out right, for whatever reason.  Maybe one of the mics dies or something.  If your center pair is configured in such a way that it can make a good recording on its own, that center pair could be called your "safety pair."  Something like XY at 50-60* might not qualify as a safety pair (MIGHT...I'm not making blanket statements here) because on its own the recording may be too mono or narrow for some tastes.  If the center pair is XY at 90* or DIN/ORTF/etc it might stand up on its own better.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on November 28, 2018, 12:03:00 PM
Can someone explain the exact idea of a “safety pair”?

Let's say your split omnis don't come out right, for whatever reason.  Maybe one of the mics dies or something.  If your center pair is configured in such a way that it can make a good recording on its own, that center pair could be called your "safety pair."  Something like XY at 50-60* might not qualify as a safety pair (MIGHT...I'm not making blanket statements here) because on its own the recording may be too mono or narrow for some tastes.  If the center pair is XY at 90* or DIN/ORTF/etc it might stand up on its own better.
The two words you use which I do not are the key: "Might" and "tastes". This is mainly about how your tastes of listening/mixing are; and any of these less than 90' coincident stereo pair "might" not "stand up on its own better". 
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on November 28, 2018, 01:44:03 PM
I noticed the hole when switching between omnis alone and both pairs. The hole narrows, but I can still hear it with the center pair included.
Yes, a hole in the center of the stereo image is probably in a wide spaced omni, but you filled it with a near spaced pair. This is one of the main Gutbucket instructions.

I never had disturbing hole in a recording of near spaced pair in FOB. When recording onstage, a wide stereo image can be created with a hole in the center. You can fill the center with e.g. vocals from sbd feed. I always enjoyed an onstage wide stereo image. It reminded me of some recordings from 60's. All instruments, including drums, were fully right or left and vocals in the middle. There is also a positive bleed between the instruments. These recordings sound very lively to me.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on November 28, 2018, 07:37:28 PM
As mentioned by the others, "safety pair" means just one microphone pair used in isolation without the others will produce an acceptable recording on its own.  There are two motivations behind that as I see it:  1) A way to salvage the recording if/when something goes wrong with the other channels.   2) Retaining a "known good" 2-channel microphone configuration reference setup for comparison with the "whole enchilada OMT arrangement" in order to make sure the OMT complications are worthwhile.  This second aspect can obviously be achieved with a second recording setup (two extra microphones and recording channels), but might also be a 2-channel subset of the OMT setup.

Usually "safety pair" in the first sense implies that pair is setup in a typical stereo-pair configuration.  But that needn't necessarily be the case.  How much insurance do you need to feel comfortable? Quite often I find that all pairs making up the OMT can be considered "safety pairs" in this way to different degrees, differing in how much work is needed afterwards to mold it into something listenable on its own, and what level of quality is acceptable for such a situation.  It's dependent on your tolerance for risk, your familiarity with the setup, how oddball you want to push things, the number of channels you want to run, and how comfortable you feel with the mixing side of things.  As the channel count increases, redundancy and post-manipulation possibilities also increase.  A 3' spaced omni pair can work fine on its own and of course an X/Y or M/S pair can too.  As for myself, I'd not hesitate to make a Mid/Side re-adjustment to "widen-up" a narrow-angled X/Y "safety-pair" in order to get it sounding as good as possible.  Yet as long as it was setup correctly with close coincidence, I have little concern over dialing in enough additional Side for a 50-degree PAS X/Y pair to sound as wide as a 90-degree X/Y pair.  The fact that the 50-degree pair was presumably Pointed At Stacks is an advantage which I suspect might result in better sound after such an adjustment (this would make for a very interesting comp!).  To my way of thinking, when recording from a distance directness is more primary and cannot be recovered, whereas width is easier to manipulate, less ephemeral, and carries somewhat less perceptual importance.  This is a set of compromise tradeoffs of a similar nature to the ones I'll mention below with regards to near-spaced configurations.

Actually I also consider center front-facing / rear-facing microphones as a "safety pair" in this sense, and have used them as such when I've had problems which rendered the other channels unusable.  That pushes this first aspect of "safety pair", but in this way even just a singular forward-facing center microphone serves as a "mono safety".  A mono recording may be preferable for some folks and some recordings, and the all important direct/reverberant balance can still be adjusted somewhat via the balance between the front and rear-facing microphones.  It's sort of like varying the polar pattern for a mono pickup from that of the forward-facing microphone through wider patterns to omni (and onward to increasingly rear-facing directionality until reaching the pattern of the rear-facing microphone if the level of the rear channel were to be brought up higher than the front - unlikely in practice, but entirely possible).  This variation of the center forward facing microphone pickup pattern is one way of thinking about what mixing in various amounts of a single rear-facing microphone does, and ignoring the spacing between front and back-facing microphones, is similar to how a dual diaphragm microphone with electrically switched patterns works.  But it doesn't have to be mono. We can do the Mid/Side stereoization trick of using the rear-facing channel as Side in a Mid/Side converter to derive a stereophonic quality, even if that doesn't incorporate left/right directional imaging but rather stereo width, spaciousness and depth. That avoids the odd Left/Right lopsided stereo output which would result from the front microphone channel routed left and the rear microphone routed right, which is typically how monitoring that pair directly sounds - although believe it or not I have a few recordings which actually work well that way.


The second, known-good setup "safety pair" for comparison thing is super valuable for making truthful assessments of what is working and what isn't.  And it's similarly valuable for confirming forward progress in determining which OMT variation is satisfactory, and whether that remains sufficient for you or if you want to push it further.  I've written a lot about this comparison aspect in these threads and don't want to repeat myself too much, but I will say that listening closely, hearing the differences for yourself, identifying what is working better and what isn't, and figuring out what to correctly attribute that to is key.  It's great if the "known good" 2-channel arrangement dovetails nicely with OMT so that you don't need to run redundant channels, but I caution folks from getting overly saddled with trying to "build up OMT" around a favorite near-spaced configuration.  One way of thinking about near-spaced 2-channel stereo configurations is that they work well partly because they represent various "best-compromises" between 2-channel coincident and 2-channel spaced configurations. I hear those compromises inherent in near-spaced configurations as very appropriate, good and necessary, yet neither subtle nor minor once exposed by their absence.  OMT is in effect a way of working around those compromises, and us most effective when it breaks free of them. 

Yes OMT introduces alternate compromises in increased channel interactions and phase relationships (and appropriate mixing requirements) and these can be as egregious as those of coincident, near-spaced or widely-spaced 2-channel configurations or even worse.  Yet when dealt with appropriately I find the compromises can be made to be considerably less significant, such that to my ear at least, a good OMT arrangement is often better suited to the recording and reproduction of live-performance music, which is in itself an oddball recording endeavour!

It is difficult to determine what is really most appropriate and what might be better than our current conception of good and best.  A lot of that comes from training one's ear as well as re-calibrating one's expectations over time.  As tapers, we've made and listened to years, decades-worth of live recordings.  We know what works well in a 2-microphone/2-channel paradigm, what sounds good to us, and our brains are trained to hear recordings which convey appropriate traits as good.  In this context we even hear necessary compromises as being good rather than inherent to 2-channel recording.  We can add a second pair of mics and it may sound better, yet we are judging that based on all our ingrained expectations.  It's hard to know what could be even better, and at the same time we are not well attuned to the new compromises our brains are less familiar with, which escape notice until we become familiar enough with the new paradigm to begin to recognize them. 

I can now listen to a recording and be completely satisfied with it in every way, a great recording, yet know that it could be still better (not necessarily made by me).  Center solidity and ambient envelopment are in this category for me.  We are so used to these things being a trade off against each other, sort of a balancing act, that we accept compromises in these things without even being aware of it.  Once the compromising constraints tying them together are eliminated and exploited we can recognize that it sounds sounds better, yet that still doesn't re-calibrate our brain to make that our "new normal" for a long time.  It's almost like we get surprised by how good it sounds when we do come across it again.  I aim to re-calibrate my unconscious expectations toward more "and's" between qualities and away from unstated "or's" - center solidity that surprises me in its solidity in combination with holographic directional stereo imaging, in combination with deep and wide envelopment along with the most appropriate direct/reverberant balance, timbre, and presence.  I want all that, even though I know I don't fully recognize what it can be if fully realized.

All this OMT stuff is just a method to try and get closer to that.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on November 29, 2018, 05:19:03 PM
https://archive.org/details/cats2018-11-21.avantCA14mix

This is my first attempt at more than 2 channels, though I’m not sure it qualifies as OMT exactly, due to not going XY in the center.  Listening back to either stereo pair in isolation gives me a good idea of the benefits/detriments of spaces omnis vs near coincident and also how the combination of the two can sound *much* better. I feel confident saying this is my best recording to date.

I ran the CK1 cards in DIN to try out a different configuration in a venue I’ve run the hypers in DINa. Listening back there’s still a somewhat noticeable hole in the middle, though not as wide of one as with the spaces omnis alone. I may try an XY configuration for the CK1s next time in hopes of addressing that more fully.

I had a chance to listen to this a bit last night. Congrats on a quite nice sounding recording. Your reasoning is good on using X/Y to fill the center, solidly. The X/Y forte of sharp directional imaging with a rock solid center does exactly that.  Meanwhile the spaced omnis provide the open, spacious, natural sound and diffuse ambient pickup that X/Y cardioids tend to lack.  This gets to the heart of the "near-spaced compromise" I mention above.  A large part of the sonic attractiveness of near-spaced 2-channel configurations to my way of thinking is that they provide some degree of both those traits in a good, reasonable balance.  Yet when we record more than 2 channels with the full intent of using all of those channels together (interdependently), we can more fully optimize each pair for one or the other of those contradictory roles.  Each is then setup to provide the aspect it is best at, so that the combination ends up being less of a compromise than a single 2-channel configuration carefully designed to "split the differences" each way. 

What makes a setup truly "OMT" or not is a good question. In my opinion it has to do with exactly that trend- pushing each pair of microphones used in the OMT array towards specialization. Lots of folks run spaced omnis in combination with their prefered "main" 2-channel setup in the center. It would be presumptive to claim all those as OMT setups.  To me what unquestionably pushes a setup into OMT-land is when none of the microphone configurations which make up the entire array are "standard" anymore.  I consider it fully oddball once I move to setting up all of the microphones making up the array differently than I would have if the pairs were to be used on their own.  PAS X/Y pair narrower than I would have chosen for an X/Y pair on it's own, omnis wider than I'd probably want on their own, the front/rear-facing center-pair thing, etc.  Each pair shifted away from its "standard optimal setup" towards a particular specialization.  In so doing each component does it's thing better, and equally important to getting it right- stays out of the way of what the other is doing better.

In that way, to really take advantage of OMT it becomes necessary to move away from a traditional "safety pair" fully optimized for best stereo on its own as an integral part of the array.  Kyle talks about that here-

Lately, we have given up on the "safety pair" concept for two reasons:
1] We know what OMT will do for us and have determined the center channels, if coincident, at 50-60 degrees works best for the OMT mix but is NOT a safety pair at that point.
2] We typically run another set of mics and/or deck so that becomes our "safety recording".
That said, we have run 90' coincident crossed cards and hypers (AKG ck61, or ck3) several times as the middle pair of a 4chOMT setup and IMO this works a bit "better" mixing wise than the front/rear facing cards.
THAT said, I still prefer a "standard 4chOMT consisting of spaced omnis with front|rear cards or hypers. (Lately we have been doing the front mic a hyper (ck3) and rear a cardiod (ck61)
Finally, I have done exactly ZERO attempts at MS adjusting of any of our center channels; it's just not my thing.

^I've long thought about the conceptual beauty of an arrangement of 3 super/hypers that have nulls at 120 and 240 degrees off-axis, setup coincidentally such that the nulls of each microphone are aligned with the primary lobe of each of the other two microphones.  More specifically, a forward facing 120 degree wide X/Y pair plus a third facing directly rearward.  Conceptually, the way the primary lobes and nulls align, it's much like Blumlein 90-degree crossed figure-8s, but three channels instead of two.  Someone with a Mixpre3 wanting to run a very compact coincident setup should try this!

If 5 channel recorders were a thing, I'd be tempted to try it in the center between wide-spaced omnis from an optimal location.  But then I'd probably narrow the front pair angle to PAS for better "full array" optimization as mentioned above. 

Exactly why I use coincident XY for the center.  With all these channels, I've been experimenting with including wide PAS cards lately, to get the "sizzle" I sometimes need.

^
This!  More of the same.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on November 29, 2018, 05:19:26 PM
Sadly I didn’t take a picture of the rig in the wild, but I ran the CA14s spread about a meter on this antenna apparatus that I found at the local salvage yard (Urban Ore in Berkeley for any of you Bay Area folks). It seems to be designed to be placed into a socket of an analog TV. There was a ribbon attached which I snipped off. I just taped the contraption to my stand with gaff tape. I need to find a more elegant solution, as this was a major hassle to take apart.

Try using a Wintech clamp.  The part of the antenna which fits into the TV socket will fit into the stud-receiver of the clamp (secured with the thumb-screw) and the clamp can be quickly and easily attached to the stand.  I know several tapers who use that exact setup.  Simple, compact, easy.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on November 29, 2018, 05:24:48 PM
^I've long thought about the conceptual beauty of an arrangement of 3 super/hypers that have nulls at 120 and 240 degrees off-axis, setup coincidentally such that the nulls of each microphone are aligned with the primary lobe of each of the other two microphones.  More specifically, a forward facing 120 degree wide X/Y pair plus a third facing directly rearward. 

Can't we basically achieve this with ambisonic mics? 
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on November 30, 2018, 09:20:58 AM
^Yes, good point.  Once I reinstall Samplitude I should try that with a Tetramic recording to see how it works out.

It's partly a conceptual thing which arose from thinking about the optimal arrangement of just 3 channels.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on November 30, 2018, 06:17:59 PM
Trying again, with another impromptu rigging.

Poway Symphony Orchestra
2018-11-18 sunday

DPA4060 pair as 16' spaced pair, with APE response balls, and mics forward @0º just emerging from the balls, with grids only exposed.
Line Audio CM3 pair as 0º forward and 180º rearward, from the stage lip, center.
Mics arranged along the stage lip edge.
Tas. DR70D 24.96

And, also Gude Head binaural stream_ R09HR 24.96 from 1st row DFC

these are shareable, and will be going to LMA

Thanks Mike!  I gave this a somewhat more in depth listen this afternoon while catching up at work, and was able to compare it with your Gude-head binaural recording. That clarinet solo piece is fantastic.

On first listen to your OMT4 mix (brief, distracted, just prior to leaving for Thanksgiving) I noted some instability of the stereo image, but didn't note that so much today even though I listened for it (less brief, still between work distractions, and a bit fatigued). As I recall, I heard that in two ways- Notes of different frequency ranges "shifting around" in their apparent positions in the solo clarinet piece; and a sort of "three spotlight" front image distribution, with no "hole in the middle" problem but rather strong left center and right positions with oh-so-slightly less-strong regions between them in the full orchestra pieces.  Not two holes so much as much as three perceptually highlighted regions which could us a tough more blending between them.  Both times I was listening through cheap Samsung phone headphones straight out of my work computer.

I intended to listen more specifically for that by contrasting your OMT4 mix against your Gude-head binaural recording today, and those imaging aspects while there seem comparatively less significant. What stood out more strongly was the difference in weight and timbre, with the OMT4 mix having increased weight, frequency extension top and bottom, clarity and presence, while the binaural sounds more midrange-centered and ambient, yet with a smooth, stable image.  I also liked the increased center/forward presence of the OMT mix which is especially apparent when the soloist speaks briefly before his piece.

I definitely notice the increased width of the the bass and ambience in the OMT mix, which is something I'm rather attuned to and like.   I suspect center-position X/Y imaging might distribute the image of the orchestral pieces more smoothly and keep the note locations during the clarinet solo from shifting about, aligning the low frequency width from the omnis with higher frequency direction imaging from the X/Y pair, and I'd be especially tempted to try that between the wide-spaced of the omnis.  Not sure if sacrificing the rear-facing channel to do X/Y center with the available four channels would be better or not, but I think so in this case.  Worth a try next time if you want to try a variation on this.

Really, this is just critiquing and picking nits in pursuit of perfection.  Your recording sounds great and I really enjoyed listening to it.  Let's just say that these imperfections of the recording itself are easily overshadowed by intonation issues in the string and horn sections (Don't tell the orchestra!)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on December 02, 2018, 07:37:18 AM
Thanks Gut for your review of Mike's recording. It is always very helpful when somebody point at the area that deserves attention. When we know where and what to look for, everything is easier.

Let me make a small turn to yoga. One part of yoga teaches concentration on fine objects (e.g. elements and their properties). The more we are sensitive, then we can practice with the smoother objects. But to find these fine objects, somebody must point to it. We would not know where and what to look for. But when we find it, it's already simple.
I remember one of my recordings. It sounded average for me, I did not see anything totally wrong. Then somebody told me that bass resonates there. He was right, suddenly it was there. But before that it did not exist for me. I remember until now what a surprise was, and how I then clearly heard it. It helped me back in yoga, I realized how important it is to point to.

I am sorry for the turn, back to Mike's recording.

Notes of different frequency ranges "shifting around" in their apparent positions in the solo clarinet piece;
What causes it? Does that mean that clarinet sounds wide?

Really, this is just critiquing and picking nits in pursuit of perfection.  Your recording sounds great and I really enjoyed listening to it.  Let's just say that these imperfections of the recording itself are easily overshadowed by intonation issues in the string and horn sections (Don't tell the orchestra!)
Mike, do not worry. If you will ask yoga master or master of martial arts, how long he will practice, their answer is: Until I die.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on December 02, 2018, 08:06:19 AM
Thanks, Lee, Kuba.
The clarinetist stood in one place, but, waved his instrument from right to left in somewhat exaggerated fashion..  That is the intonation, in regard to the clarinetist. You can literally hear him swaying in the recording.
When he soloed, during his encore, he came out onto the stage, from conductors left side, to center stage, and out by 5' additionally.
I had a comment about the conductors voice wandering. He paces the entire width of the stage array in his preambles, and is caught at full width by the array. He is also speaking thru a vocal mic, via PA.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: goodcooker on December 02, 2018, 11:42:09 AM

I just realized after following along in the thread that I used to do a version of this quite often in this one particular room that sounded muddy. I ran Peluso subcards (usually 30cm or more and about 75 degree angle so just barely wider than the line array) with a single forward facing hyper in the center all lined up on a single bar. The hyper gave me the directionality that I was craving and the subcards gave a nice balanced tone but often had too much "room". Best of both worlds.

Every once in a while nowadays I'll run both pairs of mics I typically use - Schoeps hypers and MBHO wide cards in medium size venues if I'm close enough. I usually just decide which source I like best and go with that rather than try to mix the two - although I have done a low pass on the HOs and added in the bass since the more open pattern gives that subwoofer rumble... :headphones:
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on December 03, 2018, 02:35:57 PM
^ Your setup with the wide/spaced subcards + hypercard in the middle is right in line with these techniques intended to "combine the best of both worlds".  Nothing particularly "new under the sun" with regards to each of the component techniques used to build these arrays.  It's more about thinking through well-reasoned combinations of ideas and managing things to prevent problems as the  interdependent variables increase.  And if a straight pair or combination of two standard setup pairs provides everything you want, no reason to do the unusual.  ~Rumble on!
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: jcable77 on December 04, 2018, 11:24:57 PM
GB, i have an idea and am wondering your thoughts. Id like to run ms on stage with one Adk figure 8 as side, an akg 481 as mid, and maybe the other Adk in front of that in omni. Basically looking like the 481 is piggiebacking the adk8 with the capsule almost resting on the Adk,  with the omni directly in front of that. Ill also have hyprecards and board about 40ft back at the board. Is the omni overkill you think? And if folks by the stage are somewhat chatty is ms going to be overwhelmed by crowd noise? My first try at ms. Really interested at trying more blumlein and ms oddball setups.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on December 05, 2018, 05:23:30 PM
Worth a try to find out.  Maybe the single omni on stage will be useful, can't say.  May depend on the type of music and situation.  If you want to mix the omni in with that M/S pair, it would theoretically be best to put it directly atop the ADK/481 pair so the capsules of all three microphones are as close to vertically coincident as possible.

I'm assuming the ADK is LD side-address, perhaps a TL..
Just a setup option, but with regards to the straight M/S pair you may be able to gaff-tape the 481 directly to the ADK with a couple foam earplugs in between to cushion them, then put both in the same shockmount (depending on the mount and the room within it) or support both using just a ADK hard-mount (more definitely doable).  In that case the LD side-address ADK would not be oriented vertically but horizontally so that both mic-bodies pointed directly forward.  Nice and compact that way.  Forgive me if the gaff-tape thing rubs you the wrong way, it does some folks who would never consider such a thing and always use proper mounts.  The other ADK could be mounted in the same orientation above that, with all three mic-bodies parallel, but might be best to point it directly forward where it's switched omni pattern will be better behaved.

Me? With hypers 40' back and a board-feed, I'd be tempted to use the ADKs as wide omnis on stage, and as long as you have the capability for running all three mics up there I'd probably put the 481 in the middle to make a spaced L/C/R arrangement across the stage .  If it's super chatty up there and the music soft such that on-stage omnis would be overly compromised, you could then simply switch the ADKs from omni to cardioid without having to move anything and have three spaced cardioids across the front of the stage facing away from the audience and at the band.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: jcable77 on December 05, 2018, 07:45:39 PM
Thanks man. I like the idea of pointing the 481 and TL forward. That does make it more compact and efficient. Ive tried a few different set ups at this particular spot, spaced omnis, L/C/R, and a few other weird ones, Im really interested in the mixdown part of MS. The figure8 is new to me, looking forward to messing around with it. Constant learning experience. Greatly appreciate your input as always.
Title: Improved PAS 2-channel microphone setup technique revisited
Post by: Gutbucket on December 11, 2018, 05:08:47 PM
Regulars following this thread may already be aware of this, but I figured I'd post notice here as well-

A few days ago I revised the Improved PAS microphone setup method so that it now suggests the most appropriate spacing between a stereo-pair of microphones of any 1st order directional pattern pointed directly at PA speakers which are setup traditionally, flanking either side of the stage.  This means this taper-specific microphone-setup methodology no longer applies just to cardioids but provides the appropriate spacing for omnis, subcardioids, supercardioids, and bidirectional (fig-8) microphones as well. 

Essentially, Improved PAS is the concert-taper application of the Stereo Zoom empirical data to the commonly used Point At Stacks microphone setup method, made easily applicable via a simple to read table.

I had intended to revisit this for a few years now, but have spent most of that time thinking about and exploring OMT.  Now that I've finally gotten around to readdressing and expanding Improved PAS, I consider it a significant step forward for making stereo-optimized 2-channel audience-perspective recordings of PA amplified concerts in simple and repeatable way, without the luxury of audio monitoring and readjustment of the setup to get things optimized prior to making the recording (which is simply assumed for most music recording, but almost never done for audience concert taping), even in rooms in which the taper has no previous experience.

Actually, the method can be applied more widely than amplified PA recording - it's just that it is particularly well suited for the Point At Stacks microphone setup technique.  Essentially it is a subset of the Stereo Zoom solutions where the angle between the microphones is the same as the Orchestra Angle - which is the width of the entire ensemble, or in the case of PA amplified concerts the width of the main PA speakers flanking the stage.  This provides good stereo imaging of the sources within the angle described by the microphones, with either microphone defining the outer edge of the pickup "sound-stage", and that window also corresponding to the playback "sound-stage" between speakers. 
^
In that way it works the way most novice tapers assume a stereo-pair of microphones always work, even though in the vast majority of arrangements they do not.

Improved PAS thread-  https://taperssection.com/index.php?topic=167549.msg2087409#msg2087409
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on December 11, 2018, 06:18:46 PM
And that brings me back to an interesting question we discussed earlier in this thread, which I'll paraphrase as- "If the recording is intended for 2-channel playback, and the OMT setup includes more than one forward-facing pair of microphones, should each pair be setup so as to have the same Stereo Recording Angle?"

Based on my experience with OMT the answer is no, because as I've stated previously I see the primary value of OMT as being optimal integration of different stereo aspects which each microphone pair has been separately optimized for.  The omni pair in particular being spaced to optimize diffuse decorrelated ambient pickup rather than SRA.  Yet I don't claim that as the only appropriate goal with regards to the combination of multiple microphone channels intended to make 2-channel stereo recording.  One might try to optimize for a single stereo aspect, specifically sharpest source location imaging.

I can imagine the potential value in matching the SRA of several pairs of microphones of different polar patterns and mixing them with that goal in mind.  I'd think this would be most applicable for recording sources and ensembles which have a lot of specific imaging potential, valuing image location sharpness and clarity across the front sound-stage more highly than the balance between front imaging and the sense of an immersive diffuse ambience surrounding the listener.  This may have the potential to sound less "smeared" to listeners highly sensitive to such.  It's also closer to how most tapers run two pairs of microphones, just setup in a very specific way.

For anyone wanting to try this I'd suggest using either of the two coincident arrangements on the Improved PAS table (there are only two) in combination with a pair of spaced omnis setup for the same included angle.  Those setups are:

1) A coincident pair of supercardioids with a 120 degree angle between them + a pair of omnis spaced 61cm / 24" (with the same 120 degree angle between omnis, although this is less important for omnis than getting the spacing right).

2) A coincident pair of figure-8's with an 80 degree angle between them + a pair of omnis spaced 76cm / 30" (with the same 120 degree angle between omnis..)


One would ideally want those 120 or 80 degree inclusive angles to be close to the angle between the PA stacks (or width of the ensemble), and to do so one would need to find a recording position where that occurs.  But that's not critical for the primary purpose of this experiment.  That's because what we will be listening for in this case is how closely matched the positional imaging between the two pairs is upon playback, rather than getting an optimal overall width.  And secondly, how well the two sources combine when mixed- is the positional location of each source sharper and more well-defined than when the center coincident pair is angled narrower and the omni pair spaced wider as it would be with "standard" OMT?  Is the imaging closely-matched enough so that the two pairs combine well even though they are closer to each other and intentionally have more overlap?  Do other aspects suffer too much because of that extra overlap?  Combing maybe?

Anyway I think this will be interesting to try.

[Edit- the particularly astute may note that the omni spacings I mention above are not those indicated on the Improved PAS table for 120 and 80 degree PAS omnis, but those for 115 and 75 degree PAS omnis.  That's because the coincident supercardioid and fig-8 arrangements solve for a Stereo Recording Angle of PAS +~5 or 6 degrees (which is as close to PAS+10 degrees as they can get without going "closer than coincident", an impossibility) rather than PAS+~10 degrees used across the rest of the table.  Given that, in order to keep the Stereo Recording Angles of both pairs marched as closely as possible, I subtracted 5 degrees from the PAS angle before looking up the omni spacing, making both pairs solve for approximately the same overall Stereo Recording Angle.]
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: lmgbtapes on December 11, 2018, 10:46:15 PM
Between this and the improved PAS thread, I just want to say that I fucking love you, GB.

That's all I have to contribute at this time, really.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on December 12, 2018, 09:34:14 AM
Hey thanks! That feels good. Glad this stuff is appreciated and I hope it helps.  I've huge respect for all the folks here who are so prolific in posting and sharing their recordings, whereas I contribute in this way - each of us a part of the taper community contributing what and where we can.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: ycoop on December 20, 2018, 02:30:46 PM
Sadly I didn’t take a picture of the rig in the wild, but I ran the CA14s spread about a meter on this antenna apparatus that I found at the local salvage yard (Urban Ore in Berkeley for any of you Bay Area folks). It seems to be designed to be placed into a socket of an analog TV. There was a ribbon attached which I snipped off. I just taped the contraption to my stand with gaff tape. I need to find a more elegant solution, as this was a major hassle to take apart.

Try using a Wintech clamp.  The part of the antenna which fits into the TV socket will fit into the stud-receiver of the clamp (secured with the thumb-screw) and the clamp can be quickly and easily attached to the stand.  I know several tapers who use that exact setup.  Simple, compact, easy.

Thanks for this advice! Though the socket part of the antenna wasn’t quite able to be held in place with the thumb screw. I was able to find a small piece of plastic tubing (don’t remember exactly what it’s called, but it was at the hardware store in the nuts/bolts section) that holds the antenna socket part snug and fits perfectly into the stud receiver (though only the one that holds the stud parallel to the clamp, seems like the holes are a hair different in size.) I’m going to glue the antenna into the plastic piece and now have a perfect solution. Hoping I can deploy it at my next show.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: ycoop on December 28, 2018, 03:01:55 PM
OMT rig in action: http://taperssection.com/index.php?topic=189094.msg2286338#msg2286338

Split the omnis a bit further this time, and went with XY90 for the center cards. I’m considering going with PAS hypers next time out at TxR depending on how this pull ended up.

Gave a listen on the way home, but hard to hear more nuance in my Camry.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 04, 2019, 05:32:59 PM
I came across a paper which seems to support what I've come to consider an important underlying principle of OMT, although I only came to realize it as such over time - On the Management of Direct and Reflected Sounds in the 5.0 Surround Sound Reproduction System, authors P. Kleczkowski, A. Król and P. Małecki http://przyrbwn.icm.edu.pl/APP/PDF/128/a128z1ap02.pdf (http://przyrbwn.icm.edu.pl/APP/PDF/128/a128z1ap02.pdf)

The paper compares 4 different approaches to reproducing a single isolated source over a 5 channel surround playback array, using source material in which the direct and reverberant components are completely separated from each other (anechoic direct source + reverberant component derived from convolved spatial IR responses) and those components routed to various reproduction channels of the playback array in 4 different ways.  Conclusion is that listener preference tends towards isolation of the direct sound component to one playback channel only, with the reverberant component of the sound distributed across all playback channels.

Inverting that and extrapolating to the recording side of things, the application to OMT is that direct sound arriving from a specific on-axis direction in the horizontal plane is ideally picked up primarily by a single directional microphone of the array while the reverberant component of that sound is picked up by all microphones of the array, including the on-axis microphone in which the direct sound is isolated as much as possible.  More specific to OMT, and playback as well though not covered in this paper, is the consideration of pickup of the direct sound component, early reflection components and reverberation components as three separate entities, the application of that on editing/mixing and in some cases through to the reproduction of these components as separate entities to various degrees.  Recorded in such a way, recombination of these differentiated acoustic components can be carried through to the processing and mixing stage, and in some cases through playback itself if via a surround playback array (circling back to the focus of the research paper).

This applies to 2-channel as well as multichannel playback, but it is easiest to conceptualize in the special case of a playback arrangement where each microphone channel corresponds to a specific playback speaker. 

So I see parallels here to use of a strongly-directional single forward-facing center microphone (or a tightly-focused/correlated center stereo pair), with the other microphone channels serving as ambient spatial pickup of early-reflections and reverb, and in some cases providing a welcome Hass-effect presence reinforcement, which is what I feel the OCT-like sideways-facing supercards do in a 2-channel mix when a coincident-center pair is providing L/R stereoization imaging.

Of course direct sound isolation in a reverberant space using first-order microphones placed away from the source is marginal to begin with and there will be a significant direct sound leaking into the other microphone channels.  Fortunately we need a minimal amount of that for pair-wise capture and reproduction of directional imaging of sources between on-axis points anyway. It would be ideal if that interchannel "bleed" were to occur only within adjacent directional channel pairs, not spread out across more than two adjacent channels.  The paper does not address stereo imaging as such, but rather a single on-center-axis source and the "spatialization" of that signal.  Sure, spatialization is a stereo aspect, but is not "stereo imaging" in the sense of reproduction of specific source position.

Further, I see each directional microphone in the OMT array serving as "center channel" for that particular on-axis direction, with all other microphones of the array serving as reverberant pickup array for that center-channel orientation.  All axiis work together collectively in support of each other in this way.  This requires good management of the pattern overlap between adjacent pairs around the array.

^ In other words, for each primary direction a single directional microphone picks up the direct sound, the immediately adjacent directional microphones pickup (or emulate) early reflections, and all the microphones pickup the reverberant component.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on January 05, 2019, 09:03:41 AM
I'm going to concur with the idea that the center channel (or narrowly angled coincident pair) provides a direct sound component which adds positive aspects to the mixing of multi microphone source recording; given the other microphone sources provide early reflection components and reverberation components based on their design. In a typical OMT where spaced omni microphones at least 1Meter, optimally 2Meter and possibly a fifth and sixth source adding either rear or sideways early reflection components and reverberation components allows one to mix the center, directional source to the advantage of the outcome. IMO, the outcome allows the mixer to experiment with the amount or ratio of direct to reverberent sound emphasizing whichever aspect the mixer is seeking.

I feel using OMT variants has made our recordings much more enjoyable from a practical pov, and possibly a bit more complicated to get a final 2 channel product from a results pov.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on January 07, 2019, 10:41:00 AM
Gutbucket, thanks a lot for the article link and for explanation. Just to be sure. Simply said, OMT provides direct sound by center coincident pair with high directional pattern, early reflections by side facing cardiods and diffuse field by omni and rear mics. Of course, there is some degree of bleed between all mics.
What I don't understand is how these parts were separated by those who wrote the article. They were using ambisonic mic. Do they decode virtual mics with required pattern and send these signals to the intended speaker? If it is explained in the article, I'm sorry. That article is not an easy text for me, so I may have misapprehend this.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: EmRR on January 07, 2019, 11:57:29 AM
Gutbucket, thanks a lot for the article link and for explanation. Just to be sure. Simply said, OMT provides direct sound by center coincident pair with high directional pattern, early reflections by side facing cardiods and diffuse field by omni and rear mics. Of course, there is some degree of bleed between all mics.
What I don't understand is how these parts were separated by those who wrote the article. They were using ambisonic mic. Do they decode virtual mics with required pattern and send these signals to the intended speaker? If it is explained in the article, I'm sorry. That article is not an easy text for me, so I may have misapprehend this.

I'm guilty of speaking without reading the article, but would assume they are using the same ambisonic capture to create the multiple patterns by duplicating the files and processing them separately, in parallel, and then mixing them back together at the desired levels.  Perhaps there were more mics in the picture.....
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on January 07, 2019, 02:48:31 PM
I'm guilty of speaking without reading the article, but would assume they are using the same ambisonic capture to create the multiple patterns by duplicating the files and processing them separately, in parallel, and then mixing them back together at the desired levels.  Perhaps there were more mics in the picture.....

I can imagine this procedure.  Maybe I am starting to understand (my English is weak and the text is not easy for me). They recorded impulse responses in a small wooden church by ambisonic mics. Then in anechoic test room, they played CD (Mozart, Bach ...) that was an anechoic recording. And the early reflection and diffuse field was artificially generated based on an anechoic recording and impulse responses of the wooden church. And then they looked for which speaker configuration is the best for playback.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 07, 2019, 03:23:27 PM
[edit- kuba posed while I was typing this..]

EmRR- only one source microphone + multichannel convolution reverb (spatial impulse originally measured with an ambisonic microphone).  This is how they fully isolate the direct and reverberant portions of the signal form each other.


Kuba,
The authors of the research paper above specify that the source material they used was monophonic and anechoic.  They did not record the material themselves, but rather used pre-recorded sound samples that had been originally recorded with a single microphone in such a way that only the direct sound was captured (close-mic'ed and perhaps performed and recorded in an anechoic chamber).  So the sound source samples contain direct sound only, 100% dry, without any early reflections or reverberation.

They then use convolution reverb to generate the reverberant component from that dry anechoic signal.  The output from the convolution reverb is time-windowed such that the initial peak which represents the direct sound is cut off and discarded, leaving only the reverberant tail (the 100% wet 'verb portion of the output).  In addition, they use 5 channel convolution so that the reverberant signals sent to each of the 5 speakers are decorrelated with respect to each other.  That makes the reverberance much closer to naturally occuring reverberation, rather than routing an identical monophonic reverb signal to multiple speakers.

Just to be sure. Simply said, OMT provides direct sound by center coincident pair with high directional pattern, early reflections by side facing cardiods and diffuse field by omni and rear mics. Of course, there is some degree of bleed between all mics.
^
Pretty much.  The idea is to isolate the direct sound to the center pair as much as possible, while the diffuse reverberant sound is picked up by all the microphones of the array including the center pair.  Picking up the reverberation in all channels is unavoidable unless you substitute a SBD feed for the center microphone or pair, in which case the SBD actually is mostly direct signal, excepting any artificial 'verb added at the board.  Fortunately the conclusion of the paper is that 'verb in the center channel is actually prefered for 5 channel playback. 

Early reflections end up being picked up by the omnis as well as in the front pair.  If the additional sideways-facing supercards are used their sideways orientation tends to focus on the early reflections a bit more while still picking up significant direct sound.  Supercards are prefered for this because they pickup less direct sound, with the null of the supercard pattern facing toward the opposing side source/speaker, but even supercards (or sideways figure-8s) will still pickup a lot of direct sound arriving from directly ahead. 

I suspect the spacing between the center pair and omnis (and the spacing between the center pair and optional sideways-facing supercards) also serve to create some Hass delay effect for sounds arriving from either side well off the center-axis, which sort of serve as synthetic very-early-reflections even if there aren't any well-defined actual early reflections.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 07, 2019, 03:49:21 PM
I feel using OMT variants has made our recordings much more enjoyable from a practical pov, and possibly a bit more complicated to get a final 2 channel product from a results pov.

Truth. Definitely more complicated.  Anyone using these methods will want to determine what level of complication they are comfortable with.  Fortunately one can stick with 3 or 4 channels and keep things relatively simple.  I will say from personal experience that additional channels are addictive however, and are hard to give up once I've heard what they add!

I ran an F8 for the first time last Thursday night without much time beforehand to get familiar with it.  Running an OMT8 setup into it using 8 microphones total I had my hands full during the first song just confirming that everything was running correctly and getting levels set correctly.. and that's just the recorder portion of setting up and running.  Fortunately the microphone setting up part is super-familiar and second-hand to me at this point.

Channel assignment was as follows:
ch1: L omni
ch2: R omni
ch3: C supercard (forward facing)
ch4: C fig8 (optional Side channel for C)
ch5: L supercard (sideways facing)
ch6: R supercard (sideways facing)
ch7: Ls supercard (rear facing)
ch8: Rs supercard (rear facing)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on January 07, 2019, 04:15:02 PM
Thank you for explaining. The experiment described in the article is very interesting. I'm very curious how it might sound in the test room.

I will say from personal experience that additional channels are addictive however, and are hard to give up once I've heard what they add!

Ha ha, I can imagine this very well. I tape very little now. But I have time to come back to my old OMT recordings. I am playing with it in DAW and I am starting to like post-processing. There is always something to be improved in small steps. I also like to play with mixing the rear microphone. I'm very curious what you will say about the benefit of the rear stereo pair.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 07, 2019, 05:23:17 PM
I also like to play with mixing the rear microphone. I'm very curious what you will say about the benefit of the rear stereo pair.

Loving it!  I just never had the extra channel easily available to run it easily until recently, as the sideways facing supercards took priority when I was recording 6 channels.  I've really only run this for a couple things so far and only for the most recent do I have a good base-line of comparison with past recordings that used a single rear-facing channel.  I did some experiments with a few different rear stereo pairs at a few outdoor fests years ago, but couldn't do so very easily and never seriously played around with that aspect of those recordings.

It's very nice to listen to just the rear-facing pair in isolation and dial in a good balance of those two channels, then bring that up in the stereo mix.  Even more of the good stuff a single rear-facing channel provides with less conflict with the front/center focus, providing greater crowd/ambient immersion and "stereoness".  It's nice to have everything except the narrow-focused center generating a somewhat wider stereo field, leaving the center space for the forward-facing microphone or pair. 

I hope to better determine exactly how much width is best back there- which combination of angle and spacing makes the most sense and when to modify that based on the situation.  With that in mind I'm thinking of doing some in-depth test recordings of various rear-channel orientations out in our warehouse, walking all the way around the rig with a sound source and then comparing the recordings.  But that's likely to be more of an imaging related test and different than having a high SPL source like a band in front energizing the entire room and leaking into the rears, where reducing bleed from the front may be more valuable than 360 degree image stability.


I'm still working my head around M/S pair monitoring/playback from the F8.  I had the F8 set to recorded four stereo WAVs with the intention of recording ch's 3&4 as Mid and Side.  But upon playback from the F8 those two channels seem to behave as an already encoded L/R pair with adjustable L/R panning rather than adjustable stereo width.   The stereo from them in isolation sounds good, but is wider than I'd typically use in an OMT mix.  I'll have to get my DAW back in operation to really get into it this recent recording mix-wise.  Not sure if I'll need to setup the M/S linking differently or if I'll need to record to a single polyphonic WAV instead of separate stereo WAVs to get direct playback of a mix out of the F8 to work the way I want.  I also need to setup a multichannel playback system again to fully asses how all this works in surround playback since I'm currently limited to listening and mixing in 2ch stereo.. and I miss that.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on January 09, 2019, 04:09:31 PM
I like mixing rear mic in Mid/Side or better with the constant time shift across all frequencies. It always improved the recording. And rear stereo pair must be even better. When I go to record, I will try a side facing cardiods too. I have never tried it.  I imagined that side cardiods have less effect on the sound that the rear microphone. But that was just an imagine, I should try it and listen to it.

It is great idea to use recorder as mixer and playback source. It must be more comfortable for basic mixing and listening than to do it in DAW. Of course I understand, more detailed mixing and editing need DAW.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 09, 2019, 06:58:52 PM
I like mixing rear mic in Mid/Side or better with the constant time shift across all frequencies.
By that do you mean a time delay, or a constant-phase (quadrature) shift?

Quote
I will try a side facing cardiods too. I have never tried it.  I imagined that side cardiods have less effect on the sound that the rear microphone. But that was just an imagine, I should try it and listen to it.

They are quite different in their effects.  I'll try and describe it this way-

To my ear, the rear microphone(s) primarily improve spatiality and immersion, the "I am there" feeling, the illusion of "realness" with regards to the audience and room.  They also help with the perception of the direct sound from the front energizing and interacting with the room.

The sideways facing supercards provide additional ambient width spatiality, but seem more about modifying the feeling of directness and proximity in the stereo mix (whereas with discrete multichannel or LCR playback they additionally serve to sufficiently differentiate L from C from R).  They sort of act like a zoom lens, a sort of sonic enhancer.  In some ways they substitute for the omnis in providing much of the primary L/R width (except in the bass) and in combination with the omnis provide a sort of hyper-realism effect.  This is partly where my speculation about Hass effect in the 2ch mix comes from.


In my quick mixes of the recent recording listening directly out of the F8 (still haven't gotten the center channel panning right) I found that it is not bad at all with the omnis muted.  Yeah it's lacking the lovely fat and wide bottom, but I suspect I might be able to lessen that absence with EQ.  The wide spacing on the omnis also provide some very nice decorrelated diffuse openness at mid and high frequencies, but the L/R supercards are providing the primary L/R information in this recording and mix at least.  I should note that this was recorded in a small club and I angled the L/R supercards forward (about +/- 35 to 40 degrees) rather than sideways.   Partly because I was asked to move the setup from my prefered location about 1/3 of the way back in the room to a position about 2/3rds of the way back just behind the soundboard and was concerned about picking up audience conversation back there, and party because I had angled them forward last year for the same band in the same room in my prefered location and wanted to minimize variables for comparison.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kuba e on January 11, 2019, 11:14:32 AM
I like mixing rear mic in Mid/Side or better with the constant time shift across all frequencies.
By that do you mean a time delay, or a constant-phase (quadrature) shift?

I mean constant-phase shift. I didn't try it on many recording. I have just a few OMT recordings.  I am using four mics - spaced omni and front and rear directional mics. For this couple recordings, It was the best to do constant-phase shift in comparison with Mid/Side or simple mix of the rear mic. I am using free vst plugin PhaseBug.

Thanks for describing what side facing mics provide in final mix. It is very interesting and inspiring. I will try six mics recording. I'd love to try the side microphones. I will let know here how I will be successful.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 11, 2019, 11:33:06 AM
I mean constant-phase shift. I didn't try it on many recording. I have just a few OMT recordings.  I am using four mics - spaced omni and front and rear directional mics. For this couple recordings, It was the best to do constant-phase shift in comparison with Mid/Side or simple mix of the rear mic. I am using free vst plugin PhaseBug.

Thanks for confirming this!  I've speculated here upon the possibly of that being a better option for mixing the rear microphone channel in a stereo mix.  It is essentially how the S channel (in LCRS) is encoded with older Dolby Surround (analog matrix not digital coded) in the Lt/Rt output.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: ycoop on January 12, 2019, 06:54:33 PM
OMT rig in action: http://taperssection.com/index.php?topic=189094.msg2286338#msg2286338

Split the omnis a bit further this time, and went with XY90 for the center cards. I’m considering going with PAS hypers next time out at TxR depending on how this pull ended up.

Gave a listen on the way home, but hard to hear more nuance in my Camry.

Finally got this one mastered, tracked, and uploaded.

https://archive.org/details/gl2018-12-27.SanRafaelCA.ck1.ca14.OMTmix
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kindms on January 13, 2019, 09:12:30 AM
OMT rig in action: http://taperssection.com/index.php?topic=189094.msg2286338#msg2286338

Split the omnis a bit further this time, and went with XY90 for the center cards. I’m considering going with PAS hypers next time out at TxR depending on how this pull ended up.

Gave a listen on the way home, but hard to hear more nuance in my Camry.

Finally got this one mastered, tracked, and uploaded.

https://archive.org/details/gl2018-12-27.SanRafaelCA.ck1.ca14.OMTmix

sounds really nice. i was able to listen to several tunes this morning. thanks for posting
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 14, 2019, 08:44:43 AM
^x2!  Listening now..  Well done.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on January 14, 2019, 09:37:23 AM
Y'all check out this OMT variant: https://taperssection.com/index.php?topic=189233.0
https://archive.org/details/kungfu2019-01-11.sbdakgdpa

I will come back and post pictures later today. The club allowed me to get the ladder and gaffe the DPA omnis inside their boundary mounts up high close to the stacks, directly on axis height wise about 17 feet up and spread about 20 feet apart.
Then added a mono SBD feed and two AKG ck3's in PAS for an AUD center channel pair since I had the SBD feed. So 2 Omnis spread 20 feet, 2 hypercards PAS in the center and a SBD feed. Certainly not a "classic" OMT, but a variant as I titled it.    ;)
Kung Fu
2019-01-11
Hollow Bar + Kitchen
Albany NY
Recording Info:
ch1/2 DPA 4061 omnis spread 20ft (609cm) 10 feet from PA stack, 15 feet up
ch3/4 AKG ck3 PAS 35 feet from stage 17 feet up (3 feet from ceiling)
ch5/6 SBD stereo feed Behringer m32 Tony FOH
      -> Tascam DR680|SD
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on January 14, 2019, 12:20:03 PM
Y'all check out this OMT variant: https://taperssection.com/index.php?topic=189233.0
https://archive.org/details/kungfu2019-01-11.sbdakgdpa

I will come back and post pictures later today. The club allowed me to get the ladder and gaffe the DPA omnis inside their boundary mounts up high close to the stacks, directly on axis height wise about 17 feet up and spread about 20 feet apart.
Then added a mono SBD feed and two AKG ck3's in PAS for an AUD center channel pair since I had the SBD feed. So 2 Omnis spread 20 feet, 2 hypercards PAS in the center and a SBD feed. Certainly not a "classic" OMT, but a variant as I titled it.    ;)
Kung Fu
2019-01-11
Hollow Bar + Kitchen
Albany NY
Recording Info:
ch1/2 DPA 4061 omnis spread 20ft (609cm) 10 feet from PA stack, 15 feet up
ch3/4 AKG ck3 PAS 35 feet from stage 17 feet up (3 feet from ceiling)
ch5/6 SBD stereo feed Behringer m32 Tony FOH
      -> Tascam DR680|SD

I can only listen on my crappy work speakers at the moment but it sounds great nonetheless.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 14, 2019, 01:57:32 PM
The club allowed me to get the ladder and gaffe the DPA omnis inside their boundary mounts up high close to the stacks, directly on axis height wise about 17 feet up and spread about 20 feet apart.
Then added a mono SBD feed and two AKG ck3's in PAS for an AUD center channel pair since I had the SBD feed. So 2 Omnis spread 20 feet, 2 hypercards PAS in the center and a SBD feed.
[snip]

ch1/2 DPA 4061 omnis spread 20ft (609cm) 10 feet from PA stack, 15 feet up
ch3/4 AKG ck3 PAS 35 feet from stage 17 feet up (3 feet from ceiling)
ch5/6 SBD stereo feed

Nice sounding, thanks Kyle!

Did you find you needed to time-shift the AKG channels with them recorded 35' away?

How good did the spaced omnis sound on their own?  I've found the relatively simple technique of using just a pair of wide-spaced omnis placed approximately 10' directly out in front of each PA stack to work very well,  achieving a good balance on its own when its possible to pull it off.  Plenty of clear, direct sound from each PA, with a strong center image from the monophonic content and much stereo differentiation of that direct PA sound as is present in the SBD (due to the wide spacing and close proximity to the PA), wide decorrelated room ambience and audience reaction keeping that stuff out of the center and making it more enveloping, an good positioning for pickup of early-reflections and on-stage-sound if those things are not swamped by the PA level.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on January 14, 2019, 02:21:01 PM
^^^^^^^^^^^^^^^^^^^^^^^^^^
1] The time shift was minimal, but I did delay the sbd 38ms relative to the ck3's.
2] The DPA's sounded GREAT without the SBD. Obviously not the same overall SPL in the mix, but instrumentation wise, even the vocals were good with the music great in the omni channels solo'd.
3] The oddity for me was listening to just ck3 and SBD. It had an envelopness to it which was intriguing and quite listenable depending on the overall slider levels.

all in all, not being straight AUD OMT, it stands out to me as a pretty fine recording. The lead guitar is abit low in the overall mix in all channels, and I chose to do zero EQ'ig as that is/was the only downside I hear at all in this mix.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 14, 2019, 05:50:40 PM
Thanks!

It strikes me that in one way at least this recording is sort of the opposite of OMT in that it does not try to specifically record different aspects of the soundfield and then recombine them (even though that happens anyway as by-product), instead focusing on the direct PA/SBD sound as much as possible, picked up from different locations:

Pseudo-stack taping of the PA on both sides
PAS hypercards
SBD
^
All of which are primarily direct sound contributors.  What makes it work I think is that the two non SBD sources contain different amounts of all the other stuff which is of secondary importance to the direct sound (perhaps except for the guitar which was loud on-stage and thus under represented in the SBD) : The spaced omnis providing some wide decorrelated room and audience, and the PAS hypers correlated room and audience. 

It's hard to argue against this when it works and I certainly won't! 

However, I will say that I generally find it useful to dedicate at least one pair to avoiding this direct-sound-dominant redundancy by intentionally limiting pickup of it, so that when needed those other aspects can be brought up without also raising the level of the direct-SBD sound at the same time.. as long as one is assured of having enough of that most important direct sound in the other sources.  This probably calls to mind the rear-facing microphone channel(s) primarily, yet this thought experiment also sheds some light on things:

Say I'm running a 4 channel OMT setup with wide omnis + front/rear facing cardioids.  I'm offered a mono SBD feed and need to sacrifice one microphone channel to record it.  Which microphone channel do I give up?   As long as I know the SBD is clean, good-sounding, and all representative of the desired direct sound (a gamble perhaps!) I'd be most tempted to give up the forward facing center cardioid as that channel is an attempt at providing what the SBD feed actually provides in a better way (clear, proximate, direct source), whereas the other channels while providing some of that as well are primarily focused on recording other attributes of the soundfield.  I mostly want spatialization for that dry, direct SBD, room and audience sound.  The omnis alone or maybe even the rear facing channels alone should be able to supply that.

I've not done so, and it would take cajones for a taper to try it, but this is actually an argument to try recording just the stereo SBD + a pair of rear-facing microphones if limited to recording 4 channels.  Next time I get a SBD and have stereo rear channels going I'll try a mix of just those two parts to determine how well this works.

Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on January 14, 2019, 06:21:42 PM
Thanks!
1]
It strikes me that in one way at least this recording is sort of the opposite of OMT in that it does not try to specifically record different aspects of the soundfield and then recombine them (even though that happens anyway as by-product), instead focusing on the direct PA/SBD sound as much as possible, picked up from different locations:

Pseudo-stack taping of the PA on both sides
PAS hypercards
SBD

2]
Say I'm running a 4 channel OMT setup with wide omnis + front/rear facing cardioids.  I'm offered a mono SBD feed and need to sacrifice one microphone channel to record it.  Which microphone channel do I give up?   As long as I know the SBD is clean, good-sounding, and all representative of the desired direct sound (a gamble perhaps!) I'd be most tempted to give up the forward facing center cardioid as that channel is an attempt at providing what the SBD feed actually provides in a better way (clear, proximate, direct source), whereas the other channels while providing some of that as well are primarily focused on recording other attributes of the soundfield.  I mostly want spatialization for that dry, direct SBD, room and audience sound.  The omnis alone or maybe even the rear facing channels alone should be able to supply that.

I've not done so, and it would take cajones for a taper to try it, but this is actually an argument to try recording just the stereo SBD + a pair of rear-facing microphones if limited to recording 4 channels.  Next time I get a SBD and have stereo rear channels going I'll try a mix of just those two parts to determine how well this works.
1] I agree with your technical assessment; this is not OMT. So much so that I wish I had PM'd you that day, as I ran through this thought experiment. I was prepared to do crossed hypers or cards in the middle with the spread omnis if no SBD. I then thought if I get offered SBD I would not want essentially 2 middle sources, so decided to go hypers PAS if offered the SBD (partly for OMT sake, partly due to knowledge of this room's acoustics- narrow shotgun style PA) Given your thoughts, I now grok the redundancy with my choice.     :-\

2] I thought over and over why not do front/rear cards, as in classic OMT? I did not prep for it, and so forgot about that option under setting up "pressures".   lol The other reason I decided in advance against front/rear is the design of the room itself, narrow and typically lots of chatter under the mics in that spot.
OTH- I tend to agree with the concept that the PAS mics took in about the same direct sound as the SBD and close mic'd Omnis. I will certainly try the rear facing mic/pair next time in this room with SBD feed as it makes great sense in this room.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on January 14, 2019, 07:38:57 PM
It's fun for me to analyze this stuff, so please don't sweat my critiques.  Your recording stands on its own.

As far as redundancy goes, it's hard to go wrong with overly sufficient clear directness.  A lot of folks are happiest with a straight SBD afterall, even though that's not sufficient by itself for many of us spatial teleportation junkies.  My argument is more about increased flexibility when a recording calls for it, yet this recording doesn't really need that other than the level of the guitar perhaps (I didn't specifically listen for guitar level, and am just going off your comment about it). 

I also make the argument above because its far harder to convince tapers to point extra microphones in directions other than toward the stage and PA! And in doing so they are right in the pickup of clear direct sound being the most important component.. it's just not the only one to the exclusion of all else, and most times the other stuff comes along for the ride in any case, just in a less controlled way.  Lots of folks run extra microphone pairs, lots of folks mix those pairs together, but few give much consideration to how those pairs work together as a single array, and that's what I see myself arguing for most of the time here at TS.


And oh setup pressures and how they can modify the best laid plans at best, if not outright take the helm and steer the shit ship-o-fools!  I lost the first two sets of four last Friday night partly due to that and running a new recorder (Zoom F8). The taper's blues!

I suspect that if the SBD feed is good the best one can usually do with two additional microphone channels is run an overly wide pair of spaced omnis to mix with it.  Wide omnis provide essentially everything a SBD feed does not without being so extreme as to try and eliminate as much of the direct-arriving SBD content as possible like a rear-facing pair does.  The omnis provide a more well-balanced take on the entire room sound and perhaps more importantly on the audience reaction, including the enthusiasm forward of the recording position rather than isolating and focusing on distracted folks behind.  I should rephrase that concluding statement in my previous post- I'm mostly curious how well a rear-facing pair will substitute for the wide omni pair mixed with a straight SBD, not because I think it would be a better option, but specifically because the rear-facing pair pushes the "not picking up direct sound from in front" thing to an extreme.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on February 03, 2019, 05:39:06 PM
I took an OCT2 array out for a spin this weekend.  Here's the result: http://taperssection.com/index.php?topic=189468.0

So far I really like this setup.  The stereo separation of the supercards is complimented nicely by the strong center of the middle mic.  I could've dialed in more center to give it more direct sound, but I kept the mix nearly equal between sides and center (I think I put the center only 2 dB higher than the sides).  I'm definitely going to run this sort of configuration more often.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 04, 2019, 11:53:05 AM
Heathen has kindly granted his permission for me to post here a our PM discussion about OCT (Optimum Cardioid Triangle) made prior to the recording he linked above yesterday.  It mostly concerns the spacing of the center channel forward of the L/R pair(s). I figure it may be of interest to others following the thread.  Although much of what I say below I've posted about previously in the OMT part 1 thread, here it is pulled together in the context of OCT.

I hope you don't mind me bugging you with a question out of the blue.  Having recently acquired my first pair of supercards, I want to give some sort of OCT setup a try.  While researching OCT, I came across discussion that when the ultimate goal is a stereo mixdown, the center mic should be placed further forward than the 8 cm for OCT, resulting in OCT2.  I think I saw mention of 40 cm for OCT2, but I'm not sure.

What I haven't found the answer to, though, is why the center mic should be farther forward when the ultimate goal is a stereo mixdown?  Is it to avoid some sort of phasing issue?  Is it purely to introduce greater decorellation between the center and each of the sides?

With my current setup I can achieve up to about 70 cm of spacing between the sides (that's counting the reach from the length of each mic body).  Achieving 40 cm of forward spacing for the center is not currently feasible for me, though.  Part of my desire to understand the reasoning behind the additional forward spacing in OCT2 is to figure out if I need to find a way to rig up that additional forward spacing, if OCT turns out to be something I want to use more.

I should be able to try some of this out tomorrow, and with three bands in the lineup I want to try three variations on the OCT theme.  Hopefully that will be somewhat enlightening.  As always, though, I'd appreciate any insight you can give into the nuts and bolts of why a certain array does what it does.  If you don't have time for this, no worries!

Good question.  In practice I don't have a definitive answer.  I've varied how far forward my center channel, but for the most part its as much a result of practical mounting issues than either a rigorous investigation or adherence to the recommended dimensions.  More on that later..

On the theory side- OCT2 pushes the center microphone farther forward and implements a time-delay on that channel to compensate for that forward shift.  I think that modification was developed because it retains good correlation across the 3 channels for front-arriving sound to a degree similar to standard OCT, yet increases decorrelation of the the center signal verses the sides for sound arriving from outside the SRA window (sides & back).  That's likely advantageous because OCT was conceptualized for "pair-wise" 3-channel L/C/R playback with minimal crosstalk from the channel on the opposite side for off-center positions, and the 3 signals remain fully discrete until they are reproduced by the speakers and only then do they "sum in the air" between the speakers and listener.  In contrast, when mixing the 3 discrete channels to 2, phase-correlation interactions between all three channels summing in the electrical ream are far more distinct than the signals summing in air, so increasing the forward spacing of the center channel effectively pushes the microphones out of close proximity for all directions except the forward direction.

That's part of what informed a number of lengthy posts of mine in the OMT part1 thread concerning the importance of having sufficiently differentiated signals across the multiple microphone pairs one intends to mix together.  Granted in that case, the main point I was trying to get across was an argument against the somewhat typical taper approach of mixing two or three near-spaced pairs all mounted in close-proximity on the same stand and pointing the same direction, but its really addressing the same basic issue.

In a practical sense, I'm not sure how much it really matters.  I've had little problem mixing down my OMT stuff to 2 channel regardless of the forward spacing and have never gotten around to playing with time-shifting the center channel in post. 

My OMT setup generally has the center channel pushed forward about 10" or so (say 25cm) simply due to the mounting arrangement I use.  But sometimes the outrigger arms are not at +/- 90 degrees but angled forward or backward somewhat due to any number of reasons, including mounting against a column or on stage avoiding and keeping out of walking paths of the musicians, which either increases or decreases the spacing somewhat.

Coincidentally I'll be re-rigging it this weekend for a bunch of recording next weekend, and am changing the mounting for other reasons which will shift the center microphone backwards, closer to the OMT(1) standard.  That will make for an opportunity to see if I hear a difference in the 2ch mix.

Way back when I was running 4 omnis mounted in spheres in a sort of mini-Decca tree diamond-shaped arrangement, the front and back pair were spaced more than the supercards I'm using now for OMT.  All four mics were on telescopic antennas and the spacing varied with the situation, but was typically 100cm or so for the Left/Right pair and usually something like half-that front/back pair.  I'd guess the center-front mic was usually between 30 & 50 cm forward.  Those also mixed well and I never did any time shifting.

continued below..
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 04, 2019, 12:03:04 PM
More thoughts-

The three things which primarily informed the evolution of directional portions of my OMT setups were:
Decca tree
OCT
Michael William's MMAD (multichannel microphone array design)

My OMT stuff is sort of a mix and match of all those, and with that in mind you might want to sort of mentally asses the similarities and differences between them in thinking about OCT vs OCT2 and other variations.

Decca tree uses sphere-mounted omnis and increased spacing and is familiar to most folks. Its intended for 2 channel mixing.

OCT uses 180 angle opposed supercards as a way of limiting acoustic cross-talk from the opposite side, and the use of supercardiods at such wide angles in combination with a narrower base-spacing than Decca tree setups, makes necessary shifting the center channel rearward (in position or time) to achieve stereo image "linking" between the L-C and C-R pair segments.  OCT is intended for 3 channel playback (but works fine for a 2 channel mix IME) and the latter OCT2 modification was specifically developed for 2ch mixes.

That kind of image-linking between pairs is what Williams focuses on primarily (there is obvious cross over between each of these approaches, if emphasis on different aspects). Williams is less concerned about acoustic crosstalk from microphones outside each individual pair segment, and is more concerned with smooth imaging "linking" without gaps or overlap between multiple segments around the array, sometimes all the way around 360 degrees.  His arrays are intended for discrete 3, 5, 6 or 7 channel playback and always use microphones of the same polar pattern all the way around the array.  I've used them on their own on stage for some jazz trio stuff and like them.  I did not like OCT as much in those initial on-stage tests because the sideways facing supers were not as on-axis to the musicians and picked up more sidewall reflections.  I now use the OMT setup everywhere though including on stage and I think the omnis help with that, and sometimes I angle the side-facing supercards more forwards when I think that will help, partly informed by those tests.

My current OMT setup is pretty much OCT for L/C/R (but using a center supercard) and gets more Willams when I angle the L/R supers forward, and with respect to how I setup the rear-facing supercard pair so as to have a reasonable pair-wise relationship on each side to the L/R pair.

Interestingly Williams writes about what his "Magic Array" which is his "universal" multichannel recording arrangement intended for producing 2, 3, 4, 5, 6, 7, or 8 channel output by choosing specific output channels (no mixing).  There is some parallel to OCT2 there in that he does this by starting with a typical near-spaced stereo config (think DIN, cardioids 12"/90 degrees), extends that to 3 channels by placing a center microphone well-forward of that pair and delaying it (further forward and more delayed than OCT2 due to the L/R channels being angled less and closer spaced), extends to 4ch quad by muting that center channel and adding a rear facing DIN pair (creating 4 DIN segments all the way around), extends to 5 channels by unmuting the center channel, extends that to 6 channels by adding a rear-facing cardioid as far behind the array as the front one is forward, etc..  The full 8 channel array looks like a sea urchin, with a an IRT cross arrangement in the center (4 ch DIN) with four additional cardioids extending outward from the center of each pair, something like 2 meters.

Its crazy looking and not very practical, but conceptually informative.  I've posted about and linked a photo in the OCT part 1 thread, but I'd have to go look for it.


I suppose all of this is a long way of saying, "fun to think about, but don't worry about it too much!"
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on February 04, 2019, 12:22:51 PM
I keep going back to the question of forward spacing with the center mic in a OCT/OCT2 array.  For the typical taper scenario (recording a PA, with maybe some sound coming from the stage, maybe not), how much of a difference does the center spacing make?  And I should qualify this by saying how much of an audible difference, because there's obviously a measurable difference in the time of arrival.  I'm only concerned about what is audible though.  Part of my wondering about this is driven by practical concerns.  It's far easier to set up a center mic that's only slightly forward of the side mics than it is to set up a center mic that is 25-30 cm (not to mention the 40 cm I've seen discussed in the context of OCT2).  If the difference between a few cm forward and 25-30 cm forward isn't audible, then all the better. 
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 04, 2019, 12:56:59 PM
That's my current conclusion as well-  Center forward spacing doesn't seem to matter much in comparison to the practical constraints of trying to push the center mic farther than 12" or so forward.  What I'm still curious to determine is how much difference there is between no forward spacing at all, the OCT suggested spacing of 8cm (just 3"), and the approximate 25-30cm (10-12") spacing you used above and which I've been using.  I don't think its a major difference, but I've now nailed the other variables down enough that I'm coming back to this detail.

The reworking I'm currently doing will pull the center microphone back in, because adding the fig-8 to it to form a M/S pair made it heavier and harder to support ~12" out.  So I plan to do some listening to determine if I hear any difference.

My general thoughts on this are that the microphones intended to pickup direct sound from in front should be relatively time-aligned with each other to keep transients aligned and not smeared.  And any rear-facing ambient microphones shouldn't be spaced overly far back due to inevitable leakage of direct sound into them, although a bit more spacing there is likely desirable.  That translates generally as having the microphones arranged more or less in a horizontal line, using spacing more in the Left/Right dimension than the Fore/Aft dimension.  And it works out nicely that such an arrangement is more practical to setup as well!


More from the discussion between Heathen and myself concerning center mic spacing and the OCT2 specification about delaying the center microphone to compensate for is farther forward positioning-

For the other bands I angled the supercards towards the front, so I'll be posting those and that may make for an interesting comparison.

Right on.  Glad it worked out well for you. 
Did you delay the center channel a or just mix it in straight?
What are your impressions on angling the supercards forward vs not?

I tried delaying the center channel and didn't hear any difference, so I just kept it undelayed.  When I calculated how much time the delay needed to be, it was so small that I'd be shocked if it made an audible difference.

I haven't listened to the other sets with the angled supers as much yet, but I did a quick comparison between just the 180* supers and the ~90* supers and, when compared side-by-side, there seemed to be a very big difference, with the ~90* supers sounding much more direct (whether that's a good thing or bad thing in the final mix remains to be seen).  I was surprised how the 180* supers sounded on their own...not what I'd prefer to listen to, but also not totally unusable.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on February 04, 2019, 01:37:51 PM
Some helpful info from Schoeps about OCT/OCT2:

Quote
When  one system  must  be used  for both  5.1 surround and 2.0  stereo  recording, downmix  compatibility becomes  a  prime  consideration.  OCT 2 offers  special  advantages in such  situations. OCT in general  has good  downmix  proper-ties  already,  since  a sound  from any given  direction  cannot  be  picked  up strongly  by all three  microphones  at the same time. Thus  level  differences,  rather  than  arrival-time  differences,  provide the primary  directional  cues,  and this minimizes  harmful  comb-filter  effects  in the direct  sound  when  mixing down  to two  channels.  The OCT 2  approach  improves  downmix  quality further with  its decreased  inter-channel  correlation of diffuse-field  pickup.


https://schoeps.de/fileadmin/user_upload/user_upload/Downloads/Kataloge_und_Broschueren/Anwenderbroschueren/SCHOEPS_surround-brochure.pdf
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on February 04, 2019, 04:33:09 PM
Sorry to keep hammering this thread, but I keep thinking about this stuff.  Based on my gorilla math, with the center mic 28 cm forward in the OCT2 array, that would put the center mic .8 milliseconds "ahead of" the axis of the side mics.  I didn't think this would be enough time difference to have an audible effect, but now I'm not so sure.  The delay between our ears is about .5 milliseconds, and that certainly has an audible effect in the sense that it impacts how we locate a sound.  So it would stand to reason that an even greater delay, i.e. .8 milliseconds, should have an audible effect, right?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: EmRR on February 04, 2019, 05:49:42 PM
I'd say you can hear it if you were to A/B apples to apples, but whether it's good or bad is another question.  Since they are calling for 40 cm for OCT2, it would seem a matter of taste about the amount of correlation/de-correlation, with the hard and fast versions there as starter guides.   It likely makes a bigger difference if you are mixing for surround. 

FWIW, Decca Tree center mic is about 5 feet in front of the L and R mics.   Omni's with beamy directional pattern in the treble. 
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 04, 2019, 06:27:35 PM
The delay between our ears is about .5 milliseconds, and that certainly has an audible effect in the sense that it impacts how we locate a sound.  So it would stand to reason that an even greater delay, i.e. .8 milliseconds, should have an audible effect, right?

Well yes, maybe.  Consider that this delay is not between Left and Right, but between center and sides.  So it's sort of a Mid/Side thing rather than a Left/Right thing.  Also there are three channel pair relationships to consider which are all superimposed upon one anther rather than just a single one.  We don't have just the left+right relationship, but the left+right, left+center, and center+right relationships all interacting.  That interaction is complex.  It is interacting in the electronic realm (mixing) in the air (speakers to ears) and perceptually in our ear/brain system. Taking just the perceptual part of that, the Left/Right microphone channel relationship remains fixed while the left/center and center/right relationships change on the move from OCT to OCT2.  Perhaps the left/right part perceptually "anchors things" leaving more freedom for the mid/side part to not be perfectly aligned. Or perhaps the Mid/Side difference is perceived as depth, or as first arrival presence emphasising "centeredness".

Quote
The OCT 2  approach  improves  downmix  quality further with  its decreased  inter-channel  correlation of diffuse-field  pickup.

^
Good to have my memory/presumption of what that is intended to achieve confirmed, thanks.

To step back for a moment for folks following along, correlation between adjacent channel pairs is desirable for sharp imaging, while low correlation ("increased decorrelation") is desirable across all channels for the ambient, diffuse-field sound arriving from all directions.  How to achieve both of those things at the same time, and to what extent one should go in order to achieve it is what is at issue. 

OCT2 goes to more a involved extreme to achieve this than OCT(1) does.  That's because OCT(1) was originally designed for 3 speaker Left/Center/Right playback where the center signal remains discrete and is not electronically mixed with the Left and Right channel signals until the signals pass through the speakers and "mix in the air of the room".  Phase interactions between correlated signals manifest more strongly when signals are mixed electronically, than when they mix together in air after being reproduced by speakers in a typical listening setup of speakers set some distance apart from each other in a non-anechoic room. 

To make this real-world, consider polarity-inversion.  Take a signal and duplicate it to two channels.  You have a 100% correlation between those two channels.  Invert polarity of one channel, mix them together without changing gain and you get total, or near total cancellation.  But play both signals thorough a stereo system and invert polarity ahead of one of the two speakers and you don't get total cancellation in the room.  You may notice attenuation of low frequency energy, because that remains more correlated in the room than higher frequencies.  This difference between mixing in the electronic realm verses in air is what OCT2 is intended to improve for mixing the 3-channel microphone feed down to a 2-channel stereo signal. To further extend this real-world example- If the signals in both channels are not correlated, they won't cancel when summed electronically, regardless of the polarity inversion of one channel. Think uncorrelated pink noise in two channels. It sounds the same when one channel is polarity inverted. If the two channels are correlated at low frequencies but not at high frequencies then only the low frequency part will be attenuated.

We can decorrelate the diffuse pickup by using a microphone setup geometry that introduces differences of pickup pattern + angle and/or by differences in time-of arrival (spacing).  Using microphones with a tighter directional pickup pattern combined with increasing the angle between the microphones will decrease inter-channel correlation of diffuse-field  pickup. But with 180 degree oriented L/R supercardioids, pattern and angle have already been maximised as much as possible, so increasing the spacing between the L/R pair and the center microphone is the only remaining way to do that using setup geometry.  OCT2 pushes the center microphone forward then introduces a delay to compensate.  The compensating delay realigns wavefront arrival for direct sound coming from the forward direction (it keeps the signal correlated for that angle of arrival).  For sound arriving from other directions it effectively increases time of arrival non-alignment and therefor decreases correlation. 

Can we do the same by changing the microphone setup geometry in some other way?  There are a couple options- we can push the L/R supercardioid pair wider, yet that will narrow the SRA.  We can move the center microphone up or down out of the horizontal plane, keeping time of arrival more or less the same for horizontal arriving sound, but increasing the distance between the center mic and all others for sound arriving from all directions other than the horizontal plane.  Neither of those are very practical, although I have seen some odd 3-channel arrangements using a standard near-spaced-stereo center pair plus a center microphone positioned a couple meters higher on the same stand.  The 3 positions remain more or less closely aligned for horizontal traveling plane waves, but not for sounds arriving from above or below the horizontal plane.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 04, 2019, 07:17:19 PM
I'd say you can hear it if you were to A/B apples to apples, but whether it's good or bad is another question.  Since they are calling for 40 cm for OCT2, it would seem a matter of taste about the amount of correlation/de-correlation, with the hard and fast versions there as starter guides.   It likely makes a bigger difference if you are mixing for surround. 

FWIW, Decca Tree center mic is about 5 feet in front of the L and R mics.   Omni's with beamy directional pattern in the treble.

Yes on mixing for surround, but that's the inverse of the problem.  I've never seen any mention of whether OCT2 is actually considered better for surround (or rather, 3 front channel playback) or not due to the increased decorrelation of diffuse pickup.  The OCT2 modification seems to be targeted fully at better optimizing the setup for mixing to 2 channel, without compromising discrete 3 channel L/C/R output. 

Probably not surprising, but for playback using 3 front speakers I do have a pretty strong preference for microphone setups which use three near-spaced microphone channels over those using three coincident channels or those those deriving a center.  For mixdown to 2-channel stereo I find I have a preference for a coincident center pair versus a discrete Left/Center/Right near-spaced pair (although that preference is far less strong and not a deal-breaker), mostly prefer some combination of both, and wouldn't want to give up the sideways facing pair.  That's why I've now implemented a M/S center full-time along with the near-spaced side-facing L/R supercards.  So ignoring the rear-facing channels, I'm doing a variation on OCT using a M/S center position and omnis spaced about twice as wide as the side-facing OCT supercards.


Decca Tree is not time compensated for alignment and uses larger spacing forward to the center position.  But it's also placed farther "into the orchestra" than most other main microphone arrangements, such that the orchestra wraps around the array, necessitating an Orchestra Angle of 180 degrees or more.  It's sort of an oddball in itself really.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kindms on February 04, 2019, 07:33:28 PM
RE array.

kind of interesting this discussing is happening now. i just added some clamps to our 15mm rail setup and a 90 degree. If i pick up a few more 12" sections we could probably find a place to run some funky forward experiments

basically a huge + right now would be 3ft split 1 foot section in the middle but that could easily be increased

Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on February 04, 2019, 09:00:14 PM
I just did a quick mixdown of a song to compare no delay on the center mic with .8 milliseconds delay.  All I did was get the sides to equal level as the center, adjust the delay on the center (or not), and mix them together.  I'm curious if anyone hears differences between these.  Here's a download link: https://we.tl/t-G5iWimxWaY

I'll hold off on my own comments for the time being...
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: EmRR on February 04, 2019, 09:16:29 PM
They definitely sound different.  Think I prefer the non-delayed as being more forward-present in the image.  Delayed center sounds set back, cloudier by a hair.

It strikes me a delay is not the same as actual mic position, though it does give some idea about the spacing. 
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 05, 2019, 08:39:09 PM
Thanks for making both samples available.  I'm listening at work through cheap earphones and find a slight preference for the delayed version, but really need to listen at home. [edit, upon further listening on the cheap earphones I find I prefer the non-delayed version due to the center imaging position being stronger, which better anchors the snare and high-hat in the center]. I may not be able to do so for a couple weeks though as I'm crushed at work in the short-term and will be gone the next two weekends, but I will definitely come back to this as it's been something I've wanted to get a better real-world grasp on on for a while now.

Last night, while thinking about re-arranging my OMT setup for recording this weekend, I decided to plug a few variables into the on-line Image Assistant app to help tweak my spacings, with the app set for 3 ch OCT - http://www.hauptmikrofon.de/stereo-surround/image-assistant (http://www.hauptmikrofon.de/stereo-surround/image-assistant).  It's been a while since I messed with that app and it's interesting playing with the out-front center microphone spacing.  I'm thinking you might want to mess with it a bit as well, Heathen.   

With the 25cm forward center supercard mic placement I've been using, the ~63cm L/R spacing, and no center delay, I actually cannot get the Left-Center and Center-Right segments to link smoothly unless I angle the L/R supercards forward +/- 45 degrees.  That's interesting.  Especially because I've been recording indoors for the most part recently and angling the L/R mics forward by that amount, and have been getting really good results that way. But the SRA is then something like 130 degrees total which seems over-wide.

I'm planning on setting the center M/S pair 5"/13cm forward this time while keeping the ~63cm L/R spacing the same.  With L/R supers angled +/- 80 degrees, which is about as much as I can angle forward when using the big Shure windscreens on them for outdoor recording (without also angling the entire telescopic arms forward with the omnis on the far ends), segment linking falls in line producing a 120-ish degree total SRA.  That's wider than I'd like, but to get a 90-ish degree SRA I'd need to push the L/R supercards out to 1m total.  I don't wish to do that this time, but might play with that if I can make it up to Suwannee Spring Reunion in March.  The amphitheater there has been my experimentation lab for this stuff - good and familiar.

If I then angle the L/R supercards +/-45 degrees, Image Assistant wants a 2m spacing between the L/R supers.  That seems extreme, is outside the suggested OCT range and likely outside the practical "good" envelope. However, if I push the center mic back out to 25cm again, L/R spacing drops back to about the 60-ish cm total spacing I've been using.  Hmmmm.

Tentative conclusion- When angling the the side-facing directional L/R pair forward, it's more reasonable to push the center microphone further forward by a small amount than the L/R pair wider by a large amount.  So I'm going to look into making the center microphone position adjustable using a short telescopic antenna the next time I re-rig things, so that when choose to I angle the L/R pair forward, I'll also push the center microphone farther forward at the same time.  I'm thinking I may end up with two configurations I can run for same pre-rigged setup and easily switch between without having to measure each time: 180-degree opposed L/R pair with less forward center extension (OCT), and +/-45 degree forward angled L/R with more forward center extension.  We'll see. 

I tend to like the omnis wider, regardless.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 05, 2019, 11:40:40 PM
For basic OMT3 (spaced omnis + a single center directional microphone) Image Assistant calculations suggest placing a cardioid or supercardioid pattern center microphone ~23cm / 9" forward of a ~1m /39" spaced omni baseline for imaging segment linking, producing an SRA of ~103 degrees.  The same would apply to OMT4 (addition of either a rear-facing channel or a Mid/Side center).
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on February 05, 2019, 11:57:10 PM
Here's a photo of the OCT2 setup, though note that this photo was taken after I angled the supercards a bit forward, so not technically OCT2 at this point: http://taperssection.com/index.php?topic=189495.0
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on February 06, 2019, 09:45:47 AM
For comparison to the OCT2 recording I posted, here's the next band up that night: http://taperssection.com/index.php?topic=189496.0  All I changed was angling the supercards forward about 45* each.  For this one I ended up using less of the center mic.  I think I had the center mic either -1 or -2 dB with respect to the sides.  Also I used slightly different EQ settings on this set.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 06, 2019, 11:34:34 AM
I just did a quick mixdown of a song to compare no delay on the center mic with .8 milliseconds delay.  All I did was get the sides to equal level as the center, adjust the delay on the center (or not), and mix them together.  I'm curious if anyone hears differences between these.  Here's a download link: https://we.tl/t-G5iWimxWaY

Thanks for making both samples available.  I'm listening at work through cheap earphones and find a slight preference for the delayed version, but really need to listen at home. [snip..]

Upon further listening on the same cheap earphones while at work last night I switched my preference to the non-delayed version due to the center imaging position being stronger, which better anchors the snare and high-hat in the center.  On my briefer earlier listen I was focusing more on other aspects.  It's subtle though, and I'm not listening through a high resolution listening chain.

What I'm not sure of is if a slight modification of center level would do the same and flip my preference back to the delay compensated version.  These level and timing variables interact perceptually.  I usually take a good bit of time finding the best level balance between the center mic and the side-mics.  The choice of including delay compensation or not will makes that choice more complex.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: detroit lightning on February 08, 2019, 11:02:31 AM
I just acquired another set of Berliner CM33's, so I now have 2 pairs that I can run into a R44. So I'm starting to think about possible uses...

First thought is just running in different configurations as a means of learning more about positioning and various rooms. Beyond that, any thought on some interesting things I could do?

Along those lines, I also picked up a sabra-som st2 bar. I'd like to add another set of mounts to it for all 4 mics. Any other ideas for mounts that could hold all 4 mics in different / set configurations?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on February 08, 2019, 11:14:09 AM
The Manfrotto 154 bar is a bit on the bulky side, but it's been pretty useful for me.  It can make a great place for a bunch of people to clamp, or for some OMT setups.  You could mount your ST-2 bar to the center post of a 154, with the ST-2 going perpendicular, and then have forward and rear-facing mics, in addition to a fairly wide spread L/R pair.  Or you could use the ST-2 to set up an XY or closely-spaced pair, with a wider flanking pair at the ends of the 154.

If there's a less bulky alternative to the 154 that can handle SDCs, other than the expensive (but very nice) stuff from Grace and the like, I'd love to hear about it.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 11, 2019, 06:37:50 PM
I'm not familiar with those particular mounts and bars, but echo heathen's recommendation to try these two 4-channel OMT (OMT4) setups:

1) PAS-angled X/Y pair in the center between a relatively wide-spaced pair.
2) 180-degree Front/Rear-facing pair in the center between the relatively wide-spaced pair. 
 
Both PAS X/Y and a 0-degree forward facing center mic optimize for direct pickup from onstage and PA, fulfilling the primary OMT role of the center channel position.  Don't worry about how narrow the PAS angle is.  The wide-spaced pair are what contribute most of the sense of width, openness, and depth, rather than a wide-enough inclusive angle between the center pair. Aim for as much spacing as you can achieve for the wide pair, a meter or more if possible, but at least 20" or so.  Appropriate angle for the wide pair will be dependent on both how widely you are able to space them and the acoustic environment: 

More widely spaced = less angle between mics (max limit is both microphones facing directly facing forward). 
Less widely spaced = more angle between mics (max limit is both facing directly sideways in opposite directions).
Further back in a questionable acoustic =  less angle between mics.
Outdoors/good-acoustic = more angle between mics.

I made some good indoors recordings using a Mid/Side center pair (could have been PAS X/Y) in the center between ~20" spaced supercards (could have been cardioids) angled ~+/-45 degrees.   In that case the triangular bar setup I was using limited me to no more than that spacing on the wide pair.  If outdoors or in an especially good acoustic I would have angled the wide pair a full +/-90 degrees due to the spacing limitation.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 11, 2019, 07:20:09 PM
Ran two OMT rigs at a sweet little 2-stage fest this past weekend.  OMT8 > Zoom_F8  &  OMT6 > DR680_MK2.  Photos and a few rig descriptions follow..

Friday I arrived late and ran only the bigger OMT8 rig, at the main stage on my shorter stand, from the back corner of the sbd cage behind the video camera operator.  Walking the amphitheater and listening I was amazed at how much better the sound was just ~12' forward at the front edge of the sbd, which is where I typically setup and where I made sure to setup for the remainder of the weekend at that stage using a larger and taller stand.  I post these photos mainly to show this difference in placement, which may seem minor to many folks.  I've yet to listen for the difference on the recordings, but it was very obvious listening there in person.  Note the spaced omnis (Earthworks) on separate stands at the front of the board for the official video release crowd ambience.

Main stage Friday night-
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 11, 2019, 07:26:25 PM
Same rig the next afternoon at the same stage, setup prior to audience entry at the opposing front corner of sbd cage on the large/tall stand.  Much better location and height here.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 11, 2019, 07:41:08 PM
Couple showing the OMT8 arrangement from below.

2 DPA 4061 omnis in DIY sphere attachments.
5 DPA 4098 supercardioids in the B.A.Shure windscreens.
1 Naiant X8S bidirectional coincident with the center 4098 to form a M/S pair.

Omnis ~2m wide facing +/-235 degrees (away from front, towards back amphitheater corners).
Center pair 13cm/5" forward (rather than ~25cm/10" forward) as per our discussion here last week.
L/R pair spaced ~30cm/12" from center (60cm/24" total), angled ~+/-80 to 85 degrees (the mics are somewhat angled inside the windscreens).
Ls/Rs rear-facing pair about 25cm/10" radially out from the center, angled ~+/-135 degrees.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 11, 2019, 08:05:42 PM
OMT6 at the smaller stage.  I'd intended to run the TetraMic between spaced omnis here.  Rigging it up at home late Friday night I realized that one of the four phantom adapters for the Tetramic was misbehaving which dashed that plan.  Instead I ran the good Tetramic channels as 3 cardioids angled ~120 degrees apart- a 120 degree angled L/R pair facing forwards + a single channel facing rearward and up.  To orient the tetrahedral configuration of the Tetramic that way necessitated rotating the mic and angling the body forward 45 degrees.  In addition to the TetraMic I placed a Naiant X8S bidirectional under the rear/upward-facing cardioid to form a M/S pair.  Both the TetraMic and X-8S are placed in a BAShure windscreen (I removed the internal coarse foam insert to allow them to fit) covered by a DIY faux-fur cover as it was super windy at this stage with constant wind gusting from the side directly off the ocean.

No spheres on the omnis here as I was concerned they might increase wind noise, and would at definitely increase windage.  They were in foam screens only and blew wildly around as the wind increased, wiggling all over the place, and threatening to blow the entire stand over until I weighted it.  Thankfully upon a brief check-listen Saturday night I heard no wind nor adverse sound from the wild omni movement at all.  I take this as good confirmation of my observation made years ago that "wind phasing" noise is not caused by mic-stand swaying but by wind blowing the sound around in the air between the PA and microphones.  Photo below taken while the wind was relatively light, but even here you can see the tent canopy over the SBD pushed in on the left side.  Also note the official recording spaced omnis on separate stands like at the other stage.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on February 11, 2019, 09:35:35 PM
Interesting use of the Tetramic.  So are you going to use just the raw output of the three channels, or will you run those through the calibration?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 12, 2019, 09:52:23 AM
Good question and an interesting idea. My initial thought was to simply use the raw capsule outputs, EQing as needed by ear. 

I'll try running them through the calibration filters if there is an post-calibration-correction A-format output option in VVMic for TetraMic, however I don't think it provides that option.  Granted it's been a while since I used it and my memory is fuzzy, but I think all of the output options require a complete 4ch A-format input.  If so, I might take a look at the specifications within the calibration file for my microphone to see if I can determine what filtering is specified for each capsule and emulate that.

My TetraMic is a pretty early model and I'm overdue for sending it back to CoreSound for a recalibration.  Once I do, it will be interesting to see how much it has changed.
Title: Schoeps Mono Upmix - From Mono To Stereo & LCR
Post by: Gutbucket on February 19, 2019, 05:14:19 PM
Followers to these threads know I've long been interested in exploring ways to decorrelate or otherwise spread a single recorded rear-facing OMT ambient channel across two or more mixing or output channels.  The intent being to have that ambient depth information portrayed in a more enveloping and spatially open way in both the 2-channel stereo mix and for multichannel playback where that signal is reproduced by multiple surround speakers arrayed around the back and sides of the listening space.  An equally important additional benefit in the 2-channel stereo mix is to keep that monophonic rear-facing ambient signal from interfering with the forward-facing center microphone or coincident pair tasked with picking up the primary direct sound of interest and reproducing that with tight-imaging in the center of the playback stage. 

In other words, the goal is to spread out a monophonic rear-ambient signal such that it wraps around the back of the listener perceptually, and doesn't dominate the center of the stereo mix where the forward-facing direct sound should be clear and dominant.

We've discussed here previously things like mult'ing the mono-rear-facing channel to two channels, inverting polarity on one channel and panning them left/right - which is the same as routing the monophonic rear and front-facing channels through a Mid/Side matrix with a front-facing channel assigned as Mid and the rear-facing channel as Side.  That works decently well sometimes, but not always, and causes some low bass cancellation on the right side.  Better should be a 90-degrees quadrature phase shift in opposite directions to both channels rather than flipping polarity on one side only (a la matrix-surround encoding), which kuba e has tried and reported as being an advantageous approach.  And we've discussed a few other options as well, but most "stereoization" techniques and plugins introduce various artifacts, reverb, or other unwanted stuff.

With all that in mind, I'm intrigued to find the Schoeps Mono Upmix plugin available, as it looks like it might be a good solution for addressing this.

Other than using it in stereo output mode, which may be the most appropriate way to use it, It's LCR output option apparently routes the monophonic input to Center and only the upmix spatialization (extracted ambience and generated early reflections of set to produce them) to L/R.  For a stereo mix it might prove advantageous to use it in LCR mode, discarding the Center output and using just the L & R outputs.

It might also be useful to "slightly stereoize" a single forward-facing center channel to help spread it slightly and blend better into a 2-ch stereo mix, similar to use of a coincident stereo pair in place of a single forward facing center microphone, although without providing true left/right imaging like a coincident center pair provides.

https://www.plugin-alliance.com/en/products/schoeps_mono_upmix.html (https://www.plugin-alliance.com/en/products/schoeps_mono_upmix.html)

Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on February 19, 2019, 05:22:57 PM
I'm guessing that plugin could also be useful in situations where someone is recording with just a stereo pair but loses one channel, having to make the best of a single channel...?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 19, 2019, 05:29:58 PM
Yes, probably so.  I still intend to get a thread started on the idea concerning re-creating a missing channel based on whatever attributes can be determined from the interchannel relationship measured during good portions of a recording, but have been too busy.  I'll probably repost about that aspect in that thread when I get around to starting it.

Note that I also edited the post above after your comment, to add mention of kuba e's application of +/- 90 degrees quadrature phase shift as an alternate prefered approach.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on February 19, 2019, 05:41:36 PM
your application of +/- 90 degrees quadrature phase shift as an alternate prefered approach.
I literally had to Google that.  Is this a reference to the 90 degree angle between the L/C/R mics of a OCT array?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on February 19, 2019, 06:59:13 PM
Oops, that was kuba e and the only one who's tried it as far as I'm aware.  I've theorized about it in these threads as probably appropriate but still have yet to try it myself.  Apologies for the mixup!

Not the L/C/R center mics but rather the way a single surround channel is mixed into a 2-channel matrix-encoded surround output.  Think analog Dolby surround and the other old-school analog matrix surround formats which decode from 2 channel.  LRCS > LtRt.

Found one of our posts about it a few pages back-

I like mixing rear mic in Mid/Side or better with the constant time shift across all frequencies.
By that do you mean a time delay, or a constant-phase (quadrature) shift?

I mean constant-phase shift. I didn't try it on many recording. I have just a few OMT recordings.  I am using four mics - spaced omni and front and rear directional mics. For this couple recordings, It was the best to do constant-phase shift in comparison with Mid/Side or simple mix of the rear mic. I am using free vst plugin PhaseBug.

Thanks for describing what side facing mics provide in final mix. It is very interesting and inspiring. I will try six mics recording. I'd love to try the side microphones. I will let know here how I will be successful.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on March 05, 2019, 01:17:49 PM
I've tried using the Schoeps Image Assistant app and I'm ashamed to say I can't make heads or tails of it.  I don't blame the app...this just goes to show my own limits.

Anyway, the reason I was messing with it was to figure out the viability of replacing the center card in on OCT2 array with a supercard.  Would this allow for narrowing the spacing of the side-facing supercards because of the increased directionality of the center supercard?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: DavidPuddy on March 05, 2019, 01:23:38 PM
Grabbed a set of these from ebay to experiment with.

https://imgur.com/a/NQCtChx
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: ycoop on March 05, 2019, 01:39:00 PM
Grabbed a set of these from ebay to experiment with.

https://imgur.com/a/NQCtChx

Are there more for sale?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: DavidPuddy on March 05, 2019, 02:02:29 PM
Grabbed a set of these from ebay to experiment with.

https://imgur.com/a/NQCtChx

Are there more for sale?

Looks like he has one more.

https://www.ebay.com/itm/43-inch-Long-Black-Telescopic-Antenna-Whip-Ham-Radio-DIY-Project-RC-Toy-Control/132946530149?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649


EDIT: Looks like he has some chrome ones as well:

https://www.ebay.com/itm/109cm-Long-Telescopic-Antenna-Whip-Ham-Radio-Project-RC-toy-Radio-Control/132949413541?hash=item1ef4670ea5:g:y6YAAOxyDgRQ9XmK

Here's some black ones that are twice as expensive:

https://www.ebay.com/itm/Black-Whip-45-5-inch-Ham-Amateur-Radio-144MHz-2Meter-Band-BNC-Telescopic-Antenna/143122116356?epid=1631551184&hash=item2152be2f04:g:M2YAAOxyqUpQ7pUg
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 05, 2019, 02:36:40 PM
Grabbed a set of these from ebay to experiment with.

https://imgur.com/a/NQCtChx

Nice find. 

Since those don't include a integrated hinge at the base, consider figuring a way to:
Disassemble (unscrew?) them from the support structure for transport, or..
A way of hinging them and supporting the hinged segments (like "standard" telescopic TV antennas), or..
Overlapping the two bottom-most segments and rigidly connecting them, such that they form a single unit, telescope out to either side, yet collapse down to the same length as either single antenna.

Also, the outermost section of these types of telescopic antenna is usually too thin and flexible to support a microphone and its connecting cable.   If that is the case, you can gaff tape the last half-inch or so of the second-most outboard segment to the outermost portion of the first, just inside the end-button, such that the outermost section remains un-telescoped inside the second at all times, even when the end-button and attached microphone are pulled out to "new full extended length".  The antennas will then retract to a slightly less compact overall length, but only by the width of the tape-wrap.   This makes the antenna considerably more rigid by not only keeping the thinnest segment from extending, but also by making the second-thinnest section double-walled and more rigid.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on March 05, 2019, 02:42:20 PM
Overlapping the two bottom-most segments and rigidly connecting them, such that they form a single unit, telescope out to either side, yet collapse down to the same length as either single antenna.
Duct tape has worked for me so far in holding mine together like this.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 05, 2019, 05:15:03 PM
I've tried using the Schoeps Image Assistant app and I'm ashamed to say I can't make heads or tails of it.  I don't blame the app...this just goes to show my own limits

It's not intuitively obvious what the Image Assistant display is communicating. The SengpielAudio Visualizer (http://www.sengpielaudio.com/Visualization-ORTF-E.htm) is more intuitive, but more basic and incapable of modeling 3 channel configurations.

Image Assistant main view screen works basically as follows-

The horizontal axis (abscissa) indicates the physical recording geometry side of things. Center of that axis, marked as 0-degrees across the bottom, indicates an angle facing directly forward as in looking at the middle of the stage.  Angles extending leftward and rightward are marked in degrees across the bottom, extending out to +/-90 degrees  / 180 degrees total.  The Stereo Recording Angle is indicated by the shaded area across the center, denoting an imaginary "window" as viewed from the recording position, through which sound source positions making up the sonic scene will image between the front speakers upon playback.  Sound sources outside the shaded area will either be reproduced as emanating directly from the left or right speaker (stuck to the speaker positions) or reproduced diffusely.  The more-heavily shaded center portion shows the 75% SRA point, which you can ignore for the most part.  It becomes useful not for assessing any singe setup but for comparison of setups, since most of the variation between similar setups will occur outside the central region near the periphery.

The vertical axis (ordinate) indicates the playback image "perceptual" side of things- Line segments reaching the top of the vertical axis indicate that upon playback the sound is heard as emanating directly from the right speaker location; Line segments reaching the bottom portion of the vertical axis indicate sound heard as emanating directly from the left speaker location; The mid-point on the vertical axis indicates sound reproduction from the phantom center of a 2-ch stereo speaker array, or from a center speaker in a 3-channel L/C/R playback array.

The most accurate microphone setup in terms of the translation of source positions to playback imaging positions would be indicated by a straight diagonal line running from the lower left to upper right.  The angle of that line denotes the recording angle of the setup- a steeper, more vertical line indicates a narrower SRA or acceptance angle, useful when the recording position is further away.  A flatter, more horizontal line indicates a wider acceptance angle or SRA.  In either case sound will fill the space between the two speakers upon reproduction- notice that with all setups, the lines reach both the top and bottom of the display indicating the sound emanating directly from the speaker positions. However, also notice that different setups extend more or less widely horizontally out from center before intersecting the top and bottom edges, and that shaded center area indicates the inclusive recording angle or SRA of the setup.  All sound sources located outside that area will be reproduced as if they were crushed into the speaker on that side, or reproduced diffusely, depending on the diffuse-field correlation of the particular microphone setup.

Quote
Anyway, the reason I was messing with it was to figure out the viability of replacing the center card in on OCT2 array with a supercard.  Would this allow for narrowing the spacing of the side-facing supercards because of the increased directionality of the center supercard?

More on this tomorrow, as I'm out of time now. To start:

With 3 channel arrays, the diagonal line in Image Assistant is broken into two parts a Left-Center segment and a Right-Center segment.  By adjusting spacing/pattern/angle (and level/timing as well in some advanced setups) one tries to get the two separate segments to form a single diagonal line..
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 06, 2019, 01:30:31 PM
Anyway, the reason I was messing with it was to figure out the viability of replacing the center card in on OCT2 array with a supercard.  Would this allow for narrowing the spacing of the side-facing supercards because of the increased directionality of the center supercard?

I speculated that it would behave that way when altering the center microphone polar pattern, but upon messing around extensively with the original Java-based Image Assistant years ago (I found that older version somewhat easier to grasp) it became apparent it does not. Just now I pulled up the current online Image Assistant implementation to confirm. Changing the center microphone polar pattern in an OCT setup has negligible effect on how well the imaging of the Left/Center and Center/Right pair segments link across the middle of the playback image.  Change of pattern does alter the overall Stereo Recording Angle somewhat, in that the SRA becomes somewhat tighter as the center pickup pattern is narrowed from omni through cardioid to fig-8, yet even that is not a particularly strong effect.

By contrast, what has quite strong interactive relationships are the spacing of the L/R pair, the angle of the L/R pair, and the spacing of the center microphone forward of the L/R pair.

My move from an omni to a cardioid to a supercard center microphone was primarily motivated by aspects other than achieving good imaging via optimal L/C and C/R segment linking, yet at the same time I did not want to compromise good imaging.  So the minimal affect that changing the center microphone pattern has on image linking became a positive attribute with that in mind.  I could switch the center microphone to a tighter pattern as a way of maximizing pickup of direct sound from the stage and PA while suppressing off-axis pickup of audience and room ambience in that channel as much as possible/practical.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 06, 2019, 02:31:00 PM
Continuing where I left off yesterday-
"With 3 channel arrays, the diagonal line in Image Assistant is broken into two parts a Left-Center segment and a Right-Center segment.  By adjusting spacing/pattern/angle (and level/timing as well in some advanced setups) one tries to get the two separate segments to form a single diagonal line.."

With a 2 channel array the single diagonal line is unbroken.  With a 3 channel array, there are two diagonal lines that approach each other in the center, transitioning through curved portions to opposed horizontal tails as they reach the center. The bottom line represents the L/C imaging sector and the top line the C/R imaging sector.  By manipulating spacing, angle, and pattern, the goal is to get the two seperate diagonal line portions to line-up with each other as much as possible while minimizing the gap in the center.  The horizontal line portions and center gap represent the edge-boundary between the L/C imaging segment and the C/R imaging segment.  I can go into more detail on this if you like.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: DavidPuddy on March 06, 2019, 02:34:38 PM
Grabbed a set of these from ebay to experiment with.

https://imgur.com/a/NQCtChx

Nice find. 

Since those don't include a integrated hinge at the base, consider figuring a way to:
Disassemble (unscrew?) them from the support structure for transport, or..
A way of hinging them and supporting the hinged segments (like "standard" telescopic TV antennas), or..
Overlapping the two bottom-most segments and rigidly connecting them, such that they form a single unit, telescope out to either side, yet collapse down to the same length as either single antenna.

Also, the outermost section of these types of telescopic antenna is usually too thin and flexible to support a microphone and its connecting cable.   If that is the case, you can gaff tape the last half-inch or so of the second-most outboard segment to the outermost portion of the first, just inside the end-button, such that the outermost section remains un-telescoped inside the second at all times, even when the end-button and attached microphone are pulled out to "new full extended length".  The antennas will then retract to a slightly less compact overall length, but only by the width of the tape-wrap.   This makes the antenna considerably more rigid by not only keeping the thinnest segment from extending, but also by making the second-thinnest section double-walled and more rigid.

Good top about joining the last few sections - I definitely noticed that the ends are pretty fragile. I'm going to try to rig up a metal dowel of some kind that has screw threads on each side that I can simply tape to my stand and unscrew easily for transport. Any suggestions are certainly welcome though. Maybe something using a clamp?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: ycoop on March 06, 2019, 03:14:26 PM
Grabbed a set of these from ebay to experiment with.

https://imgur.com/a/NQCtChx

Nice find. 

Since those don't include a integrated hinge at the base, consider figuring a way to:
Disassemble (unscrew?) them from the support structure for transport, or..
A way of hinging them and supporting the hinged segments (like "standard" telescopic TV antennas), or..
Overlapping the two bottom-most segments and rigidly connecting them, such that they form a single unit, telescope out to either side, yet collapse down to the same length as either single antenna.

Also, the outermost section of these types of telescopic antenna is usually too thin and flexible to support a microphone and its connecting cable.   If that is the case, you can gaff tape the last half-inch or so of the second-most outboard segment to the outermost portion of the first, just inside the end-button, such that the outermost section remains un-telescoped inside the second at all times, even when the end-button and attached microphone are pulled out to "new full extended length".  The antennas will then retract to a slightly less compact overall length, but only by the width of the tape-wrap.   This makes the antenna considerably more rigid by not only keeping the thinnest segment from extending, but also by making the second-thinnest section double-walled and more rigid.

Good top about joining the last few sections - I definitely noticed that the ends are pretty fragile. I'm going to try to rig up a metal dowel of some kind that has screw threads on each side that I can simply tape to my stand and unscrew easily for transport. Any suggestions are certainly welcome though. Maybe something using a clamp?

Maybe find something that will fit into the opening of a c-clamp?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: IMPigpen on March 06, 2019, 03:40:19 PM
Grabbed a set of these from ebay to experiment with.

https://imgur.com/a/NQCtChx

Nice find. 

Since those don't include a integrated hinge at the base, consider figuring a way to:
Disassemble (unscrew?) them from the support structure for transport, or..
A way of hinging them and supporting the hinged segments (like "standard" telescopic TV antennas), or..
Overlapping the two bottom-most segments and rigidly connecting them, such that they form a single unit, telescope out to either side, yet collapse down to the same length as either single antenna.

Also, the outermost section of these types of telescopic antenna is usually too thin and flexible to support a microphone and its connecting cable.   If that is the case, you can gaff tape the last half-inch or so of the second-most outboard segment to the outermost portion of the first, just inside the end-button, such that the outermost section remains un-telescoped inside the second at all times, even when the end-button and attached microphone are pulled out to "new full extended length".  The antennas will then retract to a slightly less compact overall length, but only by the width of the tape-wrap.   This makes the antenna considerably more rigid by not only keeping the thinnest segment from extending, but also by making the second-thinnest section double-walled and more rigid.

Good top about joining the last few sections - I definitely noticed that the ends are pretty fragile. I'm going to try to rig up a metal dowel of some kind that has screw threads on each side that I can simply tape to my stand and unscrew easily for transport. Any suggestions are certainly welcome though. Maybe something using a clamp?

Maybe find something that will fit into the opening of a c-clamp?

I actually got similar antenna pieces for my DIY antenna rig for my Naiant omnis.  I bought these:

https://www.amazon.com/outstanding-Universal-Telescopic-Stainless-Replacement/dp/B077933KMZ/ref=sr_1_fkmr0_1?keywords=E-outstanding+2Pcs+AM%2FFM+Radio+Universal+Antenna+%28M%29&qid=1551904046&s=gateway&sr=8-1-fkmr0 (https://www.amazon.com/outstanding-Universal-Telescopic-Stainless-Replacement/dp/B077933KMZ/ref=sr_1_fkmr0_1?keywords=E-outstanding+2Pcs+AM%2FFM+Radio+Universal+Antenna+%28M%29&qid=1551904046&s=gateway&sr=8-1-fkmr0)

They are M3 threaded but you can buy a 2-pack of female and a 2-pack of male antenna and one of each screw together perfectly.   They are 7-sections, 96cm each (37.8") fully extended.  So up to over 6 feet.  But I've used them at about 4 feet with mics, clips and cables (extending the thicker sections first).

After I screwed them together, I used electrical tape where the two screw together.  I actually had a small plastic tube that fit right over the antenna (from the dog's poop bag roll).  I centered that and taped it to the antenna.  Added some tape over the end and put some erasers on to clip the mic clips to.  It all slides into the hole of my Impact Micro Clamp.

I'll take some photos when I get home.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on March 06, 2019, 03:44:47 PM
I actually had a small plastic tube that fit right over the antenna (from the dog's poop bag roll). 

I love this sort of ingenuity. 
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: IMPigpen on March 06, 2019, 03:54:11 PM
I actually had a small plastic tube that fit right over the antenna (from the dog's poop bag roll). 

I love this sort of ingenuity.

Haha, as an engineer, I've had to jury-rig stuff all the time with what's on hand.  So I thought about what I had that the antenna might fit through...Bic pen was a little too tight, but the poop bag roll was perfect fit, and it's hard plastic and just a little longer than the hole in the Impact clamp.  Perfect and free!   I could build two of the rigs for a grand total of $15.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 06, 2019, 04:48:16 PM
Right on, DIY improvisational engineering is the oddball way!

beegar- There are obviously lots of different ways to do this. My first thought for you is to find a coupling nut sized to fit the antenna studs.  A coupling nut is just a long nut with enough thread length that both studs will thread in fully from either end.  You then have something similar to what IMPigpen describes with the antennas connected directly to each other.

Lacking that, below is how I'd probably approach it using the antennas you have on hand. Do you have the capability to cut a piece of metal flatstock material and drill a hole in the middle? How about drilling three holes and making a couple 90-degree bends in the bar?

Two bars, one hole each, no bending, some gluing-
Imagine a 1-1/4" or so wide by 4" long (or whatever length the collapsed of the antennas are) piece of aluminum flat-bar with a hole in the middle sized to fit over the top stud of your stand.  Basically a 4" mic bar but with only the center hole in it.  Make two and sandwich the telescopic antennas between them, one oriented left, the other right, one placed just in front of the center hole, one just behind it. Hold the antennas in place (hold the sandwich together) by using construction adhesive or epoxy to glue them to one or both of the bars so they won't squeeze out from between the flat-bar "bun" like a slippery pickle. 

One bar, three holes, no bending, no gluing-
Use a single bar as above and plastic zip ties to mechanically secure either end of each antenna to the bar instead of using adhesive.  To do so drill 3 holes in the bar instead of one, each the same diameter (sized the fit over the stand stud), each positioned on the center-line of the bar, with the additional holes located near either end of the bar.  Secure each antenna to the bar by running plastic tie-wrap through the hole at one end, over the antenna, around the front or back of the bar depending on which antenna it is, and back through the hole. Do the same at the other end of the bar.  Then do the same for the other antenna, passing the tie-through the same holes but wrapping the opposite direction around the other edge of the bar.  Four zip ties in total, two on each antenna.

^Both those options create a more rigid, easily stand-mountable, permanent version of heathen's "opposed and duct-taped together" method.

One bar, three holes, + bending and thread tapping (or gluing)-
Make a shorter bar, with a hole in the center for the stand stud and a hole at each end sized to fit the threaded stud on the end of the antenna.  Thread the smaller holes to fit the thread on the antenna studs, or drill those holes slightly large and epoxy threaded nuts to the back side of those holes.  Put the bar in a vice and make a sharp 90 degree bend at end each end halfway between the holes.  You now have a U shaped bar which fits over your stand stud and into which the antennas will thread.  The U can open either upward or downward if there is enough clearance for the stand.  Best to keep the epoxied nuts on the inside of the U as long as the studs are long enough to pass through the bar and into the nuts.  That way the epoxy only keeps the nuts in place, and the nuts transfer the load to the bar.  If the epoxy fails with the nuts on the outside, the antenna falls.

^Without the antennas removed (unscrewed) this arrangement stows somewhat longer than twice the length of each individual collapsed antenna.  With the antennas removed it stows as three separate parts.  You could probably leave the center U portion attached to the stand or your clamp.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 06, 2019, 04:58:43 PM
Back to heathen's question about center microphone pattern and L/R supercard spacing in an 3 channel OCT setup-

The primary relationship concerning spacing of the side-facing supercards is this: Narrower L/R spacing makes for a wider SRA - wider spacing makes for a narrower SRA.  It's the same basic relationship as in 2 microphone stereo configurations and there is no way around it.

What happens when other constraints require us to use a narrower L/R spacing than we might want? And what might we do to compensate?  If forced to go narrow with the L/R pair, try to keep the angle between them as wide as possible (+/-90 degrees / 180 degrees total).  That's because as the L/R pair is angled forward, additional spacing is required to compensate for the narrower angle. 

However, keeping the L/R supercards pointing fully sideways is likely to be contrary to what we'd really like when positioned far back in the room, because angling the L/R pair more forward is desirable to bring the on-stage sources and/or PA more on-axis, reducing the level of off-axis room and audience sounds arriving from the sides and back.  The problem is that in such a situation we want a narrower SRA AND a more-narrow L/R angle and BOTH those things require a wider L/R spacing.

If you retain the 180 degree angle between L/R supercards, you can narrow the spacing between a fully side-facing L/R supercard pair until they are only 22cm (~8-1/2") apart and retain good sector linking with the center microphone placed 10cm forward (requiring no delay or level manipulation of the center channel). Doing so results in a total SRA of 180 degrees.  That means the imaging window between the front playback speakers will encompass the entire front hemisphere as viewed from the recording position - a 180 degree arc of sound sources spatially compressed into the 60 degree arc between speakers. The sound sources on stage will be clustered tighter and more compactly into the middle of the playback image.  This makes for a more distant perspective in a geometric "imaging" sense than a narrow SRA that would spread out the stage-width sources until they more completely fill the arc between speakers (this aspect is why Michael William's titled his paper The Stereo Zoom ), but of course there are other psychoacoustic cues which relate to the perception of "closeness/distance" in addition to imaging perspective, and they may contradict the geometric imaging cues. Direct/reverberant sound balance and EQ balance are two among others.

Want to angle the L/R supercards forward 45 degrees?  We then need to increase the spacing of the L/R pair to 28cm and increase the spacing of the center channel to 18cm forward of the L/R pair in order to retain a 180 degree SRA, and retain decent sector linking.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 06, 2019, 05:09:41 PM
How narrow can we push it?

I've got Image Assistant up now, with L/R supercards spaced 31cm and angled a full 180 degrees apart.  I've switched the center microphone to a figure-8, as that is the only pattern available in Image Assistant which is tighter in front pickup than supercardioid, placed 8cm forward of the L/R pair.  In the taper world one might use a shotgun in the center with good reason, yet a fig-8 will be better behaved with regards to stereo imaging which is what Image Assistant is primarily about.  This produces an SRA of 138 degrees, which is still wide, but considerably more narrow than 180 degrees.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 06, 2019, 05:37:05 PM
The sideways versus forward-angling thing with the L/R supercards helps explain one reason why a considerably wider spacing is desirable for omnis when we introduce a center microphone as opposed to a pair of spaced omni's alone.  In terms of image linking at least, if one cannot arrange for optimal omni spacing, it can be advantageous to switch more directional omnis, subcards, or cardioids pointed sideways which will reduce the spacing requirement somewhat.  However, one gives up other advantages of spaced omnis when doing that, such as low bass sensitivity. 

This in one reason I suggest folks point their omnis sideways for OMT when the spacing they can achieve between them is limited, as it gets as much spacing as possible by using the mic bodies to extend the capsules out slightly farther and at the same time takes advantage of the slight top end directionality of most omnis.  Side facing subcards or cardioids can reduce the spacing requirement further if necessary.

I don't have subcardioids, but I'd not hesitate to use them facing 180 degrees apart in place of omnis, if I could not otherwise achieve as much omni spacing as I'd like.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on March 07, 2019, 09:52:33 AM
This in one reason I suggest folks point their omnis sideways for OMT when the spacing they can achieve between them is limited, as it gets as much spacing as possible by using the mic bodies to extend the capsules out slightly farther and at the same time takes advantage of the slight top end directionality of most omnis.
Here is a photo of what we chose to do after you recommended doing so. I would guess we gained a good 6-8 inches total further than the Manfrotto Triple bar's 30".
AKG ck22|460b outside; AKG ck8 fwd 0'; AKG ck61active rear 180'
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 07, 2019, 11:20:34 AM
Thanks for posting that photo and glad the arrangement worked well for you.

If you wanted you could probably gain an additional 6-8" by pushing the mic-bodies out further in the mounts, and you might gain a couple additional inches by pointing the swivel mounted capsules outwards instead of forward.

For those not be familiar with the ck22 omnis in the photo above, they are somewhat odd in that the microphone incorporates an internal end-plug which makes it more fully omnidirectional all all frequencies, even at very high frequencies were other omnis of the same diameter become more directional.  The 'pointy end' is blocked and sound enters trough ports running around the outer periphery of the capsule.  It is neither an end-address nor side-address microphone but an "all direction address" design, making it similar to miniature lavalier omnis which are fully omnidirectional due to their small size.  So for that particular microphone it doesn't really make much difference in what direction it is pointed..

But when using typical end-address omnis of a similar diameter as the ck22 I'd still suggest pointing them sideways whenever the spacing between them isn't as wide as desired.  That way their slight top end directionality becomes a feature making the most of the limited spacing - similar in a way to switching to side-facing subcards so as to leverage their directionality and make the most of limited spacing while still retaining strong bass extension, but to a lesser extent.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on March 07, 2019, 12:02:36 PM
^^^^^^^^^^
Well, you got me. I should look for another snap which shows the ck22|460's mounted with bodies extended across the clips. Actually does get us several more inches on each side when we do it that way.
top: AKG ck22|460b outside omnis; AKG ck3|nbobs|Naint PFA fwd 0'; AKG ck61|nbobs|Naint PFA rear 180   (Steal Your Peach 2018-07-25)
middle: AKG ck22|460b outside omnis; AKG ck3|nbobs|Naint PFA fwd 0'; AKG ck61|nbobs|Naint PFA rear 180 (Fully extended the mic bodies in this one) (Adam Ezra 2017-08-16)
bottom: AKG ck22|460b outside omnis; AKG ck61 fwd 0';  3 channel OMT minus a rear mic; with no cables, testing on stand at home (before DnCo 2016-06-21)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: IMPigpen on March 07, 2019, 12:17:37 PM
Here are a few photos of my antenna rig.

1.  The antenna with eraser ends in the Impact clamp
2.  Just the antenna with the "poop bag" roll in the center taped for stability
3.  Electrical tape wrapped on the end to provide a snug fit for the eraser.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on March 07, 2019, 01:30:45 PM
Here are a few photos of my antenna rig.

1.  The antenna with eraser ends in the Impact clamp
2.  Just the antenna with the "poop bag" roll in the center taped for stability
3.  Electrical tape wrapped on the end to provide a snug fit for the eraser.

That is really slick.  Does the Impact clamp hold onto the antenna by just having a screw at one point?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on March 07, 2019, 01:35:04 PM
Here are a few photos of my antenna rig.

1.  The antenna with eraser ends in the Impact clamp
2.  Just the antenna with the "poop bag" roll in the center taped for stability
3.  Electrical tape wrapped on the end to provide a snug fit for the eraser.
+T!
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: IMPigpen on March 07, 2019, 01:49:40 PM
Here are a few photos of my antenna rig.

1.  The antenna with eraser ends in the Impact clamp
2.  Just the antenna with the "poop bag" roll in the center taped for stability
3.  Electrical tape wrapped on the end to provide a snug fit for the eraser.

That is really slick.  Does the Impact clamp hold onto the antenna by just having a screw at one point?

It does hold it with just the one screw.  I was prepared to wrap more tape around and/or add a little larger metal or plastic tube over it and tape that but it holds tight as is.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: ycoop on March 07, 2019, 02:04:55 PM
Here are a few photos of my antenna rig.

1.  The antenna with eraser ends in the Impact clamp
2.  Just the antenna with the "poop bag" roll in the center taped for stability
3.  Electrical tape wrapped on the end to provide a snug fit for the eraser.

What are the erasers there for?
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 07, 2019, 02:08:55 PM
^ Very nice implementation, clean & simple.

Looking at the first photo posted above, it might be advantageous to slide the clamp left a touch.  That accomplishes two things- It centers the clamp's thumb-screw on the joint between the two antennas, where the threaded insert ends provide significant "hoop-strength" which keeps the tube from being crushed if you really crank down on the thumb-screw, and secondly centers the antenna-bar on a typical diameter stand upright, which is just a tweaky thing and of negligible acoustical significance.

The erasers are Moke's method of attaching small lav omnis.  He cuts a notch in the rubber wedge end to hold the mic cable.  Personally I never got that method to hold securely and just use a small square of gaffer tape.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: IMPigpen on March 07, 2019, 02:40:58 PM
^ Very nice implementation, clean & simple.

Looking at the first photo posted above, it might be advantageous to slide the clamp left a touch.  That accomplishes two things- It centers the clamp's thumb-screw on the joint between the two antennas, where the threaded insert ends provide significant "hoop-strength" which keeps the tube from being crushed if you really crank down on the thumb-screw, and secondly centers the antenna-bar on a typical diameter stand upright, which is just a tweaky thing and of negligible acoustical significance.

The erasers are Moke's method of attaching small lav omnis.  He cuts a notch in the rubber wedge end to hold the mic cable.  Personally I never got that method to hold securely and just use a small square of gaffer tape.

Thanks for the input Gutbucket.  That makes sense and I'll give it a try! 

And yes, I was inspired by Moke's eraser idea.  The only difference is, since the Naiant's are a little bigger than DPA or Countryman lav omnis, I use Movo lapel clips clamped onto the erasers.   They provide something for the clip to bite into and not rotate on the round antenna.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 07, 2019, 03:47:35 PM
I use Movo lapel clips clamped onto the erasers.   They provide something for the clip to bite into and not rotate on the round antenna.

That sounds like it would work well, with the sprung clip getting a good bite onto the rubber eraser.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kindms on March 25, 2019, 07:25:00 PM
Some panic OMT fun

http://bt.etree.org/details.php?torrentId=604854

Widespread Panic

2019-03-22

The Capitol Theatre
Port Chester, NY

Source:AKG ck3 (1ft split forward / Rear) >V2 >DR680
Source:AKG ck61 (2ft split left/right 90deg from stage) >DR680
Source:DPA 4061 (3f split) >V2 >DR680
Transfer:SD >Audacity >CD WAV Editor >TLH >FLAC
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on March 25, 2019, 10:23:15 PM
^^^^^^^^^^^^^^^^   rig pic
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 26, 2019, 10:44:04 AM
Crazy lookin' animatronic octopus up there!

Thx. On the torrent..
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on March 26, 2019, 11:41:50 AM
Crazy lookin' animatronic octopus up there!

Thx. On the torrent..
We were "blaming" you all weekend. "Damn that gutbucket, now we have all these channels and they DO sound great all combined"!
We did an OMT 6 on FRI night and an OMT8 on SAT night. 
the SAT 2019-03-23 OMT8 config:
Source:AKG ck3 (1ft split forward / Rear) >V2 >DR680
Source:AKG ck61 (2ft split left/right 90deg from stage) >DR680
Source:DPA 4061 (3f split) >V2 >DR680
Source:AKG c426 XY hypercardioid >V3 > DR680
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 26, 2019, 01:24:40 PM
I'll be the scapegoat!

How are you guys liking the 4061s?  You realize that with them you now have no excuse not to push the omnis out further to 5'+ !  Doing that is especially fruitful when incorporating the multiple directional mics in the middle.  Everything breathes. Super phat booty bottom.  Damn it Gutbucket! 

Curious if you tried the C426 XY hyper in place of the center fwd ck3 in the mix this time.

I'll post some photos of my OMT8 rig strapped to a narrow outdoor patio column for Marcus King last weekend.  Moved it inside for George Porter Jr Trio and the all star family jam, which served as good test of the identical rig both inside and outside, at about the same distance from and orientation with the stage/PA, and with a similar sized crowd and "room".

Tentative comparison conclusion- As expected and discussed previously, I want the L/R supers pointed mostly sideways outdoors, but prefer to angle them 45-degrees forward toward the PA in a more reverberant indoor environment so I'll be thinking more about modifying the rig to make that easier without having to removing the big Shure windscreens to angle them forward. Conclusion is tentative as the only listening so far involved two pair of headphones, nudity, and a lovely listening partner on golden sun-lit Sunday afternoon - a very highly recommended configuration BTW, for which I'm fully willing to take the blame if you find such high fidelity enjoyable.

Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on March 26, 2019, 01:33:06 PM

Curious if you tried the C426 XY hyper in place of the center fwd ck3 in the mix this time.

That's why we ran both C426 XY hyper AND fwd|rear ck3 for SAT 3-23! Not only that, but in the mix, I tried eliminating one or the other of them and ultimately kept them both and used all eight channels in the final mix (adjusted for tone and taste of course)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 26, 2019, 03:50:35 PM
Ha! 

Yep, you're hooked.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: DavidPuddy on March 27, 2019, 02:33:19 PM
Grabbed a set of these from ebay to experiment with.

https://imgur.com/a/NQCtChx

I've decided to move in a different direction (center omni) and sold my 853s. If anyone is interested in grabbing this antennae set, please PM. I can post in YS, but wanted to give OMT guys first dibs.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: ycoop on March 27, 2019, 03:06:05 PM
https://archive.org/details/spafford2019-03-24.SanRafaelCA.ycoop

My first show that I went without a safety pair and went XY90 with the center pair. I think I should have gone with a narrower angle, maybe XY60 or 75, due to using the hypers. The midrange isn’t as clear as I would like. I went with DINa hypers on the first night, but people were talking so much I can’t really make a direct comparison. I was also made aware that the PA system isn’t in stereo, so I made the decision to align my rig with the nearest PA array. I was situated pretty far LOC so this seemed the way to go. Incidentally the drummer was located stage left, and the venue is small enough that the percussion is still localized to the right channel, which is nice.

As for processing I took the omnis and split them into bass and everything else (low pass filter around 400 Hz). I summed the bass to mono and bumped the midrange and high end of the “everything else” and then mixed the three tracks (center pair, omni bass, Omni everything else) to taste. On my cans at home this sounded pretty nice, though on my cheapo work BT earbuds the bass is too high in the mix. I’m thinking the overall bass heaviness has to do with how much of the sound was reverberant and/or off axis. I would appreciate feedback on how the mix sounds.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on March 27, 2019, 03:55:23 PM
The midrange isn’t as clear as I would like.

EQ would likely help with that.

I'll hold off on commenting further until I can listen at home.  I will say that I've been rolling off bass more and more often, and particularly trying to hit the "mud" area which I often find to be in the 100Hz-200Hz region.  Dynamic EQ has been really great for dealing with the mud.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 27, 2019, 08:38:40 PM
I'll try to listen tonight at home on good phones if I have time, yet have a trade show starting tomorrow through the weekend I need to prepare for.  Sounds good on the cheap bass-less ear-buds at work. 

Not sure about summing all omni too mono at that relatively high frequency.  I usually prefer the opposite (increased wideness in the bass) for spatial reasons, unless the bass or kick are oddly uncentered or lopsided for whatever reason, and consider that width one of the main benefits of spacing the omnis widely.  There is a good argument for monoizing or at least using less width at the lowest octaves however, say under 80Hz, for maximizing low frequency reproduction energy from small woofers.  At mid and high frequencies above 400hz, you are still getting the benefit of the omni spacing with regards to decorrelated reverb and ambience providing good "openness" in that range.

Have you tried a mix without the monoization? Or pushing that monoize cross-point down low?  Worth comparison I think.  Of course what is right for your recording is what sounds right to you! 

If you like monoing the bass below 400Hz, try this alternate mix method to see if it helps with bass quality: Instead of summing both omnis to mono below 400Hz, try using only one or the other of them panned to center or duplicated to the other channel.  That will eliminate phase interaction between the two which is occurring in the sum due to the spacing / wavelength relationship. The same phase interactions which provide some of the qualities I prefer in stereo bass reproduction (above the lowest octave or two), may be muddying up things when summed to mono.

And in general, I agree with Heathen about EQ being a goto for tweaking the midrange, and dynamic EQ helping the mud-range.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: ycoop on March 27, 2019, 10:21:49 PM
I'll try to listen tonight at home on good phones if I have time, yet have a trade show starting tomorrow through the weekend I need to prepare for.  Sounds good on the cheap bass-less ear-buds at work. 

Not sure about summing all omni too mono at that relatively high frequency.  I usually prefer the opposite (increased wideness in the bass) for spatial reasons, unless the bass or kick are oddly uncentered or lopsided for whatever reason, and consider that width one of the main benefits of spacing the omnis widely.  There is a good argument for monoizing or at least using less width at the lowest octaves however, say under 80Hz, for maximizing low frequency reproduction energy from small woofers.  At mid and high frequencies above 400hz, you are still getting the benefit of the omni spacing with regards to decorrelated reverb and ambience providing good "openness" in that range.

Have you tried a mix without the monoization? Or pushing that monoize cross-point down low?  Worth comparison I think.  Of course what is right for your recording is what sounds right to you! 

If you like monoing the bass below 400Hz, try this alternate mix method to see if it helps with bass quality: Instead of summing both omnis to mono below 400Hz, try using only one or the other of them panned to center or duplicated to the other channel.  That will eliminate phase interaction between the two which is occurring in the sum due to the spacing / wavelength relationship. The same phase interactions which provide some of the qualities I prefer in stereo bass reproduction (above the lowest octave or two), may be muddying up things when summed to mono.

And in general, I agree with Heathen about EQ being a goto for tweaking the midrange, and dynamic EQ helping the mud-range.

I'm going to play around with the use of a single omni channel option, but so far I definitely prefer how having the low-pass / high-pass line falling out at 120 Hz.

Side note of coolness (this is true of either mix) is that when the drummer switches to his electric drum pad I can hear the sound move to the center.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: jcable77 on March 27, 2019, 10:36:22 PM
Not really oddball but ran 4 ch omni’s friday (pretty much thought I had 61’s on actives but the 62’s worked great). 62’s in the center and ADK’s split on stage. Picture isnt great but left is by the keys and right is next to turntable. Monitor out for two ch added some nice vocals and turntable effects.

https://archive.org/details/TG4S2019-03-22
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on March 28, 2019, 09:02:54 AM
^ Cool.  Looks like a nice little music joint.

I'm going to play around with the use of a single omni channel option, but so far I definitely prefer how having the low-pass / high-pass line falling out at 120 Hz.

120 Hz seems more reasonable to my way of thinking, but whatever works and sounds right is right!  The single omni mono option may or may not be better, you'll need to give it a listen in the mix to find out. 

Unfortunately, I was unable get a chance to listen last night.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: kindms on April 07, 2019, 07:01:49 PM
So another OMT outing

This time we ran

AKG ck22s split 4ft >V2, We had AKG ck61s basically PAS split 2ft and then we ran the AKG c426 Blumlien fig8s 90degrees

Pretty good time. The cap is really being strict with the whole 7ft thing. kind of sucks as people like to chat there. But ultimately I think a solid representation of the room and music etc

https://archive.org/details/dbb2019-04-06.AKGc426AKGck22AKGck61
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Twenty8 on April 07, 2019, 10:05:48 PM
So another OMT outing

This time we ran

AKG ck22s split 4ft >V2, We had AKG ck61s basically PAS split 2ft and then we ran the AKG c426 Blumlien fig8s 90degrees

Pretty good time. The cap is really being strict with the whole 7ft thing. kind of sucks as people like to chat there. But ultimately I think a solid representation of the room and music etc

https://archive.org/details/dbb2019-04-06.AKGc426AKGck22AKGck61

Nice recording!
I used to go see DBB all the time when I was in college.  Nice to see they are back and banging.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Moke on May 02, 2019, 03:47:12 PM
From last night... I played around a wee bit with another improvisational rigging.

I was set up at the stage-lip, center.  I had Güde Head on his torso box, which i usually run "square" in relation to a imaginary line that closes a 180º hemispherical stage presence of the ensemble.
This time, I thought I'd turn Güdes chest 90º, such that it became diagonal, or rotated 90º from normal; see image 6743. In that thought I also thought that I would be able to utilize the box as a PZM-BLE stereo arrangement. Over the PZM-BLE arrangement, I flew the CM3 pair at 0º forward and 180º rearward.
I'm not sure that there needed to be a finished mix, as the PZM-BLE two channel stereo recrdong is quite a listen in its own right. But I mixed it down anyway, and, need time to check it out.

Güde in stealth mode, again; img6734
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on May 02, 2019, 06:18:51 PM
Cool technique using the "90 degree wedge" box orientation for boundary-mounting.

Similar to Pierre Sprey's Mapleshade recording setup using modified PZMs mounted on an acrylic-wedge-

(https://www.gearslutz.com/board/attachments/remote-possibilities-in-acoustic-music-and-location-recording/691177d1504954349-boundary-room-mics-teldec-technique-redwine_trio1.jpg)

PS- I mention this mostly as a technically, but "PZM" (acronym for Pressure Zone Microphone) is a Crown trademark, referring to their original design which mounts the capsule such that it is facing the integrated boundary/base plate just a fraction of an inch away from it.  The microphones in the photo above are modified Crown PZMs, taped to the larger lexan sheets forming the wedge.  In contrast, the technique itself is simply one of "boundary mounted omnis", regardless of the make of the microphones used in a boundary-mounted arrangement.  In other words, its technically "PZM" only if one uses Crown PZM microphones.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on May 31, 2019, 01:08:02 PM
How narrow can we push it?

I've got Image Assistant up now, with L/R supercards spaced 31cm and angled a full 180 degrees apart.  I've switched the center microphone to a figure-8, as that is the only pattern available in Image Assistant which is tighter in front pickup than supercardioid, placed 8cm forward of the L/R pair.  In the taper world one might use a shotgun in the center with good reason, yet a fig-8 will be better behaved with regards to stereo imaging which is what Image Assistant is primarily about.  This produces an SRA of 138 degrees, which is still wide, but considerably more narrow than 180 degrees.

Messing with the Image Assistant more today, I am surprised at the impact a level difference can have on an OCT2 array.  Bumping up the level of the center channel even just one db has a noticeable impact on the localization.

Maybe I should just record in mono and call it good  ;)
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on May 31, 2019, 04:58:38 PM
It does, but in reality I always end up adjusting the level of the center channel against that of the L/R pair afterwards by ear to best effect. While doing that, ideal image distribution is only one of several things I'm listening for- it's important, but not most important.  A higher priority is achieving an appropriate energy balance across the entire front soundstage with good center solidity, and sufficient clarity of the sources on stage dominating the center content.

Mono is simple in terms of gear, but really good mono is considerably more constrained and thus more difficult to pull off in a situation in which we have limited control than multi-channel surround!.. or 2-ch stereo. By contrast, making a really good single channel recording requires most everything be optimally balanced prior to reaching the recorder.

IMO, a large part of what makes OMT attractive for tapers is that although the setups and gear requirements are more complicated, it provides very welcome flexibility and options for manipulating things to best sonic advantage after the recording is made.  OCT2 intended for 2-ch is similar in that way, if a bit more specialized if the optional omnis aren't recorded as well, in that it is completely dependant on the totally side-facing supercard pair alone and no other channels for adding "stereoness".   

A fundamental philosophical as well as practical attraction of both OCT and OMT for me is that they essentially start with a single "mono-like" center microphone position and build upon that, with the additional channels providing extended dimensionality past mono to 2-ch stereo and on further still to multichannel playback.  Even if that "mono-like" center position evolves into a coincident pair rather than a single microphone.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on June 12, 2019, 01:31:30 PM
After several outings now running an OCT/OCT2-type array, I'm on the fence about whether it's right for creating a recording meant for two-channel listening.  There is of course a certain "no duh" element to this because, as I understand it, OCT was made for multi-channel playback with a discrete center channel.  (Or maybe that's OCT2...or maybe both.)  That said, it also doesn't seem like two-channel playback should be out of the question.

The primary uncertainty I'm having with it is the stereo imaging on two-channel playback.  Now obviously right out of the gate there's a question here about how much stereo imaging was present from the source, since a lot of the mixes at shows I'm recording are mono or mostly mono.  Sometimes, though, I'm close enough to pick up stereo information from the stage.  Also there are sometimes stereo elements to the PA mix.

Another thing that's giving me pause about OCT/OCT2 for the type of shows I'm recording is that it introduces a lot of reverberant sound.  (Having said that I know that even when mics are pointed directly at the stacks we're still getting lots of reverberant sound, at least indoors.  Maybe the more accurate way of saying what I mean is that the side channels in OCT/OCT2 seem to pick up a greater ratio of reverberant to direct sound.)  The center mic, obviously, gets a lot of direct sound because it's pointed directly at the center of the sound source.  Listening to that on its own isn't fun because it's just mono.  In order to get some stereo sound, then, I'm bringing up the level of the side mics.  But doing that means bringing in a lot of reverberant sound.  So I'm ending up with a choice between largely mono-sounding playback or highly reverberant playback.

I'm rambling a bit here and I'm not really certain what my point is other than I'm not sure how appropriate OCT/OCT2 is for two-channel playback.  The reason I got interested in OCT/OCT2 to begin with is I want to have a really strong center to my recordings (partially because there's so much mono information at the shows I record, and partially because I think it gives recordings a really nice sense of presence? immediacy?  I'm not sure what term fits here).  At the same time, I do want to have good L/R information.  I think about what the sound is like at shows I attend, and usually it feels more like a wall than something with a lot of depth and dimension to it.  So, how can I capture that so that on playback there is this wall of sound coming at the listener?  That's what I'm trying to figure out, in the big picture context.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on June 12, 2019, 07:16:39 PM
I think about what the sound is like at shows I attend, and usually it feels more like a wall than something with a lot of depth and dimension to it.  So, how can I capture that so that on playback there is this wall of sound coming at the listener?  That's what I'm trying to figure out, in the big picture context.

Godspeed you fellow knight chasing the dragon's tail. Having drunk from the same chalise I wish for the same. If our listening experience at a concert is an immersive one of a large all-encompassing wall of sound in front supported by live audience and room ambience all around us, then expecting a strong emulation of that experience from two speakers placed in front of us (and neither directly in front) is a quite tall order.  The best way I've found for translating the "big solid wall of sound" experience aspect you describe is to use a reproduction system which enables a more robust emulation of the original experience, tailoring the recording setup to suit that playback arrangement.  I do that using three to five speakers across the front, seven to nine in total all the way around.  I also realize this is not the answer you are looking for.

It's the answer hardly anyone accepts, including tapers, which is ironic in that I find the most useful application of surround reproduction, other than movie sound and gaming where it has achieved acceptance, is the enjoyment of "live performance from the audience perspective" recordings.  Its best for the stuff we do.

But enough pie-eyed thinking, lets talk OCT/OCT2's suitability for 2-channel stereo playback.. or more specifically, it's suitability for the situations in which you are recording...
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on June 12, 2019, 07:50:47 PM
Quote
Another thing that's giving me pause about OCT/OCT2 for the type of shows I'm recording is that it introduces a lot of reverberant sound.  (Having said that I know that even when mics are pointed directly at the stacks we're still getting lots of reverberant sound, at least indoors.  Maybe the more accurate way of saying what I mean is that the side channels in OCT/OCT2 seem to pick up a greater ratio of reverberant to direct sound.)  The center mic, obviously, gets a lot of direct sound because it's pointed directly at the center of the sound source.  Listening to that on its own isn't fun because it's just mono.  In order to get some stereo sound, then, I'm bringing up the level of the side mics.  But doing that means bringing in a lot of reverberant sound.  So I'm ending up with a choice between largely mono-sounding playback or highly reverberant playback.

I concur with your observations-  OCT can be pretty 'verby.  When mixed to 2-channel, the L/R side-facing supercardioid pair pretty much acts in a way similar to the Side channel of a Mid/Side pair and its polarity inverted copy, except with the two channels physically spaced away from each other rather than being coincident.  Think of it like dialing in a Mid/Side matrix- only a small range of ratios works well, and although the ability to make that adjustment is a godsend, we are essentially stuck with the direct/reverberant ratio present at the location in which we recorded.  We can choose clearer and more solid but overly monoish or over-verby but with good stereo width. (EQing the center and sided differently can help somewhat if you want to try that)

Other than selecting a different recording position, the answer is essentially the same regardless of the number of microphones used: Point the directional mics that are intended to provide directional stereo imaging aspects more toward the sources, and compensate for the reduced angle between those microphones with increased spacing.

I think of OCT as especially well-designed in concept, and very good for its intended use, yet rather specific in appropriate application.. sort of like Blumlein in the real world.  Variations on it are more useful for me than it is on its own, but its an excellent conceptual 3-microphone starting point.  I never run OCT on its own, just like I never run M/S on its own, yet both are core components of my setup.  I no longer run just a single pair of omnis either, so I guess it apples there as well.

Quote
I'm rambling a bit here and I'm not really certain what my point is other than I'm not sure how appropriate OCT/OCT2 is for two-channel playback.  The reason I got interested in OCT/OCT2 to begin with is I want to have a really strong center to my recordings (partially because there's so much mono information at the shows I record, and partially because I think it gives recordings a really nice sense of presence? immediacy?  I'm not sure what term fits here).  At the same time, I do want to have good L/R information.

TL:DR-
If you want to give OCT a few more goes, try revising the setup by angling the supercards forward 45 degrees while moving them wider apart.  That will trade away some L/R channel separation and level-difference stereo for a less verby, more direct sound by pointing all three mics closer to on-axis with the sound sources, yet compensates for the loss of stereo difference information by moving the three microphone positions farther apart to help achieve a similar Stereo Recording Angle.   Also consider trying a PAS X/Y pair in place of the center microphone.  Actually you might want to try a coincident center pair first.  Do both.  It's then no longer OCT, but these changes should help improve the aspects you are seeking.

My current thinking about increasing the flexibility of the OMT setup I'm using in order to make it rapidly adaptable to all the typical open recording situations I encounter, is to figure a way of easily adjusting angle and spacing of the OCT-style 180-degree opposed supercardioid pair within a small but sufficient range of adjustment.  I want to be able to run an straight OCT-like center microphone triplet outdoors or in a really great room, yet be able to angle the L/R microphones up to 45 degrees forward for most things indoors or on-stage, while increasing the spacing between them to compensate.  Using a coincident pair at the center microphone positions helps too.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on June 12, 2019, 09:45:20 PM
I think about what the sound is like at shows I attend, and usually it feels more like a wall than something with a lot of depth and dimension to it.  So, how can I capture that so that on playback there is this wall of sound coming at the listener?  That's what I'm trying to figure out, in the big picture context.

Godspeed you fellow knight chasing the dragon's tail. Having drunk from the same chalise I wish for the same. If our listening experience at a concert is an immersive one of a large all-encompassing wall of sound in front supported by live audience and room ambience all around us, then expecting a strong emulation of that experience from two speakers placed in front of us (and neither directly in front) is a quite tall order.  The best way I've found for translating the "big solid wall of sound" experience aspect you describe is to use a reproduction system which enables a more robust emulation of the original experience, tailoring the recording setup to suit that playback arrangement.  I do that using three to five speakers across the front, seven to nine in total all the way around.  I also realize this is not the answer you are looking for.

It's the answer hardly anyone accepts, including tapers, which is ironic in that I find the most useful application of surround reproduction, other than movie sound and gaming where it has achieved acceptance, is the enjoyment of "live performance from the audience perspective" recordings.  Its best for the stuff we do.

But enough pie-eyed thinking, lets talk OCT/OCT2's suitability for 2-channel stereo playback.. or more specifically, it's suitability for the situations in which you are recording...

Actually I've thought very seriously about moving to, at a minimum, three-channel L/C/R playback for exactly the sort or reasons you're talking about.  I still can't help but think about the fact that most other listeners will be using two-channel playback, but how much I should care about that is a whole 'nother philosophical discussion...
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on June 14, 2019, 07:53:15 PM
Actually I've thought very seriously about moving to, at a minimum, three-channel L/C/R playback for exactly the sort or reasons you're talking about.  I still can't help but think about the fact that most other listeners will be using two-channel playback, but how much I should care about that is a whole 'nother philosophical discussion...

This gets to the crux of my own recording journey, with the open taping part of it reflected in this thread.  I ventured into 3+ channel reproduction out of curiosity, exploring whether it made a significant improvement for listening to my own recordings as well as the processes of making them. I was similarly concerned about complications and potential problems in diverging from the standard 2-channel stereo reproduction path.  Yet the improvement of having three identical speakers set up correctly across the front was so compelling for a number of reasons that I couldn't let that go, even if it was only for my own listening.  I began to feel that stereo reproduction over speakers really should have been 3ch LCR from the start (the conclusion Harvey Fletcher's Bell Labs research group reached back in the 1930's) although the limitations of 30's-50's era tech imposed a maximum practical of channel count of two. Once stereo was commercially realized via the stereo LP in the late 50's and widely adopted by the mid to late 60's, two channels had become the de facto standard for music.  Commerce had spoken.

IMHO it would have made better conceptual and engineering sense to achieve stereo and beyond by building upon mono in a hierarchical way.  Start with single channel mono, and rather than discarding that and starting over again in the move to stereo, instead build upon that basic foundation by adding Left & Right channels to the already established strong center, extending it to 3ch stereo (LCR).  And further extended to 4 channels with the addition of a single ambience channel.. and so forth.

Like my addition of the center channel, the introduction of a single recorded "room and audience channel" was a similarly large improvement.. one of a very complementary but different nature.  I introduced this at the same time I added the front center channel - after all I was using a 4 channel recorder.  A single ambience channel can do a very good job of capturing and carrying the ambient information.  The L/C/R channels are all somewhat similar in their role.  They are direct-sound focused and define the reproduction quadrant in which clarity, solidity and good directional imaging are key attributes. The ambience channel(s) is perhaps most useful in representing the opposite of that LCR stuff.  What is important for it to contain is not imaging, solidity, and up-front LCR stuff, but rather the exclusion of as much of the direct-sound present in the LCR channels as practical, allowing the ambient sound to be captured clearly and not masked by redundant front-arriving direct sound.  In the big picture, this ultimately allows it to serve a sort of a perceptual negative feedback role in relation to the primary sound arriving from the front, making the sound presented through the LCR quadrant perceptually clearer, less cluttered, less reverberant and more open.   The immersiveness it provides, with audience reaction coming from all around is cool too, as is how it frequently makes the bass sound more correct, but what is really interesting to me is how the inclusion of a channel which ideally contains only reflections, audience reaction and reverb makes the perception of the front quadrant material clearer and more like the real thing.
 
The ambience channel is also categorically different from the center in that it is ideally reproduced very diffusely, with its content spread all around the back of the room via a number of speakers.  This is another from of stereo information, an entirely different aspect than directional imaging and just as valuable..  which becomes increasingly valuable the more distant and reverberant a recording is, where directional imaging sharpness becomes minimal.  In a way, its focus is the opposite of imaging.. representing the "anti-front" stuff.  Ironically the front stuff becomes stronger with its inclusion rather than less so, the opposite of what most tapers assume when they see an extra microphone or two pointed directly away from the stage and PA.

I took some time trying to determine which additional channel would be more important to me if I were limited to a total of three channels rather than four- the center channel or the ambience channel?  This was much more difficult to decide than I thought it would be. I initially figured the center channel would certainly be the top choice, and eventually concluded that is indeed my preference, but not at all to the degree I expected. It wasn't like the addition of each channel altered one particular set of aspects in isolation, such that it was easy to choose the more-solid imaging, stronger center solidity and increased clarity that the center channel addition provided over what the ambience channel added.  Because what the addition of the ambience channel provided was not more ambience for an already reverberant AUD, but rather something more like a cleaning up of the ambience already in the recording, resulting in increased spatial clarity, openness and dimension (in addition to the immersive aspects of extending the reproduction of ambience and audience around the sides and back to envelop the listener).  Mostly, the additional channels helped everything work together in a better way..  a case of the whole being greater than the sum of its parts.  If I was really forced to choose I'd grudgingly take the center channel over the ambient one in most cases.  However, my actual conclusion was that I was unwilling to sacrifice either, and fortunately had no need to do so.

I still feel to this day that 4 recorded channels (LCR + dedicated ambience channel) are where things really blossom strongly compared to 2 channel, and for the past decade all my stealth recordings have been made in a LRCB format ("B"=back-facing "ambience" channel).  Yet I'd not hesitate to record 3 channel LCR instead of 2 channel stereo if I were limited to 3 channels.  The issue later became wanting to run the center position as Mid/Side + L/R directional microphones, which left no available channels for the ambient information.

With that LRCB scheme, "B"=back, specifying the directional aspect of that recording channel. I used that convention to differentiate it from LRCS, which is 4-ch matrix surround ("S"=surround, the single channel of ambient surround information), which is closely related, yet not quite the same in important ways.

The open taping OMT rig I run now has grown to 8 channels, which is at the edge of my practicality and cost restraint envelope.  Yes it is better, which I why I do it, but I admit I am chasing the dragon's tail at this point.  4 or 6 channels are probably an good OMT channel count for most folks wanting to try these ideas.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on June 14, 2019, 08:15:43 PM
^ That's mostly about the capture and multichannel playback side of things.  As for suitability for mixing to 2 channel stereo, I've found almost everything that works well recording for LCR stereo or multichannel surround playback also applies and works well for 2-ch stereo. The areas where there are different are few and relatively subtle. I'm happy to discuss them if you like.

Actually, rather than think of it as mixing to stereo, I think of it more like mastering from stems in comparison to mastering from a 2ch mix where things are more fixed.  It gives me more control and that's especially useful for recording in live taper situations where I cannot check the setup beforehand like in a professional recording situation.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: heathen on June 14, 2019, 11:53:18 PM
I began to feel that stereo reproduction over speakers really should have been 3ch LCR from the start (the conclusion Harvey Fletcher's Bell Labs research group reached back in the 1930's) although the limitations of 30's-50's era tech imposed a maximum practical of channel count of two.

You're in good company.  Paul Klipsch did a lot of work with three channel, for example: http://www.aes.org/e-lib/browse.cfm?elib=235 http://assets.klipsch.com/files/Dope_611120_v2n13.pdf?_ga=2.195201452.1609077799.1560570380-259552099.1560570380

I spent a bit of time reading about the Meridian Trifield system, and went so far as to look for an old Meridian preamp with it but didn't end up pulling the trigger.

I still may very likely implement a center channel, but it would require some serious lead time to get one that perfectly matches my L/R.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on June 18, 2019, 06:07:56 PM
I've also been curious about Trifield.  As I recall it is essentially an equal-energy-vector Mid/Side upmixing scheme derived by Gerzon.  The patent should be expired at this point, with parole-board release from commercial proprietary prison following. It shouldn't be very complex, maybe someone will make a plugin available for us to play around with outside of Meridian gear.  [edit- link to Trifield article describing the Meridian implementation, and discussing the Bell labs stereo experiments, Klipsch, Hafler.. http://www.meridian-audio.info/public/trifield%5b2563%5d.pdf]  Similarly, I'd like to play around with Logic 7 without being tied to Harmon gear and gear-related specific implementations of it.

I had lots of fun years ago playing around with the two recorded channels feeding more than two speakers thing, using Klipsch/Hafler sum/difference wiring setups. Most often ended up using a pair of difference channel speakers (L-R & R-L) spliced into a standard 2-ch stereo setup bouncing off the walls.  Later played with matrix surround modes (Dolby PLII, DTS neo, etc) which sometimes worked very well but often seemed overly tied to the specific implementations, varying from device to device, setup to setup, tweaking for different material. Three identical speakers in front helped a lot for arrangements trying to derive a center, as did using more speakers than ambience channels around the back.

The commercial surround matrices do a pretty good job of extracting ambience from a stereo difference signal, but I suspect something like Trifield would be far better at deriving a pseudo-discrete center channel in comparison to a simple (L+R) mono sum or the similar schemes used by the standard upmix matrices, which sometimes mess with the purity of the primary L/R channels too much.

In messing around with all that stuff, playing with the recording side of things, and playing around with what manipulations might be done in the processing phase in between I've put a lot of thought into the fundamental relationship between recording and playback.  Ignoring multi-take/multitracked panorama/mixed material (the majority of modern music) and modern proprietary 3D object-based cinema rendering schemes for material recorded using a single microphone-array (of which taper stuff is subset), consider that there are the following points at which the number of channels can vary:

The number of microphones used
The number of channels recorded
The number of channels used for processing/mixing
The number of channels delivered
The number of speakers used

The Bell Labs guys doing initial stereo research in the 1930s explored various combinations of that in a simplified form:
Number of mics
Number of transmission channels
Number of speakers
[edit- see the article linked above which has some description of the Bell experiments with regards to this]

Simple parity is the obvious straightforward solution: 2 mics > 2 channels > 2 speakers (or  3>3>3; 5>5>5; 7>7>7..)
This is standard stereo taping, and also me plugging my 4-8 ch multichannel recorder directly into the 5/7ch analog DVD inputs of a home theater receiver for playback.

But the asymmetric configurations get interesting:
~Recording few microphones, yet playing back through more speakers. ex: 2ch stereo > upmixed multichannel playback via Trifield, matrix surround upmixing, etc.
~Recording more microphones, yet playback using a lesser number of speakers. ex: OCT/OMT/SBD matrix > 2ch stereo.
   ^
The first is standard 2ch taping played back via a matrix surround mode, Trifield, Hafler, etc. The second is mostly what this thread is concerned with, likely to be the focus of most tapers reading it, and what you were posting about above concerning the suitability of OCT mixed down to 2ch.

~As does an "hourglass shaped" (many channels > fewer channels > many channels) symmetrical arrangement.
  ^
  This one has always interested me in that it fits standard 2-ch stereo distribution, making it universally compatible.  Likely not as good as a pure symmetric (many > many > many) arrangement, yet could it be made good enough to be acceptable (to me) if I could find an appropriate way to matrix encode it?  I could then mix to a single 2-ch master delivery format regardless of playback.  Everybody wins.  I've not been able to answer this yet.
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: rocksuitcase on July 04, 2019, 11:54:50 AM
submitted for your OMT consideration:
https://taperssection.com/index.php?topic=191131.0

Phish

2019-07-02

Saratoga Performing Arts Center
Saratoga Springs, NY

Source: AKG ck22 (4ft) >V2 >Tascam DR-680 >SD
Source: AKG ck3 fwd (0') AKGck61 rear (180') >V2 >Tascam DR-680 >SD
Transfer: SD >Audacity >CD WAV Editor >TLH >FLAC
Taped by Kyle Holbrook

SET 1:
01] Cathy's Clown[1]
02] Tweezer Reprise >
03] Carini >
04] AC/DC Bag >
05] The Moma Dance >
06] Theme From the Bottom
07] Meat
08] Home >
09] Bathtub Gin >
10] Walls of the Cave   

SET 2:

01] Cool Amber and Mercury >
02] Down with Disease[2] >
03] Scents and Subtle Sounds >
04] Twist >
05] Wilson >
06] Scent of a Mule
07] Fuck Your Face >
08] Halley's Comet >
09] Harry Hood   
10] -encore break-
11] Fee
12] A Life Beyond The Dream
13] First Tube

Notes: On lawn, 35 feet from repeaters
second pic is of the center lawn repeaters
Title: Re: Oddball microphone technique (OMT) - part 2
Post by: Gutbucket on September 18, 2019, 06:39:19 PM
Time to lock it up and start a new thread.  Discussion continues here- https://taperssection.com/index.php?topic=191953.msg2311359#msg2311359 (https://taperssection.com/index.php?topic=191953.msg2311359#msg2311359)