Topic: Oddball microphone technique (OMT) - part 3

[Gutbucket]

^ I think some do.  I believe when done properly hearing loss compensation requires a dynamics-based EQ correction rather than just a static one.  Do you know if the airpods do that?

[Gutbucket]

The Smyth Realizer doesn't do that inherently as far as I know, although a corrective or preferred EQ curve can be manually applied on top of the emulation.  What it does is measure the transfer function from each speaker to each outer ear canal, using miniature measurement mics inserted into earplugs. That makes it "aware" of speaker response, room response, head and ear geometry and orientation.. and of the response of the headphone > ear coupling as worn, all in detail, but its not automatically correcting for anything internal beyond the outer ear canal.

grawk, did you get a chance to demo it youself back when?

[checht]

^ I think some do.  I believe when done properly hearing loss compensation requires a dynamics-based EQ correction rather than just a static one.  Do you know if the airpods do that?

Great point, and I think the airpods are just static eq...

[Gutbucket]

Alternate fig-8 / stereo-shotgun center mic-

For a while now I've wanted to try an alternate fig-8 as Side channel in my center Mid/Side pair.  The inexpensive Naiant X8 I've been using and have recommended to others has been working well, but.. well, you know, curiosity for one thing.. and physical format.  The Naiant X8 consists of two back to back cardioids wired out of polarity in a 'T' shaped housing.  With some effort I've been able to wedge it into a big Sure windscreen or Movo along with the tiny DPA 4098 as Mid strapped on top of it, but a more typical single-tube-body side-address fig-8 would fit more easily.  And I've wondered if a more technically-correct single-diaphragm fig-8 might perform even better.

I've also been curious about alternate Mid mics, partly in the quest for as much clarity and isolation in that Mid channel as possible.. as long as it images smoothly in in combination with the near-spaced pair, since it serves as the center mic of that triplet. We previously discussed shotgun mics in OMT arrays back in 2019 in this thread and another (ORTF + Central Omni thread at GS).  Here's a snip of what I posted back then-

[snip..] Comparison of the shotgun against a mid super-cardioid derived from the MKH 800 Twin, haven't done that yet. 

Likewise I'm currently curious how a true shotgun (albeit a short one) as Mid compares against the supercard Mids I'm using (Microtek Gefell M21 or DPA4098 which does incorporate a miniature interference tube, although its pattern is supercardioid rather than gun-ish) as the logical next step in OMT evolution, following a decade long trend of ever-increasing center mic forward directivity from omni to cardioid to supercardioid..  and from mono to M/S stereo for that forward-center position in the array.  It's also what motivated my suggestion in the B9Audio thread this morning, upon the proprietor's post about some potential design variants of B9 mics, requesting consideration of an end-address M/S stereo microphone with an interchangeable Mid capsule, where any Mid pattern from omni to gun could be swapped in. https://taperssection.com/index.php?topic=187681.msg2311215#msg2311215

My current thoughts are that the ultimate cost-is-no-object microphone for that center OMT position in terms of performance alone could be Neumann RSM 191A, or an imaginary M/S version of the DSP directionally-enhanced SuperCMIT, with an analog M/S output.  Thinking I'll to try a lesser performing but reasonably priced stereo shotgun as proof of concept.

Unfortunately B9 Audio decided not to pursue that modular Mid/Side stereo mic idea - I still wish someone would!  Late last summer DSatz had the Neumann on offer in the yardsale.  Beautiful but too costly and too precious for me, and cannot be used directly into a recorder without its special powering box, so I passed.  Instead I finally picked up a "reasonably priced stereo shotgun" in the form of the AT BP4029 short stereo shotgun from TS member BlueSky71 last October (good transaction, thanks!).  So it took almost 5 years but I'm finally to the point of trying this out for myself.

Back then when we were discussing this, EmRR went on to try some interesting arrangements using a shotgun mic as an alternate Mid in the center.  He also included a second center shotgun pointed directly at the nearer PA speaker.  Here's a link to discussion of that earlier in this thread, along with photos of a couple of his setups-  https://taperssection.com/index.php?topic=191953.msg2316452#msg2316452

My intent has been to substitute the AT stereo shotgun in place of the DPA/Naiant M/S pair in the center.  In December I was able to run both at three quite different venues.  The first was at a small local show at an outdoor patio stage (Electric Kif at Guanabana's), the second was from the last row of a 3000 seat amphitheater (DSO at the Pompano Bch Amp), and the last was from just in front of the board at the back of the pit in a mid-sized indoor venue (Oteil & Friends @ Revolution Live in Ft. Lauderdale). For each I was more or less centered and used the stereo shotgun oriented directly forward in the typical way.

For the first two shows I ran both M/S pairs concurrently, recording the DPA/Naiant M/S pair into F8 as usual and the AT stereo gun into OCM R-44 (omnis analog patched from the F8 into the other 2 channels of the R-44).  I still need to transfer and align/stretch the files to do a proper comparison in the OMT8 array, but I'm really liking the bit of extra clarity the shotgun provides for vocals when comparing the OMT4 version of both filesets (omnis + M/S center).  Instrumental-wise both are more on par.  I think I'd be happy with either.  It's that last little bit of vocal clarity (without relying on matrixing with SBD) that this change seems to achieve.  That's really welcome.  More listening to do, and need to try it on-stage as well, but this is the first time I've really come to believe that I may have figured out a single arrangement that works optimally everywhere from onstage to the back row of an amphitheater, to an indoor bar.  Although I've been using my setup in that way for convenience reasons, it actually being an optimal arrangement for most all situations is quite unexpected.

A few photos to follow..

[al w.]

Happy to hear it worked well, and to your satisfaction!  Thanks for the report, photos, and links.  I'll try and give the recordings a listen tonight.

Curious about your thoughts on the rear-facing center center mic used the second night.  Did you use any of that in the mix?

I used a tiny bit. As mentioned in other posts on the subject, I found I liked the mix better with it in than without, but not too much. The hall was very long, so using too much created a very reverb-y sound.

A couple of your comments struck me-

To my ear, the addition of a near-spaced directional pair to the baseline OMT4 arrangement of omnis (or subcards) + center coincident pair does exactly as you say - it improves clarity.. and sort of provides a sense of greater proximity to the source.  Almost a zoom-like effect, though more so in terms of clarity and perceptual closeness rather than in terms of imaging geometry.  When adding that pair to a single forward facing mic in the center (say, going from OMT3 to OMT5), the resulting near-spaced triplet predominantly provides the sharp directional stereo information.  My frequent suggestion to space that L/R pair twice as wide as one would ordinarily space a typical near-spaced stereo pair when used on its own is rooted in achieving the best integration of that stereo triplet - such that if the center mic is muted there will be a hint of hole in the middle, thereby providing room for the center mic content inhabit, but with the center mic unmuted the image hands off nicely from the left across the center to the right in a very smooth, stable and position accurate way.  Such a 3-mic triplet is even more solid and stable and sharp imaging than a coincident center pair.  I hear the most accurate image from an L/C/R pair in the center that is optimized like that.

Unfortunately, stretching that 2-ch near-spaced pair config to work best in combination with the center mic is somewhat inconvenient because the near-spaced pair needs to be either angled more widely (not desirable because it points them farther away from the PA) or spaced more widely, or a bit of both, making it less optimized for use as a stereo pair on its own.  Also, angles narrower than +/-45° in the effort to get close to PAS require that pair to be very widely spaced, and its nice to keep the near-spaced pair from getting too close to the omnis.  The use of pickup patterns that are highly-directional helps somewhat in allowing us to position and angle that pair somewhat less widely than we'd otherwise need to, and is what lead to my current arrangement of L/R supercards about 2' apart angled +/-45°, which is about as narrow as I feel I can make it while retaining good sharp imaging.

Indeed, I felt a bit limited by the width of the bar. I went narrower because I wasn't sure how the audience would react to a 1m+ bar in the air, haha. Thank you for this info. I will try the hypers instead of the cards next time.

When you say +/-45°, what factors would influence making that angle wider/narrower? (And how much margin are you implying?)

Another thing-
When adding the near-spaced L/R directional pair to a center coincident stereo pair (X/Y or M/S) rather than a single mic in the center (going to OMT6), there are now two pairs potentially contributing sharp directional stereo imaging cues across the center.  Without making the near-spaced pair wider angled or spaced, they may be in conflict somewhat, which could be why you found night one more difficult to mix than night two. If you want to play around a bit with it, you might try summing the center X/Y hypercardioid pair to mono (which will produce something akin to a single forward facing cardioid) and see if that makes it easier to mix. 

Its always very interesting to me to go back and forth between listening to omnis + center coincident pair, and omnis + center triplet.  Both are good, but different.  I do this pretty much every time.   Most of the time I end up using both in the mix.  I first establish a good balance within the triplet, getting that balanced with the omnis and whatever other channels, then use the Side channel of the M/S pair more as the "special sauce", rather than the primary source of forward directional imaging.  The imaging is actually sharper without any Side channel, but it adds such a lovely sense of width, sparkling lushness and depth that its hard to leave it out.  Sometimes I ride or automate its level - less when it gets really loud, energetic and dense (sharpening things up), more in the atmospheric parts and during good audience interaction segments when it really shines.

Aha! I'll have to give these ideas a try. Thank you for the feedback! I need to figure out how to convert XY to M/S... I read a bit about it here, but need to re-read.

I very much enjoyed the listen to your suggested tracks last night, Al. Well done!

I did EQ it a bit to work best for me, some of which is accommodating my non-calibrated headphones (Senn HD650), another project I keep kicking down the road along with getting a proper loudspeaker monitoring system back in action.  Mostly that was a scoop in the upper-bass/low-mid region centered around 300Hz, compensated for with a boost down low, which perceptually translated more or less as an upper midrange enhancement, but I don't expect that to necessarily translate elsewhere. More important to my way of thinking is that it responded well to EQ without problems, which indicates to me that everything is working together correctly and it remains robust in the face of any adjustment the listener feels is needed, which is the primary basis I use to judge recordings.. and microphones.  After tweaking the EQ a bit and shifting mindset, I felt like I was there, transported to the venue. That's very much what I look for from an OMT recording - big, open and natural with a good sense of the of the room dimensions and portrayal of the audience.  Only thing I found myself wanting was a bit more level and presence of the vocals, which is something I've been recently concentrating on improving further in my setup, and plan to post about in a bit.

I'm glad you enjoyed them. I am very pleased and can't wait to keep trying these methods.

I am not surprised that you felt the need to EQ in that area, because that was the region of the spectrum I had the hardest time EQing myself. And yes, I agree about the vocals. I'm glad I was able to get more focus and clarity with this setup compared to others, but I do think more presence (good word) would be nice!

[Gutbucket]

I used a tiny bit. As mentioned in other posts on the subject, I found I liked the mix better with it in than without, but not too much. The hall was very long, so using too much created a very reverb-y sound.

Yep. Very much dial to taste. This is what provides some welcome control over direct/reveberant ratio after the fact. And a nice sense of depth dimension.

When you say +/-45°, what factors would influence making that angle wider/narrower? (And how much margin are you implying?)

I feel that angle is about as narrow as I feel like I can go in combination with the center mic facing forward.  Otherwise there isn't enough angle between L and C, and C and R to produce significant level difference for good imaging.  To go narrower, I'd want to push L/R out wider to compensate, and that gets them out very wide, which is probably ok, but gets them uncomfortably close to the omnis in my way of thinking, unless the omnis are very widely spaced. 

Generally, the narrower that pair is angled without moving them wider to compensate, the wider the recording angle.  The three mic OCT arrangement which partly influenced OMT uses L/R supercards oriented +/-90° for optimal trade-off from L to C to R, and only their spacing is changed to alter recording angle, not the angle of the microphones themselves.  But that's not so appropriate for taper recording, which is why I rotated them to +/-45°, and increased their spacing somewhat.  The ideal arrangement might have angle and spacing linked, so you can point them as needed and the spacing automatically follows from that.

Also, +/-45° works nicely with the center and rear-facing directional mics in my OMT8 array to split up the ambient reverberant field in a more evenly sliced portion sort of way.  See the photo looking up at my array I'm about to post next..

[Gutbucket]

1st outing with the AT BP4029, Electric Kif at Guanabana's. 

1st photo - I've never before setup a mic stand spanning a waterfall! Always wanted to try that at Guanabana's as the little bridge and waterfall are centered in the sweet spot.  I usually setup on the other side of the bridge, about 5 feet further back, further left. In this photo the stage is to the right.

2nd photo - This is the only good photo of the center of the array itself over the course of these three gigs where you can see the position of both center pairs.  Stage is off to the right.  The DPA directional mics including the center M/S pair are in Movos, the AT in a furry windjammer (the 4061 omnis extend beyond the top and bottom of the frame, and have no windscreens on them. The APE balls with windscreens on them were removed for all of these recordings). I would have liked to position the two center pairs one directly over the other to eliminate that extra variable, but wasn't able to do so easily, so I positioned the AT stereo shotgun slightly farther forward with its side capsule ~20cm in front of the array center, as I've speculated is likely most appropriate based on Image Assistant modeling.

3rd photo - View of stage from recording position (taken from the center of the bridge).

[Gutbucket]

2nd outing at DSO, Pompano Bch Amphiteater-

My stand is on the other side of the pole with the B sign on it.  Rig in the middle is Cliff (trying to recall his TS handle), rig to the left is spyder9.

[Gutbucket]

3rd outing at Oteil & Friends, Revolution Live-

Very hard to see the array due to lighting, so didn't take a photo of it, but here is a view of the stage from the recording position.  Couple other local tapers there, one of which was spyder9.  Instead of running both center pairs for this I ran the DPA/Naint center night 1 and switched to the AT BP4029 night 2.

Spyder's recordings of DSO and Oteil & Friends are now up at archive. 

[al w.]

I used a tiny bit. As mentioned in other posts on the subject, I found I liked the mix better with it in than without, but not too much. The hall was very long, so using too much created a very reverb-y sound.

Yep. Very much dial to taste. This is what provides some welcome control over direct/reveberant ratio after the fact. And a nice sense of depth dimension.

When you say +/-45°, what factors would influence making that angle wider/narrower? (And how much margin are you implying?)

I feel that angle is about as narrow as I feel like I can go in combination with the center mic facing forward.  Otherwise there isn't enough angle between L and C, and C and R to produce significant level difference for good imaging.  To go narrower, I'd want to push L/R out wider to compensate, and that gets them out very wide, which is probably ok, but gets them uncomfortably close to the omnis in my way of thinking, unless the omnis are very widely spaced. 

Generally, the narrower that pair is angled without moving them wider to compensate, the wider the recording angle.  The three mic OCT arrangement which partly influenced OMT uses L/R supercards oriented +/-90° for optimal trade-off from L to C to R, and only their spacing is changed to alter recording angle, not the angle of the microphones themselves.  But that's not so appropriate for taper recording, which is why I rotated them to +/-45°, and increased their spacing somewhat.  The ideal arrangement might have angle and spacing linked, so you can point them as needed and the spacing automatically follows from that.

Also, +/-45° works nicely with the center and rear-facing directional mics in my OMT8 array to split up the ambient reverberant field in a more evenly sliced portion sort of way.  See the photo looking up at my array I'm about to post next..

Ah, I understand now! I was misinterpreting +/-45° to mean 45° ± Nº (and therefore wondering what range of N to expect) but I realize now you mean +45° on one side and -45º on the other for a total angle of 90° fixed. Thank you.

[goodcooker]

Spyder's recordings of DSO and Oteil & Friends are now up at archive.

Can you upload your mixdowns to the LMA for these bands? This would be a great opportunity for others to compare these setups to other taper's rigs.

[kuba e]

Al W, thank you for your recordings and your observations.
Gutbucket, thank you for sharing your new ideas.
Goodcooker, you may already know the answer. Gutbucket likes to explain the theory and likes to share it with us. Finishing and sharing recordings is not his goal. And that's perfectly fine. OMT is represented by recordings of our friends - e.g. Rocksuitcase, Fireonshakedwonstree, Emrr. You can find a lot of their OMT on LMA. And you can easily compare them to a recording with one stereo pair. For me personally, the most important thing is not to make a better recording although I wish that. The main reason I do it is for fun and to learn something. And that is absolutely without debate, I learned a lot here, not only theory, but I also trained my listening skills. As a self-taught amateur, I wouldn't learn this on just the stereo pair alone.

[Gutbucket]

Can you upload your mixdowns to the LMA for these bands? This would be a great opportunity for others to compare these setups to other taper's rigs.

Getting these mixed and available to you guys is a goal of mine.  I recognize I'm terribly lacking in that department and am hoping to make more progress toward that goal.  Life is complicated and intervenes.

Kuba is correct that my primary goal here at TS is to share these techniques and the development of them with other tapers. I believe that's the strongest and most lasting contribution I can make to the taping community.  On that point, I've long been wanted to post more examples of what I'm talking about in these threads, and will try to work toward that as well.

Thinking I might post links to raw files for anyone interested to play around with themselves, along with suggestions on general level settings of channels and what to listen for when mixing.  That seems a more easily achievable goal, in face of life's complicated interventions.   Would be fun and interesting to hear how different folks mix the same fileset.

Thanks for your patience, understanding, and interest!

[Gutbucket]

[snip..]
Ah, I understand now! I was misinterpreting +/-45° to mean 45° ± Nº (and therefore wondering what range of N to expect) but I realize now you mean +45° on one side and -45º on the other for a total angle of 90° fixed. Thank you.

Yes, that's it.  A few more thoughts on that in my next post..


Initial thoughts on the change to the stereo shotgun center mic-
Since I've not yet transferred, much less sync'd and aligned the E Kif and DSO file sets to be able to make a comparison, the only full-up OMT8 version I've listened to so far using the AT stereo shotgun in the center is night 2 of Oteil, straight off the recorder.  Very much liking what I hear.  The shotgun brings up vocal clarity/intelligibility a bit more than the DPA4098 supercard Mid when the level of the center channel is otherwise set to be perceptually-correct relative to the other channels, and does so in this particular instance by just about the right amount to my ear, which is exactly what I was hoping to achieve.  At the same time, I don't hear any problems from the off-axis response of the shotgun being less than smooth, which even if problematic in isolation I expect would be masked by the other channels in the mix.  This is encouraging.

I now wonder how it might work onstage.  Sometimes if the drummer is positioned farther back, I'd like a little more "reach" from the center Mid, which I generally point directly at the snare-drum, as I find a similar need for clarity and presence there in instrumental groups which play with higher on-stage SPLs.  General pickup of the entire kit is already good balanced and quite stereo-delicious, but similar to vocals when recording from farther back in the room, the snare can sometimes use a touch more up-front clarity and presence, and I suspect this arrangement could achieve that.  Other times when recording on stage the drum kit and other instrumentation is quite close to the recording position (generally low to the floor, front of stage, center), and I that's where I wonder if a wider pattern such as a non-interference tube supercard (confirmed to work in that situation) or cardioid might be most appropriate.  Speculating there, but it gets me wishing again for a modular Mid/Side microphone.  Would be great to have the ability to change Mid pattern by simply unscrewing the capsule from the stereo mic body that has the fig-8 built into it and installing a capsule with a different pattern in its place.  [OT- and as mentioned back when I made that pitch to B9, alternately a side-address capsule such as fig-8 or any other pattern could be installed, which would then make the mic side-addressed, fully vertically coincident, and Blumlein capable.]  I think such an arrangement would make for a super cool modular single-point stereo microphone system.

One other comment-
One of my initial intents when doing these recordings was to position the Side capsule of the AT directly over the Naiant fig-8, so that I could directly compare the two different fig-8 channels, paired with the same Mid.  But, since I couldn't easily configure it that way I don't expect to be able to do that with these file sets, due to the mis-alignment in coincidence of each Mid and the alternate Side channel.  However, I still look forward to listening to the difference between the straight 2ch stereo output of each Mid using its own Side channel verses the alternate Side channel.  Only now the primary effort will be to try and "listen around" any differences between the two fig-8s themselves (and between the two Mids in combination with the different Sides), and instead listen for what the increased mis-alignment in coincidence between Mid and Side does in each case.  In one instance (AT shotgun Mid / Naiant Side) the Side mic is a few inches behind the Mid, in the other (DPA supercard Mid / AT Side) the Side mic is a few inches in front of the Mid.

[goodcooker]

I hope that my comment was taken how it was offered - as encouragement towards a possible learning experience for everyone following along - and not criticism. 

We all learn differently. I learn best through critical listening and comparison.