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Author Topic: Oddball microphone technique (OMT) - part 2  (Read 42707 times)

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Offline Gutbucket

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Re: Oddball microphone technique (OMT) - part 2
« Reply #315 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.
« Last Edit: February 19, 2019, 07:00:00 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 heathen

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Re: Oddball microphone technique (OMT) - part 2
« Reply #316 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?
Recordings on LMA: https://archive.org/search.php?query=taper%3A%22Lucas+Lorenz%22
Mics: AT4050ST | AT4031 | AT853 (C/SC) | Line Audio CM3 | Sennheiser e614 | Sennheiser MKE2 | DPA 4061 | CA-14 omni Pres: CA9200 | DPA d:vice Decks: Zoom F8 | Roland R-05

Offline Gutbucket

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Re: Oddball microphone technique (OMT) - part 2
« Reply #317 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.
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 heathen

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Re: Oddball microphone technique (OMT) - part 2
« Reply #318 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?
Recordings on LMA: https://archive.org/search.php?query=taper%3A%22Lucas+Lorenz%22
Mics: AT4050ST | AT4031 | AT853 (C/SC) | Line Audio CM3 | Sennheiser e614 | Sennheiser MKE2 | DPA 4061 | CA-14 omni Pres: CA9200 | DPA d:vice Decks: Zoom F8 | Roland R-05

Offline DavidPuddy

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Re: Oddball microphone technique (OMT) - part 2
« Reply #319 on: March 05, 2019, 01:23:38 PM »
Grabbed a set of these from ebay to experiment with.

https://imgur.com/a/NQCtChx
Mics: nbobs/480+ck61/62/63; C568EB; MKE2
Recorders: MP6; A10
puddylivemusic@gmail.com

Offline ycoop

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Re: Oddball microphone technique (OMT) - part 2
« Reply #320 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?
Mics: Avantone CK-1s, AT853 c+o
Pres: CA9100
Recorders: DR-60d mkII, DR-2d


Offline Gutbucket

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Re: Oddball microphone technique (OMT) - part 2
« Reply #322 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.
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 heathen

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Re: Oddball microphone technique (OMT) - part 2
« Reply #323 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.
Recordings on LMA: https://archive.org/search.php?query=taper%3A%22Lucas+Lorenz%22
Mics: AT4050ST | AT4031 | AT853 (C/SC) | Line Audio CM3 | Sennheiser e614 | Sennheiser MKE2 | DPA 4061 | CA-14 omni Pres: CA9200 | DPA d:vice Decks: Zoom F8 | Roland R-05

Offline Gutbucket

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Re: Oddball microphone technique (OMT) - part 2
« Reply #324 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 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..
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 Gutbucket

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Re: Oddball microphone technique (OMT) - part 2
« Reply #325 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.
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 Gutbucket

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Re: Oddball microphone technique (OMT) - part 2
« Reply #326 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.
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 DavidPuddy

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Re: Oddball microphone technique (OMT) - part 2
« Reply #327 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?
Mics: nbobs/480+ck61/62/63; C568EB; MKE2
Recorders: MP6; A10
puddylivemusic@gmail.com

Offline ycoop

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Re: Oddball microphone technique (OMT) - part 2
« Reply #328 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?
Mics: Avantone CK-1s, AT853 c+o
Pres: CA9100
Recorders: DR-60d mkII, DR-2d

Offline IMPigpen

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Re: Oddball microphone technique (OMT) - part 2
« Reply #329 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

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.
Mics: Neumann KM184s; Naiant X-R omnis & cards; MM-BSM-7M omnis
Pres/Battery boxes: Naiant IPA; Sound Professionals SP-SPSB-6
Recorders: Tascam DR-60Dmkii; Tascam DR-40; Roland R-07
Cassette Transfers:  Nakamichi CR-1A->Tascam DR-60Dmkii
DAT Transfers:  Tascam DA-20mkii->Marantz PMD-670

My LMA uploads:  https://archive.org/details/@brandon_smith

**Have any old Strangefolk or Eddie From Ohio shows not on the LMA?  Let me know!**

 

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