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Author Topic: Oddball microphone technique (OMT) - part 2  (Read 81661 times)

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Offline Gutbucket

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Re: Oddball microphone technique (OMT) - part 2
« Reply #300 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).
« Last Edit: February 06, 2019, 08:48:18 AM 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<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline heathen

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Re: Oddball microphone technique (OMT) - part 2
« Reply #301 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
Mics: AT4050ST | AT4031 | AT853 (C/SC) | Line Audio CM3 | Sennheiser e614 | Sennheiser MKE2 | DPA 4061 Pre: CA9200 Decks: Zoom F8 | Roland R-05

Offline heathen

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Re: Oddball microphone technique (OMT) - part 2
« Reply #302 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.
« Last Edit: February 06, 2019, 09:56:18 AM by heathen »
Mics: AT4050ST | AT4031 | AT853 (C/SC) | Line Audio CM3 | Sennheiser e614 | Sennheiser MKE2 | DPA 4061 Pre: CA9200 Decks: Zoom F8 | Roland R-05

Offline Gutbucket

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Re: Oddball microphone technique (OMT) - part 2
« Reply #303 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.
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<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline detroit lightning

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Re: Oddball microphone technique (OMT) - part 2
« Reply #304 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?

Offline heathen

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Re: Oddball microphone technique (OMT) - part 2
« Reply #305 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.
Mics: AT4050ST | AT4031 | AT853 (C/SC) | Line Audio CM3 | Sennheiser e614 | Sennheiser MKE2 | DPA 4061 Pre: CA9200 Decks: Zoom F8 | Roland R-05

Offline Gutbucket

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Re: Oddball microphone technique (OMT) - part 2
« Reply #306 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.
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<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline Gutbucket

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Re: Oddball microphone technique (OMT) - part 2
« Reply #307 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-
« Last Edit: February 11, 2019, 07:23:06 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<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline Gutbucket

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Re: Oddball microphone technique (OMT) - part 2
« Reply #308 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.
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<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline Gutbucket

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Re: Oddball microphone technique (OMT) - part 2
« Reply #309 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.
« Last Edit: February 11, 2019, 07:44:33 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<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline Gutbucket

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Re: Oddball microphone technique (OMT) - part 2
« Reply #310 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.
« Last Edit: February 11, 2019, 08:11:08 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<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline heathen

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Re: Oddball microphone technique (OMT) - part 2
« Reply #311 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?
Mics: AT4050ST | AT4031 | AT853 (C/SC) | Line Audio CM3 | Sennheiser e614 | Sennheiser MKE2 | DPA 4061 Pre: CA9200 Decks: Zoom F8 | Roland R-05

Offline Gutbucket

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Re: Oddball microphone technique (OMT) - part 2
« Reply #312 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.
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<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline Gutbucket

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Schoeps Mono Upmix - From Mono To Stereo & LCR
« Reply #313 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

« Last Edit: February 19, 2019, 07:00:49 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<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline heathen

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Re: Oddball microphone technique (OMT) - part 2
« Reply #314 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...?
Mics: AT4050ST | AT4031 | AT853 (C/SC) | Line Audio CM3 | Sennheiser e614 | Sennheiser MKE2 | DPA 4061 Pre: CA9200 Decks: Zoom F8 | Roland R-05

 

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