Topic: Oddball microphone technique (OMT) - part 4

[EmRR]

It is quite frequent that I presume I might use delay to fix a thing, and it sorta does, but I come away with evidence that a better mic placement would have in fact been the only truly satisfactory way, given all the multi-path information. 

[F0CKER]

Hey all, back to reading TS.com after a long time away and catching up on this thread. Really interesting chain. Does anyone have any samples of running subcards / widecards on the outside in place of omnis. I don't have omnis but have a pair of DPA2015s coming my way. Will be dipping my toes into the OMT waters when they arrive. I'm assuming these are a suitable substitute after reading the PMT progression document. Love the experimentation happening here

[Gutbucket]

^Welcome back! Others have run subcards in place of the omnis. I've long been meaning to but don't have a pair of them to do so myself. Was going to pickup a pair of LineAudio CM3 in the yard just last week to do my own tests but missed 'em.  That said, they fit into and nicely satisfy the theories.  I have used OMT4 setups that have a M/S pair in the center between medium spaced cardioids or supercards as mentioned below a number of times with good results.

Here's a link to a post in the previous OMT thread with most recent updated OMT PDF's to date- https://taperssection.com/index.php?topic=191953.msg2311360#msg2311360
Also quoted here:

Updated OMT PDFs attached.  Still need to roll these into a revised complete booklet along with a few additional sections I'm still working on.  These currently supercede the booklet linked in my signature.
* OMT overview (rev 4)_introduction.pdf (77.88 kB)
* OMT overview (rev 4)_standard arrays.pdf (100.2 kB)
* OMT overview (rev 4)_OMT progression.pdf (96.79 kB)
* OMT overview (rev4)_OMT3.pdf (81.67 kB)
* OMT overview (rev4)_OMT4.pdf (122 kB)
* OMT overview (rev4)_OMT5.pdf (90.47 kB)
* OMT overview (rev4)_OMT6.pdf (116.79 kB)
* OMT overview (rev4)_OMT7.pdf (83.99 k)
* OMT overview (rev4)_OMT8.pdf (80.51 kB)
* OMT overview (rev4)_OMT6-8 with MS omnis.pdf (126.67 kB.)

And now here we are in 2025 and I've still not gotten around to updating the original OMT booklet linked in my signature with the above revisions.  Really need to make time to do that.  Last year I instead worked on updating the Improved PAS thread to include an illustrated PDF that extends it to cover not just 2-channel PAS, but also 3-mic position PAS arrangements using 3 or 4 microphones total, placing a coincident pair or just a single mic in the center.  I decided to focus on that in my free time instead since I considered it more helpful to most tapers and more likely to get applied than this more esoteric multichannel OMT stuff.  Extending PAS to 3 or 4 channels also begins to converge it into OMT.  It's now become a special subset of OMT2, 3 and 4 configurations specific to PAS.

Here's that latest Improved PAS PDF- PAS, 2 & 3-microphone (Rev2).pdf (211.72 kB)

[checht]

Hey all, back to reading TS.com after a long time away and catching up on this thread. Really interesting chain. Does anyone have any samples of running subcards / widecards on the outside in place of omnis. I don't have omnis but have a pair of DPA2015s coming my way. Will be dipping my toes into the OMT waters when they arrive. I'm assuming these are a suitable substitute after reading the PMT progression document. Love the experimentation happening here

Following Gut's advice, I have put together a config with mk22s on the outside and mk41s x/y in the center. My faceorite outdoor rig ever.
https://archive.org/details/LosLobos2024-05-27/LL20240527.omt4.2448-01.flac

Encourage you to see if a similar config works for you.

[VibrationOfLife]

I don't get it.  When you say x/y PAS (41's), from your description, you are recording from inside the gazebo behind the band?  A couple things there don't make sense to me.

Also, got a picture of your bar?

I'd love to see the setup if you grabbed a picture.  I like the idea.

[checht]

Gazebo is in the back of the house, not back stage.

Make more sense?

[VibrationOfLife]

Gazebo is in the back of the house, not back stage.

Make more sense?

Very much so.  I was looking at your picture of the stage.

[F0CKER]

Thanks gut and checht for the responses. My 2015s arrived so I’ll be looking to test it out in the near future, will report back here with results. The primary place I tape, Ardmore Music Hall, probably wont let me spread them too far so I'm going to work with a 2' spread to start and see how it goes. We. tape LOC directly in front of the left stack about 30-40 feet back. Going too far would basically put the left side right over the bar area which gets pretty chatty as it is. I can increase it by running a boom going right about 5-6 feet, which I'm debating but that would put the mics over a seated crowd area for VIP tickets - not sure how the venue would feel about that - unless I were to consider going up much higher than I normally do go get out of their way a bit. Either way, will come back with my results

[checht]

Glad to spread the gospel.

One think I appreciate about omt4 is the incredible versatility. Starting with choices around outside spread and inside config then moving to post-processing options, one can really create a wide range of final product.
Lately I've been taking the mk41 track and pulling out the vocal stem then adding that back into the mix to reinforce the vocal and increase presence.

Fun to play with all the variables, and sometimes the original sounds best too. Ratio of center to outside mics is huge.

Have fun!

[goodcooker]

Thanks gut and checht for the responses. My 2015s arrived so I’ll be looking to test it out in the near future, will report back here with results. The primary place I tape, Ardmore Music Hall, probably wont let me spread them too far so I'm going to work with a 2' spread to start and see how it goes. We. tape LOC directly in front of the left stack about 30-40 feet back. Going too far would basically put the left side right over the bar area which gets pretty chatty as it is. I can increase it by running a boom going right about 5-6 feet, which I'm debating but that would put the mics over a seated crowd area for VIP tickets - not sure how the venue would feel about that - unless I were to consider going up much higher than I normally do go get out of their way a bit. Either way, will come back with my results

This is one of those situations where tapers run into hurdles. If running a wide split is just going to piss off the venue and other patrons and introduce a bunch of chatter into your recordings you hit diminishing returns for your efforts. I only run wide splits outside where I can do it without intrusion on others and reap some of the benefits. A lot of my inside taping opportunities are marred by chatty patrons, drunks and reflective surfaces of poorly executed sound systems/venues so I don't get to experiment as much as I'd like.

During the last decade the ability to run lots of channels in the field has gotten much easier so it's opened up the ability to experiment. If you find that the additional channels aren't adding what you are looking for when you are mixing it you have options - and options are great. I've often done things like described in this thread like low passing open pattern mics and only mixing that into my main pair of more directional mics. Having those options to draw from later is pretty awesome.

[Gutbucket]

Good points.  I find it really helpful to set things up in such a way that I can easily adapt my setup to the situation- running the outside pair wide whenever and wherever possible, while compromising to something more compact when necessary allows me to make the best of each situation while avoiding pissing anyone off.

I will say that when possible, I find a wide spacing particularly beneficial in regards to how the audience reaction is portrayed, and that applies to both good and bad audience reaction - enthusiastic engagement and distracted chatter.  Recording from the same position and using the same polar patterns, the audience reaction remains at about the same level in the resulting recording either way, but sufficient spacing decorrelates much of the off-axis content that arrives to one microphone a fraction of a second before the other, serving to differentiate that content and pull it away from the more highly correlated content arriving from the stage and PA more or less simultaneously across all channels.  It helps make specific audience conversation streams easier to ignore via the psychoacoustics associated with the "cocktail party effect".

Switching from omnis to subcardioids or a tighter pattern is one way to make the best of a narrower spacing without as much compromise but ideally requires angling that pair more widely to compensate- essentially trading spacing against level difference derived from the combination of pattern and angle.  But that can be a tough trade-off in a less than acoustically ideal indoor situation where keeping the spaced pair pointed more toward the stage and PA is advantageous, since a more narrow angle between mics ideally requires more spacing not less. It's a situation of opposing constraints. And that relationship is the basis upon which Improved PAS was extended to three mic-positions last year.

This OMT stuff is all about exploring ways of making the best of the situation.  In reality, a lot of the time the practicalities of what we are able to do are going to overshadow what we might prefer.

[Gutbucket]

New thread so I'll add some of my latest thinking-

Sometimes I flip the script a bit regarding the position(s) in the mic-array in which which I want the most forward directionality - that is to say, the microphone positions in the array that are intended to pick up the least room and audience.  This is basically what the OMT4 "tough room variant" is intended to do, mentioned on page 2 of this PDF- OMT overview (rev4)_OMT4.pdf (122 kB), in which a more-directional narrower-spaced pair is substituted for the wide spaced omnis and angled toward the PA.  What isn't mentioned in the current "tough room variant" PDF write up is that when doing that I'll sometimes shift to using a wider Mid microphone pattern in the center Mid/Side pair.  Because if the near-spaced directional pair in PAS is providing most of the upfrontness and vocal clarity, I can use a more open Mid pattern to sort of flesh out a bit more room and depth dimension from the center Mid/Side pair.   

In a way, that's the opposite of what has been my standard OMT thinking about having the center pair primarily focused on providing the direct sound to the greatest extent possible with minimal room and audience content.. which encouraged me to switch to using a shotgun Mid a year ago - a practical improvement I like for the most part.  Recently that has me thinking about the potential of a further optimization to the OMT8 setup I'm using (also applies to OMT 5 or 6 without rear facing mics) that uses the combination of a wide spaced pair of omnis, a pair of near-spaced directional mics and a coincident center pair.  I'm thinking I might ideally use the current arrangement with the shotgun Mid and near-spaced superard pair angled +/-45 degrees when recording from a relatively close sweet spot audience position or on-stage (pointing the shotgun Mid at the snare drum), but when far away switch out the near-spaced +/- directional pair for PAS shotguns and switch the center Mid to a wider pattern.  This comes from how I use the channels in a 2ch L/R mix.  When farther back, the ~2' near-spaced supercard pair angled around +/-45 degrees often provides much of the clarity up front proximity and zoom-in-ness. Switching those to PAS shotguns might optimize those qualities further when recording from a position farther back, while the more open mid helps make up for the more ambient stuff that the less open and more tightly angled near-spaced shotgun pair is longer proving to the same extent.  Alternately when recording from the sweet spot or on-stage, the roll is reversed with more isolated direct clarity from the Mid and more openness and stage imaging from the near-spaced pair.

This comes from the practicalities of what each pair is providing in the stereo mix.  In a no holds barred type situation where I can "put whatever setup wherever I like", I still think it best to keep the room out of the center pair (keeping it SBD like) as much as possible and to likewise limit pickup of direct SBD-like content in the mics focused more on translating the audience and room sound.. which I suspect remains the right thing to do for surround playback regardless of the situation.  But in a stereo mix where the various mic channels of the array are no longer dedicated to specific playback speakers and are instead being mixed together in such a way as to provide a more convincing illusion, we are freed to use the channels in somewhat different rolls.

So that's yet another potential acquiescence to practicality.  I may never actually get around to trying it.  But I would love to try a pair of DPA 4017s in place of the near-spaced 4098s, and if that pans out, have the option of switching one of those over to the center Mid position when called for.

[Gutbucket]

My previous two posts above both use too many words to essentially make these points-

• In a distant, noisy room, point 'em at the PA, and if you can, space them more widely apart to compensate for the narrower angle between the pair.  Improved PAS technique provides specific answers to "how wide?"
  

Dealing with audience noise is made easier by configurations that use wide spacings for a few reasons:

• A wide spaced mic setup does not increase the pickup of audience noise any more than a narrow-spaced or coincident mic configuration.
• A wide spacing doesn't by itself reduce audience noise, but will make it less annoying and attention grabbing in the resulting recording. Particularly audience noise which occurs near the recording location.
• Without moving to a different recording position or increasing mic height, the only way to reduce pickup of off-axis audience noise as much as possible is to point a pair of directional mics directly at the PA/stage (PAS).
• A pair of directional mics arranged in such a PAS configuration is going to have less angle between mics than typical stereo microphone setups.  The smaller angle reduces pickup off-axis, including audience noise, while maximizing clarity and pickup of the PA/stage sound by keeping those sources on-axis.
• The sound from a stereo pair of directional mics with a narrow angle between them is going to be greatly improved by using a wider spacing in order to achieve good stereo qualities.

In general, wider mic spacings are good in multi-mic stereo arrangements whenever possible, although there are plenty of situations in which a wide spacing isn't practical.  But if and when you can do it, wide helps when positioned farther back, when the room acoustics are not so good, and when the audience is noisy.  Wider is also good when the situation is great and more open polar patterns can be used.  Narrow is also good in a multi-microphone array since it serves as a good counterpoint center anchor balancing the Wide.

When using more than two mics, wide is good, but can be challenging to achieve.  Switching to more directional mics can somewhat reduce the need for going quite as wide.  Go for good without stressing yourself out or pissing other people off.

[Gutbucket]

Gaffer tape-

Found myself on something of an archeological dig last weekend reworking the multichannel rig before recording Sat night.  Rig was in bad need of rework and I still plan to totally reworking it prior to Amp Jam #1 on the Suwannee in early March, but just needed to get it all back together in straight presentable shape quickly for use that night.  Found myself digging through layers of old gaff tape, some from more recent quick ad-hoc repairs (chopstick or two as repair splints on kinked telescopic TV antenna mic-bars), and some deeper layers foundational to the core structure and wire-routing.  That made for a few interesting observations on extended long-term gaff tape use. 

The more recent repairs and mods were made using the cheapo Amazon gaff tape, ranging from a couple months to a couple years old. It's 2", fabric backed, black adhesive. Seems to work about the same as classic gaffer tape when fresh.  Rips and conforms nicely. I actually prefer its black adhesive over white as long as its fresh.  Good medium adhesive tack, the tape is thinner, doesn't show any white edge, and pulls away cleaner without residue from some surfaces.. when fresh.  After aging it retains its stickiness and never seems to dry out which is good, but grows increasingly "slimy sticky" making it sort of slide around under load, and it's residue becomes difficult to get off hands and whatever else it touches.  Pulled off layers of old tape strips are super tacky gooey on both sides.  Ugh, a real mess to disassemble!

The older tape underneath more foundational to some of the rig structure and wire-routing is maybe around 5 to 7 years old.. dunno might be 10.  Its classic well known good stuff, ProGaff or ShureTape not sure which. 2" fabric backed, white adhesive.  It aged as expected, remaining fully attached, but with the adhesive drying out completely. Pulling it off, the removed tape was completely tack-free on both sides, produced a little cloud of white dust and left behind a hard white textured residue on the surface which wiped off easy enough with acetone.

Thing was I needed to reassemble this thing and had no roll of fresh tape at hand.  Couldn't reuse the older "better tape" strips with no adhesive remaining.  Salvaged the best of the A'zon tape stripa that were the least slimy and least sticky on the front side and made do.  Yuck.  Nasty.  Gotta do what you gotta do. Got it done. Worked out fine.

I've been meaning to rework this rig since my posts about doing so here a year ago which included a few drawings of a new support structure.  All the while last Saturday I was scheming on the redo with a reemphasized goal of the elimination of as much gaff tape if possible, at least in its "as new" state.  Anything goes to affect needed repairs in the field as always.  Gaff tape is great stuff and will always be in the bag, but..

[Gutbucket]

Temporary revision eliminating tape-