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Author Topic: Oddball microphone technique (OMT) - part 3  (Read 13435 times)

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Offline kuba e

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Re: Oddball microphone technique (OMT) - part 3
« Reply #90 on: December 12, 2019, 05:53:15 AM »
Thanks you all for great posts. I love to read it. I would like to ask one question. I have two old shotguns that I have never use. Gutbucket suggested that it should be possible to use shotguns in xy pointed at PA as the center mics. I am using xy cards in the center with spaced omnis now. Mostly I am M/S widening cards in post to fit it with spaced omnis. Has anyone experience of M/S widening of shotguns? Does it sounds good?

Maybe I can do something similar as EmRR. I can record six tracks, so I can add pair of cards and wide the center image by this pair. But I have no idea in which configuration should I setup the cards.

Offline EmRR

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Re: Oddball microphone technique (OMT) - part 3
« Reply #91 on: December 12, 2019, 09:44:58 AM »
I have two old shotguns that I have never use. Gutbucket suggested that it should be possible to use shotguns in xy pointed at PA as the center mics. I am using xy cards in the center with spaced omnis now. Mostly I am M/S widening cards in post to fit it with spaced omnis. Has anyone experience of M/S widening of shotguns? Does it sounds good?

Maybe I can do something similar as EmRR. I can record six tracks, so I can add pair of cards and wide the center image by this pair. But I have no idea in which configuration should I setup the cards.

I have not widened a shotgun pair before. 

If you haven't seen it, search member dsatz and shotgun, he has some good commentary about their usage and problems. 

I think the first experiment I would recommend would be for you to make an array with one coincident shotgun as part of your center, either aimed center or aimed at the closest stack (depends on the space you're recording) and see how that goes.  Since you are widening already maybe aimed dead center is best.  Experiment from there. 
Mics: DPA 4060 w/MPS 6030 PSU/DAD6001/DAD4099, Neumann KM 131, KMR 81i, Oktava MK 012, Sennheiser MKH 105, MKH 20, MKH 30, MKH 40, MKH 800 TWIN, lots of other studio appropriate choices
Recorders: Zoom F8n, Sony MZ-R50, portable MOTU based multitrack DAW for client work

Offline kuba e

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Re: Oddball microphone technique (OMT) - part 3
« Reply #92 on: December 12, 2019, 01:12:18 PM »
Thank you EmRR, I will look for more commentary about shotguns. It is good idea to use xy with shotgun. I can compare mix with and without it. Couple years ago, I bought JVC mics (clone of Nak300) with cardiod caps and I got short shotgun caps too. I put shotguns in the drawer and forgot about it. But thanks to your and Gutbucket posts, I remembered them.

Offline Gutbucket

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Re: Oddball microphone technique (OMT) - part 3
« Reply #93 on: December 12, 2019, 01:24:28 PM »
How clean/direct/SBD-like is the pickup from your PAS X/Y cardioids in isolation?  The intent of switching from using cardioid directivity in that configuration to supercards, hypers, or shotguns is the pursuit of more clean/direct/SBD-like aspect from the center pair.  If you have enough of that already from your cardioids, or have direct SBD feed recorded, you needn't shift to using the shotgun(s).

DSatz raises excellent points about the problem of stereo recording using shotgun mics.  The switch from X/Y cardioids to supercardioids/hypercardioids is a generally straightforward one of increased directivity and reduced off-axis sensitivity.  The switch to shotguns is more complicated in that their off-axis misbehaviors come into play.  Non-uniform off-axis sensitivity affects things in a few ways: pickup of discernible off-axis sounds may sound odd, and any pattern-misbehavior which affects the stereo overlap region may affect imaging and tonal qualities of what the shotgun pair is intended to be focused on picking up.

While it's certainly true that shotguns aren't intended nor well-suited for typical stereo-pair mic'ing (other than MS shotguns), that never kept Grateful Dead section tapers from using them as PAS near-spaced pairs.. frequently in combination with a single omni.  The single omni not only extended low frequency response, but also served to audibly bury the lower-level off-axis misbehavior of the shotguns as it was not typically low-pass filtered.  The omni essentially covered up much of the shotgun problems as long as it could be used at a high enough level in the mix.  Too much would make the recording width collapse as all stereo width information was provided by the shotguns.

In a way, OMT takes that practicality-driven approach, inverts and optimizes it.  Combination with a wide-spaced omni pair (could be some other pattern) helps to bury the off-axis pickup of the shotguns in the mix in the same way, while using a single shotgun or coincident pair in the center reduces the phase-differences inherent to any near-spaced center microphone arrangement, especially the problematic phase behaviors of a near-spaced pair of shotguns.  The wide-spaced pair also contributes open and spacious sounding stereo room-reverberation/ambience/audience-reaction sound (highly decorrelated due to the wide spacing), rather than a single omni providing monophonic/100%-correlated pickup of all that stuff which is intended to be perceived as wide and enveloping rather than narrow and centered.  We then get phase and time-of arrival differences where that is beneficial, combined with cleaner, flatter level-difference stereo pickup where it is beneficial.
« Last Edit: December 12, 2019, 02:56:53 PM by Gutbucket »
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Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<<

Offline Gutbucket

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Re: Oddball microphone technique (OMT) - part 3
« Reply #94 on: December 12, 2019, 01:27:12 PM »
I'm in agreement with EmRR about the best way to experiment with this.  Ideally do so by leaving your current setup using center PAS X/Y cardioids unchanged as a basis of comparison.  Add to that the PAS X/Y shotguns (cross them at the diagram locations at the back of the interference tubes) or a single center shotgun, as long as you have the ability to record those channels at the same time.

A single shotgun will give you some idea of how much increased isolation (clean/direct/SBD-like quality) an arrangement using shotguns can provide, while a PAS X/Y arrangement will be a better comparison for determining if direct replacement of the cardioid pair with an shotgun pair makes sense.  Of course if you have a fig-8 you could do MS with a single shotgun as an alternative to two in X/Y PAS.  However, I'm very interested in X/Y PAS shotguns as it represents a sort of maximum logical extension of the OMT for PA recording idea with regards to the center pair being optimized for role of direct sound pickup from an acoustically-distant* far-field location. 

If you then decide that a center X/Y PAS shotgun pair does what you want and wish to explore other uses for the cardioids as additional channels, we can discuss appropriate options for doing that.


*"Acoustically-distant" meaning further away than the direct/reverberant critical radius of the room, which is almost always considerably less than the distances from which tapers are recording, even when recording on-stage or from the stage-lip in smaller rooms.  Granted, it can be argued that the presence of directional PA reinforcement radically alters the normal critical distance relationship, which is one reason audience taper recording is an oddball endeavour to begin with compared to studio and non-PA amplified live performance recording.
« Last Edit: December 12, 2019, 03:25:30 PM by Gutbucket »
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<<

Offline EmRR

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Re: Oddball microphone technique (OMT) - part 3
« Reply #95 on: December 12, 2019, 01:37:20 PM »
Note the white tape on my KMR81's, that's where the diaphragm sits in those.  There's some slots behind it too. 

MS with the KMR81 worked pretty well, I really can't fault it.  You can't get very wide with that if you are at distance, but you can get some representative stereo spread. 
Mics: DPA 4060 w/MPS 6030 PSU/DAD6001/DAD4099, Neumann KM 131, KMR 81i, Oktava MK 012, Sennheiser MKH 105, MKH 20, MKH 30, MKH 40, MKH 800 TWIN, lots of other studio appropriate choices
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Offline Gutbucket

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Re: Oddball microphone technique (OMT) - part 3
« Reply #96 on: December 12, 2019, 04:35:07 PM »
The idea behind X/Y shotguns is to get maximal clean detail from the PA by keeping the shotguns directly on-axis with the PA stacks.  Then adjusting the stereo width of that with a MS ratio adjustment to blend it with the wide pair and provide the appropriate direct-sound imaging stereo-spread across the center.  In addition to maximizing pickup of PA direct sound in the center pair, a PAS X/Y arrangement should maximally capture any stereo difference information present through the PA, even if those stereo elements are only reverbs and effect returns rather than left/right stereo placement panning of sources - which is common even in many otherwise "mono" PA mixes.

EmRR's setup adding a single shotgun pointed at the nearest stack is intended to increase the capture of vocal clarity and on-axis PA detail, and uses that to bolster the forward-facing MS center pair which is providing stereo imaging across the center.  An X/Y PAS shotgun pair should better capture the direct-sound PA stereo elements.  It will be interesting to determine if a center X/Y PAS shotgun pair makes the original MS pair unneeded or overly redundant, such that those two channels could be repurposed or simply eliminated.

MS using a single shotgun Mid pointed directly forward attempts to maximally capture the direct sound from both PAs via one shotgun aimed between them.  The Side fig-8 "stereoizes" that with a microphone oriented perpendicular to the stage.  Rather than both microphones of the pair being pointed directly on-axis with the PA sources, neither is actually directly on-axis with the PA (even though the Mid is hopefully close to being so, unless your recording position is close making and the angles to the PA speakers wide). In some ways, this calls to mind discussions of the real-world practical difference between setting up a Blumlien crossed fig-8 arrangement as MS rather than XY.  Both arrangements are equivalent mathematically in terms of XY/MS matrix transformations, but it is argued that having the Mid microphone directly on-axis with a source directly in front of the microphone position represents a practical advantage for the MS arrangement using real world microphones.  Likewise its my hypothesis that it having two shotguns arranged so as to be directly on-axis with the PAs may be more advantageous than a single shotgun in MS.

But it needs to be sufficiently better that it makes the awkwardness of running a X/Y shotgun arrangement worthwhile!

Practicality reigns supreme.
« Last Edit: December 12, 2019, 04:53:16 PM by Gutbucket »
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<<

Offline EmRR

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Re: Oddball microphone technique (OMT) - part 3
« Reply #97 on: December 12, 2019, 04:49:48 PM »
OK, this slightly simplified version is going out tomorrow.  More compact, less to fight.  This loses the 'dual' part of the MS, the rear channel.  Should get a board feed with it too.  Hopefully can share results. 







« Last Edit: December 12, 2019, 04:52:59 PM by EmRR »
Mics: DPA 4060 w/MPS 6030 PSU/DAD6001/DAD4099, Neumann KM 131, KMR 81i, Oktava MK 012, Sennheiser MKH 105, MKH 20, MKH 30, MKH 40, MKH 800 TWIN, lots of other studio appropriate choices
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Offline kuba e

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Re: Oddball microphone technique (OMT) - part 3
« Reply #98 on: December 12, 2019, 04:57:23 PM »
Thank you very much for the explanation. I don't have a lot of practical experience. Sometimes happened, when I used xy cards and spaced omnis, that I had to use very little of omni in the final mix. I think it was because bad acoustic in the room. More clean and dry xy signal would be useful. It would allow me to add more omni in the mix.

On the other hand, when I was taping in great acoustic room, unfortunately that is not often, I didn't use much of xy. I have never experience big hole in the stereo omni track of the audience PA recording. So I am adding xy cards only to gently strengthen the center and bring more clarity.

You are right, the best will be to use two xy cards and two xy shotguns. It is the easiest how to compare. And I am curious how xy shotguns sound. Thank you for your help. I will prepare my staff. It will take me time to go to tape. But then I will let you know the results. Maybe the test will tell nothing, because the mics are cheap, for hobby.

Note the white tape on my KMR81's, that's where the diaphragm sits in those.  There's some slots behind it too. 

Yes, I will check where is the capsule in the tube. I don't even know if the shotguns work, I've never tried them. Must be nice to use KMR81 with fig 8 for the center in OMT. Your picture looks great. I am looking forward for your comments about the recording. I like your snake cable too. I saw your posts about it. I should do something similar. It has to make the setup easier.

Offline Gutbucket

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Re: Oddball microphone technique (OMT) - part 3
« Reply #99 on: December 12, 2019, 05:53:53 PM »
OK, this slightly simplified version is going out tomorrow.  More compact, less to fight.  This loses the 'dual' part of the MS, the rear channel.

Cool. Have fun with it.

I'd love to try an alternate version of that using the same mics, but with the two shotguns in X/Y PAS and the Mid of the MS pair facing rearward. 

..with three things in mind:
First, it's a test of the X/Y PAS shotgun thing for all the reasons mentioned above.
Second, it retains ambient/room/audience rear facing pickup in an overall arrangement of six channels in total.  The presence of which may make elimination of the forward facing MS pair more palatable.
And third, it retains the fig-8 Side mic.  I find that channel adds something compelling even when I don't or can't do a proper MS>LR conversion of the center pair (using the Zoom F8 for direct playback, as we've discussed elsewhere with regards to that F8 monitoring quirk) and simply bring up some of it in the OMT mix without any polarity inversion to the right channel.  It's part glue, part tonal.  Although that be more attributable to my particular setup using the 5 near-spaced miniature DPA supercards in the middle.


Thank you very much for the explanation. I don't have a lot of practical experience. Sometimes happened, when I used xy cards and spaced omnis, that I had to use very little of omni in the final mix. I think it was because bad acoustic in the room. More clean and dry xy signal would be useful. It would allow me to add more omni in the mix.

On the other hand, when I was taping in great acoustic room, unfortunately that is not often, I didn't use much of xy.

Makes sense, and is perfectly okay.  That you arrived at such a different balance between the two in different scenarios can be interpreted as exercising the powerful flexibility the arrangement provides.

Quote
I have never experience big hole in the stereo omni track of the audience PA recording.

Two things here:
I realize that it may not be practical to do so, but try spacing them further apart if you are able to.  If you do get a detectable center in the middle, the X/Y center pair will fill it, while the wider spacing will let the omnis do the wide-omni thing even better and any detectable hole arguably allows the X/Y pair to do its center-thing better in combination. 

This is one of the things that makes taper recording of PAs an oddity in the recording world.  Even huge 30 to 50 foot omni spacings can sometimes work.  Even though the stereo distribution of non-PA sounds are likely to pull strongly into either speaker with a big hole in the middle, monophonic PA content will be centered and not have a hole as long as the distance from the PA speakers on each side to the microphone location on each side is the same (identical content in both sides of the PA remains phase correlated at both microphones), while stereo pickup of any differential stereo stuff thru the PA such as stereo verbs, effects, maybe drum panning, is maximized using time-of-arrival differences from the widely spaced omnis (rather than via directionality of X/Y shotguns).  Truly diffuse non-direct sound such as venue reverberance and non-specific audience reaction is be completely decorrelated between channels to even the lowest frequencies due to the very large distance between microphones, making those recordings sound really big, open, and enveloping.

musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<<

Offline EmRR

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Re: Oddball microphone technique (OMT) - part 3
« Reply #100 on: December 16, 2019, 03:54:59 PM »
6 channel rig worked fine.  Not as much difference in the two shotguns as I'd hoped, but definitely some.  Need more snare, the center.  Need more vocals/horns, the PAS.  I can turn on both mids and the PAS with no obvious combing/phasing problems, so that's great.  Just starting to check it out. 

At least one startled person emitted a 'GODD@^#M!!' when they noticed the rig as they walked by, so that was worth it alone. 

Mics: DPA 4060 w/MPS 6030 PSU/DAD6001/DAD4099, Neumann KM 131, KMR 81i, Oktava MK 012, Sennheiser MKH 105, MKH 20, MKH 30, MKH 40, MKH 800 TWIN, lots of other studio appropriate choices
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Offline Gutbucket

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Re: Oddball microphone technique (OMT) - part 3
« Reply #101 on: December 16, 2019, 05:17:04 PM »
Heh, heh. Nice totem pole!

Sounds encouraging.
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<<

Offline EmRR

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Re: Oddball microphone technique (OMT) - part 3
« Reply #102 on: December 17, 2019, 07:04:00 PM »
6 channel rig worked fine.   Need more vocals/horns, the PAS.  I can turn on both mids and the PAS with no obvious combing/phasing problems, so that's great.

OK, one suspicion confirmed.  The angled coincident PAS when panned center still sounds like it's pointed at the angle, in other words the center image shifts in the pointed direction.  It can be offset by panning the other direction.  Mostly.  Only really obvious if you listen only to it and the side mic.  Slightly obvious when mixed with the other mid mic. 
« Last Edit: December 18, 2019, 04:00:32 PM by EmRR »
Mics: DPA 4060 w/MPS 6030 PSU/DAD6001/DAD4099, Neumann KM 131, KMR 81i, Oktava MK 012, Sennheiser MKH 105, MKH 20, MKH 30, MKH 40, MKH 800 TWIN, lots of other studio appropriate choices
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Offline rocksuitcase

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Re: Oddball microphone technique (OMT) - part 3
« Reply #103 on: December 17, 2019, 07:11:07 PM »
Looking Good EmRR!
I can add to GB's thoughts on widely spaced omnis. The few times we have been able to go 10 feet or wider have resulted in very smooth, buttery omni tonality. twice was in large OTS' where we shared/clamped to someone else's stand 10 or so feet apart from our stand and only once we had three stands at a gig where we had a lot of leeway with the soundcrew and the omnis were about 12 feet apart. My opinion is as GB posits: spacing the omnis as wide as possible, with the exception of not being outside PA stacks can result in high quality decorrelated tonality and overall yumminess (technical term!)
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Offline EmRR

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Re: Oddball microphone technique (OMT) - part 3
« Reply #104 on: December 18, 2019, 12:21:51 AM »
Thanks!   I gotta try wider omni soon.  In this particular room AB60-70ish mixes well with the coincident set, maybe because it’s a shallow space.  I can see wider being definitely cool with greater distance.  Need to try it in this room for comparison. 

I tried applying the crossover theory I mentioned earlier, then modified it.  I didn’t really like tossing the treble from the AB set, and lowered the HPF cutoff on the side signal of the coincident down to around 800.  Then changed it from a HPF to a low cut shelf with the same initial slope, max cut of -18.  I preferred the way the bass blended across the stereo field with the AB. At least in this case. 

The AB is currently -12 relative to the MS.  Adds a bass width that matched the treble info in the coincident set.

The shotguns are EQ’d with a low shelf cut to focus upper mid intelligibility and set -9.

This room has problems with vocal intelligibility in recordings, not as obvious to the ear.  I tried EQ’ing the board feed to be mainly upper mid vocal range and put enough in so it’s a slight improvement, lower than becomes obvious. 

Maybe laying out thought process on this will help someone else. Anyway, digging the experiments. 
Mics: DPA 4060 w/MPS 6030 PSU/DAD6001/DAD4099, Neumann KM 131, KMR 81i, Oktava MK 012, Sennheiser MKH 105, MKH 20, MKH 30, MKH 40, MKH 800 TWIN, lots of other studio appropriate choices
Recorders: Zoom F8n, Sony MZ-R50, portable MOTU based multitrack DAW for client work

 

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