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Gear / Technical Help => Microphones & Setup => Topic started by: Gutbucket on December 21, 2007, 10:50:32 PM

Title: Oddball microphone techniques
Post by: Gutbucket on December 21, 2007, 10:50:32 PM
This thread documents some out-of-the-mainstream stereo and surround microphone techniques I've been using, as well as those of some other members here.  For ease of access, following is a list of links to subsections within the thread, which I'll revise as new stuff is included.


[edited to add links below to each of the techniques in this ever-evolving thread]

Telescopic TV antenna spreader bar for spaced omni mini mics (w/painter pole - chair base stand) (http://taperssection.com/index.php/topic,96009.msg1279052.html#msg1279052) this post in its original form that starts the thread below-

Spaced miniature omni's, stage-lip on thin welding rod 'stalks' for near invisibility-  (http://taperssection.com/index.php/topic,96009.msg1279100.html#msg1279100)

Richard's ceiling mounted all-in-one on a stick- (http://taperssection.com/index.php/topic,96009.msg1279106.html#msg1279106)

Boundrisphere head sized boundary mounted baffle- (http://taperssection.com/index.php/topic,70134.msg939786.html#msg939786)

Seperate thread with more details on the boundrisphere- (http://taperssection.com/index.php/topic,70134.msg939786.html#msg939786)

Bug Eye compact stereo adjustable spaced omni rig- (http://taperssection.com/index.php/topic,96009.msg1338924.html#msg1338924)

Elliptical and oversized Jecklin disk baffles- (http://taperssection.com/index.php/topic,96009.msg1365710.html#msg1365710)

Moke's rearwardly baffled omnis- (http://taperssection.com/index.php/topic,96009.msg1364095.html#msg1364095)

Quad Eye compact surround rig- (http://taperssection.com/index.php/topic,96009.msg1517359.html#msg1517359)

Chandalier surround-  (http://taperssection.com/index.php/topic,96009.msg1523288.html#msg1523288)

Four evenly spaced miniature omni's in a row, stage-lip on thin welding rod 'stalks'-  (http://taperssection.com/index.php/topic,96009.msg1539955.html#msg1539955)

Improved quad-eye portable stereo/surround rig (with integrated cable management for rapid deployment and tangle-free cabling) (http://taperssection.com/index.php?topic=96009.msg1713305#msg1713305)

Octo-ear portable surround rig adds ambisonic Tetrmic at center, increases A-B omni spacing to 2 meters, adds 12 total channel capability-  (http://taperssection.com/index.php?topic=96009.msg1864048#msg1864048)

Four channel surround rig with six foot (2m) omni spacing plus center and rearward facing cardioids (full sized MG cards and miniature ATs)-  (http://taperssection.com/index.php?topic=96009.msg2003117#msg2003117)

Revised four channel surround rig with six foot (2m) omnis spacing plus center and rearward facing cardioids (miniature DPA 4098H supercardioids) and smaller recorder package for increased portability-   (http://taperssection.com/index.php?topic=96009.msg2067584#msg2067584)

Reference 6-channel surround rig- OCT for Left/Center/Right using Microtech Gefell cardioid and supercardioids, + six foot (2m) spaced omnis as dedicated Left/Right surrounds and rear facing Gefell cardioid as center back surround channel (http://taperssection.com/index.php?topic=96009.msg2093960#msg2093960)

All DPA miniature microphone version of the same 6-channel array substituting DPA 4098H super/hypercardioids in place of the Microtech Gefells.  New experimental addition of two Naiant X-8S figure-8 mics, turning the front/back facing center mics into Mid/Side pairs.  8 channels total-  (http://taperssection.com/index.php?topic=96009.msg2181501#msg2181501)

Explanation of correlation / decorrelation between channels and its importance in stereo recording-  (https://taperssection.com/index.php?topic=96009.msg2244172#msg2244172)



I've been doing a lot of spaced omni recording.  The technique is obviously nothing out of the ordinary, but here's two interesting implementation ideas that work for me.  These ideas take advantage of smaller, lightweight mics, in this case DPA 4060's.  Can't do these with the ADK TL's.

The first is using an old set-top style TV antenna as a spreader bar to get up to a 5' spacing between mics using one stand.  Some antennas may go even wider, but I usually settle around the around 1 meter (that's 39" in America :P) after adjusting the spacing while monitoring with 'phones.  The telescopic aerials make it really easy to adjust the spacing on the fly.  I've got my eye out for a black pair which should visually disappear better than the 'classic' chrome version.

When I first whipped this up the night before a festival a year or so ago I was just getting back into taping again and didn't have a stand, so I gaff taped the antenna to a telescopic painter pole that slid perfectly into the back support tube of a folding chair.  Fortunately, the omnis out on the ends of the antennas didn't seem to pick up any handling noise when I sat down or moved around.  The chair & pole deal actually turned out to be an advantage because I could leave an identical chair at another stage and easily move the rig between the two.  I keep the mic preamp and recorder in a small shaving kit bag so the whole rig is pretty compact.  When it's time to change stages I just un-telescope the pole, fold the antenna arms down parallel and wrap a velcro cable tie around the pole to secure them, pull the pole out of the chair back and go.  Takes about 30 seconds to break down or set up once it's rigged.  Note for the DPA 406x users, I'm using the short (6' I think) micro-dot extension cables to extend the mic leads from the pole to the MMA6000 preamp. Here are some photos, sorry I don't have any 'in use' at the 'fest shots.

First the painter pole & TV aerial with mics mounted wired to the recorder bag.  The mic leads are just wrapped loosely around the antenna and gaff taped down the pole-
Title: Re: Oddball mic techiques that worked
Post by: Gutbucket on December 21, 2007, 10:53:20 PM
Here's a few shots showing how the pole slides into the chair back.
Title: Re: Oddball mic techiques that worked
Post by: Gutbucket on December 21, 2007, 10:58:40 PM
A few of the system rigged and ready to go but packed up to move, details of the gaff tape attaching the mics to the ends of the antennas (with out the windscreens) and the shaving kit bag with the MMA6000 preamp > R-09.
Title: Re: Oddball mic techiques that worked
Post by: Gutbucket on December 22, 2007, 12:47:30 AM
Ok, here's #2-

In this case I was taping MMW at a local joint, who were in town for a two night run.  This place, like most bars and clubs is not a place where omni's typically work well.  The management has put the nix on what was the usual position of choice for stand placement next to the soundboard (I guess that would be SOB?). Fortunately we could set up stage lip.  MMW is instrumental so no problem missing FOH vocals, but John Medeski had this fortress of gear stacked around him blocking both sight and sound lines to the entire right half of the stage so everyone taping up there was trying to figure out how best to configure things.  Chris Wood (bass) was center stage and Billy Martin's drum kit was sideways facing Medeski with his percussion table behind him.  There is a wall at the edge of the stage which is about armpit height from the house floor and about 8" higher than stage level, so the first night I taped my mics to the inside of this wall facing in, centered on the band about 4' apart, with my recorder bag on-stage behind the wall. Totally invisible to the crowd.  ;)  Recording turned out OK, not spectacular.

The next day I grabbed two pieces of stainless TIG welding rod before leaving work and taped the leads of the mics to the rods with narrow strips of black gaff tape.  At the venue that night I placed my gear behind the stage lip and considered where to better arrange the mics. I figured I'd shoot for a nice clear, present image of Billy's drum kit and percussion table with a direct line of sight to Chris Wood's bass amp and let the obscured keyboard amps (and baby grand at the back corner of the stage) be more atmospheric and diffuse since their level was plenty loud. I shifted left so that the 4' spread between mics was centered on the side-on drum kit, with the percussion table to the immediate left and the bass amp directly in front of my right mic towards the rear of the stage.  I bent the rods into a nice gentle curve and taped them to the wall so that they rose about 2-1/2' above the stage and projected about 18" in towards the band and away from the crowd.  The result was two thin, black bug antenna-like stalks with the mics on the ends, nearly invisible from the crowd eventhough they were directly in the line of sight from the floor.  The recording worked out quite well if a bit unconventional in its sound staging.  The percussion table segments are clean & clear on the left, the drum kit is present though unnaturally wide, filling the stage L-R, the basses are centered and the keys are to the right with a nice reverberant ambient depth.  Even Medeski is much cleaner sounding than the night before when the mics were closer to him, probably since the mics were up in 'clean air' with nothing around them. Anyway it worked great and I can't wait for another opportunity to try this again.

Apologies for the long winded explanation, here are the pics.  First assembling the rods and mics with the gaff tape, no windscreens used-
Title: Re: Oddball mic techiques that worked
Post by: Gutbucket on December 22, 2007, 12:51:13 AM
Finished and ready for the show, I didn't bend them until I was at the venue-
Title: Re: Oddball mic techiques that worked
Post by: jeromejello on December 22, 2007, 12:53:58 AM
gutbucket, you must have been the guy that i met at Bear Creek.

i really did like your chair set up.  envious of the small rig for sure.  and the you had the extra r-09 to patch the 722 rig too.

+t
Title: Re: Oddball mic techiques that worked
Post by: Gutbucket on December 22, 2007, 12:55:09 AM
Here's the rods bent as used (I actually took these photos the next day)-
Title: Re: Oddball mic techiques that worked
Post by: illconditioned on December 22, 2007, 12:58:41 AM
Great work "repurposing" whatever you find around you.

Not a new position for mics, but I wanted something to suspend mics from the ceiling and have no wires getting in peoples' way.  This is a pair of Beyerdynamic MC930 > self made (18v) battery box > Edirol R09.

(http://soundmann.com/hanging-mics.jpg)
Title: Re: Oddball mic techiques that worked
Post by: Gutbucket on December 22, 2007, 01:00:49 AM
gutbucket, you must have been the guy that i met at Bear Creek.

i really did like your chair set up.  envious of the small rig for sure.  and the you had the extra r-09 to patch the 722 rig too.

+t

That's me.  Good to meet you up there.  The chairs work pretty well, but I'm thinking of switching to a small stand if I can find one that is small but goes high enough, I don't want or need anything too big.  I think that would be just as portable, but I could use it without the chair.  The pole rotates pretty easy in the chair too so I have to be careful that it stays oriented right.
Title: Re: Oddball mic techiques that worked
Post by: Gutbucket on December 22, 2007, 01:04:23 AM
Here's the whole rig laid out on the floor to give you a better idea-
Title: Re: Oddball mic techiques that worked
Post by: Gutbucket on December 22, 2007, 01:17:23 AM
And finally here are a few shots from the show.  If you look very closely you can see thin curving black lines in each shot in front or around Mr. Martin, mostly on the left side of the photos.  The shots of him working the percussion table show both stalks, one in front and one behind him.  It's easier to make out the left one with the percussion table cloth behind it. I didn't take these but found them on the web.
Title: Re: Oddball mic techiques that worked
Post by: Gutbucket on December 22, 2007, 01:33:30 AM
Great work "repurposing" whatever you find around you.

Not a new position for mics, but I wanted something to suspend mics from the ceiling and have no wires getting in peoples' way.  This is a pair of Beyerdynamic MC930 > self made (18v) battery box > Edirol R09.

I like the all-in-one hang from the ceiling unit, Richard.  I'm looking for some cardioids and considering the Beyer930's so I'm interested in your batt. box.  I think they'll operate on 12-48v, no? And with a sensitivity of 30mV/Pa you probably don't much gain from the R-09 I'd guess.
Title: Re: Oddball mic techiques that worked
Post by: illconditioned on December 22, 2007, 10:40:00 AM
Great work "repurposing" whatever you find around you.

Not a new position for mics, but I wanted something to suspend mics from the ceiling and have no wires getting in peoples' way.  This is a pair of Beyerdynamic MC930 > self made (18v) battery box > Edirol R09.

I like the all-in-one hang from the ceiling unit, Richard.  I'm looking for some cardioids and considering the Beyer930's so I'm interested in your batt. box.  I think they'll operate on 12-48v, no? And with a sensitivity of 30mV/Pa you probably don't much gain from the R-09 I'd guess.

Yep, they work great with the Edirol R09.
The battery box is two 9V batteries in series (18V), and uses 2k resistors (instead of 6.8k for regular phantom).  It is unbalanced (just uses wire 2 (+) of the XLR).  The result is 12v drops accross the mic, which powers just fine.

 Richard
Title: Re: Oddball mic techiques that worked
Post by: illconditioned on December 22, 2007, 10:56:31 AM
Richard,
I've seen the pciture of that rig before, and always wondered,... what is the deal with the headphone jack connection?
Both the headphone and the mic in jacks have a "jack extender", a male rt angle miniplug, about 2" of wire, and a female jack.  This is to protect against the "weak jack problem" on the Edirols.  Oh yeah, since that photo I've glued the plugs in with (matching) black hot melt glue  :).

 Richard
Title: Re: Oddball mic techiques that worked
Post by: Gutbucket on December 22, 2007, 11:11:41 AM
...
The battery box is two 9V batteries in series (18V), and uses 2k resistors (instead of 6.8k for regular phantom).  It is unbalanced (just uses wire 2 (+) of the XLR).  The result is 12v drops accross the mic, which powers just fine.

 Richard


Simple. If I go the MC930 route I'll put one of those together for sure.  Thanks for the R&D.

Lee
Title: Re: Oddball mic techiques that worked
Post by: illconditioned on December 22, 2007, 12:59:46 PM
...
The battery box is two 9V batteries in series (18V), and uses 2k resistors (instead of 6.8k for regular phantom).  It is unbalanced (just uses wire 2 (+) of the XLR).  The result is 12v drops accross the mic, which powers just fine.

 Richard


Simple. If I go the MC930 route I'll put one of those together for sure.  Thanks for the R&D.

Lee

I should note that this only works for the MC930s.  The reason this works is that there is an internal dc-dc converter in the mic to generate the (approx 50V) capsulse polarization voltage.  Other mics have different powering requirements.  In addition, the current through the mic determines the proper resistor value (so 12V actually drops accross the mic).  The internal wiring determines if you can "unbalance" the mic by simply using wire 2 (+) on the XLR.

  Richard
Title: Re: Oddball mic techiques that worked
Post by: Gutbucket on December 22, 2007, 01:21:44 PM
I should note that this only works for the MC930s.  The reason this works is that there is an internal dc-dc converter in the mic to generate the (approx 50V) capsulse polarization voltage.  Other mics have different powering requirements.  In addition, the current through the mic determines the proper resistor value (so 12V actually drops accross the mic).  The internal wiring determines if you can "unbalance" the mic by simply using wire 2 (+) on the XLR.
Understood & thanks for the clarification.

Moke, I'm surprised I missed your thread before.  I've gotta hit the dollar store and see if they have some black ones.
Title: Re: Oddball mic techiques that worked
Post by: Gutbucket on December 27, 2007, 02:13:36 PM
Here's a link to my all in one mics/pre/recorder package using half a 'nerf' style basket ball as a baffle.  I put this thing together to have an integrated unit that I could easily pull out of my guitar bag and place on the floor to record some acoustic guitar classes with some stellar players a couple summers ago.  (http://taperssection.com/index.php/topic,70134.0.msg939786.html)  Makes some excellent HRTF type recordings without any setup other than pulling it out, setting levels and pushing record.  Also works nicely in the center of a circle of seated musicians.  Details near the bottom of the first page.

(http://taperssection.com/index.php?action=dlattach;topic=70134.0;attach=44294)
Title: Re: Oddball mic techiques that worked
Post by: rockthing on January 27, 2008, 10:37:47 PM
literally, an oddball.
This is a great thread. I wish I'd found it earlier. I've posted some of my odd-ball (^^^ well, compared to that, just 'odd' :) ) rigs.

I'm a big fan of nylon rope. (They call me spiderman)
I'll be back with pics. or links to the threads I already posted in.
Title: Re: Oddball mic techiques that worked
Post by: rockthing on February 26, 2008, 04:44:05 AM
A month later and I've finally managed to copy the link to one of my nylon rope+t-bar-no-riser spiderman jobs... tho it seems like I have a knack for killing threads. I'll just link to the already posted message to save bandwidth. I have photos from a different nylon rope suspension, but that may take another month to put together at the moment.

http://taperssection.com/index.php/topic,90103.msg1291614.html#msg1291614
Title: Re: Oddball mic techiques that worked
Post by: audBall on February 26, 2008, 07:01:38 AM
Did someone say Odd ball?   :P
Title: Re: Oddball mic techiques that worked
Post by: Gutbucket on February 26, 2008, 09:00:12 AM
^^^
wonderin when we'd hear from you. :P

A month later and I've finally managed to copy the link to one of my nylon rope+t-bar-no-riser spiderman jobs... tho it seems like I have a knack for killing threads. I'll just link to the already posted message to save bandwidth. I have photos from a different nylon rope suspension, but that may take another month to put together at the moment.

http://taperssection.com/index.php/topic,90103.msg1291614.html#msg1291614

Ok, now I get the spidey thing with the supporting web and all.. built in shock suspension to boot with that nylon line.

Not super important here, but one useful property of nylon line is it's ability to stretch, absorb shock and spring back.  As I recall, Jacques Cousteau made the deepest ocean anchoring in history using an absurdly long nylon mooring line on the Calypso in the '70's.  At the other extreme and usually more useful to me, I've found modern low stretch line (usually available at marine stores for sail boat halyards and such) made from spectra, vectran, and the like to be worlds superior to common polyester for tying or hanging things that shouldn't sag.  It's like high performance tires for hanging a hammock -  totally transforms it from a sagging rusty Cadillac suspension to a taught German road machine. 
Title: Re: Oddball mic techiques that worked
Post by: keith on February 26, 2008, 01:53:36 PM
I'm a little late looking at this thread, but what was this rig attached to up top?  Did there just ahappen to be a rod hanging down from the ceiling to tape your gear too?   :)

Great work "repurposing" whatever you find around you.

Not a new position for mics, but I wanted something to suspend mics from the ceiling and have no wires getting in peoples' way.  This is a pair of Beyerdynamic MC930 > self made (18v) battery box > Edirol R09.

(http://soundmann.com/hanging-mics.jpg)
Title: Re: Oddball mic techiques that worked
Post by: illconditioned on February 26, 2008, 01:56:15 PM
^^^^^^^^^

Yeah, the rod goes up about 2', then hanging from a hook or anything else I can grab on the ceiling.

Almost all of my "Starlight" and "Boathouse" recordings at Soundmann.com were made this way.

  Richard
Title: Re: Oddball mic techiques that worked
Post by: evilchris on February 26, 2008, 02:40:58 PM
How is the R-09 attached to the pole?
Title: Re: Oddball mic techiques that worked
Post by: Nick's Picks on February 26, 2008, 08:33:06 PM
Carl pulled a good tape last weekend w/the mic actually pointed backwards and aiming at the mens room.
:P



Title: Re: Oddball mic techiques that worked
Post by: eric.B on February 26, 2008, 11:52:12 PM
there is this thread..  http://taperssection.com/index.php/topic,61699.0.html (http://taperssection.com/index.php/topic,61699.0.html)

and of course the touchdownrohponic technique..    :P     http://taperssection.com/index.php/topic,61476.0.html (http://taperssection.com/index.php/topic,61476.0.html)
Title: Re: Oddball mic techiques that worked
Post by: Brian Skalinder on February 27, 2008, 12:51:11 AM
Carl pulled a good tape last weekend w/the mic actually pointed backwards and aiming at the mens room.

Heh...I ran on-stage a while back for Unwed Sailor, opening up for Lotus.  Ran Mid/Side, with the C34 set to subcardioid for the Mid, and realized about half way through the opening set that I had the Mid facing the audience instead of the stage.  Whoops!  Fortunately, the audience was darn quiet during their set.  I tweaked it in post (inverted the Side channel, boosted the Mid to compensate for the mild rearward attenuation) and the recording turned out just fine.  Not great, but very listenable.  Phew!
Title: Re: Oddball mic techiques that worked
Post by: Gutbucket on February 27, 2008, 12:59:45 AM
there is this thread..  http://taperssection.com/index.php/topic,61699.0.html (http://taperssection.com/index.php/topic,61699.0.html)

and of course the touchdownrohponic technique..    :P     http://taperssection.com/index.php/topic,61476.0.html (http://taperssection.com/index.php/topic,61476.0.html)

Amazed I missed those threads back then 'till now.  There's treasure buried at TS.  Nice AVI.. Whacchhhhaaaaaa.
Title: Re: Oddball mic techiques that worked
Post by: rockthing on February 29, 2008, 09:55:18 PM
^^^
wonderin when we'd hear from you. :P

A month later and I've finally managed to copy the link to one of my nylon rope+t-bar-no-riser spiderman jobs... tho it seems like I have a knack for killing threads. I'll just link to the already posted message to save bandwidth. I have photos from a different nylon rope suspension, but that may take another month to put together at the moment.

http://taperssection.com/index.php/topic,90103.msg1291614.html#msg1291614

Ok, now I get the spidey thing with the supporting web and all.. built in shock suspension to boot with that nylon line.

Not super important here, but one useful property of nylon line is it's ability to stretch, absorb shock and spring back.  As I recall, Jacques Cousteau made the deepest ocean anchoring in history using an absurdly long nylon mooring line on the Calypso in the '70's.  At the other extreme and usually more useful to me, I've found modern low stretch line (usually available at marine stores for sail boat halyards and such) made from spectra, vectran, and the like to be worlds superior to common polyester for tying or hanging things that shouldn't sag.  It's like high performance tires for hanging a hammock -  totally transforms it from a sagging rusty Cadillac suspension to a taught German road machine. 

I bet Cousteau got a good pull.... er... nevermind. ::) :D

I like the suspension systems for the exact reasons your stated.
built-in shock absorption, in which case, I think the Cadillac might be better than the Beemer...

The negative, is set up time.  It takes some time to get it together, but even with a stand, it can take some time, I guess.
I couldn't find the photos of the stage omnis I hung above the stacks in a small rock club back in January. I'm sure I took photos, but I don't know what happened to them.

That was a pretty crazy rig, getting the mics to point toward the center of the room while hanging from the front edge of the lighting rig, then running the cable from one side to the next.

I seem to have been thwarted by low frequency vibration from the bass guitar, however.

Those nerf balls look pretty interesting, even if just as a substitute for a T-bar.

The basketball above, I remember seeing a while back. That deserves some kind of award. :)
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: Gutbucket on March 12, 2008, 10:36:10 PM
Update on the first rig that started this thread-

Revised the system a few days before Langerado to also use at Suwannee Springfest at the end of the month.  I think about this stuff all the time, but I only get it together under a deadline.  ;)

I ditched the painter pole I was using into the back of the chair since sitting in the chair wiggled the pole and could cause noise.   The portability was great, it just was not an elegant solution.  Instead I improved the thing so that I could collapse the whole rig down to 19" to fit in a day pack all wired and ready to go, but still fly up to 10' (or more) and space the omnis up to 6-1/2' apart.  I also made everything 'nothing to see here' black instead of 'look at that' shinny chrome.

To do that I substituted a Manforotto 001B for the painter pole, built two stand extensions out of 5/8" threaded rod, lock-nuts and couplers  for use above 8', and replaced the chrome TV antenna with a black one. I fashioned a little attachment bar to attach the antenna spreader bars to the stand or the extensions which allowed everything to fold up without disassembly and covered the extensions and bar with heat shrink.

It all worked out nicely.  OK, the rig is out of the ordinary to begin with, but here's the real oddball parts-
I've used some firm green foam Nerf ballistic balls (come in 5 pack refills for Nerf guns) as feet to keep the thin legs of the stand from sinking into sandy festival soil.  They also make for a nice grip and cushion on concrete floors.  I just slit the balls with a razor knife, slipped the thin rubber tips of the stand legs and slipped the balls on.

I also wanted to experiment with placing a spherical baffle on the 4060's to give them some increased directionality and presence on-axis that could be beneficial when micing from a distance.  I'm shooting for emulating the effect of the DPA acoustic pressure equalizer (APE) balls for the full size 4006's and the plexiglass sphere of the Neumann M-50 (or modern M-150).  Here's a PDF article (http://www.dpamicrophones.com/Images/DM02449.pdf) from the DPA site that goes into detail about what those things do if interested, as well as some discussion around p.19 & 20 of the DPA, Gefell, & ADK in Classical Venues thread (http://taperssection.com/index.php/topic,3863.285.html).

I selected the green Nerf ballistic balls since they are just about the same diameter as the 40mm APE's, lightweight, relatively dense, sound opaque and easy to work with.  I heated up a nail and used it to melt some nice smooth bore holes through the balls into which I fitted some soda straw sections that the mics could slide through until the capsule grids were flush with the surface of the sphere.  A short end section of bamboo chopstick (the tapered end) inserted from the cable exit side, locks the mic in place by wedging the cable against the straw wall.  Another hole at a right angle to the first and only partway into the ball allows it to fit snuggly on the end of the telescopic TV antenna.  Radio Shack foam mic windscreens slip over the balls for wind protection.  I ended up also using my ghetto Rycote wind baskets as well since the wind was fierce over the weekend.  Details on those are in this DIY basket style windscreens - AKA ghetto Rycotes thread (http://taperssection.com/index.php/topic,100537.0.html).

[edit- foam alone is sonically better for all mics as long as it is effective enough.  Trapped air space under foam could improve wind protection without resorting to the more problematic basket.  Baskets are probably only really needed for directional mics. Details in the above thread]

I didn't have a chance to do any testing of the ball baffles before Langerado, so I just flew the things.  I still haven't listened enough to determine their worth or if I'll refine the system further (perhaps with different material or size balls - yellow foam practice golf balls are the same foam but are slightly smaller diameter).  I may end up removing the balls and going back to just the 4060's with small foams on the ends of the antennas which is much less visually distracting and virtually disappears in a crowd since the antennas are so thin.  I wouldn't be able to call it 'bug eye' then unless I break out the ghetto Rycotes.  I did set up in a parking lot and did some walk around tests last night  at various mic spacing with the balls on, but haven't assessed those tests either.. so stay tuned.

OK, the pictures-

Here's the whole rig collapsed, but wired up and ready to deploy.  R-09 and MMA6000 are in the shaving kit bag, I'm using the microdot extension cables to reach to the preamp in the bag when the stand is extended to 10'+. 

It's a wierd looking contaption.  I was walking between stages at Langerado when some dude passing by said 'WHAT THE HELL IS THAT?'.  I hurried on to catch the start while by girlfriend stayed back to play with his mind a bit. ;D
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: Gutbucket on March 12, 2008, 10:44:17 PM
The short heat-shrink covered bar that bolts to the top of the stand or extensions which the TV antennas attach to.  It's bent to allow the telescopic arms maximum rotation so that they can fold down parallel to the stand when collapsed, and rotate up as much as desired to get increased height in use, while still allowing access to the attachment screws and mounting bolt.

[edit- you may notice that there is a fat piece of tech-flex-like wire sheathing attached with a velcro wire tie that the mic leads run through.  When using the threaded stand extensions, I insert them into the tech-flex sheathing which neatly conforms to the extensions and secures the mic cables.]
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: Gutbucket on March 12, 2008, 10:56:14 PM
Here are the stand extensions.  It's just a 36" piece of 5/8" threaded rod cut to make two 18" pieces, with a threaded coupler on one end, secured by a nylon-insert lock nut, and a second nylon-insert lock nut on the other end.  All heatshrink wrapped for cable protection, dark color and to keep from scraping up the stand or other things in the bag.
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: Gutbucket on March 12, 2008, 11:01:57 PM
On to the odd foam balls-

First the leg tips to keep the stand from sinking into soft ground and to provide some cushioning.  The balls keep the stand from making scraping noises if I have to move it on a concrete surface as shown here.  Just slitted and pushed on, nothing fancy.
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: Gutbucket on March 12, 2008, 11:25:47 PM
Now for the APE-like mic balls.  I'm rather proud of the fact that the one and only Dan Healy signed one of them for me at Langerado.  I recorded DSO pretty much just to catch him working his magic (Dan was filling in for their soundman who was out for the tour with a bad back).  I got there after the first couple songs, raised the rig and looked back to him making the OK? gesture, and he shouted "TV ANTENNA'S" and gave me two thumbs up.  The living legend of live concert sound was smiling and dancing all about the whole show, thoroughly enjoying himself.  It was so good to once again hear his clean, clear, detailed mix in glorious wide stereo without the typical bloated kick drum 'whomp'.  The best sound of the whole weekend by far.  He had the crew roll back the canopy cover over the soundboard so he could hear clearly despite the earlier monsoon rain and tornado warnings and continuing rain threat.  The man cares and is still the best in the business in my mind.  It was great to talk with him after the show, thank him for the great sound that night and over so many years and get the blessing of his autograph on my measly foam mic ball.  My buddy back at camp said to me, 'only about 20 people here would appreciate that'.  I told him, "without Healy, they wouldn't be listening to those huge sound systems at all", only slightly exaggerating his contribution to concert sound.
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: illconditioned on March 12, 2008, 11:30:38 PM
Hey Gutbucket

Are those mics on the green balls?  They look like boundary mics.  What are the balls made of?

  Richard
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: Gutbucket on March 12, 2008, 11:36:56 PM
Richard,

The mics are DPA 4060's through a hole in the balls so that the grids are flush with the surface of the ball.  The balls are hard Nerf foam from a toy store.  The balls work as baffles to the rear and boundary surfaces for the high frequencies.

:lol:

Sarge made me some new stand bags. So, my stands are now sporting tennis ball buffers on them, at the pressure points.
Good idea for the scraping noise, and it probably adds a bit of mechanical isolation as well.

I covered some extensions with heat shrink. Now everything else in the bag beats up on it.

Mike, I was going to use tennis balls, but I fell in love with the green ones and they work better on the small stand.  They also don't fuzz up over time and they don't look 're-purposed'.  ;)
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: Gutbucket on March 12, 2008, 11:37:57 PM
The foam windscreens over the balls, loose ends secured by a small binder clip.
And the $10 Rycote-a-likes over the foams (for now, the foams underneath made it easy to use the baskets in the fierce wind at Langerado.  I'll fix them so I can eliminate the foam later and just use the baskets with thin nylon material when needed).

[edit- I no longer think the baskets are necessary or even a better idea than foam windscreens for pressure omni mics.  They do look cool though.  8)  Why in this thread on them (http://taperssection.com/index.php/topic,100537.msg1667387.html#msg1667387)]
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: Gutbucket on March 12, 2008, 11:40:36 PM
Deploying the stand-
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: Gutbucket on March 12, 2008, 11:51:44 PM
Fully deployed at low height.
Max height without extensions (narrow footprint to reach 9', but quick setup, just telescope and power up).
Max height with extension sections and wider base stance (about 11', but need to screw the extensions together to setup).

Someday I'll get my house back together, too.  ::)
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: KLowe on March 12, 2008, 11:55:36 PM
greatest mic stand/ contraption ever???
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: Gutbucket on March 13, 2008, 12:31:10 AM
Yup. These are them-
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: balou2 on March 13, 2008, 02:26:19 AM
That is fantastic!  Thanks for the photos.

us-play, ee-tay.
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: jeromejello on March 13, 2008, 02:57:15 AM
great job!  i really liked the "chair rig", but this is seriously in a whole new level of awesome.

you keep this up and i will be looking to grab a pair of these 4060s sooner than later.
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: evilchris on March 13, 2008, 03:49:23 AM
wow ... i really need to work on making my rig an ez-up rig before 'roo.

this is great.  +t
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: djs on March 13, 2008, 04:28:23 AM
clever work in this thread... inspiring.  thanks for sharing, i had fun reading about and viewing your crafty rigs.
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: palmettobum on March 13, 2008, 07:34:58 AM
ok, that has got to be one of the best homebrew devices I have ever seen on this site.  major props on that.    what a perfect festival rig.  I'll see you at springfest (i'll be carrying about 5x as much gear).  -pb
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: Nick's Picks on March 13, 2008, 07:53:10 AM
I had a celebrity sign my balls once.
ONCE !
(http://videodetective.com/photos/103/004329_24.jpg)
(joe piscopo humor)
Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: Gutbucket on March 13, 2008, 01:16:43 PM
^^^^^
I knew I was asking for that one.. I was just waiting for it. ;)

Thanks for the kind words, everyone.  Those ideas germinated from this board.  Love this place, positive T's for all.
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: silentmark on March 17, 2008, 08:05:53 AM
Wow, awesome work, +T
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: Gutbucket on March 17, 2008, 09:09:23 AM
jbanyai97 posted some photos from Langerado over in rig pics, a couple caught my rig up front-

Bad Plus (if it wasn't so windy I could have eliminated those big windcreens and been near invisible)
(http://i19.photobucket.com/albums/b168/jbanyai97/Langerado%202008/tbp2.jpg)

Medeski Scofield Martin Wood (barely discernable, stand is just to the left of the acoustic bass, left mic infornt of Chris Woods right elbow, right obscured by fan's arm in foreground)
(http://i19.photobucket.com/albums/b168/jbanyai97/Langerado%202008/msmw1.jpg)
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: rowjimmy on March 17, 2008, 10:27:46 AM
Hey, GB, I've been following this thread a while.. great stuff. Have you posted any torrents of your langerado recordings?
(apologies if you've mentioned it somewhere)

thanks.
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: Gutbucket on March 17, 2008, 10:56:31 AM
I haven't yet.  The recordings I've been making with this are quite encouraging but need eq work (bloated festival subs + omnis bring the bass boom home).  I've been primarily focusing on the capture side since I've gotten back into recording again - most of my catalog untracked at this point.  I need to get into the post side enough to do some limited (but necessary) eq work, SRC, dither to 16bit and tracking, but I'm a bit of a perfectionist and just can't get myself to do it half-assed.  I need to sit down and dedicate some time to doing it right and just haven't had the time to do that. But then I figure I better capture it now! editing and tracking can wait a bit.

I do have great admiration for the guys uploading shows withing a few days.  I'll let you know when I finally get that side together.

I finally did some limited 'walk around the rig with a shaker calling out the numbers of the clock' testing of various mic spacings with and without the baffle balls to check the effect on both the directionality that the balls impart and the effect of various omni spacings and angles on the playback image.  The balls do change the response relatively dramatically.  I need to do some more of that testing and include variations with a jecklin disk too.  I'll post short clips and details of those tests here when I get a chance.  Likely next month after Spingfest.
Title: Re: Oddball mic techiques that worked - evolvution to 'Bug Eye' rig
Post by: illconditioned on March 18, 2008, 07:55:41 PM
jbanyai97 posted some photos from Langerado over in rig pics, a couple caught my rig up front-

Bad Plus (if it wasn't so windy I could have eliminated those big windcreens and been near invisible)
(http://i19.photobucket.com/albums/b168/jbanyai97/Langerado%202008/tbp2.jpg)


Hey, love that pic!  Looks like an alien landed.  You give a whole new meaning to FOB...

  Richard
Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: Gutbucket on March 19, 2008, 09:12:53 AM
Oh, they're streaming in the stiff breeze, dangling down and caressing the heads of the pious spagnostics up front.  The FSM in it's benevolence has adopted the methods of the Invisible Pink Unicorn and made the majority of it's body transparent to both critical sound frequencies and the electromagnetic spectrum that humans require to enjoy both a sonic & visual stage performance.  FSM respects sight lines.

[edit - perhaps I should rename the thread: Oddball mic techiques that worked - evolution to intelligent design of 'Bug Eye' rig.
Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: illconditioned on April 16, 2008, 11:50:05 PM
Hey Moke, can you explain how you made the Jecklin disk?

I'm thinking of using a Jecklin disk with cardioids.  Why?  Well, suppose I'm in a long room, about halfway back (where a light fixture is hanging :)).
Now if I do ORTF or DIN or whatever, mics get all kinds of reflections from the walls.  I figure if I point mics forward, with a Jecklin baffle, I'll get more music and less walls.  Does this make sense?  Maybe this is obvious, but I just don't like ORTF or DIN recordings in long narrow rooms.

  Richard
Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: Gutbucket on April 17, 2008, 10:24:24 AM
Rearwardly baffled spaced-omnis...
The chair-back baffles cut the applause by 12dB(?), naturally...
This is exactly the opposite of what usually occurs.

Nice visual confirmation in those screen shots.  So how does the applause and quality of the room ambience sound to you?  Does the room ambience 'close up' somewhat with the baffles?  Is the applause just lower in level or does the tone of the applause change?

This is positive confirmation of what i've heard by changing the placement of the 4060's on a torso shaped baffle ;) with the array in a similar position relative to the audience and performers.   In my experience in a good sounding but relatively reverberant room, placement of the mics on the sides of the 'baffle' similar to a Jecklin disk (well, it would be a 20" thick, small diameter Jecklin disk) provides the best ambient capture of the sound of the room.  Moving the mics to the front of the baffle cuts applause and other AUD noise significantly and also increases the upper midrange clarity slightly for the on-stage sources (both positives), while loosing some of the ambient capture of the room and changing the 'tone' of applause and sounds to the rear by reducing the mids & highs a bit more than the bass.  That placement also reduces the stereo separation as the mics are less separated and there is little baffling between them.  That can be an useful trade-off to make depending on the scenario.

If I can offer a suggestion, one thing you might want to try if you use this technique again is angling the chairs slightly in a shallow 'V' shape to provide a slight bit of baffling between the mics as well (if you'd like to capture some Jecklin sound staging qualities vs. spaced A-B) while still baffling the audience.  I'd suspect adjusting the amount of 'V' would correspond to my observations above.
Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: Gutbucket on April 17, 2008, 10:59:09 AM
Innovation born of necessity.. fertile soil.

You could also run the J-disk lower on the stand and flank with the chairs in an inverted V to block the diagnosticians and origamists.

W baffle.
Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: Gutbucket on April 17, 2008, 07:24:19 PM
Got home and gave a listen. Interesting to hear, thanks.  The Gefell sample has the applause attenuated in post, correct?  The applause in that sample doesn't sound obnoxiously loud at the end of the piece, though obviously louder than the rear baffled 4060 sample.

The chair baffles certainly cut the rearward sound significantly, which is the idea of course.  Similar to my own experiences with such rearward baffling, personally I find the tonal change for those reduced sounds less desirable. I even notice the same 'dulling of rear sound' effect to a lesser extent in my limited experiments with the 1.5" diameter nerf foam balls APEing the DPA spheres.  The balls do give the 4060's more directionality and a bit of midrange focus that can be useful, but as for their reduced rearward sensitivity, I find I'd almost rather have well recorded, exceptionally clear ambient noise than muffled sounding rear noise.

A thought that has crossed my mind in the past is that 'applause', though not the usual focus of our interest, seems difficult to record really well.  By that I mean really natural, realistic sounding applause.  Maybe it's just that we don't really set-up to capture applause accurately or that the level of applause often does not match especially well with that of the music from the mics perspective and recorder gain settings.  Or maybe its the distribution of clappers near the mics and the highly dynamic, frequency rich transient nature of the sound. :shrug:
Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: Gutbucket on April 17, 2008, 10:15:47 PM
Totally agreed on the omni bass aspect, the bassoons really grabbed me in the omni sample too.  The Geff's are generally brighter, but even with the more extended bass I don't find the 4060 sample too dull sounding for the sounds on-stage, only for the rearward baffled sounds. I like that Geffel midrange clarity bump, which works fine here but really shines and focuses the sound from farther back to my ear.  That midrange presence is the region that I sometimes find could use some help in my 4060 recordings and the primary reason for experimenting with the APE-like ball baffles.
Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: Gutbucket on April 17, 2008, 10:16:59 PM
Hey Moke, can you explain how you made the Jecklin disk?

Here are some photos of my DIY Jecklins, using the same embroidery hoop starting point.  I got this together a year ago based on everyone else's ideas in the TS Jecklin threads (thanks Mike!).  As usual, mine are a bit oddball, first because they are ellipses not disks. The idea behind the ellipse was to give more baffle separation for forward arriving sounds while keeping the overall size of the thing as small as practical, allowing for less baffling effect for the ambient room information from above and behind. The ellipse shape  also just looks cool.

Going possibly a bit farther than necessary to damp reflections off the surface of the baffle, I listened to the reflected sound off of various materials by angling the material like a mirror in front of a speaker and listening though a tube placed near the reflection point. Doing that, I could judge pretty well how much sound and of what frequency range was reflected by the material. I tried various foams but settled on a layer of short cut pile carpet remnant salvaged from the shipping department at work that seemed to absorb the midrange best, covered by a layer of felt moving blanket that really sucked up the higher frequencies. I thought about using some cork material as the rigid center board portion (pic below), but ended up using a piece of three layer corrugated cardboard to keep the weight down and possibly form a bit of a 'constrained damping layer' with the heavier carpet sandwiching it on either side.  I covered each side in typical dead rat style faux fur for appearance more than anything else (it's supposed to be nearly transparent to sound used for 'rats' so I used it for looks more than it's sound absorption.. maybe it damps some top octave) and wrapped the wooden hoop with a strip of 2" black gaffer tape.  Just cut the pieces, assemble the sandwich and camp the hoop. Then figure how to attach it to your stand (or light fixture  ;)) I used a short square section wooden dowel that fit into the painter pole I was using as a mic stand at the time.

Photos-
Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: Gutbucket on April 17, 2008, 10:20:52 PM
More showing the sandwich of materials, and one with the unused cork and a regular circular hoop-

[edit- one side shown only, obviously there is carpet, felt and fur on the other side too.]
Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: Gutbucket on April 17, 2008, 10:38:50 PM
OK, below is a photo of the other oddball Jecklin that I never worked up the guts to fly.  Same construction as the smaller one. Reasoning for the fast-food super meal sizing to follow in another post. The sandwich photos above are of this one, which is why the scale of things may appear a bit off. I sacrificed the fur cover for the 'possum' windscreen (http://taperssection.com/index.php/topic,100989.msg1348542.html#msg1348542) to run the TL's coincident in a breeze.  This one is the big boy. Lookout Ray Kimber!

it's based on another, larger ellipse embroidery hoop. Small disk for comparison and hand photo for scale-
Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: illconditioned on April 17, 2008, 10:45:12 PM
OK, below is a photo of the other oddball Jecklin that I never worked up the guts to fly.  Same construction as the smaller one. Reasoning for the fast-food super meal sizing to follow in another post. The sandwich photos above are of this one, which is why the scale of things may appear a bit off. I sacrificed the fur cover for the 'possum' windscreen (http://taperssection.com/index.php/topic,100989.msg1348542.html#msg1348542) to run the TL's coincident in a breeze.  This one is the big boy. Lookout Ray Kimber!

it's based on another, larger ellipse embroidery hoop. Small disk for comparison and hand photo for scale-

Thanks for the details.  Got to get in gear and make one...

  Richard
Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: Gutbucket on April 18, 2008, 12:16:27 AM
Richard,

Your application halfway back in the room is what stirred me to dig up these photos.  I experimented with various omni spacings using the rabbit ear TV antennas and the small disk and I think the Jecklin technique (with a normal sized disk) works best when used up close to the performance.  My experience using the smaller disk with omnis farther back was less than ideal. I ended up preferring a wider un-baffled omni spacing. In order to have the disk baffle the mic for sounds on the opposite side of a normal sized disk, the mics need to be pretty close to the disk surface - It's just a matter of geometry.  Recording at a distance I found that 'tight to the surface' spacing cut the highs unacceptably and didn't provide enough distance between the mics to develop the nice open spaced omni sound at mid and lower frequencies. 

A bigger disk would allow for wider mic spacing while still providing baffling for sounds at the edges of the soundstage.  Of course the size of the disk needed to do that grows rapidly as you move deeper into the room and/or move the mics further apart.  You soon end up with something the size of the Kimber monster.  You could try moving the cards towards the back edge of the disk to increase the effective baffle area and narrow the 'shadowing angle' somewhat from deeper in the room.  I also considered making two small disks and spacing them apart. That would allow enough distance between mics for a decent A-B spaced omni recording at mid & low feqs but get the disk surface close enough to each mic to provide a decent shadowing effect for the high end. Something like that might be unpractical with a mic stand considering sight lines, but could work from the ceiling.  If you are pointing the Beyers directly forward and not using the pattern directionality for stereo purposes, they are like omnis as far as imaging is concerned and you either need to space them far enough apart or have the baffle shadow the mics for stage originating sounds from the opposing side.  That's my working theory anyway.

Interested in other thoughts on all this,

Lee
Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: Gutbucket on April 21, 2008, 09:20:32 PM
Oddball comp (http://images1.wikia.nocookie.net/muppet/images/thumb/d/d0/Janice_Season_1.JPG/200px-Janice_Season_1.JPG) fer shur.

Listening to the right channel only, alternating DPA tracks, the 4028 sounded slightly hotter, adjusted volume by ear and the bass is very similar, more midrange focus with the 4028's, more room reverb with the 4060's (the attack of the pizzicato fiddles).  The drier 4028 is nice at that distance, though the applause and reverb is still very natural, just slightly attenuated and that's what I love about those sub-cards.  Alternating between left channels the tone difference is clear. The bass leanness of the  mv692's is obvious but that top is so sweet.  Tonally the balance of the mismatched pair is really complementary if you ignore the wacky imaging.. didn't listen in mono.

Bummer on the DOA.
Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: hypnotoad on April 21, 2008, 09:50:57 PM
Those bent rods are pretty cool Gutbucket.

 :)
Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: Gutbucket on April 22, 2008, 08:49:16 AM
Those bent rods are pretty cool Gutbucket.

 :)

Thanks, I really liked that application.  Unfortunately I haven't had another chance to do that since.

[edit, I got to do this again a few months back for Stanton Moore trio.  4060s on stalks flanking the Peluso P-Stereo in M/S]
Title: Re: Oddball mic techiques - evolution to 'Bug Eye' now 'Quad Eye' rig
Post by: Gutbucket on November 19, 2008, 05:57:58 PM
The bug eye rig has sprouted a few more antennae.

First some back story-
I've been playing around with some surround sound recording ideas since last spring.  My approach is to not compromise my standard two channel stereo recordings by changing the stereo mic array, but to add two optional, additional mics recorded as center and back channels.  I've been doing this for a while now for low-profile recording using baffled omnis and the results have been highly encouraging- adding another dimension of reality to what I had previously considered very good stereo recordings that already convey the illusion of 'being there'.  It has been so encouraging that I decided to try and apply the technique to a standing, open rig, somehow without the baffles that would block sight lines.

I'd already been running two simultaneous stereo rigs for some outdoor festivals which is great for comparing techniques and equipment and have sometimes toyed with surround playback. I'd usually run my 'big rig' with ADK TLs or Pleuso P-Stereo mic in say Blumlein a few feet in front of the little spaced omni bug eye rig pictured here previously.  The two micstand formation formed a sort of triangular Deca tree shape.  Setting up the two separate stereo rigs that way allowed me compare the two stereo recordings on their own, or to try sending the blumlein pair to the front L/R speakers and the omni pair to the surround speakers. I also played with summing the blumlein pair to form a single forward facing fig-8 (M/S technique) and using that as a center channel along with the L/R omnis for L/C/R playback.  All good fun but none of those surround experiments really added that much over the stereo recordings, certainly nothing like the baffled surround recordings I've been making. 

I figured that the baffle was an essential element to provide enough directionality and isolation of sound between front and back channels with the meter or so spacing between mics that I was using for practical reasons. Eliminating the baffles I needed something to provide directionality to the highly omnidirectional miniature 4060s.  I considered using clear plastic CD jewel case covers or the clear 'CD's that cap the stack on CDR spindles like mini-baffles and boundary mounting the mics to them, one at the end of each telescopic antennae, but the more I thought about it the more that seemed a bad idea.  I instead decided to return to using the APE-like Nerf foam balls I've pictured here previously which provide some top end directionality, seem in keeping with the obvious Decca tree using classic Neumann M-50s influence or the modern DPA surround tree using omnis with APE attachments. They are also much more practical to use and to keep less visible.

I've used the rich sounding and costing DPA surround tree and APE attachments (http://www.dpamicrophones.com/Images/DM04458.pdf) as design inspiration and developed the 'poor man's' version that you see below.  Other big influences that have shaped or confirmed my thinking on this are Michael Williams' Magic Arrays for simultaneous recording of 1,2,3,4,5 or more channel sound, each of which stands on it's own, with a single array and his previous MMAD data for 4-channel quad arrays using omnis and subcardioids (http://www.soundsscot.com/MMAD_04/Readme.htm).

I'll just address the non-low profile open recording here and the modification of the bug eye rig I've posted about previously. The signal path is (4060s > CA-Ugly > R-09) x2.  One rig records the L/R pair and the other the C/B pair.  For playback I currently hook up both recorders' outputs to the 6-channel DVD input of my stereo amp (splitting the back signal to both surround speakers) and play both recordings simultaneously. It takes a few quick jabs of pause/play to match up a percussive impulse and sync both machines, but they do not seem to drift audibly over the course of a 90 minute recording. Unlike matrixing a 4 channel recording the signals are not summed and are somewhat less susceptible to comb filtering problems if slightly off sync.  I have not found the time to play around with the recordings on the computer in post yet, but plan to eventually look into syncing the two stereo recordings (L/R & C/B) and encoding to 24/48 DTS surround.  I mostly play everything off the computer into the home stereo these days but I could also burn DTS encoded surround CDs or DVDs. I also plan on trying various methods of decorrelating the mono back channel feeding the two rear surround speakers.  Any ideas on ways of doing that are very welcome.  I need a four channel output sound card for my editing machine before I can do any of that.

First a photo of the previous dual rig setup. This was from a month ago, Peluso P-Stereo up front, antenna spaced 4060s one row directly behind. Here the 4060s are not mounted in the foam Nerf balls and so are 'fully omni'.  Both sound very nice as stereo recordings but there is not enough distance between rigs or imparted directionality to make the 4060s useful as surround feeds. (five rigs can be seen, the Peluso is in front, the antenna spaced 4060s are directly behind another rig)-
Title: Re: Oddball mic techiques - evolution to 'Bug Eye' now 'Quad Eye' rig
Post by: Gutbucket on November 19, 2008, 06:01:57 PM
Now behold the Quad Eye rig.

These are from Bear Creek this last weekend. Here Saturday morning down low and up front for Jim Weider's Project Percolator with a few closeups-
Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: Gutbucket on November 19, 2008, 06:06:40 PM
I painted the green Nerf balls charcoal gray with automotive vinyl and fabric paint. A bit less alien but they don't glow so much.

Rigged higher and farther out from the stage-
Title: Re: Oddball mic techniques that worked - evolution to 'Bug Eye' rig
Post by: Gutbucket on November 19, 2008, 06:13:15 PM
Stage lip again (different stage) for Robert Walter Trio, here I have foam windscreens on the balls which are just cut down cheapo Shure ball mic style foams to form a half sphere, pinned onto the foam balls.

Soundcheck-

Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: Gutbucket on November 19, 2008, 06:14:44 PM
Live set-
Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: Javier Cinakowski on November 19, 2008, 06:15:50 PM
that is a sweet set-up....  Thanks for sharing!
Title: Re: Oddball mic techiques that worked - evolution to 'Bug Eye' rig
Post by: Gutbucket on November 19, 2008, 06:18:40 PM
Inside the music hall for New Mastersounds, Skerik as guest-
Title: Re: Oddball mic techniques that worked - evolution to 'Bug Eye' rig
Post by: rastasean on November 20, 2008, 10:17:05 AM
Stage lip again (different stage) for Robert Walter Trio, here I have foam windscreens on the balls which are just cut down cheapo Shure ball mic style foams to form a half sphere, pinned onto the foam balls.

Soundcheck-



You REALLY do what your signature says: record > listen > revise technique

Great technique here!
You do record into two separate recorders, right?
Title: Re: Oddball mic techniques - evolution to 'Bug Eye' now 'Quad Eye' rig
Post by: Gutbucket on November 20, 2008, 12:42:29 PM
Splainin? I lost count, 5 or 6 times over the weekend, but not as much as I would have thought for such an odd looking contraption.  Most people that asked about it were more than content to learn it was 'microphones for recording' and leave it at that.  It was fun playing with a few, telling them it was a detector for ______ (fill in the blank with various detectables) indicating direction, quantity and quality.  'Whoa, look at that meter jump!' They'd always smile.

Sean, Yes two recorders.  I keep thinking about the R-44 to do all four tracks and will probably break down and get one since I've been doing more of this.  I do dig the modularity of the system and the fact that I can easily break it down into two separate rigs in less than a minute, though. Too bad I can't link two R-09's for 4 tracks like you can link two R-44's for 8. 
Title: Re: Oddball mic techniques - evolution to 'Bug Eye' now 'Quad Eye' rig
Post by: illconditioned on November 20, 2008, 12:46:47 PM
Splainin? I lost count, 5 or 6 times over the weekend, but not as much as I would have thought for such an odd looking contraption.  Most people that asked about it were more than content to learn it was 'microphones for recording' and leave it at that.  It was fun playing with a few, telling them it was a detector for ______ (fill in the blank with various detectables) indicating direction, quantity and quality.  'Whoa, look at that meter jump!' They'd always smile.

Sean, Yes two recorders.  I keep thinking about the R-44 to do all four tracks and will probably break down and get one since I've been doing more of this.  I do dig the modularity of the system and the fact that I can easily break it down into two separate rigs in less than a minute, though. Too bad I can't link two R-09's for 4 tracks like you can link two R-44's for 8. 
That is just crazy!  I love the pic of that onstage.  And people think I'm nuts...

 Richard
Title: Re: Oddball mic techiques - evolution to 'Bug Eye' now 'Quad Eye' rig
Post by: Gutbucket on November 20, 2008, 02:05:07 PM
It's fun playing the mad scientist.

A few technical details if anyone is interested-

I melted the holes through the Nerf balls with a nail heated in a propane torch.  One hole passed all the way through to accommodate the mic capsule and cable, held in place by a piece of bamboo chopstick where the cable exits (the black rectangular thing sticking out the back of the ball in the photos).  The other hole is for the interference fit over the antenna tip. It's the same diameter as the first, offset from the cable exit hole by 45 degrees and only penetrates the ball about 1/2". I considered going making additional holes at 90 degrees for the option of pointing the L/R mics fully forward with no angle between them but found I had more than enough adjustment without doing that.  The straight pins stuck in the balls in some of the photos are for securing the foam windscreens and are just being stowed there.

The 45 degree mic mounting axis works well because I can angle the front antenna up 45 degrees and rotate the ball to face the front mic directly forward and do the same with the rear antenna to point the back mic.  If I was recording purely ambient sound scape material I would do the same for the left and right mics so that each mic faced its cardinal direction and make the lengths of all four telescopic arms the same.  With forward oriented music recording I adjust the left and right antenna angles lower and rotate the mic balls so that they both face forward and out, angled somewhere near +/- 45 degrees from the front.  That makes the front R/C/L mics face mostly forward in a \ | / sort of shape.

I stuck with the approximate 1 meter spacing between the L/R pair that has worked well for me in the past for both distant and stage lip omni spacing. This time I figured out a way to make setup easy without whipping out the piece of measurement string in my pocket to check the spacing each time I unfolded the arms, by setting the antennas to that 1 meter (39") distance with the mics pointing out, level with the horizon and gaff taping the mic cable t either end of it's antenna.  I could then retract the telescopic segments to pack the stand away or to shrink the size of the array if it were to get in the way at the stage lip, and then just extend them again until the cable was straight and return to the 1 meter spacing without measuring.  I set up the front/back mics the same way with the same 1 meter measurement.  In use, those were the ones that I tended to retract at times so they didn't poke out into the crowd or too far onto the stage.  I could also rotate the left and right antennas so they pointed forward a bit, reaching over the stage edge.  All together the system lends itself to great flexibility and adjustment of both mic spacing, angle and height.

The telescopic arms help for extra height as well as mic spacing, at full extension I can get the mics up above 8' on the small Bogen 001B stand and the whole thing still folds down to 19" and fits in my day pack.  I gaff tape the tiny CA-Ugly preamps directly to the stand since the mic leads are not quite long enough with the stand at full extension to reach the shaving bag holding the recorders which I hang from the bottom section stand knob for ballast. 

[edit- here are a few photos of the mic cables gaff taped to the telescopic antennae for quick, measured mic spacing at setup]
Title: Re: Oddball mic techniques - evolution to 'Bug Eye' now 'Quad Eye' rig
Post by: Gutbucket on December 02, 2008, 10:49:06 AM
Two bits of quadrasonic Thanksgiving documentation.

Recorded the annual family Monopoly game in surround with the rig at the center of the board, mics pointed in the 4 cardinal directions and the telescopic arms angled down as shown below.  Interesting to hear voices all around the room as they were placed around the table.  Also interesting that conversations held across the room in the kitchen area can be clearly heard and understood while the game participants are talking loudly - the 'cocktail party' effect - and are not obscured by the louder, closer voices.  On playback I could easily focus on one conversation to the exclusion of other just like at the actual event.

Photographed on the deck, but as placed on the Monopoly board-
Title: Re: Oddball mic techiques - evolution to 'Bug Eye' now 'Quad Eye' rig
Post by: Gutbucket on December 02, 2008, 10:55:35 AM
Bracket with the telescopic arms removed from the stand and arranged along with the two recorders and preamps in the chandelier, set to record everyone around the table telling family stories at Thanksgiving dinner-
Title: Re: Oddball mic techiques - evolution to 'Bug Eye' now 'Quad Eye' rig
Post by: Gutbucket on December 02, 2008, 11:01:53 AM
The four mics, wired and ready in the baffles, attached to the collapsed telescopic rig and stand. It all fits in the small bag (beer bottle shown for scale).  The two recorders and preamps fit in the small shaving kit bag shown previously along with extra batteries and SDHC cards.
Title: Re: Oddball mic techiques - evolution to 'Bug Eye' now 'Quad Eye' rig
Post by: Gutbucket on December 02, 2008, 07:49:41 PM
It certainly helped that the light fixture was and was all black, constructed from loopy flatbar and tubes.

A funny insight into human nature - of course all the family members were aware of both recordings, yet the Monopoly game with giant TV tower-like mic array dominating the center of the board was less intimidating to free and uninhibited interaction than the inconspicuous chandelier rigging for dinner. That's obviously due more to social conventions than the visual aspect.

A week ago I also setup this array onstage for a local acoustic jazz trio -friends who've allowed me to hone my undercover skills over the years at their weekly gig.  Even though they know, they act and play totally differently when I record them unannounced.
Title: Re: Oddball mic techiques - evolution to 'Bug Eye' now 'Quad Eye' rig
Post by: digifish_music on December 03, 2008, 09:24:39 PM
A week ago I also setup this array onstage for a local acoustic jazz trio -friends who've allowed me to hone my undercover skills over the years at their weekly gig.  Even though they know, they act and play totally differently when I record them unannounced.

That's one of the reasons I tell vocalists that I am 'just setting the levels', can they run through the song once and then we will start the recording session proper...I often get the best take :)

virtual +T's for all the pics of your quad rig BTW  ;D

digifish
Title: Re: Oddball mic techniques - evolution through 'Bug Eye' to 'Quad Eye' rig
Post by: Gutbucket on January 05, 2009, 08:12:28 PM
Last week I expanded on the mics on welding rod stalks at the stage-lip technique that I posted about on the 1st page of the thread. (http://taperssection.com/index.php/topic,96009.msg1279100.html#msg1279100)  I used the same construction as before, I increased the mic count from two to four 4060s on separate stalks, evenly spaced across the front of the stage. The center pair was about 4' apart and a second stereo pair was flanking that, 4' to either side of the central pair, with a 12' total distance across the front of the stage. They are so thin and black that they were nearly invisible even in the direct line of sight from the crowd and just wiggle a bit if bumped on stage. I setup like this for Bonerama / New Mastersounds on NYE, then again for MMW at a different venue last Saturday.  The venue MMW played in here this year was a bit of a pain.  There was no stage-lip so I had to tape all wires down well and hang the shaving bag containing preamps and recorders from a strategically located hook under the center stage lip so I had  enough cable to space the center pair properly.  In addition, I had to quickly re-tape the outside stalks when the heavy, motorized stage-front curtain pulled them over.

I've panned the center L-R pair inwards, halfway towards the center and left the outsides panned hard left-right which spreads the sources across the playback stage and solidifies the center nicely.  The NYE recordings are sounding really good.  The MMW needs more work as the massive venue subs were directly under center stage and the band was a bit farther back on the stage making the direct drum sound a bit less forward. Regardless, I'm quite pleased with the technique.

There is no isolation between mics at all so perhaps contrary to appearance (four mics arranged in a line across the front of the stage), this is not at all like FOH mixing. I felt a little kindred with Owsley's OAITW technique mixing to stereo, but also thought about Harvey Fletcher's Bell Labs 'curtain of mics' experiment from the 30's.  It would be interesting to play the 4 channel recordings back with four speakers in a line, like a very limited version of the Bell Labs 'curtain of speakers.  From the Wikipedia article-

In the 1930s, Harvey Fletcher of Bell Laboratories investigated techniques for stereophonic recording and reproduction. One of the techniques investigated was the 'Wall of Sound,' which used an enormous array of microphones hung in a line across the front of an orchestra. Up to eighty microphones were used, and each fed a corresponding loudspeaker, placed in an identical position, in a separate listening room.

Unfortunately I didn't have a camera at either concert. If I get some photos from others I'll post some here later, but here are some I took today to help explain the setup-

Aluminum TIG welding rod (a straightened coat hanger would work the same), closeup of one mic taped on the rod, & the full bent rod which points the mics at the band and gets them farther onstage, up and away from the crowd.
Title: Re: Oddball mic techniques - evolution through 'Bug Eye' to 'Quad Eye' rig
Post by: Gutbucket on January 05, 2009, 08:16:01 PM
The four stalk array layed out on the floor in the shop.  Primary stereo pair on the inside to one preamp/recorder, outside secondary flanking pair with the DPA extension cables to a second pre/recorder in the same bag.  In use the mics were spread farther apart (~4' between each) and taped to the front of the stage so that they projected up about 2-1/2' and towards the band.


Title: Re: Oddball mic techniques - evolution through 'Bug Eye' to 'Quad Eye' rig
Post by: Gutbucket on January 05, 2009, 08:18:24 PM
The entire rig stowed and ready to go. The biggest issue is cable management and potential 'rats-nestage'.  I carry each stereo set of 2 rods with mics and cables attached in a piece of techflex material which kept the cables from tangling.  The outside pair still has the extensions attached which I just coiled and placed in the ziplock back when I broke-down.

Title: Re: Oddball mic techniques - evolution through 'Bug Eye' to 'Quad Eye' rig
Post by: illconditioned on January 05, 2009, 08:53:13 PM
The entire rig stowed and ready to go. The biggest issue is cable management and potential 'rats-nestage'.  I carry each stereo set of 2 rods with mics and cables attached in a piece of techflex material which kept the cables from tangling.  The outside pair still has the extensions attached which I just coiled and placed in the ziplock back when I broke-down.


Hey, that's looking really cool.  Hopefully noone gets impaled with those aluminum wires!  Perhaps you could bend a loop at the end or something.

I just recently installed a setup with two hanging Countryman B3 mics, about 16' split, 8' up, and 10' back from the stage.  So one is hanging in front of each speaker.  50' XLR cables snake along the ceiling to connect the mics to the back of the venue by the soundboard.  I just bring in my (Fostex) recorder and hook up.

I used to have AKG 463's hanging (on the XLR wire itself with a 12ga house wire to hold and point them forward.  Think the AT853 hanging mics that hang on their own cables).  Now these have been replaced by, almost invisible, hanging lav mics!

I'll try them out in about a month.  I'm trying to take a break from taping.  Take bets on how long I last before I cruise in to try my new installed setup!

  Richard
Title: Re: Oddball mic techniques - evolution through 'Bug Eye' to 'Quad Eye' rig
Post by: Gutbucket on January 05, 2009, 09:23:07 PM
The rods, though stiff enough to keep their shape, are pretty flexible to begin with.  With the curve bent into them, even a freak direct hit along the axis of the rod should cause them to collapse before causing damage.


So does hanging the B3s in front of each FOH speaker prevent the 'hole in the middle' that would develop due to such a wide spacing if it was purely acoustic without reinforcement from the speakers?

Good luck with your withdrawal symptoms, let me know how those Countryman mics work out once you cave.  They seem like quite nice lavs.
Title: Re: Oddball mic techniques - evolution through 'Bug Eye' to 'Quad Eye' rig
Post by: illconditioned on January 05, 2009, 09:30:47 PM
The rods, though stiff enough to keep their shape, are pretty flexible to begin with.  With the curve bent into them, even a freak direct hit along the axis of the rod should cause them to collapse before causing damage.
I'm thinking of just bending the *end* back on itself.  Like one inch from the end.  Also, have you considered shrink wrap to cover the wires.  I've done that before :).

Quote
So does hanging the B3s in front of each FOH speaker prevent the 'hole in the middle' that would develop due to such a wide spacing if it was purely acoustic without reinforcement from the speakers?
Most of the sound comes from the speakers.  I would opt for a jecklin disk or something, but the speakers are far apart, and there are no "fills" in the middle, so this is pretty much the only setup that sounds good.  The other alternative is to go way back, but then it sounds too "distant" for me.  Oh yeah, I've also tried an ORTF pair pointing at one stack.  I like that too, but this spaced setup is the most foolproof for an "installed" setup.  Listen to some of my AKG463 "Starlight" recordings on http://Soundmann.com and tell me what you think.

Quote
Good luck with your withdrawal symptoms, let me know how those Countryman mics work out once you cave.  They seem like quite nice lavs.
I love the B3s.  IMO the sound is much smoother than the DPA.  I don't know why, but it just sounds warmer.  Maybe I lose *a bit* of detail, I'm not sure, but they just sound warm and natural.  I find DPA sound great for ambient, but music just doesn't sound enjoyable to me.  I'd be curious to hear what you think.  I've got a ton of B3 "hat" recordings on my website.  LMK what you think...

I give myself about a week before I cave and just "check" my installed mics...

 Richard
Title: Re: Oddball mic techniques - evolution through 'Bug Eye' to 'Quad Eye' rig
Post by: kgreener on January 05, 2009, 10:36:41 PM

I love the B3s.  IMO the sound is much smoother than the DPA.  I don't know why, but it just sounds warmer.  Maybe I lose *a bit* of detail, I'm not sure, but they just sound warm and natural.  I find DPA sound great for ambient, but music just doesn't sound enjoyable to me.  I'd be curious to hear what you think.  I've got a ton of B3 "hat" recordings on my website.  LMK what you think...

I give myself about a week before I cave and just "check" my installed mics...

 Richard


Richard, which cap do you use with the B3's?  I assume the +0 dB (flat) cap?  Listening to some of your samples now and they do sound nice and natural.

 :hmmm:

thanks,
Keith
Title: Re: Oddball mic techniques - evolution through 'Bug Eye' to 'Quad Eye' rig
Post by: illconditioned on January 06, 2009, 12:15:23 AM

I love the B3s.  IMO the sound is much smoother than the DPA.  I don't know why, but it just sounds warmer.  Maybe I lose *a bit* of detail, I'm not sure, but they just sound warm and natural.  I find DPA sound great for ambient, but music just doesn't sound enjoyable to me.  I'd be curious to hear what you think.  I've got a ton of B3 "hat" recordings on my website.  LMK what you think...

I give myself about a week before I cave and just "check" my installed mics...

 Richard


Richard, which cap do you use with the B3's?  I assume the +0 dB (flat) cap?  Listening to some of your samples now and they do sound nice and natural.

 :hmmm:

thanks,
Keith
yes, the flat cap.

  Richard
Title: Re: Oddball mic techniques - evolution through 'Bug Eye' to 'Quad Eye' rig
Post by: Gutbucket on January 06, 2009, 01:09:39 AM
Quote
So does hanging the B3s in front of each FOH speaker prevent the 'hole in the middle' that would develop due to such a wide spacing if it was purely acoustic without reinforcement from the speakers?
Most of the sound comes from the speakers.  I would opt for a jecklin disk or something, but the speakers are far apart, and there are no "fills" in the middle, so this is pretty much the only setup that sounds good.  The other alternative is to go way back, but then it sounds too "distant" for me.  Oh yeah, I've also tried an ORTF pair pointing at one stack.  I like that too, but this spaced setup is the most foolproof for an "installed" setup.  Listen to some of my AKG463 "Starlight" recordings on http://Soundmann.com and tell me what you think.

Sounds very good.  I think the direct speaker orientation eliminates the hole in the middle effect for the music.  I do notice it with the ambient crowd sound, but that doesn't bother me and I wonder if I'd notice at all if I wasn't listening for it.

I really liked the sound of the Beyerdynamic MC833 recording with the crowd singing along.
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: rastasean on January 06, 2009, 12:30:53 PM
Its good to see you got to use your rig! I can't wait to hear the recordings from it.
I just got my very own bogen 001b tripod and its very well made and I love the compact size of it.
I'm interested in making a setup similar to yours in order to record drum circles and I want something small and unobtrusive so I do believe I will peruse this.

Last night I got the nerf balls and a TV antenna since I didn't have an extra one. simple tv antenna. (http://www.target.com/Magnavox-Indoor-Passive-Antenna-MANT-110/dp/B0006N14L0/qid=1231259402/ref=br_1_11/177-3525368-5322506?ie=UTF8&node=3987991&frombrowse=1&rh=&page=1)

Now I have a question....Do you think it would be better to separate the antennas from the bracket device they are in  and mount it like yours or figure out a way to mount it as is to the tripod?

I don't quite understand, on page 3 of this thread, what the stand extensions are for. At what point do they mount to the 001b?

This is a great device and I'm looking forward to using it and hearing your recordings.

Peace,
Sean
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: Gutbucket on January 06, 2009, 05:00:50 PM
Originally I just used a dollar store TV antenna which had the aerials attached to a little plastic 'T' piece that fit into a socket on many small TVs, no base to it.  I clipped the wires off and gaff taped it to the painter pole and it worked fine. 

If you discard the base so that you just have the two individual antennas, you'll need some way to hold the them together and attach them to the stand.  Moke posted a link earlier in the thread to his telescopic antenna spreader bar where the threaded aerials screw into a nut coupler to connect them (if I recall correctly). When I built the second rig with the stand, I fabricated a little aluminum bracket, sort of like a mini mic bar.  It has three holes, one for the stand stud and two smaller ones for the antenna studs.  The ends of the bar are bent up at a 45 deg angle and the antennas attach to the bottom side, so all the studs exit the top of the bar.  I did that to provide enough range of motion to the antenna hinge joints so that they would fold down parallel to the stand when stowed and pivot up to around 55 degrees above horizontal, which gives me plenty of height.  I can get the mics an easy 2' above the top of the stand that way and don't need to use the extension bars at all.  I've never needed to use them on this rig.

The extension bars can be useful for other things though.  Simply, they are made of all-thread rod with the same thread as the stand stud, so they can screw into each other or directly onto the stand.  If you want to use them on the 001B stand, keep in mind that it was not designed for a tall heavy load and risks toppling. The steel rod is much heavier than the aluminum stand sections and creates a lot of weight aloft.

The Nerf balls are great as stand feet.  But I suggest using the stand with your choice of small microphones as a straight spaced omni rig by just gaff taping or clipping your mics to the ends of the antennas.  If arranged so the antennas go close enough you could do directional mic arrays too of course.  But I don't recommend duplicating the specialized spherical APE mic baffles unless you really get your head around how and why they work and what they are supposed to do.  You then would need to determine if they will actually work for your choice of mic theoretically, make sure you can build them so that they perform correctly, and figure out when and where and how best to use them.  They can easily make your recordings worse not better.  The rest of the rig is easy and straightforward, the sphere baffles are the experimental part which I can't yet endorse fully without the above disclaimer!

A Jecklin disk is much more straight forward and would be my 1st choice in the center of a drum circle.  You can build one that attaches to the stand's stud along with the antenna.  Set up the antennas so the mics land in the center face of the disk with the aerials straight up and you can adjust spacing and angles as you wish from there.  I can do that by flipping over my antenna bracket before attaching the disc to the stud.

Thanks for the kind words,
Keep on DIY'ing..
(http://moldychum.typepad.com/moldy_chum/images/robert_crump_keep_on_truckin.jpg)
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: mblindsey on January 16, 2009, 09:08:09 PM
Admittedly, I haven't read this entire thread.  I know the first post asks for techniques that worked, but I thought I would share one that I've tried several times with split omni's and have experienced "hole in the middle".  I haven't got it quite right...just yet.  If it's windy, I get phase issues (even though the rig is pretty damn solid).  I've tried spacings from roughly 3' to 5.5'.  I affectionately call the setup "death by lightning".

It is made by salvaging the boom arms from two mic stands and some generic clamps used by drummers to attach heavy things to cymbal stands.  I typically run my MC 930's in the middle on a Shure vert bar.  Sometimes I mix all four mics with some success, but the result is usually pretty light on the omni's.

I've posted about this rig before on the Internet (somewhere)...so, if it was here...consider this an update...I've got some more experimenting to do.

--Michael
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: Gutbucket on January 17, 2009, 02:21:00 AM
Nice! That thing looks super solid, though a lot of weight aloft. The wind phasing is the sound waves being blown around in the air, probably not the stand moving. 

Narrow up the spread to eliminate the hole. Personally I don't go beyond a meter. You can try the spacings recommended in the Stereo Zoom charts if you feel the need for exactitude. Williams' charts don't go that wide but if you follow the trend of the graphs, a meter or so spacing (39") works out to about a +/- 20deg recording angle for a full left-right stage, pretty tight.  More space would be even narrower and risk the hole. The charts cover more typical wider recording angles with the mics spaced up to about 2' max.

Regardless of how it works, that rig looks cool with those long arms!
Great name, though death by powerline looks just as likely. 
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: mblindsey on January 17, 2009, 12:08:23 PM
Nice! That thing looks super solid, though a lot of weight aloft. The wind phasing is the sound waves being blown around in the air, probably not the stand moving. 

The arms move "a little".  Even thought it is amazingly sturdy, you are absolutely correct, it is also pretty top heavy.  The phasing is not as noticeable on the center MC930's in winds.  I assume this is because they don't have the opportunity to sway independently. 

Narrow up the spread to eliminate the hole. Personally I don't go beyond a meter. You can try the spacings recommended in the Stereo Zoom charts if you feel the need for exactitude. Williams' charts don't go that wide but if you follow the trend of the graphs, a meter or so spacing (39") works out to about a +/- 20deg recording angle for a full left-right stage, pretty tight.  More space would be even narrower and risk the hole. The charts cover more typical wider recording angles with the mics spaced up to about 2' max.

Regardless of how it works, that rig looks cool with those long arms!
Great name, though death by powerline looks just as likely. 

Thanks for the numbers!  Much appreciated.  I've seen the Stereo Zoom charts, but I've forgotten to look back for what they said about spacing omni's.  Now, I've got some more to try.

On a similar note, I saw The Cure at an outdoor amphitheater last year. I noticed that the sound guy was running spaced AKG 414's, at maybe 15-20 feet, on either side of the SBD.  Wouldn't that create a huge "hole on the middle"...regardless of what pattern they were switched to? 

Heh...Those power line's are an optical illusion...way off in the distance...

What does this sound like?
http://www.archive.org/details/cracker2008-08-01
http://www.archive.org/details/matisyahu2008-06-24.naiant-xt.flac16

Full disclosure..there is some processing with a "Stereo Field" plugin for Reaper on both of these.  It was a feeble attempt to salvage what initially sounded really, really bad.  The stereo image was almost dizzying to listen to.
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: Gutbucket on January 17, 2009, 02:28:15 PM
You can use any of the Stereo Zoom carts regardless of pattern to determine omni spacing.  Just read the value at the bottom of the chart for a zero degree angle between mics.  The angle of the graph line changes with pattern but they all intersect the zero degree line at the same point for any given spacing.

I think the very wide spacings can work in two different scenarios for different reasons:  The first is the situation of being relatively close to a wide acoustic source like the classic application of mic'ing a big band, orchestra or choir.  It seems to me that situation introduces amplitude differences as well as phase differences for sources on either side.  The second is the more typical TS situation of mic'ing PA amplified material that is mixed mono, or with alot of mono content. People here are often recording in the second situation which is really an unusual acoustic situation compared to the traditional recording techniques developed stereo recording of acoustic sources.  Widely spaced PA speakers with mono content, mic'ed widely can still create a solid phantom center since the mono information is identical from each speaker and at each mic.  A wide spacing in that case could actually reduce comb filtering of the mono portion by creating a longer path length from each mic to the FOH speaker on the the opposite side (or at least lower the frequency, where it may or may not be a problem).  It also makes for a very open, wide and diffuse crowd sound.  So a super wide application can work but is more specific to the particular situation.

A perfect example of well applied situation #2 is Richard's widely spaced hanging omni lavaliere installation.  Discussion about this and his link to samples are just a few posts back in this thread.
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: Gutbucket on December 07, 2009, 06:45:42 PM
I recently reworked the 'quad-eye' portable recording rig for stage-lip recording use at the '09 Bear Creek music festival last month.  I had put together the original 4 channel version for the same festival last year and was very pleased with the results. Most of the music is instrumental, so stage-lip recording worked nicely. There is little if any time between sets at that festival- one stage starts as soon as another finishes.  If I care to record a following act at another stage, I need to be able to sprint from one stage to the other with gear ready and get into position rapidly.  To successfully record from that position I need a setup that is portable and self-contained, easy to block solo, and able to be swiftly moved if a trombonist decides to crowd surf off center stage (happened) or things otherwise get out of hand up front.

The changes made this year are mostly refinements of the previous design.  The primary change is using Techflex to route all cabling.  The unique application is using sections of black ½” Techflex on the telescopic arms, with both the telescopic antenna and the mic cable running though it.  The sheathing is cut to length so that it is in its expanded state when the arms are retracted and in its fully long-thin state when the arms are extended. It is secured to the telescopic arms with 1” black gaff tape.  The Techflex sections keep the thin 4060 mic cables well protected and completely free of entanglement even when the antenna arms are fully retracted and excess cable bunches up harmlessly beneath the expanded sheathing. To accommodate the configurations I wanted to run for this outing, I only needed this arrangement of Techflex on the Left & Right arms, which I wanted to be able to telescope out enough for a 49” (1 meter) mic spacing.  The Center/Back arms could be much shorter, so I simply gaff taped the cables to the arms and can fold them down to stow without telescoping.

The four mic cables meet where the four arms attach to the top of the stand and are secured there with a Velcro tie-wrap.  The four cables are then fed through a smaller diameter section of Techflex which travels down the stand and is about the thickness of a pencil or a single strand of standard mic cable. 

The Left/Right 4060 pair has standard microdot connectors, which attach to a short adapter cable (microdot> 1/8” TRS stereo male).  The Center/Back pair is already terminated to an 1/8” TRS stereo male.  Two stereo mini-jack extension cables then run though a larger ½” diameter section of Techflex in an umbilical to the recording bag. The mic cable junctions are gaff-taped and with the stand fully raised, excess cable at the junction point is gathered and secured using three plastic wire ties around the stand’s next to bottom-most  extension tube clamp.  The cabling is arranged and tied on a diagonal so that it does not interfere with collapsing or extending the telescopic stand sections. Nice and tidy.

Using the extension cables allows me to put the preamps in the recording bag instead of gaff taping them to the stand itself- which is both more secure, more weather protected, and makes for very rapid setup and breakdown.  I carried the hemispherical foam windscreens, but never needed to use them for this outing.

A few photos of setup in a parking lot are shown below.

(http://farm3.static.flickr.com/2751/4166922924_ebc5f5e268.jpg)

(http://farm3.static.flickr.com/2594/4166163083_0a76046586.jpg)

(http://farm3.static.flickr.com/2647/4166922144_bcd0c95315.jpg)

(http://farm3.static.flickr.com/2609/4166921494_d7a829c12b.jpg)

(http://farm3.static.flickr.com/2675/4166921334_34da189e5f.jpg)

(http://farm3.static.flickr.com/2713/4166158869_eb131d1362.jpg)

(http://farm3.static.flickr.com/2745/4166161679_cce5d6f6ab_o.jpg)

(http://farm3.static.flickr.com/2773/4166920850_bb7700cdfe.jpg)

(http://farm3.static.flickr.com/2495/4166920542_d20a7cf6c5.jpg)

(http://farm3.static.flickr.com/2457/4166920286_6e7e3980b8.jpg)

(http://farm3.static.flickr.com/2658/4166160671_af026f9d0b.jpg)

(http://farm3.static.flickr.com/2676/4166159525_2a0b498ac0.jpg)

(http://farm3.static.flickr.com/2739/4166918802_a48619abc2.jpg)

(http://farm3.static.flickr.com/2526/4166158989_ea002c8108.jpg)

(http://farm3.static.flickr.com/2709/4166158737_b5d74a38da.jpg)

(http://farm3.static.flickr.com/2784/4166158653_1ba0e2fb78.jpg)

(http://farm3.static.flickr.com/2788/4166918100_c902e4dbb1.jpg)

Click here for a link to a Flickr slideshow with many more detailed photos and descriptions. (http://www.flickr.com/photos/41278426@N07/sets/72157622830304777/show/)
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: cybergaloot on December 07, 2009, 07:45:40 PM
Here's few more pics.
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: Jimna on December 07, 2009, 09:05:05 PM
badass!  how did the tapes turn out?
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: illconditioned on December 07, 2009, 10:02:55 PM
This rig is so cool.  I gotta wonder what the audience (or the band) thinks of this thing.  The aliens have landed to take them away :).

  Richard
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: cybergaloot on December 08, 2009, 07:37:22 AM
I'd worry about it looking like a toy to play with to the Wookies but Lee was out in the masses with it at Bear Creek. I saw him when the singer from Galactic began crowd surfing right in front of him. It was so crowded that I was surprised anyone could move out of the way.
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: Gutbucket on December 08, 2009, 11:49:26 AM
Thanks for the kind words all, and for those photos Walter- I didn't realise it was as visible as that from back in the amphitheater (my inner Jedi cringes slightly).  I don't leave this thing unattended in those situations. It's so easy to manage I can quickly fold an arm out of harms way, or pick the whole thing up and get out of there if necessary. If I go to take a leak it either goes with me, goes back to the section or stays there with a competent & situationally aware friend. 

I need to get some samples together Jim, I ment to have that done by now.. life intervenes.  If it sounds good up there the recordings do too.  The straight L/R stereo pair sounds good alone, but mixing in some center in a stereo mixdown is usually better.  Surround playback is best- big & wide with the crowd cheers coming from behind.  I'm a bit concerned that my second-hand 4060 C/B pair may be falling off spec, one mic seems to sound somewhat dull and the've never been as well matched as my original pair.  Maybe I should send some photos to Bruce at DPA America and plead for a price break on a matched set of 5 for the next revision.
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: illconditioned on December 08, 2009, 01:15:24 PM
Maybe I should send some photos to Bruce at DPA America and plead for a price break on a matched set of 5 for the next revision.

Good idea.  Nothing like this to drive up demand for the DPA capsules!

  Richard
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: Ben Turnbull on December 08, 2009, 03:33:38 PM
Very interesting... just remember, "Green side down".  ;)
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: Gutbucket on December 08, 2009, 03:56:26 PM
Yep. Similar to what I tell boating customers: "Keep the dry side up".

Maybe I should consider rigging a Countryman mic'd version, Richard.  Isn't the B3 your current miniature omni of choice?
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: illconditioned on December 08, 2009, 04:07:10 PM
Yep. Similar to what I tell boating customers: "Keep the dry side up".

Maybe I should consider rigging a Countryman mic'd version, Richard.  Isn't the B3 your current miniature omni of choice?
Yeah, the B3 is my favourite now.  The sound quality/tone on this mic is wonderful.  Also, quite a bit cheaper than the DPA.  It is something like $150 each, with a pigtail.  Use a simple battery box to power.

*But* I have had trouble getting closely matched mics.  There is something funny about the manufacture process (perhaps welding the metal screen on front?) that messes up the match.  Many other mics I've tried are identically matched.  I mean you can put both side by side, play pink noise on your speaker, and the power spectra are identical!

  Richard
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: dactylus on February 25, 2010, 01:35:39 PM

>>>for future reference<<<

 ;)

Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: rastasean on May 04, 2010, 10:51:38 AM
*bump to the top*
anyone willing to try the ca-1 with this setup?
http://taperssection.com/index.php?topic=134524.0
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: Gutbucket on June 09, 2010, 09:20:15 PM
Continuing an oddball micing discussion here to keep from hi-jacking another thread (http://taperssection.com/index.php?topic=136112.msg1773207#msg1773207)..

..In another thread, Chris Church proposed the idea of split omnis, with a homemade baffle blocking the rear, sides, and top/bottom of each mic. The baffle would be covered by acoustic foam. I've bought/ordered supplies to create this but haven't tried yet.

Have you tried anything like this? What do you think? Any tips?

Thanks,

Brendan

Thanks Brendan,

I've thought a lot along similar lines.  My apologies jnorman, this is going way off topic, and I typed a long reply so I'll answer in that other thread to keep from hi-jacking this one.

One problem as I see it is that complex baffles get unwieldy and impractical.  The little spheres in the surround rig above are a way of adding some high frequency directionality without unwieldy, sight-blocking baffles.  I've used more traditional Jecklin-type baffles for side to side and front-back baffling, and Moke once posted about using padded chairs to block rear sound arriving at his spaced omnis up front at a seated concert, which is similar.  Further along those lines I've considered using two small jecklin disks to get a bit more A-B spacing than a single disk of reasonable size allows, keeping each mic close to it's own disk so that the baffles can be relatively small and effective, but the two can be spaced further apart.   The two baffles could then also be angled as well to make the directionality of the array point more forward.  I still think that could be worth playing around with. 

Turning the closed box idea inside out- If I could get away with it, I'd build a closed box shaped baffle with a non-sonic reflective exterior (think four Jecklin discs connected at the edges to make a box) and mount my four mics around the outside of it, or more simply use a hard, reflective surfaced box and boundary mount the mics on each face.  I've drawn up weird star shaped baffles on the back of napkins that favor the front direction, but still pickup sound from all directions in an attempt to get more isolation between adjacent channels.  For the same reason, the sphere baffles on the rig above all point more forward except for the back channel.

The baffling idea behind all that is somewhat similar to what your mention, but the motivation is different- One of the basic ideas that is important to me is that if I put a baffle up, I want a mic on the opposite side of it too.  A big reason why I like recording with omnis and have extended that to surround is I’m drawn to their natural sound and the way they record the sense of space, the complete sound of the room.  To me that quality is an essential component of a really good, open and natural sounding recording that takes me back to the event.

Because of that, one idea I’ve placed importance on is that I want the combined response of the entire array (considered as a whole) to have a somewhat even response in all directions, at least all horizontal directions, even though I might want to split up the circle unevenly between mics to favor the forward direction.  So if I'm using 4 mics to record Left, Center, Right and Back channels, I might want the Left & Right mics favoring the front direction and the back mic picking up a wider angle for the back and more sides. That way I keep more of the room and crowd sound in the Back channel and the sound from the stage in the other three.  I’m not blocking out sound arriving from one horizontal direction to a mic without picking it up with another mic instead.  If I do just block out crowd sound to the rear for instance, it’s often still there, but just sounds muffled and less realistic to me, unless completely silenced, and even then the ambient room sound suffers.  Believe it or not, I often find audience noises more acceptable in my surround recordings than my stereo ones for that very reason
Title: Octo-ear surround array
Post by: Gutbucket on April 21, 2011, 01:18:28 PM
New configuration time-

Tetramic added to Quad-eye to form Octo-ear surround array!

I've been recording ambisonically with the Core Tetramic for the past year which I've posted about in a few other threads.  I primarily use it onstage or at stagelip for jazz performances, but I've also used it for outdoor festival recordings.  Since the details about how it works and the interesting approach to recording and processing it uses is covered in those other threads, I won't go into those details here, but will instead simply focus on the rigging.

Before Suwannee Springfest last month I added the Tetramic to the center of the quad-eye rig and fashioned a way to quickly and simply hang the entire pre-rigged small stand from a larger stand which I permanently staked at the main stage for the weekend, along with a couple chairs and a buried SBD feed.  I could then un-hook the fully-rigged small stand to move to a different stage or head back to camp anytime.

For this application, I eliminated the APE spheres and the techflex sleeving protecting the mic cabling along the telescopic antennas to the 4060 omnis.  Those features are most useful in managing things when I'm recording up-front in the crowd at Bear Creek.  Instead, I arranged the telescopic antennas to get a full 2 meter spacing on the Left/Right A-B omnis, with an 20" spacing on the Center/Back omni pair for a surround Decca tree-type arrangement and placed the Tetramic at the center of that diamond.

I recorded the Tetramic into channels 1-4 of the Tascam DR-680 with those channels ganged to keep their relative gains locked and plugged the buried SBD feed into channels 5-6.  The spaced omnis are powered by Niant PFAs and recorded to the Oade Mod R-44.  I run a SPDIF coax cable from the R-44 to the DR-680 so the 680 clocks to the R-44 and  all 10 channels are kept in sync.

Everything is pre-wired and ready to go.  All 8 channels of mic cabling from the small stand to the recorder bag runs through a thin tech-flexed snake. I can roll in, unpack and be recording in about 30 seconds flat.  All the parts are modular- the two A-B bars with telescopic arms, the Tetramic shock mount attachment and the top plate with hole to hook over the stud of the larger stand, all stack on an extension to the small stand’s mounting stud.  Any one of those can be removed or added as required and one of Ted’s umbrellas screws onto the same stud extension.

I didn’t take any photos at the festival, but here’s some photos I took of the setup after getting back home.  Not shown are the chairs and big stand, and the windscreens are off the omnis (3 x DPA 4060 for L/C/R and one Countryman B3 for the Back/surround channel).

Here’s a link to the full set of photos with descriptions on Flickr-
 http://www.flickr.com/photos/41278426@N07/sets/72157626421689065/ (http://www.flickr.com/photos/41278426@N07/sets/72157626421689065/)

(http://farm6.static.flickr.com/5182/5640385423_50362d2269.jpg)

(http://farm6.static.flickr.com/5269/5640385079_d1ea0b911b.jpg)

(http://farm6.static.flickr.com/5310/5640955670_28d61ebf5b.jpg)

(http://farm6.static.flickr.com/5225/5640955450_878e0e6a6e.jpg)
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: Jimna on April 21, 2011, 01:21:18 PM
Lets see the mics too, please. :)
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: Gutbucket on April 21, 2011, 01:27:28 PM
(http://farm6.static.flickr.com/5146/5640384535_f446abc59f.jpg)

(http://farm6.static.flickr.com/5143/5640955296_acd0648992.jpg)

(http://farm6.static.flickr.com/5223/5640384311_89dba4fd82.jpg)

(http://farm6.static.flickr.com/5306/5640955082_bc3585b0a4.jpg)

(http://farm6.static.flickr.com/5146/5640384175_4922041618.jpg)
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: Gutbucket on April 21, 2011, 01:30:46 PM
(http://farm6.static.flickr.com/5222/5640383887_1b7e3673b3.jpg)

(http://farm6.static.flickr.com/5141/5640383753_a57ab73fdd.jpg)

(http://farm6.static.flickr.com/5105/5640954442_63efc343ee.jpg)

(http://farm6.static.flickr.com/5310/5640954346_e5ab9c7c8c.jpg)
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: Gutbucket on April 21, 2011, 01:34:00 PM
(http://farm6.static.flickr.com/5227/5640383057_7d270329a0.jpg)

(http://farm6.static.flickr.com/5301/5640382973_24f7c542a0.jpg)

(http://farm6.static.flickr.com/5189/5640953658_b2c00f64e4.jpg)

(http://farm6.static.flickr.com/5105/5640953610_58ea18a412.jpg)
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: Gutbucket on April 21, 2011, 01:36:42 PM
(http://farm6.static.flickr.com/5105/5640953500_7d9ee939e2.jpg)

(http://farm6.static.flickr.com/5265/5640382609_b938f09cce.jpg)

(http://farm6.static.flickr.com/5108/5640382509_176abb1e66.jpg)

(http://farm6.static.flickr.com/5109/5640953276_984e80a816.jpg)
Title: Re: Oddball mic techniques - evolution to the Octo-Ear 8+ channel surround array
Post by: illconditioned on April 21, 2011, 01:48:25 PM
^^^ :) if anyone asks, just say the aliens have landed!
Title: Re: Oddball mic techniques - evolution to the Octo-Ear 8+ channel surround array
Post by: darby on April 21, 2011, 01:54:39 PM
(http://farm6.static.flickr.com/5105/5640953610_58ea18a412.jpg)
(http://farm6.static.flickr.com/5146/5640384175_4922041618.jpg)
is that your recording assistant?  ;D
Title: Re: Oddball mic techniques - evolution from 'Bug Eye' to 'Quad Eye' rig & beyond
Post by: Gutbucket on April 21, 2011, 01:57:54 PM
Lets see the mics too, please. :)

Hi Jim, I posted some photos of the Tetramic without windscreen here. (http://taperssection.com/index.php?topic=135045.msg1768542#msg1768542)
Title: Re: Oddball mic techniques - evolution to the Octo-Ear 8+ channel surround array
Post by: Gutbucket on April 21, 2011, 02:35:22 PM
is that your recording assistant?  ;D

Hey darby,
That's my dead rodent fur harvester, resting after providing supplies for the new Tetramic wind-cutter I sewed up.  ;)
Title: Re: Oddball mic techniques - evolution to the Octo-Ear 8+ channel surround array
Post by: rastasean on April 21, 2011, 05:02:31 PM
How far are the antennas with the mics sticking out? looks like the length is as tall as the height. Its pretty nice that you have the ability to set this up and be undisturbed at the festivals you attend.
Title: Re: Oddball mic techniques - evolution to the Octo-Ear 8+ channel surround array
Post by: Gutbucket on April 21, 2011, 05:51:32 PM
How far are the antennas with the mics sticking out? looks like the length is as tall as the height. Its pretty nice that you have the ability to set this up and be undisturbed at the festivals you attend.

This time the Left/Right antennas extend about 39" each, for a total of ~78" or 6-1/2' overall.  The height of the small stand alone is a bit over 7', but when hooked onto the taller stand the arms and mics are up around 8-1/2'. The antenna arms extend out over the chairs on either side in the same row and are nearly invisible from behind.  The Center/Back pair can extend just as far, but I set them to extend only about 12" forward and back (~24" total) partially because I didn't want them overhanging the walking isles in front and back in case someone came through carrying a flagpole banner or wearing a huge costume head or something.  Historically, Springfest has been pretty laid back that way, but it's a festival so you never know. 

[edit- the other reason for less extention on the center mic arm is to help achieve an even stereo recording angle across multiple mic pairs in the array- what Micheal Williams calls critical linking between recording segments.  The idea is that the SRA (stereo recording angle) of the Center-Left pair should cover an angular region that smoothly transitions to the SRA of the Center-Right pair.  The available variables for adjusting SRA are spacing, mic angle, level and delay.  Eliminating angle (using omnis) and delay, that leaves manipulation by spacing alone (and level, which I can adjust later).  The one meter spacing of the L/C and C/R segments produces a very narrow SRA, so the Center mic need not be very far forward to have the edges of those two adjacent SRA segments line up closely at the center.]

I've made a big effort to keep the rig svelt to minimally block sight lines.  Many of the straight stereo rigs at the same festival are far more bulky and visually intrusive.  I also set everything up to be as resiliant, snag-free, and disturbance-proof as practical.  So far so good.

It survived a direct beachball hit at one point that weekend, capturing the ball like an open hand, with no tapers around in the FOB section to remove it during the Friday evening headline act- I posted the story about in the wrong thread- http://taperssection.com/index.php?topic=140444.msg1862041#msg1862041 (http://taperssection.com/index.php?topic=140444.msg1862041#msg1862041)
Title: Re: Oddball mic techniques - evolution to the Octo-Ear 8+ channel surround array
Post by: Jimna on April 21, 2011, 06:54:59 PM
Thanks for sharing!!
Title: Re: Oddball mic techniques - evolution to the Octo-Ear 8+ channel surround array
Post by: rastasean on April 21, 2011, 10:54:41 PM
I've made a big effort to keep the rig svelt to minimally block sight lines.  Many of the straight stereo rigs at the same festival are far more bulky and visually intrusive.  I also set everything up to be as resiliant, snag-free, and disturbance-proof as practical.  So far so good.

While we can all agree that these light stands we use for mic stands are not that attractive they work well because it gets above the crowd and it doesn't require a huge radius all the way around it. It does sound like your method of mounting it would get it above a potentially rowdy crowd  and minimise the chance of it being tackled.

nice job.
Title: Re: Oddball mic techniques - evolution to the Octo-Ear 8+ channel surround array
Post by: Gutbucket on April 22, 2011, 10:05:53 AM
I edited my post above to try and help better explain the technical reasons behind the arrangement I used here.

I try to take into account the entire situation and design my approach around it.  In this case I was recording from slightly farther back with a mostly mellow, mostly seated crowd.  In that situation using more extention on the arms was both attractive for recording reasons and achievable practically, because of the low visual impact of the thin arms and miniature mics and also the nature of the crowd.  For Bear Creek which is held at the same venue, I'm usually recording farther forward near the stagelip in a rowdier, standing crowd, with the mics either around head level or low on-stage peering over the monitors.  That situation calls for shorter arms, with APE spheres installed for poke-protection as much as anything, and the telescopic sections and mic cableing sheathed in tech-flex instead of having the cable looped and taped at each telescoping segment.  The tech-flexed version doesn't allow nearly as much total extention and makes the arms slightly fatter and so more visible, but protects the cables completely and makes the arms snag free regardless of if they are extended or retracted.  I can grab the stand and swiftly move the whole rig out of the way if neccessary, which has happened a couple times- like when the trombone player jumped off stage almost directly over it.  :o
Title: Re: Oddball mic techniques - evolution to the Octo-Ear 8+ channel surround array
Post by: rastasean on June 11, 2011, 09:11:24 PM
Well you won't believe this but I think your nerf balls by themselves are a collector item. I checked out a target, two wal-marts, and even a toys r us for a pack but I couldn't find ANY. A couple years I got a pack but my mics were too heavy with the antenna I had so I must have lost them in a couple moves or just thrown them out. I wasn't even able to find anything close to it because everything else was much heavier and too big. Of course ebay has some but it seems so ridiculous to get a pair online when it seems like something easy to get in any retail store.
Title: Re: Oddball mic techniques - evolution to the Octo-Ear 8+ channel surround array
Post by: Gutbucket on June 15, 2011, 09:03:37 PM
Hmmm, thanks for the heads-up.  I'll have to look for some locally to stock up.

I've also found slightly smaller diameter versions made from the same material sold as solid ping pong balls.  Downside is that they are bright yellow instead of cool green, but you can always paint them dark grey with automotive vinyl spray paint.
Title: Re: Oddball mic techniques - 4 channel omni+cardioid surround array
Post by: Gutbucket on November 06, 2012, 11:59:51 AM
Six foot (2m) omni spacing with center and rearward facing cardioids-

Photos attached below of the setup I ran at Magnolia Fest on the Suwannee last month.  I often run four spaced omnis at this festival in sort of a four point decca tree, so this year I substituted forward and back facing cardioids for the center and back omnis.  By pointing one cardioid forward and the other backwards I intentionally sacrificed the ability to use the two cardioids alone as a typical stereo pair.  I also spaced the omnis a little over 6 feet (2 meters) which is more than I would if I was using them alone for stereo.  The entire idea was to give up the ability to use one pair or the other alone, and instead optimize the combination of them. 

The cardioids were full body Microtech Gefell M94/MV692, placed as close as possible on the center line and angled 180 degrees apart facing directly forward and rearwards (capsules spaced ~13"). The omnis were DPA 4061 omnis. This was intended for use as 3 channel L/C/R stereo (excluding or mixing in the backward facing mic), 4 or 5 channel surround, or for mixing all four channels down to 2 channel stereo.

I wanted to do this for a few reasons, some sound related some simply practical:

1) practical issue- less spacing required between the cardioids verses omnis means no telescopic antennas overhanging the 'isle' between rows of folding chairs at this outdoor amphitheater.  Makes for a more compact setup with less possibility of problems if someone parades by with banner, some giant costume head or something.  There is less practical problems with wide spacing the L/R pair along the length of the rows.
2) sonic issue- I wanted more forward bias (stage focus) in the center channel, with sources to the sides and rear less represented in that channel.
3) sonic issue- I wanted more level difference rather than time difference between the Center and Rear (surround) channels.
4) practical and sonic issue- I wanted more time difference in between Left and Right omnis with the addition of a center mic.
5) sonic issue- the M94 Gefell cardioids have a rolled off low end response and a more prominent high frequency response.  I felt this would work really well mixed to center (or to a dedicated center speaker) in combination with the more bass heavy spaced L/R omnis both in frequency response and in spatial distribution on playback (mids/highs biased slightly towards the center, low bass biased to Left/Right)

2) through 4) above work into my current thinking on stereo and surround recording which is that I generally want more time stereo information in the Left/Right axis and level difference in the Front/Back axis.

Haven’t had a chance to do much with the files yet, but listening back it worked astoundingly well and I plan to do more like this. Somewhat surprisingly the patch I gave out of the R44 to the M10 of another taper here also sounded very good even though the center cardioid was routed hard Left and the back facing one hard Right due to the lack of panning ability on the R44’s outputs, and the levels of the mix with the omnis wasn’t dialed in optimally.  I expected that patch to have more of a left side bias with the center mic panned to that side and the audience facing rear mic to the other, but it sounded big open and clear.

I’m going to do something similar, just on a smaller scale for Bear Creek this weekend, narrowing the A-B spread to 3’ and replacing the full sized Gefells with small AT cardioids for a stage-lip/way-FOB rig that is more lightweight, compact, and has lower visible impact.

Full extension with 6 foot spacing on the L/R omnis-

(http://farm9.staticflickr.com/8477/8161220180_f1d3fa81b9_c.jpg)

(http://farm9.staticflickr.com/8486/8161188199_ff10181c90_c.jpg)


Detail showing side-by side cardioid mounting on the diagonal mic bar to accommodate the mic stand, give equal weight balance, and to keep the Gefells under umbrella if required.  Also shown is the support wire which hooks under the telescopic arms to support them without sagging at full extension-

(http://farm9.staticflickr.com/8486/8161220094_4880b2cea7_c.jpg)

(http://farm9.staticflickr.com/8350/8161187793_7b0637ce64_c.jpg)


With the arms telescoped in for a 3’ total omni spacing-

(http://farm9.staticflickr.com/8487/8161220496_700f75a2b0_c.jpg)

(http://farm8.staticflickr.com/7115/8161187677_ff55cb5413_z.jpg)
Title: Re: Oddball mic techniques
Post by: Gutbucket on November 15, 2012, 04:22:02 PM
Same setup as last month, but substituting Audio Technica miniature cardioids for the full-sized Gefells for use at the stage-lip or way-up-front FOB in the impact zone at the Bear Creek music festival.  Same 6' spread on the 4061s, same spacing on the cardioids.  All four mics > Naiant PFAs > OCM R44.  Rig stayed wired and ready to roll all weekend, just unfold, power up and hit record.

Omni extensions retracted.  The circle of blue tape indicates the forward (center) mic arm-

(http://farm9.staticflickr.com/8487/8189307478_e2863f54ed_z.jpg)

Detail of reverse side showing left/right telescopic arm support wire for wide spacings and attachment tang with hole to hang the whole thing from a bigger, taller, staked down stand in the section (not used this fest)-

(http://farm9.staticflickr.com/8207/8189307234_d1b61ba35d_z.jpg)

Deployed with full extension-

(http://farm9.staticflickr.com/8198/8189307572_029a22f65a_z.jpg)

Detail-

(http://farm9.staticflickr.com/8340/8188226695_9fdbf2a349_z.jpg)

Stand folded in carrying bag with mics and wiring hooked up and ready to go-

(http://farm9.staticflickr.com/8348/8189307044_9232c6ea5d_z.jpg)

Entire pre-wired rig-

(http://farm9.staticflickr.com/8198/8188226887_5947527e3d_z.jpg)
Title: Re: Oddball mic techniques
Post by: Moke on November 15, 2012, 09:50:46 PM
thats a really cool rig, Lee!  I like that brace between the width/wide spaced omnis. good idea.
Title: Re: Oddball mic techniques
Post by: Jimna on November 15, 2012, 10:00:54 PM
badass!  Love the compact aspect when your walking away too.   well done!

I am curious to hear it.
Title: Re: Oddball mic techniques
Post by: F.O.Bean on November 15, 2012, 10:21:57 PM
lookin great as always Lee! i like running omnis like you run your cards except i run the omnis parallel to the stage in the healy method. sounds so frickin killer at a festie
Title: Re: Oddball mic techniques
Post by: Gutbucket on November 16, 2012, 11:25:36 AM
Thanks guys!
Notice your Geffs, Moke-bar and clips in the full size version Mike!
Jim, I'll get some stuff together for you someday.  I'd love to put up comparitive comps of all these setups.  As you know, I'm OK at recording, but absolutely horrible at getting around to doing anything with the files other than playing them back off the recorders.  At some point I'll probably stop or slow down on recording and actually start processing it.  :P
Bean, try a bit more space between those omnis next time.  Like 2'-3' instead of 12".  I think you'll like it!
Title: Re: Oddball mic techniques
Post by: F.O.Bean on November 16, 2012, 11:33:12 AM
Thanks guys!
Notice your Geffs, Moke-bar and clips in the full size version Mike!
Jim, I'll get some stuff together for you someday.  I'd love to put up comparitive comps of all these setups.  As you know, I'm OK at recording, but absolutely horrible at getting around to doing anything with the files other than playing them back off the recorders.  At some point I'll probably stop or slow down on recording and actually start processing it.  :P
Bean, try a bit more space between those omnis next time.  Like 2'-3' instead of 12".  I think you'll like it!

Thanks. Yea I knew I should've held onto my Large AB Nolabars :(
Title: Re: Oddball mic techniques
Post by: Gutbucket on November 16, 2012, 11:37:47 AM
Photo of the on-stage setup I ran last night with two seperate multi-channel configurations, recorded into one recorder-
 
(http://farm9.staticflickr.com/8482/8191206358_a1ec9ebae5_z.jpg)

The primary setup is a five-channel configuration with the three ADK TLs as Left/Center/Right channels (all in supercardioid pattern) and two DPA 4060s boundary-mounted to the front face of the stage under the lip, about 8' apart facing into the room and audience as Right/Left Surround channels. 

The secondary setup is the Gefell cards in ORTF and a single DPA 4060 boundarymounted to the stage surface in front of the drumkit on the snare side- in front of the center TL you can barely make out a small square of gaff tape between the planks of the floor.

Title: Re: Oddball mic techniques
Post by: F.O.Bean on November 16, 2012, 11:40:18 AM
Nice Lee! Is it possible to hear a sample?
Title: Re: Oddball mic techniques
Post by: Gutbucket on November 16, 2012, 11:43:25 AM
Nice Lee! Is it possible to hear a sample?

Eventually  :-\
http://taperssection.com/index.php?topic=96009.msg2005173#msg2005173 (http://taperssection.com/index.php?topic=96009.msg2005173#msg2005173)
Title: Re: Oddball mic techniques
Post by: rastasean on November 17, 2012, 06:52:12 PM
Nice job on your new setup!

That's a very nice way to do stage lip and get all the mics up there. hopefully you can at least take a listen to the file once in awhile.
Title: Re: Oddball mic techniques
Post by: silentmark on November 18, 2012, 02:29:48 PM
Really great stuff lee !!!  8)
Title: Re: Oddball mic techniques
Post by: Gutbucket on November 21, 2013, 12:31:30 PM
Re-rigged the 4-channel highly portable surround setup that has been a frequent topic in this thread for the Bear Creek music festival this year, sticking with the same 2-meter Left/Right omni spacing I used last year and also the move to using directional mics facing front and rear which I started playing around with 2 years ago instead of the ball-mounted semi-directional omnis all around which was closer to a classic Decca-tree config but with a rear facing mic included. 

Other than a few test runs, this was my first real use of the DPA 4098H supercardioids (http://taperssection.com/index.php?topic=163927.0) as front and rear facing directionals.  I picked up a used pair over the summer to replace the borrowed ATs I’ve used in this rig for this event the past two years. They aren’t as good as the full bodied MG cards and supercards (http://taperssection.com/index.php?topic=96009.msg2003117#msg2003117) I’ve used for this when the rig doesn’t need to be as compact and lightweight, but I find them superior to the miniature ATs I've used previously for this. (http://taperssection.com/index.php?topic=96009.msg2005010#msg2005010)  Their DPA clarity is unmatched for miniature low powered directionals and for this application the limited low frequency response is actually beneficial and compensated for by the Left/Right omnis.  The limited low frequency response of the 4098 when used at a distance would probably be a deal killer when used as a straight stereo pair by themselves for recording music at a distance, except perhaps for situations that are overly bass heavy to begin with and can benefit from the bass reduction.

I used dollar store sourced foam hair curlers treated with some silicone water repellant as windscreens on the 4098s.  The 4098s were connected via DPA microdot extension cables to the MMA6000 preamp in the small bag that hangs under the stand.  The 4061 omnis use a 3.5mm TRS extension cable to connect to a CA-UGLY preamp in the same bag.  I used the DR2d as 4channel recorder with an external lithium battery supply that powered it easily for 4 days without needing recharging.  All that reduced size and weight over using the R44 and PFAs to power the mics which I’ve done the past few years so everything fits in the small shaving bag and also allows use of the remote to stop and start recording.  I just need to leave the bag unzipped enough to see the red recording LED indicator on top of the DR2d which doubles as the IR receiver for the remote.

The shaving bag hangs on the bottom knob of the stand so its center of gravity is low and centered, stabilizing the stand while keeping the bag off the ground.  I can simply grab the stand and move the entire rig around hunting for best Left/Right balance in the sweet spot, or grab it and run away if I ever needed to, with the bag attached to the stand.  That's important as this thing is designed to be placed in the center of enthusiasm up front to record the live experience, where things can get unpredictable. It also makes it easy to retract and fold the telescopic arms, lower the stand and dash off to another stage with the bag still hanging on the stand to catch the next act.

Title: Re: Oddball mic techniques
Post by: Gutbucket on November 21, 2013, 12:45:33 PM
stand up and telescopic arms extended-
Title: Re: Oddball mic techniques
Post by: Gutbucket on November 21, 2013, 12:49:57 PM
Loading and hanging the shaving bag with recorder, external battery, preamps (+ extra batteries, SD card, earplugs, notepad, pen, cards, beer tickets, etc.)-
Title: Re: Oddball mic techniques
Post by: Gutbucket on November 21, 2013, 12:53:24 PM
Low centralized center of gravity. Quick start of recording whenever necessary with remote-
Title: Re: Oddball mic techniques
Post by: cashandkerouac on November 21, 2013, 01:06:07 PM
damn!  ^ that's some really really cool stuff.   8)
Title: Re: Oddball mic techniques
Post by: Gutbucket on November 21, 2013, 01:15:33 PM
Thanks!  I dig playing around with this stuff and blazing fresh trails off the beaten path.
Title: Re: Oddball mic techniques
Post by: phil_er_up on November 21, 2013, 05:12:26 PM
Gutbucket states:
" I can simply grab the stand and move the entire rig around hunting for best Left/Right balance in the sweet spot, or grab it and run away if I ever needed to, with the bag attached to the stand."

======================================================

That is quite unbelievable. Really is. Put up your whole rig in like 2-3 minutes. It is portable. You can use an umbrella.

This gives a whole new meaning to FOB. Now we can have a new term- "Portable Moving FOB"...."PM-FOB"...

======================================================

What a great line gutbucket - " and run away if I ever needed to"!

I have felt like that though never could pick everything up and move that easily...you given me ideas to reduce setup time for my big rig!!!

======================================================

What do the tennis balls do on the end of the stands?

Title: Re: Oddball mic techniques
Post by: Gutbucket on November 21, 2013, 05:50:45 PM
It takes more time to setup and pre-wire everything beforehand (which I do at home or back at camp), but makes setting up and breaking down super quick.  I can walk in, setup and be rolling in well under a minute including pulling the stand out of the transport bag (which is currently a repurposed bag from a small child size folding chair).  Folding it up to move between stages only takes something like 20 seconds as does setting it up again.

The balls are Nerf brand "ballistics balls" which are hard foam balls for Nerf guns.  Details are here earlier in the thread. (http://taperssection.com/index.php?topic=96009.msg1338951#msg1338951)  The ones on there in the photos above are simply for use as stand feet.  They work well to support the stand on both sandy soil or damp ground and cushion it on concrete.

Previously I also flush mounted the omnis in them and there they served two purposes- the practical one is that they simply protect the mics and people from potential eye pokes when I used to set this thing up at the stage lip around about head height with the arms extended about half as far as they go now. The technical one is that they make the omnis somewhat directional and cardioid-like at higher frequencies and also add a presence boost to the frequency response.  DPA and others like Neumann make them as slip-on attachments for their larger pressure omni mics and I took that idea to use with the miniature DPA omnis.  Here's a link to a DPA web page describing them. (http://www.dpamicrophones.com/en/Mic-University/Technology-Guide/Acoustic-Modification-Accessories.aspx)  They refer to them as APEs (Acoustic Pressure Equalizers).  I think I posted a photo of the one I got Dan Healy to sign for me years ago when I first started doing that earlier in the thread a few posts down from the link above.  That was a cool thing only tapers can really appreciate.
Title: Re: Oddball mic techniques
Post by: Jimna on November 21, 2013, 06:19:49 PM
I thought the tennis balls were for protection against lightning strikes. :P  awesome re-work on the rig!
Title: Re: Oddball mic techniques
Post by: Gutbucket on November 22, 2013, 09:50:17 AM
Ha.  Thanks Jim. Hopefully I'll never find out about their lightning strike protection capabilities.. here in the state with the highest lightning strike rate in the country.  Just to give a sense of scale, those balls are about squash-ball diameter rather than tennis-ball size.  In fact I've seen yellow 'floating practice golf-balls' made from the same dense foam material which are only slightly smaller in diameter.
Title: Re: Oddball mic techniques
Post by: Gutbucket on November 22, 2013, 10:31:44 AM
For any of you all interested in the Stereo Zoom stuff, here's a link to a PDF of the Michael Williams' diagram I think is most applicable to this config. (http://www.mmad.info/MAD/5Ch/5ch_FSSC/Omni/Root/FTC40/Plan%2016.pdf) It is a link to one of the many configuration diagrams available on his website. (http://www.mmad.info/)  It's a diagram with mic spacings and angles for a 5 channel omni setup, but in this case it's only the front three mics there I'm referring to, so just ignore the two other mics in back.

I had already determined that I wanted to use a 2-meter spacing with the left/right omnis, and that I was going to use a supercardioid center mic.  The next question was then "what is the most appropriate spacing forward of the omnis for the center mic?"  For practical reasons I didn't want to try and extend it too far forward, but I could extend the small 4098 on the forward TV antenna farther than I could the full bodied mics I'd used previously in the center which were attached to a standard mic bar turned 90-degrees to face front/back.  I decided to go with the spacing on the diagram above, which provides a Stereo Recording Angle of +/-40 degrees or 80 degrees total for the forward segment handled by the three front mics.  This is a bit more forward spacing than what I used the previous two years at this festival using the miniature ATs in the center. The spacing to the rear facing center mic in back is slightly less, and about what it was to both the front and rear previously using the ATs. 

The front/back center mic spacing is something I want to play around with further to see what works best and will be one of the differences I'll listen for when comparing recordings made this time verses the previous setup.  I could probably use slightly less spacing to the front facing center mic than what Williams suggests since I’m using a supercardioid rather than an omni, but since the left/right mics are still omnis, I doubt it would change the center spacing that much as far as stereo imaging is concerned, and stereo imaging is really the only aspect that the Stereo Zoom suggestions address.  The primary reason I’ve switched to using directionals in the center and back is to increase channel separation between the direct sound in the forward-facing mic and the ambient/audience/room sound in the rear facing one, rather than for left/right imaging reasons.
Title: Re: Oddball mic techniques
Post by: illconditioned on November 24, 2013, 10:56:45 PM
Are you playing back in Stereo or with some type of surround system?

Can you give some idea of the mixdown you use (or did I miss it earlier in the thread?).

  Richard

Title: Re: Oddball mic techniques
Post by: Gutbucket on November 27, 2013, 02:58:39 AM
Both. It may be touched on earlier in the thread but I don't remember and here's more about it. 

For both multichannel playback and for a 2-channel stereo mix-down the process of dialing everything in is the same, though the result of the choices are somewhat different. I level balance channels, sometimes eq balance them as well, and sometimes do some work on dynamics.  I don't know how different exactly, since I've only made stereo mixes directly and never tried to sum a multichannel playback balance down to 2-channel.  I start by getting a good left/right level balance alone, eq that if necessary. Then bring up the center channel (routed to it's own speaker or panned to stereo center) and adjust the center/sides balance and imaging across the front.  I play around with it, listening at different balance settings.  Depending on the recording, 'just enough center level', 'about the same level of center as left/right', and 'more center than left/right' might all be viable choices, and it takes returning to each and listening for a while to decide which of those I like best.  For each of those very different gross-center-level choices, I usually pretty quickly home in on a preferable fine-level adjustment for each one of them. I don't know why and find that very interesting.  A few dB makes the difference in things 'snapping into place' in each case, but the center level may vary by 10dB or more between the three primary gross level choices. Regardless, after a while it becomes evident which one is best. Besides imaging, center level provides some control over the reverberant balance and forward presence.

Last I bring up the rear facing mic(s). If mixing to 2-channel, I'll pan the single rear mic to center, or if I have a pair I'll pan them fully to each side or inwards somewhat if necessary to make it seamless, EQ that as necessary.  The use and level of the rear facing mic(s) is probably the biggest difference between a 2-channel mixdown and multichannel playback, but I almost always use some in the stereo mix, if just enough to get a sense of depth, width and richness, just enough to make the room sound or audience more natural.  Or I'll get fancy and automate it’s level, changing it between songs for great crowd reaction, sometimes between more sparse/quiet tunes and more sonically-dense/louder ones.  Managing the rear channel level is far more important in a 2 channel mix than with direct speaker playback where I get the level and eq to sound right and leave it, unless something annoying happens back there.

The ability to tweak the center/sides and front/back balance after the recording has been made which makes the 4-mic setup very flexible and less dependent on getting stereo mic spacings and angles just right, but what I really like is the control over presence, sense of depth, and envelopment that lets me adjust those things for a seamlessness sense of naturalness.

Sometimes I'll go farther and EQ or compress the center differently than the sides and subtle adjustments there beyond the need for simple corrections can be really useful for imaging.  Rolling off the low bass in the center mic sometimes helps clean things up and is one reason I'm not concerned about a strong low bass response from the small ATs or DPA 4098s I'm often using as center mics.

I play these back at home with something similar to a home-theater setup, but one used mostly for reproducing my multichannel recordings.  Left, center and right mic channels to left, center and right speakers arranged in a wide equidistant arc across the front.   If I lean back from the center of the couch I see something like a standard 60 degree angle between L/R speakers, if I lean forward over the coffee table they are at 90 degrees, and sitting normally they are somewhere in between.  The rear facing mic channel is mult'd to 4 or 5 speakers around the back.  The 8 speakers form an arrangement close to an equal sided octagon.  All speakers are full range, with floor standers across the front and the matching one directly behind, with two dedicated surround speakers in the back corners, and two bookshelves to the sides, no subwoofer.  The median line through the center of the playback arrangement is on a diagonal in the room. Most of the surround recordings from rigs in this thread are 4 channel, except the on-stage 5 ch stuff over in the on-stage recording thread.  For the 5 channel recordings I use 5 or 7 of the 8 speakers.   

Starting to work on a portable version with smaller out-door patio speakers clipped around a pre-wired pop-up canopy, a suitcase sub or two and a deep-cycle battery.  Will be cool to pop-open in friend's backyards, and to be able to play the surround recordings back at the remote campsite above the banks of the Suwannee as I make them at that festival.

Title: Re: Oddball mic techniques
Post by: Gutbucket on May 20, 2014, 01:39:05 PM
Here's a few photos of my latest variant on the multichannel recording setup.  This six-channel version is my current ‘reference’ open surround recording configuration. 

Three TS member rigs can be seen in the photos-  Dnuggs' black stand is to the right (with a pair of Beyerdynamic mc930's I think), T-90's silver stand is immediately adjacent to mine with his AT 4051 pair on the Shure vert-bar, both using big Sure windscreens.   Jon took these photos.  This was Suwannee Springfest 2014 in Live Oak, FL a few months ago in March.  Great music and an absolutely beautiful weekend.

This 6-channel setup consists of the Microtech Gefell M94 cardioids in the middle, one facing directly forward, the other rearward, both wearing the big Shure screens; Microtech Gefell M21 supercardioids facing directly Left and Right  wearing smaller windscreens, forming an OCT setup in combination with the forward cardioid, and a wide-spaced pair of DPA 4061 at the far ends of the telescopic arms to which the M21 pair are also attached.  All mics were run directly into the Tascam DR-680, the 4061 pair via Naiant PFAs. 

I first tried this setup experimentally at Springfest last year along with a few other variants, and it worked so well that it’s now my standard ‘full-effort’ big setup.  I’m quite pleased with it and the result played back directly from the recorder. 

The OCT (Optimum Cardioid Triangle) arrangement with the sideways pointing supercards in combination with the directly forward pointing center cardioid works really well for even greater improved clarity and optimum imaging separation across the 3 front main channels.  The rear facing cardioid also makes for an almost identical OCT setup facing rearwards, and although that front/back symmetry isn’t necessarily intended for the same reasons as the OCT arrangement in front the symmetry may be useful.

The orientation of the rear facing cardioid is intended to exclude as much of the sound arriving from in front as possible to help isolate the ambient sound pickup of the 'room' and the audience reaction around back.  Here, it's slightly farther back from the center-line than the forward facing center cardioid, about as far as I could manage using that bar and about as far as I would want it for practical purposes anyway hanging off a single stand, still easily configurable for an umbrella if necessary and not overhanging the isle in back.  The spacing between all the other microphones is measured and intentional given the distance from the stage and the Stereo Zoom SRA angles, but that rear facing cardiod might be more optimally placed a meter or two farther back.  I haven't experimented with that aspect since it's one of the least important constraints.
Title: Re: Oddball mic techniques
Post by: Gutbucket on May 20, 2014, 02:30:43 PM
How I use the resulting channels-

For 2-channel mix listening I use the built-in monitor mix output of the DR-680.  The DPA omnis and MG supercards are panned Left/Right and the center/back MG cardioids panned to center, the level of each balanced as appropriate in the mix.  During the fest I can do a simple check to make sure everything is working when I get back
to camp at the end of the day (internal stereo mix > 680 headphone jack out > SennHD650).  On the long drive home I can route the same mix through the 680 RCA stereo outs > rental car minijack stereo input.  Back at home I can listen to the 2-ch mix using a better DAC/headphone amp (680 SPDIF > Mytek DAC > Senn HD650).

For full 6-channel surround playback which is my primary interest with this, I’m also playing the files off the DR-680, but unmixed through the recorder’s 6-channel RCA outputs into the multi-channel analog DVD home theater receiver input.  With 6-channels there is no longer a need to mult’ a single recorded surround channel to all the surround speakers.  The biggest playback question for me was whether to route the wide-spaced omnis to the front Left/Right channels as I have done previously (probably mixed with the supercards in this case) or whether to route the wide omnis fully to the Ls/Rs surround channels and route only the supercards to the front Left/Right speakers.  I also played with it the other way, sending the supercards to the surrounds and the omnis Left/Right.  The rear facing cardioid is routed to a center back surround speaker.  For that 6th channel I repurpose the subwoofer line level output on the surround receiver along with an external amp to drive the center rear surround speaker.  Doing that provides global level and tone control over all 6 channels through the receiver.

Using the omnis as dedicated Ls/Rs surround channels worked very nicely, blending smoothly in the room with the supercard pair dedicated to the L/R channels in front.  The intended OCT setup with the sideways facing supercardioids and forwarded facing center cardioid works really nicely.  The wide omnis make it even better.  Solid immersion with nice clean imaging all the way around and excellent clarity.  I did a walk around test at the camp site and that tracks correctly around the playback room, which demonstrated improved imaging accuracy and channel isolation in all directions even though this is obviously designed primarily for recording ‘music from in front’.

So the 6-channel surround playback routing which works best is: M21 supercardioid pair > Front-Left/Front-Right, M92 cardioid pair > Front-Center/ Surround-Center(back), 4060 pair > Surround-Left/Surround-Right.
Title: Re: Oddball mic techniques
Post by: Gutbucket on May 20, 2014, 02:35:12 PM
As usual the recording setup was all prewired using the same small Bogen stand I use for the smaller, more compact 4-channel rig.  All cabling routed through a single tech-flex bundle to the recording bag.  Doing that allowed me to setup and break down very quickly at the amphitheater each day. I could walk in, attach the full body Gefells to the pre-wired stand (4061s remained attached), and unfold and telescope the extension arms to get the microphones arranged correctly before lifting and hanging the entire apparatus on the larger stand which remained staked in place with a couple chairs the entire weekend.  With the heavier full body Gefells up there I wouldn’t trust the small stand on its own, other than standing alone momentarily while getting it arranged, but its fully secure and stable once attached to the big stand.
Title: Re: Oddball mic techniques
Post by: Gutbucket on May 20, 2014, 02:38:17 PM
This is my favorite surround recording setup of those I've devised up to this point, and will be the baseline-reference moving forward for all my open surround recordings. 

In addition to this 6-channel setup, I also made alternate test recordings each day to determine how well the DPA 4098H hypercards might substitute for either or both pairs of Gefells.  However, before I can really make useful a determination I'll need to sync and align those extra files, which were recorded on a separate DR-2d (along with a copy of the 4060 pair patched out of DR-680 to make the alignment and syncing files easier).  The first day the 4098s were mounted immediately atop the M94s, to directly compare them as C/Cs mics.  The second day I mounted them atop the M21s to directly compare them as L/R mics.  Once those comparisions were done, the third day I left them mounted atop the M21 bodies but bent their miniature goose-neck mounts 90 degrees so they were pointed directly backwards to determine if 30" spaced, parallel-arranged rear-facing directional surround channels might be useful, and how well they may work in that roll.  That was the only previously untried configuration of the weekend.

Once I can do those comparisons, the next development step will be messing around with ways to do this 6-channel setup or something similar with the compact, light-weight rig using all miniature microphones substituting the DPA 4098H in place of the excellent but bulkier and more costly Gefells.  The Gefells are unquestionably better microphones, but by how much and how significant that difference becomes in the full 6-channel playback scheme (or a 2-ch mix down) remains to be fully determined.  The 4098H beat the miniature ATs I used in developing the simpler 4-channel variants on this arrangement posted about earlier, yet the ATs worked nicely in combination with the 4061 pair.  However, the 4098H are relatively bass insensitive in comparison to both the Gefels and also the ATs, so I’d not recommend using them as a stereo pair on their own unless recording something that required mucho bass attenuation or if willing to make a significant EQ correction.  But in combination with a pair of wide spaced omnis providing a strong and enveloping low end response that aspect becomes moot.  I probably already mentioned much of this earlier in the thread when I began experimenting with the 4098H last year.
Title: Re: Oddball microphone techniques
Post by: T-90 on May 21, 2014, 07:53:15 PM
nice pics.....the best part about all of this is that i ran my cards in din and then grabbed your feed from the 4061's, which perfectly flanked my mics.....4 chan goodness with half the work  8)  i dont get the chance to be lazy too often so im always on the lookout for opportunities....just look at my internet typing techniques, im destroying the english language one meaningless post at a time :)
Title: Re: Oddball microphone techniques
Post by: dnuggs on May 21, 2014, 09:23:48 PM
Gutbucket's setup is the ultimate festy rig...Mighty fine weekend of music and weather. Springfest FOB crew in the house!
Title: Re: Oddball microphone techniques
Post by: Gutbucket on May 21, 2014, 11:30:40 PM
Hey, always good to hear from the most choice fellow FOB crew around! ..who actually make it down to the river too! which is sort of like hanging out away from 'the office'. 

Thanks for the 'work pix', T.  And the late-night jam patches after my ridiculous monstrosity had been hauled back to camp for the night, D.  Come to think of it, thanks to both you guys for the windscreens I'm using in those photos from a few years back.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on March 25, 2015, 02:42:49 PM
Below are a couple photos of the latest variation on the 6-channel rig from last weekend, again at Suwannee Springfest.

Two changes-
First, Thurs & Fri I used a Gefell supercard (M21) as the center forward facing microphone rather than the Gefell cardioid (M94) to help isolate the direct PA and stage sound and reject diffuse pickup from all other directions as much as possible in the front center channel.  I retained the rear facing Gefell cardioid for maximal rejection of sound arriving from directly in front.  This arrangement used the same mics I've been running previously but is a modification to the overall directional sensitivity of the array in that the center front/back mic pair is no longer identical but use asymmetrical pickup patterns.

Second, Saturday and Sunday I substituted a second pair of DPA 4098H miniature supercardioid microphones for the center front/rear facing Gefells.   The DPA phantom power adapters allowed me to plug these into the same XLR mic cables already present in the 6ch snake to the recording bag.  This retained the greater-than-cardioid directionality of the forward facing center microphone, and provides identical microphones across the Left/Center/Right triplet providing most of the stereo playback imaging cues across the front.  The miniature DPA are far smaller, lighter, more weather resistant, less costly, and can run off low-voltage power.   They are much better suited to the compact/portable variant of this rig I walk around with at Bear Creek.  If they are "close enough" to the sweet sound of the Gefells, I may just use these instead for situations like Springfest as well, where a bigger fixed-rig setup on a taller staked-down stand isn't so much of a problem, but rain protection can be.

Below are the four 4098H in a cross formation (part OCT-inspired, part L/C/R/S) centered between the 6' wide spaced 4061 pair.  The sideways facing left/right 4098H pair are easier to support than the Gefells on the same extending telescopic antenna arms used to space the omnis.  They have generic ball-mic foam screens slipped over and pinned to the smaller 1" diameter cylindrical foam screens I've been using with the 4098H.  The super thin windscreens DPA provides with the 4098H are perhaps sufficient for a permanent install indoors well away from any air drafts, but aren't sufficient indoors otherwise, much less so outdoors.

The microdot input DPA XLR phantom adapters that the center forward/rear facing pair of 4098H were directly attached to were simply gaff-taped to the standard mic-bar, and I rigged up the arrangement using a chopstick blackened by gaffer tape to support the weight of the (BAS) Shure windscreens used on them.  Otherwise the positionable articulated arm section on each 4098H could not support the weight of the windscreen and would droop.  Like the L/R pair, the BAS foams fit over smaller 1" diameter cylindrical foam screens, and the support chopstick slid between the two separate foam layers.  Worked very well for this trial outing.  I plan to use just the smaller foams but with a fur cover on them on all four 4098H rather than the BAS, which should offer about the same degree of wind protection with significantly reduced bulk and mass.

More photos of this rig along with a bunch of others FOB at the amphitheater are posted in the rig-pictures section- http://taperssection.com/index.php?topic=172315.msg2133737#msg2133737 (http://taperssection.com/index.php?topic=172315.msg2133737#msg2133737)
Title: Re: Oddball microphone techniques
Post by: Gutbucket on March 25, 2015, 03:13:14 PM
BTW, counter to my expectations, I haven't found the DPA 4098H to be overly light in the bass region when listened to on their own without inclusion of the omnis.  They don't have that super-solid, fat bottom the wide omnis provide, but I'd actually not hesitate to run them alone as a pair for amplified stuff, especially if the music or the PA was bass heavy.  In combination with the omnis they work extremely well.
Title: Re: Oddball microphone techniques
Post by: phil_er_up on March 25, 2015, 03:42:05 PM
Gutbucket do you have any audio samples of the above rig that I can listen to?

Thanks.

-p
Title: Re: Oddball microphone techniques
Post by: Gutbucket on March 25, 2015, 04:41:43 PM
Not posted anywhere online currently.  However, I'll revisit and post links in this thread at probably elsewhere at TS at some point so you can hear a 2-channel stereo down-mix, and also links to samples of the individual pairs or channel components so you can hear how this all adds up and comes together.  I've currently no good way to distribute the optimal 6-channel discrete surround version, but whenever I make a 2-ch down mix, I use some matrix-surround encode tricks and always check to make sure that the resulting 2-ch mix works both for straight stereo playback and is matrix-surround playback compatible (DTS-Neo6/music mode).

Back at camp during the fest I check individual channels and listen to a 2ch stereo monitor down-mix direct off the DR-680 through headphones or plugged into the car stereo.  I can patch-out that quick 2-ch mix.   At home these recordings are replayed directly as discrete 6-channel surround, with each mic feeding it's own speaker channel in their full 3D tele-transportative/time-machine glory.  I'm working on portable 6-channel playback at the campsite based on speakers wired into a hexagonal pop-up canopy and a car subwoofer or two. 

I'm now starting to go through my back catalog of these 4 and 6 channel surround recordings, with the intention of mixing the best of it down to two channel stereo so others can enjoy them.  I can usually dial in the DR-680's 2ch monitor mix pretty good on it's own, but the effort in making a proper mix on the computer, including polarity correction for a couple channels, global and individual EQ per pair as required for best balance, and 'volume-envelope' gain-riding automation of the audience ambiance channels as necessary makes a big difference in the ultimate quality of the 2 channel stereo mix.  To meet my own quality standards for a proper 2-ch stereo mix, that stuff needs to be done.  Ironically perhaps, excellent direct 6-ch surround playback is far easier and a lot less work with less potential for complications.  In that case, the level and EQ adjustment is done on the fly using an outboard mixer, there is far less need for audience gain-riding, and of course no worries about mix-translation.
Title: Re: Oddball microphone techniques
Post by: Ultfris101 on March 27, 2015, 10:10:48 AM
BTW, counter to my expectations, I haven't found the DPA 4098H to be overly light in the bass region when listened to on their own without inclusion of the omnis.  They don't have that super-solid, fat bottom the wide omnis provide, but I'd actually not hesitate to run them alone as a pair for amplified stuff, especially if the music or the PA was bass heavy.  In combination with the omnis they work extremely well.

Good to hear. One idea I've had is to create a pop-up rig inspired by yours for two channel/point-at-stack type stuff where I'd typically run hypers or supers.

I found these windscreens (http://www.frontendaudio.com/Audix-WS1281-Windscreen-p/9999-09549.htm) made for the Audix micros worked great with the Naiant X-R caps. Two stages like the Shures but fit smaller diameter mics. The 4098h are 10mm diamter and the audix are 12mm diameter by spec so they might still be a bit loose. More bulky than the stock ones with fur but might perform better in heavier wind.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on March 27, 2015, 11:53:08 AM
Thanks.  Those Audix windscreens may be just the ticket.  I like the dual foam construction.  May order one or two to check them out.

Yes, by the posted specs indicate the 4098H is 10mm in diameter, but they seem smaller than that to me.  I'll have to measure but my initial guess is that they are actually closer to 5 or 6mm OD.  If the Audix screens are too loose, they might be able to be used over the very thin DPA foam screens, which I'd guess are about 12mm OD.  Will need to make sure the Audix screens are long enough to completely cover the miniature interference tube and back ports on the mic-body though, that's the unusual dimension for tiny mics of this diameter.  Worth a try.  If these provide sufficient wind protection, I'd prefer this to using a fur cover.

When I was rigging all this up at the campsite last week, I was working at a table with a big floor fan next to it which belongs to a fellow taper here.  I had headphones on checking signal and connections and used the fan while playing around with various windscreen combinations to see what would be approriate.  The hair curler foams alone weren't enough, which I already knew.  Adding the ball-mic screens over those helped, but using the big Shures over them was what was really needed.  The DIY fur I had on hand was too large, but holding it snug around the hair curler foam seemed equally effective as using the big Shure.

So if it turns out fur is needed I'll either DIY my own or look into Rycote miniwindjammers, assuming they make one which either fits this mic directly or fits over the hair curler foams.  I like the non-matting fur Rycote uses.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on May 05, 2015, 01:48:14 PM
I found these windscreens (http://www.frontendaudio.com/Audix-WS1281-Windscreen-p/9999-09549.htm) made for the Audix micros worked great with the Naiant X-R caps. Two stages like the Shures but fit smaller diameter mics. The 4098h are 10mm diamter and the audix are 12mm diameter by spec so they might still be a bit loose. More bulky than the stock ones with fur but might perform better in heavier wind.

Received a pair of these Audix WS1281 windscreens from Front End Audio.  They are double layer foam screens, but unlike the big Shures they don't actually use two different types of foam.  The Shures use a coarse open mesh foam on the inside, which mostly serves to center the mic inside the larger outer foam.  These are actually what appear to be a typical large lavaliere-sized windscreen nested inside a larger, typical SDC-sized windscreen, both made of the same foam. 

The insertion depth (mic coverage) is about 1" which is insufficient to cover the 4098H, which needs a bore-depth of 1-3/4" or more.  However, the nested screens pulled apart easily, held together only by a couple small dots of glue.  The bore of the larger screen measures a bit over 2", deep by a bit less than 1" in diameter.  Fortunately the hair-curler foams I was using previously on the 4098H fit inside the larger foams perfectly.  Looks like this combination will work out well, pending a real-world wind test.  May also need fur to achieve equivalent wind-noise reduction to that provided by the big Shures, which is the goal.

These now fit snugly and are light enough that the flexible goose-neck of the microphone can support them without droop.

Photo's below.  The lighter colored cylindrical windscreen is the hair curler foam-
Title: Re: Oddball microphone techniques
Post by: Gutbucket on May 05, 2015, 01:50:21 PM
Here it is modified, with the alternate insert-
Title: Re: Oddball microphone techniques
Post by: 2manyrocks on May 05, 2015, 09:34:08 PM
After reading "hair curler foam,"  I was extremely disappointed not to see pink foam in the pictures. 
Title: Re: Oddball microphone techniques
Post by: Gutbucket on March 24, 2016, 12:11:14 PM
Latest variation is using all miniature DPA mics in the 6 channel array (2 x 4061 omni, 4 x 4098 hypercardioid), rewiring to convert all former TRS minijack/plug connections to locking mini-XLR, and Naiant PFA powering for all 6 mics.  These are incremental evolutionary changes, making things more reliable, more weather resistant, and smaller, without a significant sacrifice in audio quality.

However, the latest new test which is obvious in the photos below, is the addition of two Naiant X-8s figure-8 mics, each placed coincident with the front and rear-facing 4098 hypers to form center front/rear-facing Mid/Side pairs.  I want to determine if the ability to adjust center image width (without introducing additional phase difference information) will be advantageous and if moving to regular use of a M/S pair in the center will be worthwhile.  As for the rear-facing M/S pair I'm curious to see how well that provides "stereozed surround" information using the current single rear-facing mic.  These two side-mic channels may be discarded without any impact on the "normal" 6-channel setup. 

The bendable gooseneck section on the 4098s makes arranging them so as to be coincident with the X-8S really easy.  I can't imagine a more closely coincident two mic M/S setup.  I just gaff taped the mic pair to the fore/aft facing mic bar.  To allow for proper polarity orientation of the font X-8s, I notched out one of the holes in the bar to allow the cable from the chopped right-angle XLR to exit downwards through the hole without interference from the bar.

The big Shure screens fit over the front and rear-facing M/S pairs for wind protection.  I used the Audix foam windscreens on the side-facing 4098s, with the hair curler foam inserts in them which I mentioned above, plus an additional outer foam layer from a ball-mic windscreen (probably Shures) which fit nicely over the Audix foams.  The small foam inserts from the Audix foams were used on the 4061 omnis, simply slipping over both the mic and the end of the TV antenna.

First photos show the mics, with one 4098 laying atop one of the X-8S for length comparison, two of the new female microdot to stereo mini-XLR cables I made to connect them to the Naiant PFAs, and the PFAs.  The third shows the tri-nested windscreen arrangement for the side-facing 4098 pair-

Title: Re: Oddball microphone techniques
Post by: Gutbucket on March 24, 2016, 12:35:32 PM
Close ups of the front/back Mid/Side arrangements with the 4098 "goosenecked" around the X-8S for optimal coincidence-
Title: Re: Oddball microphone techniques
Post by: Gutbucket on March 24, 2016, 12:43:00 PM
The side facing 4098's are spaced ~32" apart.  Adjusting the spacing changes the Stereo Recording Angle of the OCT 3-mic triplet, and one meter makes for about +/- 45 degrees or 90 degrees in total, which is appropriate for the distance from the stage in the amphitheater where I would be recording.  32" just fits under the umbrella in case of rain.  Note the bend in the gooseneck which accommodates the windscreens.  Alternately I could poke a hole through the screens for the TV antennas to pass through, leaving the mic body adjacent to the antenna tube. 
Title: Re: Oddball microphone techniques
Post by: Gutbucket on March 24, 2016, 12:52:03 PM
Only three stereo-wired mini-XLRs accommodates all signal connections for the primary 6-channel rig.  The experimental addition of the two X-8S use standard balanced XLR cables (chopped well used Gakcables, thanks Ted). 
Title: Re: Oddball microphone techniques
Post by: Gutbucket on March 24, 2016, 01:00:26 PM
Revised umbrella mount with just a simple nut to screw the umbrella atop the stand.  Simpler and faster than using a Windtech clamp, and better centers the umbrella to maximize coverage.  The side facing 4098s fit just barely under the edge of the umbrella at this spacing.
Title: Re: Oddball microphone techniques
Post by: rocksuitcase on March 24, 2016, 01:12:04 PM
Very sweet, simple yet complex. I dig the method of creating MS with the NAIANT X-8S and DPA supercard. I'm only a bit covetous of the fine DPA's in your collection!  ;D >:D
Thanks for the snaps and explanations of how you use them.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on March 24, 2016, 01:14:55 PM
Thanks man!

Set up at the fest.  Pre-rigged and ready to record out of the carry bag. Moble rig on small stand before being hoisted to hang from the top of the tall stand.  Tall stand is double dog-screwed into the ground.  Last photo also shows Dnugs rig, also using TV antennas to space omnis is one row in front, with T-90's mics clamped to his stand.

Title: Re: Oddball microphone techniques
Post by: Gutbucket on March 24, 2016, 01:20:06 PM
Umbrella up.  Each TV antenna attaches to the edge of the umbrella with an elastic hair band, which stabilizes both the umbrella and arms, secures the geometry, and makes sure the rain coverage remains secure.  T-90s mics are clamped underneath mine with a Windtech.

I used a Grace V3 to provide P48 to the rear facing M/S pair and as a way of recording those additional two channels onto the DR-680 via it's digital input (making for 8 recorded channels in total with the inclusion of the digital "stereo channel").

Channel assignment of the analog input channels on the DR-680 changed only slightly from before, to allow front M/S decoding of that pair during stereo mix playback directly from the recorder:
ch 1&2 = 6' spaced 4061 omni pair
ch 3 = center forward-facing 4098
ch 4 = center forward X-8S (side mic, front)
ch 5&6 = sideways facing 4098 pair (spaced ~32", forming an OCT triplet with the center 4098)
stereo channel left = center rear-facing 4098 (digital input)
stereo channel right= center rear X-8S (side mic, rear; digital input)

(Files were recorded as stereo pairs on the DR-680. Usually the rear-facing directional mic occupies ch 4)
Title: Re: Oddball microphone techniques
Post by: Moke on March 27, 2016, 11:18:58 PM
Thanks for posting those microdot cable links, Lee. I just bought a pair of 12' extensions for my 4060's.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on March 28, 2016, 09:25:41 AM
Good to hear, Mike.  I'm happy with these cables.  The female microdots at the mic end of the cable eliminate the need for microdot barrel adapters (the barrels work well but can be easy to loose), and I like the RG174 flexible cable.  I wasn't sure which choice of the multiple cable types they have available would be most appropriate, but the these seem well suited to our use as mic cables, and aren't as costly as some of the other cable types intended for signals well above the audio frequency range. Were you able to order them with male dots on one end instead of female on both ends?

For others reading this thread, here's the source for the microdot terminated cables were talking about-  https://www.cdint.com/catalog/category/Cables/RG174+flexible/10-32+female.  I posted that link along with a few photos in the Team DPA thread- http://taperssection.com/index.php?topic=175358.msg2179858#msg2179858.  I ordered the cables terminated with female microdots on both ends, twice as long as I needed, cut them in half and retermintated the cut ends to the stereo wired TA3F mini-XLR pictured above, for connection to the Naiant PFAs.   The cable is easy to work with and I found the center conductor larger and much easier to strip and solder than the integral cables of the DPA miniature omnis.
Title: Re: Oddball microphone techniques
Post by: Moke on March 28, 2016, 09:42:56 AM
I got the 12' pair from this page:
https://www.cdint.com/catalog/category/Cables/RG174+flexible/10-32+female/to+10-32
terminated like this:
http://www.cdint.com/catalog/popup_image.php?pID=40317

I'm going to use them as an extension pair to fit the MMA6K_HPF-Dremel-mod preamp
Title: Re: Oddball microphone techniques
Post by: Gutbucket on March 28, 2016, 09:48:58 AM
^ Perfect. 

Ah, the custom Dremel mod of yore, heh heh.
Title: Re: Oddball microphone techniques
Post by: Moke on March 28, 2016, 10:22:33 AM
As an aside to the Oddball mic techniques....
I introduce the Oddball Mic Cables.
I built a pair of adaptor ends to make a single XLR cable (Canare L4E6S) into a single run stereo cable, for use with the MMA6k.  I built a 3.5mm TRS>3-pin xlr end to come out of the MMA6k, and at the other end, an XLR>RCAx2 connector end, to which i have a pair of RCA>1/4" TS adaptors that I can use with the Tas DR70D.  In several recordings now, they have worked great.

(http://img.photobucket.com/albums/v729/MokePics2/Homemade%20gear/DSCN2556_zpsoynvwlhg.jpg)
Title: Re: Oddball microphone techniques
Post by: rocksuitcase on March 28, 2016, 11:24:39 AM
^^^^ Nice, I like that Canare cable choice. reliable and pliant, not stiff.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on April 05, 2016, 12:21:24 PM
Found the photo below of a Michael Williams 8-channel "magic-array" on this Posthorn webpage- http://www.posthorn.com/Micarray_williamsstar.html

(http://www.posthorn.com/Images/williams_8channelmagicarray.jpg)

Williams' Stereo Zoom concept, and the more advanced multichannel array design which is an extension of it, has greatly influenced my thoughts on recording.  His "Magic-Arrays" are a fascinating and penultimate extension of the concept, so called because they are designed to produce optimal 1, 2, 3, 4, 5, 6, 7, or 8-channel content simultaneously and without compromise from a single microphone array.  One can't just keep adding microphones and expect it to work correctly.  Things quickly get complicated as more microphones are used.  The combination of spacing, angle, time-delay, and polar-pattern provide for "critical-linking" between each stereo pair segment all the way around the array, so that the edge of one stereo imaging section lines up with the edge of the neighboring section without a gap or too much overlap.

This is a "purist recording" type setup where the number of active microphones used always equals the number of reproduction channels.  There is no 'mixdown' of multiple microphones to a fewer number of reproduction channels intended (although the design should alleviate the problems inherent in doing so if one is so inclined).   For lower playback channel counts, fewer microphones are active, yet the clever array arrangement retains "critical linking" between each recording segment and it's neighboring segment around the array.  That means the edge of the reproduced image between each speaker pair lines up with the edge of the reproduced image from the adjacent speaker pair, so the stereo playback image is not anchored to the speakers or distorted as a sound source moves around the array. Rather, it pans optimally around the room without getting "stuck" at the speakers, without "hole in the middle" problems, and without being overly monophonic and center heavy between any particular speaker pair. 

Another interesting thing about this is that because the array is symmetrical, we can choose which direction we wish to point it afterwards by 90 degree intervals.  By re-routing the recorded signals, we can point the array forward, 90 degrees left or right, or backwards, designating the cardinal direction as the center in the resulting playback.

An identical microphone pickup pattern is used for all channels, and any directional pattern from supercardioid to hypocardioid may be employed.  The spacing between microphones is determined by the choice of pickup pattern.  Using all supercardioids requires significantly less spacing between microphones than using all hypocardioids.

Title: Re: Oddball microphone techniques
Post by: Gutbucket on April 05, 2016, 12:21:32 PM
Here's a simplified explanation of how the "8-channel Magic Array" pictured above works, lets assume using we are using cardioid microphones all the way around. 

For mono, only the center forward-most microphone is used, producing single channel mono from a single forward facing cardioid.

For 2-channel stereo, only the +/- 45 degree forward angled Left/Right pair close to the center, on either side of the forward most center mic are used, producing a DIN-like cardioid pair with a 90 degree SRA pickup angle.

For 3 channel stereo (LCR) the center microphone is used along with the L/R microphone pair.  The center microphone is positioned relatively far in front of the L/R pair, and is time-delayed to bring it into alignment with them.  That does several things: the imaging between the +/- 45 degree L/R mic pair in the L/R speaker pair is unchanged from the 2-channel stereo configuration.  The center mic is positioned far enough away from that pair to have it's diffuse-field pickup (the ambience, reverb, audience reaction, everything outside the SRA 'playback image' window) decorrelated from what the pair is picking up.  This avoids the problem of "too many mics, positioned too close together, with the intend of mixing them" which I've posted about here at TS.  That's a common problem for tapers running 4-channels consisting of two typical stereo pairs mounted on the same stand with the intent of mixing them all together. In this case the combination of the extended spacing, the delay, and the angle difference between the center and Left microphones forms an SRA segment which images only between the Left and Center speakers, and links across the center with the SRA segment between the Right and Center speakers.  Because of that, the imaging cues in the L/R segment, the L/C segment and the C/R segment do not conflict with each other upon playback.  And therein lies some of the "magic".

Playback with more than 3-channels uses various combinations of what I describe above around the array.  For four channels only the central four microphones are used, which produces a 90 degree SRA between each quadrant.  For five channel playback, the forward center microphone is added to those four in the same way it is added to the stereo pair in the 3-channel LCR example above. And so on up to 8 channels total.

[edit- BTW, a Williams "Magic array" needn't have the full 8 channels pictured and described here.  The simplest version, recording content for 1, 2 or 3 channel playback, uses just 3 microphones as described in the 3-channel stereo example above, and would consist of like a NOS-like pair plus the single center mic extending forward.  The 4 channel version which works for 2-channel stereo (re-pointable to each of 4 directions) and also works for 4 channel quad, is identical to a setup quite commonly used for location ambience recording called the IRT-cross.  Partly because it is manageable and compact, IRT-cross is popular for recording location sound for 5.1 television and film, in that situation feeding all but the center channel which is reserved for dialog).  A 5-channel magic array consists of the IRT-cross plus the well-forward placed center mic.  So it's incremental, and doesn't ahve to be overly complex with smaller overall channel counts.]

Williams intends this as a way for production to economically record stereo and surround content simultaneously, using one array.  I share that goal, and although I don't need every combination, the concepts behind this are invaluable.  I'd love to try variants on this and in some ways I have been doing so already for the last few years.  In particular, since I originally came across this a few years ago I've been scheming on ways to mount a single cardioid 1.5 to 2 meters forward of the other mics, sort of like how I now fly the wide omnis out to either side.  Imagine the photo above with only the four center mics and the one extending forward (okay, I'd keep the wide-spaced omnis, so it would look like the photo above without the backwards extending microphone). The main problem in doing that is anything extending forward or aft is difficult to manage at outdoor festival events where things are typically setup in rows of chairs, folks may pass carrying flag poles, totems, inflatable balloon critters on a leash or whatever.  The omnis extending to the sides are in-line with the row of chairs and thus far less vulnerable than a forward (or aft) arm extending over the next row of chairs.  I could possibly setup a second stand two rows forward of my main stand, or clamp to another taper's stand setup there, but getting the spacing adjusted correctly that way would be more difficult.  Anyone here should be able to relate to those issues, even if running a simple 2-channel setup.

Anyway, I just came across the image this morning (Posthorn is selling the mounting system for doing this using Schoeps mics, as well as doing 4 and 5 channel "star arrays"), which fired me up again about these Williams' Magic Arrays in particular, and although I've gone on an on about Stereo Zoom and MMAD at TS numerous times, I don't think I've ever really discussed "Magic Arrays" in much detail.
Title: Re: Oddball microphone techniques
Post by: cybergaloot on April 05, 2016, 12:37:27 PM
It was sooo much simpler when you just had a mop handle with rabbit ears stuck on top to spread two mics.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on April 05, 2016, 02:32:42 PM
Simpler yes, but that part never went away!  Well, I did trade the painter-pole/mop-handle for a Bogen stand, but that arrangement is still the basic foundation upon which all the other crazy stuff has grown.
Title: Re: Oddball microphone techniques
Post by: cybergaloot on April 05, 2016, 02:37:48 PM
Simpler yes, but that part never went away!  Well, I did trade the painter-pole/mop-handle for a Bogen stand, but that arrangement is still the basic foundation upon which all the other crazy stuff has grown.

The good old days! Ever since I saw that rig I grab every set of rabbit ears I see. They just wont hold up my ADK-TLs but maybe if I used several sets of rabbit ears in some sort of geometric configuration ... (yep, I'm bored at work right now)
Title: Re: Oddball microphone techniques
Post by: Gutbucket on April 05, 2016, 02:44:10 PM
Asked to support the heft of the mighty TLs those little telescopic TV antennas would snap like a twig, unless you're talking TV transmitter tower antenna! You need one of those compact self-unfolding NASA-probe type trusses.
Title: Re: Oddball microphone techniques
Post by: 2manyrocks on April 05, 2016, 04:46:23 PM
It was sooo much simpler when you just had a mop handle with rabbit ears stuck on top to spread two mics.

Have you noticed that mop handles lately ain't what they used to be?   

Title: Re: Oddball microphone techniques
Post by: cybergaloot on April 07, 2016, 12:06:47 PM
It was sooo much simpler when you just had a mop handle with rabbit ears stuck on top to spread two mics.

Have you noticed that mop handles lately ain't what they used to be?

German mop handles are much better
Title: Re: Oddball microphone techniques
Post by: Moke on April 07, 2016, 02:27:39 PM
Baltic Birch handles are the best sounding.

he says sarcastically......
Title: Re: Oddball microphone techniques
Post by: Gutbucket on April 07, 2016, 03:25:43 PM
I've little doubt Scandinavian design birch ply janitorials with the DPAs atop would mop it up most excellently, flooding the place with deep enveloping sound, plunging though crystal clear waves, no mud to muck about in but rock-solid bottom, atmospheric highs, and a tight-smooth midrange like the rippling abdomen of the Viking dude standing astride the bow, posed to leap ashore onto the New World of sonic bliss.

he waxes half-poetically....
Title: Re: Oddball microphone techniques
Post by: cybergaloot on April 08, 2016, 05:10:09 PM
I've little doubt Scandinavian design birch ply janitorials with the DPAs atop would mop it up most excellently, flooding the place with deep enveloping sound, plunging though crystal clear waves, no mud to muck about in but rock-solid bottom, atmospheric highs, and a tight-smooth midrange like the rippling abdomen of the Viking dude standing astride the bow, posed to leap ashore onto the New World of sonic bliss.

he waxes half-poetically....

You get those at IKEA?
Title: Re: Oddball microphone techniques
Post by: Gutbucket on April 08, 2016, 05:35:04 PM
Straight outa Hollywood Woodstock, of course.

[edited for improved punchline]
Title: Re: Oddball microphone techniques
Post by: rocksuitcase on April 09, 2016, 11:53:11 AM
GB, kindms says you have infected our minds with your oddball mic techniques! I say it is a very good thing!  8)
While we would probably reserve this pattern for outdoors, we had a chance to record one of our favorite bands, and another old favorite of mine indoors last night in Saratoga Springs NY.
We had a newly purchased ck22 capsule to test since we now have two so:
what you have here is the two ck22's on the 460 pre-amps spaced at 90 cm, and the AKG 414 XLSII's both in figure 8, but one facing forward and the other at 90 to it (facing sideways).
Once we get them processed we will share.
Once again, thank you for infecting errrr showing us some new ways to use our microphones!    >:D
Title: Re: Oddball microphone techniques
Post by: Gutbucket on April 11, 2016, 10:56:07 AM
YES!

Funky looking setup for sure, love it.  I've been curious about using a forward facing figure 8 rather than other patterns in the center between the omnis.  I've run Blumlein (X/Y 8s) between the omnis years back, pictured rather early on in this thread I think (using ADK TLs and later a Peluso P-Stereo LD mic), but I don't think I played with summing the two Blumlein channels together equally to form the equivalent of a single forward facing 8.  I think I ran the Blumlien as M/S a few times two like you are doing here.  Might have to dig up and revisit those recordings.

A center forward facing 8 between the omnis interests me due to what it may do for the 3-mic imaging and the distribution of reverberance and audience ambience across the playback image.  The 8 pattern has the tightest forward lobe of any 1st order pattern, which produces the most-rapid fall-off in level as the source moves off-axis.  Sound arriving from 45 degrees off axis is -3dB down in level, and level drops off rapidly beyond that at angle of arrival approaches 90 degrees off-axis.  So depending on the appropriate mix level balance we end up with between the omnis and the forward facing 8, we get some interesting behavior. 

Say we set mix levels so that sound arriving from directly ahead will be 3dB louder through the center channel than the omnis.  Sound arriving from 45 degrees off center will be picked up with equal level in all three channels, and sound arriving from anywhere in the plane perpendicular to forward facing axis 90-degrees off to either side, below and above, will be picked up only by the omnis.   That gives us a +6dB Mid verses Side level difference at minimum in the resulting 3 mic mix for sounds arriving from directly in front compared to those arriving from anywhere in the plane perpendicular to forward axis, producing good fore/aft reach for the "center image stuff" and pulling the off-axis ambient audience and room 'verb stuff out to the edges of the playback image.

Putting a 3rd omni in the center goes a long way towards fixing the primary problem with a spaced omni pair.  But a directional mic in the center improves upon the spaced omnis in these other ways as well- increased fwd sensitivity bias, and sharpened directional imaging.  An 8 in the middle may be the most optimal for improvement of directional imaging, where as a supercard (or shotgun) is going to be most optimal for improvement of forward sensitivity.
 
At first glance, the two omnis + center forward facing 8 array would seem fully symmetrical in terms of front/back sensitivity, but it should actually produce some forward sensitivity bias at lower frequencies where the spacing between the omnis and 8 becomes acoustically small in terms of wavelength, because at those frequencies the combination of omnis and 8 will produce a forward facing cardioid shaped sensitivity pattern.

Inside, I'd be tempted to set the forward facing (Mid) 414 to supercard or hypercard pattern, to get more of that forward sensitivity bias across all frequencies.  Without the omnis, that makes the M/S center pair sort of a more forward biased version of M/S Blumlein.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on April 11, 2016, 11:28:12 AM
In the small amount of playing with stereo mixdown playback of the recordings made at Springfest last month from the latest array I posted pictures of above, I've found turning the center mic into a M/S pair is very useful in combination with the omnis alone, and far less important but still possibly helpful when the sideways facing OCT supercardioids are in play as well. 

Perhaps not surprisingly, when only listening to the center M/S pair on it's own, use of a lot more Side-channel in the decode ratio is appropriate.  In combination with the spaced omnis, less Side is most appropriate, and in combination with both the omnis and the sideways facing OCT supercards, very little Side component if any works best.  In that case, the sideways facing OCT supercards are already contributing plenty of rich near-spaced 'Side' information.  However, in all cases I seem to prefer at least a slight touch of Side from the M/S pair, which seems to make the stereo image spread slightly smoother across center and less center detented when the center is mixed in at higher levels.  But that might be because I was using a supercard center microphone to maximize direct pickup over ambient pickup in that channel,  instead of a cardioid (or even omni) center called for with the OCT technique.  If I switched to a cardioid center, or perhaps spaced the side-facing OCT supercards a bit less far apart, I may not need any additional Side from the M/S 8 to "slightly open and unstick" the center.

So I think in terms of practicality, I'd probably choose either OCT + omnis, or M/S + omnis, rather than both, unless it's easy and I have plenty of recording channels to spare.  But it's a bit too early for conclusions so the experiment continues..  This weekend at Wanee I'm going to limit the channel count to 6 so I don't need to haul and power the V3, and will probably do that by eliminating the rear facing pair all together.  I plan to record the wide-spaced omnis, OCT supercards and center forward-facing M/S pair.  This will allow for more listening to combinations of spaced omni and/or OCT and/or M/S center recordings made in a different recording environment- still outside, but recording from further back at the soundboard in a much bigger outdoor stage setup.  Also the music is less acoustic Americana stuff and more amplified rock stuff.  Likely recording from within the board cage (or immediately adjacent to it), with the board tent and a beer tent immediately behind, so there isn't the same clean rear audience ambiance I'd want to pickup from behind as there is when recording from well FOB in the "excitement zone".

Rocksuitcase- My suggestion in playing with your combination mix is to try bringing up the omnis first, then the center (Mid) 8 in combination with the omnis, and once you get a good level balance between those three, play with adjusting the M/S ratio by bringing the Side 8 into play.
Title: Re: Oddball microphone techniques
Post by: Moke on April 11, 2016, 11:51:12 AM
I played around a bit this weekend. I ran a baffle disc with my DPA4060 pair. I also ran a sub-card directly over the top of the baffle, at 0º, and vertically time aligned to the 4060 pair, for a three mic mix.
For me, it is an unusual departure from my two channel stereo approach.
I'm still playing around with it a bit, to see if I like the results.
Title: Re: Oddball microphone techniques
Post by: rocksuitcase on April 11, 2016, 12:05:01 PM
I so I think in terms of practicality, I'd probably choose either OCT + omnis, or M/S + omnis.   But the experiment continues.. This weekend at Wanee I'll probably limit the channel count to 6 so I don't need to haul and power the V3, by eliminating the rear facing pair all together. I plan to record the wide omnis, OCT supercards and M/S center pair.  That will allow for more listening to those combinations of recordings made in a different recording environment- still outside, but recording from further back at the soundboard in a much bigger outdoor stage setup.  If recording from within the board cage, with the board tent and beer tent immediately behind the board, there isn't much clean rear audience ambiance I'd want to pickup from behind anyway, as there is when well FOB.

Rocksuitcase- My suggestion in playing with your combination mix is to try bringing up the omnis first, then the center (Mid) 8 in combination with the omnis, and once you get a good level balance between those three, play with adjusting the M/S ratio the Side 8 into play.
We found the V2/V3's sure do suck up a bunch of power, even using the Eco-Charge SLA's!

kindms will be mixing this, and I have directed him to this thread. Thanks for your tips!
What I can say is that we decided to listen to it with the forward facing figure 8 and the two omni channels. We found that pushing the single mid channel up by about 4 dB put just enough oomph in it to really bring out some depth and not so oddly to "reduce" the annoying effect of the chatterers!
We will keep you posted when the shows get upped.
Thanks once again for infecting errr influencing us to try new things!   ;D
Title: Re: Oddball microphone techniques
Post by: cybergaloot on April 13, 2016, 12:45:04 PM
Lee, if you go back to your mop stick, you might want one of these adapters: http://www.filmandvideolighting.com/modern-studio-baby-pin-paint-stick-adapter.html?utm_source=April+13%2C+2016&utm_campaign=Newsletter-4-13-2016&utm_medium=email
Title: Re: Oddball microphone techniques
Post by: Moke on April 14, 2016, 08:36:42 PM
A question about mixing a three mic recording.  I ask, because I've never run an M/S array before.

I ran with my DPA4060 pair as baffled omnis; nothing too unusual about this.  I typically use a rather tight spacing from the disc face. But this time, went even closer, ~1" naway from the disc face, each side.
I also ran a single L.A. CM3 sub-card directly over the baffle, and maybe only 2" in front of the omni pair; so the timing alignment is really quite close.
In post, and after I did my main mix, I farted around with trying a quasi-M/S mix by taking the omni pair and flipping the phase on the left channel of the baffled mics.
In the mix, it sounds great thru headphones; but presently, my main stereo amp that is hooked up to the DAC/Computer, seems to want to be a two channel mono amp, so I'm not getting any stereo separation, except via headphones.

The mix consisted of the tightly spaced baffled omni pair, with the center sub-card mic sounding best when left a couple of dB below the omni pair.

OK,.... thoughts?  Am I right in thinking this might be called a quasi-M/S mix? Can the pair of tightly spaced omnis be thought of as a figure of eight response with an omni low end?
 
The rig can be seen here:
http://taperssection.com/index.php?topic=176324.msg2184245#msg2184245
Title: Re: Oddball microphone techniques
Post by: 2manyrocks on April 14, 2016, 11:39:13 PM
^don't believe its m/s.  M/s could be possible with two cards on each side with one omni in the center, but one figure8 for the sides LR is the usual mic of choice.  My limited understanding is alignment of the card capsules is the problem and why a fig 8 pattern is normally used instead.

Having two Omni's for LR is why you sense mono when you playback. 

At least that is what I think, but I may be mistaken.

Title: Re: Oddball microphone techniques
Post by: John Willett on April 15, 2016, 04:40:25 AM
A question about mixing a three mic recording.  I ask, because I've never run an M/S array before.

I ran with my DPA4060 pair as baffled omnis; nothing too unusual about this.  I typically use a rather tight spacing from the disc face. But this time, went even closer, ~1" naway from the disc face, each side.
I also ran a single L.A. CM3 sub-card directly over the baffle, and maybe only 2" in front of the omni pair; so the timing alignment is really quite close.
In post, and after I did my main mix, I farted around with trying a quasi-M/S mix by taking the omni pair and flipping the phase on the left channel of the baffled mics.
In the mix, it sounds great thru headphones; but presently, my main stereo amp that is hooked up to the DAC/Computer, seems to want to be a two channel mono amp, so I'm not getting any stereo separation, except via headphones.

The mix consisted of the tightly spaced baffled omni pair, with the center sub-card mic sounding best when left a couple of dB below the omni pair.

OK,.... thoughts?  Am I right in thinking this might be called a quasi-M/S mix? Can the pair of tightly spaced omnis be thought of as a figure of eight response with an omni low end?
 
The rig can be seen here:
http://taperssection.com/index.php?topic=176324.msg2184245#msg2184245

No - this is not MS in any way.

You may find it an effective recording method - but it's *NOT* MS.
Title: Re: Oddball microphone techniques
Post by: Moke on April 16, 2016, 04:21:27 PM
OK,... thanks.
I guess I'll call it sub-card_mid/omni-8_side.
Title: Re: Oddball microphone techniques
Post by: voltronic on April 16, 2016, 05:23:39 PM
^don't believe its m/s.  M/s could be possible with two cards on each side with one omni in the center, but one figure8 for the sides LR is the usual mic of choice.  My limited understanding is alignment of the card capsules is the problem and why a fig 8 pattern is normally used instead.

Yes, you want a figure-8 Mid mic.  Not only that, some people will tell you that to really make a proper M/S recording, you should only use a single-diaphragm figure-8, rather than  a dual-diaphragm arrangement (either fixed or in a multipattern mic) which is less expensive but much more common.  Others here will be better equipped to speak to how valid that advice may or may not be.  There are only three single-diaphragm figure-8 condenser mics out there I know of: the Senn MKH 30, Schoeps MK8, and Neumann KK 120, and they're all pretty expensive.  My experience doing M/S with the Schoeps MK4/MK8 combo tells me they're worth it, though.  You could use ribbons which are always figure-8 and obviously also single-diaphragm, but I don't know how well they would mix tonally with a non-ribbon Mid mic.  Or you can use two ribbons in a Blumlein setup, and that solves that the tonal balance problem at the expense of your bank account.

Side note: I just now realized that DPA doesn't offer a figure-8 mic at all; they must be one of the only high-end mic builders not to offer that option, even in a multi-pattern mic.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on April 18, 2016, 12:46:45 PM
Ha! Thanks for the paint-stick adapter post, Walter.

Mike, you can theoretically produce a dipole (figure 8 pattern) using two closely spaced omnis.  To do so you'd invert the polarity of one of them then sum them together.  Problem is that then they mostly cancel each other out that way and produce very little output.   The closer together, the better the dipole but the greater the cancellation too.  Without the two mics mounted very close together there will be less cancellation at high frequencies, but at that point you'll no longer have a figure-8 pattern with uniform phase and reverse polarity, you'll instead get the random phase relationship spaced omnis provide.

However, in the situation you describe above, you have the advantage of a baffle between the two omnis.  The mics are mounted quite closely together and are also no longer acting like omnis at all frequencies.  The baffle will make them behave somewhat like back-to-back opposed cardioids at high frequencies. 

I wouldn't call it a normal Mid/Side setup, but if you want to try a mid-side mix, here is how you can go about doing it-

Load the two omni channels into your editor.
Invert the phase of the right omni only.
Sum the two omnis and adjust the relative levels of the two to achieve the maximum cancellation possible.  Low and low mid frequencies should cancel significantly, you should hear only high mids and highs in the resulting mix of the two.
Save that sum as your "synthesized figure 8 Side" file, then use it as you would a regular Side signal from a single figure 8.

It will not work to simply sum the Mid and left omni and route that Left, and sum the Mid and inverted polarity right omni and route that Right.   Or rather that will produce sound,  but will not be a M/S manipulation. You need to first sum the omnis with one of them inverted to produce the Side signal, then use that side signal the normal way along with the Mid signal in a M/S matrix.

Since the omni-difference Side signal will be mostly high-frequency information, the resulting M/S output will be strongly monoized at low and mid frequencies and have increasing stereo width up top. 

Should be an interesting experiment.  I suspect the straight-up baffled omnis plus some amount center to taste will work best for you though.
Title: Re: Oddball microphone techniques
Post by: Moke on April 18, 2016, 01:20:50 PM
Thank you very much GB! You understand the concept to which I was eluding.
I messed around a bit with it. I flipped the wrong channel polarity; left channel flipped, not right. 
Also, I don't think that I have an MS decoder available in the editing programs that I have (Audacity, Sound Studios, Reaper).
I've got some homework to do in tracking down an MS decoder ring. So I will try to mess with it a bit later.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on April 18, 2016, 01:53:35 PM
Once you have a Side signal, you can "roll your own" MS decoder in your sound editor if you like rather than using a M/S decoder plugin.  It's a lot easier and straightforward if you do the step outlined above to produce the side channel first, rather than attempting to do both parts in a single editing session.

Once you have both Mid and Side channel files, you can produce Left/Right using three channels in the editor-
Mix Mid and Side to produce the virtual Left microphone.
Mix Mid and polarity inverted Side to produce the virtual Right microphone.

You'll probably want both Side levels to be similar, yet keeping the side levels matched absolutely is no longer critical at that point.   If you were to use a bit more inverted Side for virtual Right than non-inverted Side for virtual Left, you'd simply be changing the pattern and angle of the virtual microphone on that side independently of the other side.  That could be useful in some situations where the situation is unbalanced left/right, like recording from off to one side or whatever.

Or you can simply download a VST plugin.  Many are free.  Here's a page link to the free Voxengo MSED plugin which is very useful- http://www.voxengo.com/product/msed/ It includes two M/S instances in the single plugin, so in addition to the simple task of decoding a Mid/Side recording to Left/Right (or switching a L/R recording to M/S), you can also feed it a L/R signal, adjust the Mid/Side balance of it to your liking, and have it output the modified L/R signal again.  That can be very useful for mastering.  You can use it to make stereo width adjustments on any stereo recording, or to process the Mid information differently than the Side info before recombining them to Left/Right.
Title: Re: Oddball microphone techniques
Post by: rocksuitcase on April 18, 2016, 02:24:58 PM
Thank you very much GB! You understand the concept to which I was eluding.
I messed around a bit with it. I flipped the wrong channel polarity; left channel flipped, not right. 
Also, I don't think that I have an MS decoder available in the editing programs that I have (Audacity, Sound Studios, Reaper).
I've got some homework to do in tracking down an MS decoder ring. So I will try to mess with it a bit later.
kindms found a video on youtube he references every time he does the MS decode. I bat signaled him and hopefully he can post it downthread.   :turnevil:
Title: Re: Oddball microphone techniques
Post by: Gutbucket on April 18, 2016, 03:10:40 PM
Volt, I believe MBHO also makes a single diaphragm figure 8 SDC, and the newer version of the Emesser uses the MBHO 8.

The Naiant X-8S figure-8 I'm using for these recent experiments consists of two back to back cardioid SDCs mounted in a single housing.  The 'back' one is phase inverted and they are then summed together in the mic body prior to the signal leaving the mic.  By design, the two cardioid capsules must be very well matched and level adjusted to achieve a decent null and produce a good figure 8 pattern.  They can never be as fully coincident as a single diaphragm figure-8 so I suppose pattern might suffer at very high frequencies, but that's probably too high to matter for M/S purposes.

In terms of what is happening when producing a figure-8 response by summing two back to back carioids with one out of polarity with the other, begin by considering the essential essence of the cardioid pattern as being the equal sum of omni plus 8.  For sounds arriving from directly ahead, both the omni and the 8 component signals are equal and in polarity with each other, for sound from directly behind, both are equal in level yet opposite in polarity, and cancel each other out (producing the rear-facing cardioid null point), and so on around the circle.

We can invert the polarity of an 8 by pointing it the opposite direction, but the polarity of an omni doesn't change regardless of the direction it points. When two cardioids are placed back to back and summed with the polarity flipped on one of them to form a virtual figure 8 pattern, the two omni components have opposite polarity and cancel each other out entirely, but two figure 8 components have the same polarity and reinforce each other and the result is a single figure 8.

In poor form algebra.. (fig 8 + omni)     +         (-        (-fig 8 + omni))                      =    2x(fig 8 )
                                             ^               ^          ^                  ^                                             ^
                                         cardioid   |    sum  |  invert | opposite pointed cardioid)      |     figure 8




Tonal match between Mid and Side channels isn't critical like it is between Left and Right channels, although the overall combined tonal output of the M/S pair is just as important as a L/R pair.  The tone of the Side signal primarily determines "where the stereoness happens" in the resulting L/R output.  Primarily, variation in the frequency response of the Side channel is going to effect which frequency ranges are more stereoized and which frequency ranges are more monoized.   In Mike's oddball M/S setup using invert-summed baffled omnis for the Side signal, the Side signal will consist of mostly high-frequency information and will not be tonally matched at all with the Mid channel.  The L/R output will be stereoized up top and monoized down low.  It will also be slightly brighter since the the side signal is only adding energy to the resulting overall mix at high frequencies.

Lets assume a flat L/R response is desirable, and we have a flat output from our Mid microphone.  The tonal variation of the Side channel IS going to effect the tonal balance of the resulting recording somewhat, depending on how much is used, as well as affecting which frequency ranges are more stereo and which are more mono, yet in a way which is symmetrical between the Left and Right sides.  So a tonal mis-match between Mid and Side effects "stereoness by frequency" and the tonal distribution from the center out to the sides across the stereo image.  But things won't sound lopsided if the tonal balance between Mid & Side differs greatly.
Title: Re: Oddball microphone techniques
Post by: kindms on April 18, 2016, 03:12:38 PM
Thank you very much GB! You understand the concept to which I was eluding.
I messed around a bit with it. I flipped the wrong channel polarity; left channel flipped, not right. 
Also, I don't think that I have an MS decoder available in the editing programs that I have (Audacity, Sound Studios, Reaper).
I've got some homework to do in tracking down an MS decoder ring. So I will try to mess with it a bit later.
kindms found a video on youtube he references every time he does the MS decode. I bat signaled him and hopefully he can post it downthread.   :turnevil:

I have this youtube video bookmarked as I seem to need to refer to it all the damn time.

https://www.youtube.com/watch?v=eVOBRx7zGzw

Title: Re: Oddball microphone techniques
Post by: Gutbucket on April 18, 2016, 04:30:10 PM
Thanks for the input Jon..  both the microphone and this thread.
Title: Re: Oddball microphone techniques
Post by: kindms on July 04, 2016, 09:06:35 AM
http://taperssection.com/index.php?topic=178302.0

We ran spilt omnis from the lawn with the forward and rear facing cards from the Lawn at SPAC night 1. It rained pretty hard prior so we kept it "low key" for night 1 LOL. I did a quick mix with all 4 channels. I think it came out pretty good.

Night 2 we ran spilt ck22s again this time opting for AKG414 coincident blumlein fig8s in the center as well as a AKGck8 short shotgun and a rear facing ck61

I was not at night 3 last night but was told 10foot spilts with center mic stand 414s mid side etc. Should be interesting
Title: Re: Oddball microphone techniques
Post by: rocksuitcase on July 04, 2016, 11:41:06 AM
http://taperssection.com/index.php?topic=178302.0

We ran spilt omnis from the lawn with the forward and rear facing cards from the Lawn at SPAC night 1. It rained pretty hard prior so we kept it "low key" for night 1 LOL. I did a quick mix with all 4 channels. I think it came out pretty good.

Night 2 we ran spilt ck22s again this time opting for AKG414 coincident blumlein fig8s in the center as well as a AKGck8 short shotgun and a rear facing ck61

I was not at night 3 last night but was told 10foot spilts with center mic stand 414s mid side etc. Should be interesting
I am planning to "fill in" this thread with the pics and ideas we tried from Dead & Co, as well as the three phish shows.
Last night, 7-03. we ran 10 foot Omni split with a Ck61 card in center plus 414's in MidSide with the Mid being a forward facing fig 8.
Ed, airbladder, ran his Neumann TL's on the Omni stands and also Neumann short shotguns in the center plus pair of small crossed cards.
Pictures coming up later.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on July 11, 2016, 12:10:50 PM
Thanks for the updates and recordings, Mr. rock'case.  I've been mostly off line for the past week and need to catch up with some listening.  I did pull your Phish recording and as I usually do, made EQ and surround upmix parameter adjustments to slip a toe through the door which defines an invisible psychological threshold my brain needs to cross before I can consciously ignore all the technical aspects of a recording and simply experience an auditory "like there" experience as a lover of music rather than as recordist/technician.  To me that's the acid test of any live recording - Not how the raw recording sounds, but rather if it allows for those kinds of manipulations necessary to help that mental magic trick work convincingly.  The adjustments most appropriate for me in this particular situation may not be the same for everyone or every playback situation, and most likely aren't.  The more important thing is that the recording has within it the capability for that kind of transportive experience.

I should really get to work on posting some of my recordings made using these oddball techniques here for you all to listen to and play around with.  Posting samples of both the individual multichannel elements along with a few different stereo mix variants made from them.  I'm hoping that will help illustrate how there can be several vastly different subjective mix options for any one recording made using these techniques, each viable on it's own terms.  Some listeners will tend to lean towards one presentation over another, while others may find all of them equally enjoyable, if for different reasons.  Listeners interested in diving deeper, playing around with fine-tuning the mix relationships themselves to find what subjectively works best for them versus what doesn't, can mess around with recombining the individual parts in various ways. That these multi-mic techniques give us so many equally viable alternate options is one of the big attractions of these approaches for me, with the flip-side being the burden of having to choose one over the other.
Title: Re: Oddball microphone techniques
Post by: rocksuitcase on July 11, 2016, 01:08:22 PM
I was thinking about something similar concerning posting the raw files so you could check them out and play around to see what type of mix you (or any of us) come up with.
so far, only one of our Phish shows has been posted. we have 7-03 ready to up. and 7-02 should be up after that. For now, I will post the Rig pic links and the DnCo plus Phish night one recording links in this thread:
Rig pic links:
http://taperssection.com/index.php?topic=178302.0
http://taperssection.com/index.php?topic=178319.msg2193613#msg2193613
http://taperssection.com/index.php?topic=178320.0
http://taperssection.com/index.php?topic=178321.0

http://taperssection.com/index.php?topic=178139.0
https://archive.org/details/dnCo2016-06-21.DnCo2016-06-21.OmniHyper24

Title: Re: Oddball microphone techniques
Post by: rocksuitcase on August 19, 2016, 10:10:52 PM
Here are the first results from Greyfox. 2 sets which are on LMA.
https://archive.org/details/delmccoury2016-07-15.24.ck22ck8ck61
This one is:
ch 1&2: AKG ck22 Omni spread 100 cm
ch 5&6: AKG ck8 shotgun fwd 0'|AKG ck61 naiant active cardiod rear 180' ->
Tascam DR680|SD 24/48
Transfer: SD|Dell Latitude E5530-> Audacity
CDwav-> TLH (flac level 8)
Mixing notes:
CH1&2=AKG ck22 Omni spread 100 cm -3dB
ch3  =AKGck8 fwd 0'               -7dB
ch4  =AKGck61 rear 180'           -9dB
Equalization applied-(<4dB) bass reduction under 400 Hz.

https://archive.org/details/steepcanyon2016-07-14.24.ck22ck414.flac
This one is:
ch 1&2: AKG ck22 Omni spread 36 cm
ch 3&4: AKG c414XLS/ST cardiod fwd 0'|AKG c414XLS/ST cardiod rear 180'
Tascam DR680|SD
Transfer: SD|Dell Latitude E5530-> Audacity
CDwav-> TLH (flac level 8)
Mixing notes:
CH1&2=AKG ck22 Omni spread 36 cm - 2dB
ch3  =AKGc414 fwd 0'            - 7dB
ch4  =AKGc414 rear 180'         -18dB
Equalization applied- bass reduction below 200Hz.

The 414's in the center definitely impart a smoothness which is not typically there with the ck8.
I include the mixing notes from the text file in this thread. Didn't put them in the main LMA page cause no one cares except us taper freaks.
We still need to upload Phish 2 & 3.
Please listen critically and comment in this thread (especially if you're not me, gut, or kindms, cause we'll be all over this thread!)
For photos of the Greyfox set ups:
http://taperssection.com/index.php?topic=178908.0
 

Title: Re: Oddball microphone techniques
Post by: Gutbucket on June 27, 2017, 02:21:10 PM
Big thanks those of you trying some of these ideas for yourselves.  Seems like using a center mic between spaced omnis is becoming more common around TS.  I'm happy to see that and hope it's working well for those trying it.

There is a good discussion on the relationship between a spaced pair of omnis and a center microphone is currently going on over here- Relationships between spaced omnis and center mic (http://taperssection.com/index.php?topic=182579.msg2231283#msg2231283).  I didn't intend to totally commandeer that thread, yet took it as a good opportunity to sum up my thinking about spaced omnis in general and when and why the addition of a center mic may be advantageous.  My contribution there, which starts here (http://taperssection.com/index.php?topic=182579.msg2231799#msg2231799), is in some ways a summary of much of what I've been pursuing and figuring out in this thread over the course of so many years.   I've more to post there, but am giving it a rest for a few days to see if others have comments.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on June 27, 2017, 03:36:07 PM
Figure while I'm revisting this thread I'll post a few photos of my most recent outdoor variation on these themes, from the Wanee festival earlier this spring at the Spirit of the Swannee in Live Oak, FL. as I'd meant to post these here a few months back.

This year at Wanee I broke out my old hard Nerf-ball DIY APE's (Acoustic Pressure Equalizers as DPA calls them) which I was using years ago on my 4-omni rigs discussed at length earlier in this thread.  In these photos they are the round black balls on the far ends of the thin telescopic antennas and have hemispheric foam windscreens pinned to them.  The omnis are flush to the ball surface under the apex of the foam hemispheres.   Years ago, I originally used those to give the omnis a bit more forward directionality, focus and a presence range boost, partly to help compensate for less spacing than I would have preferred.  This time I have sufficient spacing between the omnis (5' instead of 3') and get all the focus and presence I need from the four near-spaced 4098 supercardioids pointing forward, left, right, and backwards.  I now use the left and right facing supercards as the primary Left and Right channels.  The wide spaced omnis still provide all important deep bass extension and stereo bass information to the Left and Right main channels, which are qualities unaffected by the sphere attachments.

The intention of using the APE spheres this time is to give the omnis some rearward directionality preference and presence above the bass range, reducing their sensitivity in the mids and highs slightly with respect to pickup of direct sound from in front.  That's because, outside of the bass range, I'm now mostly using the omnis for ambience in a 2-channel mix, and as dedicated surround channels for surround playback.  A bit less direct sound pickup pickup from in front allows me to use more ambience / surround level.  The APEs are probably not giving me the 6-10 dB reduced sensitivity towards the front which I figure would be optimal, but it was easy to implement with what I had on hand.  If wondering about their angle in the photo, made apparent by the hemispheric windsceens, their primary rearward axis actually face about 135 degrees and 225 degrees away from the front, which aligns their minimum sensitivity point with dead-ahead since the polars for spherical APEs show a small rear lobe.  Plus I'd originally designed them to face +/- 45 degrees forward, so it was easy to just turn them around.

I'd been thinking of using rear-facing subcards in place of the omnis, which would provide about that amount of directionality without compromising bass extension too much or tonal quality of what is picked up from in front, but I don't have any subcards.  I've also thought about placing the Naiant X-8S bidirectionals coincident with the 4061 omnis so I could vary the pattern from forward facing through omni to rear-facing how ever I like as in the Schoeps Polar Flex system.  That would be the ultimate in terms of control- I could even vary the pattern with frequency (omnidirectional at LF routed to the Left and Right main channels, and rear facing cardioids for ambience and surround channels excluding the front sound) but that would would require two additional recording channels.   And both of those options would be too heavy to be able to be supported by the telescopic antennas at a 5' spread anyway.

The other modification was punching holes through my two big Shure windscreens for use on the left and right facing 4098 supercards.  That kept the heavy screens supported by and tight to the telescopic antennas, keeping things from flopping around and making setup, breakdown and hauling a bit easier.  As you can see from the one photo of the rig setup up low at the front rail, those B.A.Shures are due for replacement anyway, so I didn't feel too bad punching holes through them for this test run.  I think I'll make this a permanent feature once I replace the screens.

There was also a certain synchronicity in pulling out the Nerf APEs in that one of the bands playing this year was DSO (they did a mightily fine rendering of Cornell 5/8/77) and the last I'd recorded them was years ago at Langarado out in Big Cypress when Dan Healy was running their sound and I was first experimenting with the APEs.  He loved the antenna spaced omnis and signed one of the APE balls for me.  I think I blathered about that early in the thread, but it meant a lot to me.

Edit- here's the one Healy signed for me-

(http://taperssection.com/index.php?action=dlattach;topic=96009.0;attach=77802;image)
Title: Re: Oddball microphone techniques
Post by: heathen on June 27, 2017, 03:48:07 PM
I've read most of this thread, with particular interest to your antenna mount for the small omnis.  One question I have, though, is about shock mounts.  It looks like you don't have any kind of shock mount for yours.  Is the natural "give" of the extended antenna enough to absorb any movement so that a shock mount isn't necessary?

I like how low profile the antenna idea is, and want to give it a try in my setup.  Any recommendations for how to attach antenna to a stand, short of fabricating a mount or just taping it to the stand?
Title: Re: Oddball microphone techniques
Post by: Gutbucket on June 27, 2017, 03:56:14 PM
If you look closely in the above photos you'll see the splint I made to repair one of the antenna arms.  After a decade of use I finally broke one of them at Snarky Puppy's Ground Up fest in February in my haste to break down one night.  Somewhat surprised they made it this long without damage considering all they've been through over the past 10 years, often way FOB up front in the impact zone.

A few more from the section out in the Meadow (Peach stage) where there were numerous of spaced omni rigs flying this year-
Title: Re: Oddball microphone techniques
Post by: Gutbucket on June 27, 2017, 04:07:25 PM
I've read most of this thread, with particular interest to your antenna mount for the small omnis.  One question I have, though, is about shock mounts.  It looks like you don't have any kind of shock mount for yours.  Is the natural "give" of the extended antenna enough to absorb any movement so that a shock mount isn't necessary?

I like how low profile the antenna idea is, and want to give it a try in my setup.  Any recommendations for how to attach antenna to a stand, short of fabricating a mount or just taping it to the stand?

Well the omnis are pretty resistant to handling noise to begin with, and I find I don't really need shock mounts even with the directional mics.  If someone actually whacks the stand or something during a quiet section I can hear that in the directional mics, but not during the music.  I've never found it a problem which required further shock mounting, and the whole thing is much easier to rig with all these mics and far more compact without shock mounts.

I built a custom mount for the antennas out of aluminum bar-stock covered in heat-shrink.  It's like a very small mic bar with a hole in the center for stand mounting and the ends bent up at 45 degree angles.  The bend allows me to fold the antennas flush with the stand for travel, straight out perpendicular, or angled upwards.  I think I have detail photos of that posted earlier in the thread and will link to that post here once I find them.  But you can often just rig something and tape them in place with gaffer tape.  The  original silver pair I was using at the very start of this thread always remained attached to their own small center plastic thing, which originally stuck into a receptacle on the back of an old CRT TV.  I'd just tape the plastic thing to the painter pole and the antennas could still fold up.

Edit-
Here are photos of my antenna mount (from this early post in the thread (http://taperssection.com/index.php?topic=96009.msg1338931#msg1338931)).  I made two of these, one for each pair of telescopic antennas.  I can use them singly as shown here or use both together crossed at right angles to have antennas extending forward and back as well as left and right-

(http://taperssection.com/index.php?action=dlattach;topic=96009.0;attach=77778;image)

(http://taperssection.com/index.php?action=dlattach;topic=96009.0;attach=77780;image)
Title: Re: Oddball microphone techniques
Post by: 2manyrocks on June 27, 2017, 04:49:49 PM
Fwiw, I've always taped my 4061s to something by the wire and the wiggle room in that I guess acts like a shock mount.  So small could probably fly them from a pair of trained butterflies.
Title: Re: Oddball microphone techniques
Post by: voltronic on August 16, 2017, 04:34:20 PM
Just came across this and there are a few arrays I've never seen.  The surround-specific setups are probably familiar to many here, but In terms of "oddball" for non-surround recording, I'd really like to try out the Omni+8 setup.

http://www.sanken-mic.com/en/qanda/index.cfm/18.56? (http://www.sanken-mic.com/en/qanda/index.cfm/18.56?)
Title: Re: Oddball microphone techniques
Post by: heathen on August 16, 2017, 04:55:46 PM
Just came across this and there are a few arrays I've never seen.  The surround-specific setups are probably familiar to many here, but In terms of "oddball" for non-surround recording, I'd really like to try out the Omni+8 setup.

http://www.sanken-mic.com/en/qanda/index.cfm/18.56? (http://www.sanken-mic.com/en/qanda/index.cfm/18.56?)

Great link.  I may try a bastardized version of Omni+8 this weekend.  (Bastardized because I don't have the means to get the figure 8 40 cm in front of the omnis...I may be able to get close to that, though.)

I think the OCT also looks pretty cool.
Title: Re: Oddball microphone techniques
Post by: voltronic on August 16, 2017, 08:52:56 PM
Just came across this and there are a few arrays I've never seen.  The surround-specific setups are probably familiar to many here, but In terms of "oddball" for non-surround recording, I'd really like to try out the Omni+8 setup.

http://www.sanken-mic.com/en/qanda/index.cfm/18.56? (http://www.sanken-mic.com/en/qanda/index.cfm/18.56?)

Great link.  I may try a bastardized version of Omni+8 this weekend.  (Bastardized because I don't have the means to get the figure 8 40 cm in front of the omnis...I may be able to get close to that, though.)

I wonder how the 40cm forward placement for the fig8 works without causing phase issues.  Lots of wavelengths in the audible range there.  It's not like a Decca Tree where the distance from the mid mic back to the flankers is relatively large.
Title: Re: Oddball microphone techniques
Post by: rocksuitcase on August 17, 2017, 11:52:39 AM
Just came across this and there are a few arrays I've never seen.  The surround-specific setups are probably familiar to many here, but In terms of "oddball" for non-surround recording, I'd really like to try out the Omni+8 setup.

http://www.sanken-mic.com/en/qanda/index.cfm/18.56? (http://www.sanken-mic.com/en/qanda/index.cfm/18.56?)

Great link.  I may try a bastardized version of Omni+8 this weekend.  (Bastardized because I don't have the means to get the figure 8 40 cm in front of the omnis...I may be able to get close to that, though.)

I wonder how the 40cm forward placement for the fig8 works without causing phase issues.  Lots of wavelengths in the audible range there.  It's not like a Decca Tree where the distance from the mid mic back to the flankers is relatively large.
I've been holding off typing in this thread because We've donbe about 20 sets with various OMT's this summer and I was hoping to start a discussion about mixing these sources. (Have spoken with Gut about this who of course welcomes the input).
HOWEVER, looking at that Omni + 8 I can say you would not have to goo out 40cm, you could just line it up horizontally with the Omni's. Remember the article is for "surround sound" techniques; while using OMT's could be of use when creating surround sound, we are not doing that typically and my experience with Omni plus supercard middle, Omni plus card middle, Omni plus Hyper pair X-Y in the middle tells me you should try this Omni + 8  as I describe, in line with each other.
And THANKS to Volt for posting that link, it is very useful.
Title: Re: Oddball microphone techniques
Post by: heathen on August 17, 2017, 12:03:53 PM
HOWEVER, looking at that Omni + 8 I can say you would not have to goo out 40cm, you could just line it up horizontally with the Omni's.

That's encouraging to hear because I tried setting it up last night and I can only get my figure 8 about 21 cm in front of the omnis.

I guess the follow-up question is whether, for pure stereo purposes, it would be better to have the figure 8 mic 21 cm in front of the omnis or closer to in line with them?  I don't think I can get them exactly in line, but I can get them pretty close.
Title: Re: Oddball microphone techniques
Post by: rocksuitcase on August 17, 2017, 12:14:48 PM
^^^^^^ doesn't have to be exact.As long as the difference is no more than 20cm it will not be audible. we've been running the ck8 or cards about 10-12 cm in front and there is no problem with phase alignment in post.
Title: Re: Oddball microphone techniques
Post by: thatjackelliott on August 17, 2017, 12:56:15 PM
For that OCT layout . . . what does "omni directional" mean?

Also, on the left side we have two mics with complementary 100Hz high and low pass filters being summed. No such setup on the right side, just the "omni directional" mic. The asymmetry puzzles me. Perhaps that arrangement on the left side creates a single "omni directional" mic and we see it simplified on the right. It baffles science.
Title: Re: Oddball microphone techniques
Post by: heathen on August 17, 2017, 01:02:44 PM
For that OCT layout . . . what does "omni directional" mean?

Also, on the left side we have two mics with complementary 100Hz high and low pass filters being summed. No such setup on the right side, just the "omni directional" mic. The asymmetry puzzles me. Perhaps that arrangement on the left side creates a single "omni directional" mic and we see it simplified on the right. It baffles science.
I assumed they intended the same arrangement on the right side, but didn't duplicate it just to save space.  That's just my assumption though.

Edit: Here is some info on OCT from Schoeps that doesn't include the omnis (interesting that it also provides different recording angles depending on the spacing of the supercards) http://www.schoeps.de/en/products/oct-set
Title: Re: Oddball microphone techniques
Post by: rocksuitcase on August 17, 2017, 01:15:21 PM
For that OCT layout . . . what does "omni directional" mean?

Also, on the left side we have two mics with complementary 100Hz high and low pass filters being summed. No such setup on the right side, just the "omni directional" mic. The asymmetry puzzles me. Perhaps that arrangement on the left side creates a single "omni directional" mic and we see it simplified on the right. It baffles science.
I assumed they intended the same arrangement on the right side, but didn't duplicate it just to save space.  That's just my assumption though.
seconded, because if not, then thatjackelliot sure does have a point! (according to the physics I learned)
Title: Re: Oddball microphone techniques
Post by: jbosco on August 17, 2017, 01:24:08 PM
Just came across this and there are a few arrays I've never seen.  The surround-specific setups are probably familiar to many here, but In terms of "oddball" for non-surround recording, I'd really like to try out the Omni+8 setup.

http://www.sanken-mic.com/en/qanda/index.cfm/18.56? (http://www.sanken-mic.com/en/qanda/index.cfm/18.56?)

The Double MS looks interesting, I assume the three mics would be coincident, would the body of the reverse facing cardioid interfere with the front facing one in anyway (reflections, baffling, etc)? I guess you would just use the front facing M as a center channel in a 5.1 scenerio?
Title: Re: Oddball microphone techniques
Post by: heathen on August 17, 2017, 01:30:21 PM
Here's some Schoeps double m/s setups: http://www.schoeps.de/en/products/categories/doublems
Title: Re: Oddball microphone techniques
Post by: rocksuitcase on August 17, 2017, 01:54:05 PM
gutbucket and I have discussed DBL MS. we have run M/S with a ck8 middle, but never a DBL MS. I am betting for certain applications (Orchestral, ambient, surround recording) with certain mics  it rocks.
Title: Re: Oddball microphone techniques
Post by: heathen on August 20, 2017, 03:48:34 PM
For logistical reasons I wasn't able to try the omni+8 configuration as it's specified in that Sanken link this weekend.  I was only able to get the omnis spread about 20 inches, and the figure 8 was only a couple inches in front of the omnis (there's a picture in the Rig Pictures subforum). 

Anyway, here's a sample: https://drive.google.com/open?id=0B1n0IflrIOocMEJiUlhEb3RVYUE

(I suspect, but am not sure, that the battery in my battery box lost some juice part of the way through this song.  Maybe I'm crazy, but it seems like the bass drops out a bit around halfway through.  I could just be imagining things though.)
Title: Re: Oddball microphone techniques
Post by: Gutbucket on August 25, 2017, 04:02:11 PM
Glad to see such a flurry of activity in this thread upon my return (out since last week an eclipse trip to Idaho, just back on-line today), and find it somewhat ironic that this thread was relatively quiet until just last week.  I've input on a lot of the posts above and will try to address each over the next few days as I catch up.  Cheers to all, and look forward to the discussion..
Title: Re: Oddball microphone techniques
Post by: Gutbucket on August 25, 2017, 04:42:01 PM
Just came across this and there are a few arrays I've never seen.  The surround-specific setups are probably familiar to many here, but In terms of "oddball" for non-surround recording, I'd really like to try out the Omni+8 setup.

http://www.sanken-mic.com/en/qanda/index.cfm/18.56? (http://www.sanken-mic.com/en/qanda/index.cfm/18.56?)

Thanks for that link Volt.  Those are all relatively well known and documented "purist" location surround mic'ing techniques.  I'll post a link to some free AES papers assessing and comparing these techniques once I can locate them again for those interested in more specifics about them.

Much of what into the development of the oddball arrays I've been playing with over the years is informed by these techniques.   I've found some basic core relationships that apply broadly to all these arrays, and based on that I've combined elements from many of these techniques in ways which better apply to the specifics of the recording situations I find myself in.  The key is understanding those basic relationships, testing things to confirm the understanding is accurate, and then furthering a more nuanced understanding of specifics.  One very useful array not mentioned in the Sanken page which I've found useful in concept and practice is David Gresinger's (acoustics expert, sound engineer, former Lexicon head scientist) array of 5 spaced omnis (or forward pointing directional microphones) in a line across the front of the stage - somewhat unique in that all mics are arranged in a single line, which has unique technical merits as well as being practical in terms of setup. More about that later and how it can be combined with these other techniques.


As a general statement I will say this-  These arrays are all primarily intended for 3, 4 or 5-channel stereo playback rather than 2-channel stereo playback.  Some "fold down" (mix) to 2-channel stereo better than others.  We can get in to why that is, and how to develop a understanding for when they will and when they won't.  Yet in general, I've been extremely encouraged regarding how well these techniques or variants on them work when mixing down to 2-channel in comparison to simple dedicated 2-microphone arrays.  When chosen wisely, there is typically far more advantage than conflict with regards to 2-channel playback, and when there is a problem it's typically easily mitigated by having total control over the mix.  Techniques which work especially well for surround recording are usually advantageous for 2-channel stereo as well in my experience.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on August 25, 2017, 06:01:45 PM
In terms of "oddball" for non-surround recording, I'd really like to try out the Omni+8 setup.

That setup has interested me and in other threads at TS I've suggested tapers give it a try in certain situations.  It's a variation on spaced omnis + center mic, which is the starting point of most of my oddball techniques.

I think it's applicable to TS partly because it is relatively simple, using just 3 channels.  In terms of 2-channel stereo, I see it as a variant on the classic Decca tree 3-omni triangle approach.  The advantage I see in using a bidirectional center mic rather than some other pattern is maximally increased forward directivity of pickup in the center (an ever-increasing incremental change moving from center-omni > center-cardioid >  center-supercard > center-bidirectional).  In some ways it's similar to using a shotgun mic in the center in that sense.

Several basic aspects in play here:
1) A bi-directional achieves the most-narrow angle of forward sensitivity achievable in the center mic (other than a multi-capsule DSP shotgun like the Schoeps CMIT), along with a very smooth and well behaved polar pattern.  A typical shotgun may be similarly forward directional, or perhaps even more so at high frequencies, but it's polar-pattern varies far more with frequency and is typically quite ragged.  Combination with the omnis covers that raggedness to a significant extent in contrast to a shotgun or pair of them alone, but it helps if all three mics share the same timbre for best tonal blend and image stability.  A bi-directional is more likely to be of the same timbre as the omnis (above several hundred Hz) than a shotgun and blend more smoothly in a mix.

2) As a great practical setup advantage, the increased degree of forward directivity allows for a less wide L/R omni spacing without introducing to much inter-channel crosstalk which would otherwise compromise image width and make things overly monophonic.  Remember, if you are using any kind of center mic at all, you'll want the R/L mics spaced wider (or angled further apart, or both) than you would if using just the two microphones alone. If I'm using 3 omnis instead of 2, I generally want to double the L/R spacing. A more directional center mic allows for somewhat less wide L/R spacing.  A bi-directional or shotgun center is the logical conclusion of that trend, allowing for a more reasonable spacing of the omni pair, more easily achievable on a single mic stand.

3) The bi-directional pattern has the least sensitivity to the immediate surroundings beneath the microphone in the immediate vicinity around the mic stand.  It does have equal sensitivity to the front and rear, but if up say 9 or 10' on the stand, the most proximate audience nearby (and thus the loudest by proximity) is in or near that null.

4) I like arrays which include a rear facing microphone (when recording four or more channels).  Just a bit of that rear facing channel mixed in makes the recorded ambience sound far more natural to me.  Obviously how much can be used depends on the sound of the venue and the behavior of the audience behind the recording position, but Rocksuitcase has confirmed to me the value of a rear facing mic in his experiments as a well.  A center mic pattern with some "rear lobe" achieves that without a 4th microphone, if in a less controlled way.  In a good room with a good audience, a bidirectional center could provide a perfect balance in that regard.  Consider that the omni + 8 is equally sensitive to the front and rear.  In that aspect if not others it is similar to Blumlein or a pair of spaced omnis.  Yet it will have more front/back reach than a pair of omnis or Blumlein with less sensitivity to the sides, above, and below.   In most cases I expect using a hyper-card or supercard in the center will be preferable, providing greater forward sensitivity bias with with less sensitivity to the rear, but still enough to help with this ambient naturalness in comparison to a center shotgun.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on August 25, 2017, 07:10:41 PM
On center mic forward spacing (all arrays not just spaced omnis + center 8 )-

As for spacing of the center mic forward of the L/R pair, I wouldn't worry overly much about it.  Play around with it, and with timing alignment of the center channel in post if so inclined, but I find it's far less significant than L/R spacing.  Much of that may be residual from Decca tree geometry history, intended to be flown over the conductor's head almost above and within the orchestra.  We are mostly recording from considerably further away, and the general trend is more L/R spacing with less forward spacing as the recording position is moved increasingly further back.  The most important basic mode of thought in this regards is IMHO good time-of arrival alignment for each side, independent of the other.  Spacing the center mic forward just enough to achieve good time of arrival between the center mic and outer mic on that side for the sound source(s) on that side.  Consider an imaginary line drawn between the Center mic and Left mic and arrange that to be perpendicular to an imaginary line drawn from the Left PA speaker to it's intersection with the line between the two mics.  Do the same for the right mic / center mic pair with respect to the right PA speaker.  With that arrangement, direct sound from the left PA speaker will arrive simultaneously at the Left mic and Center mic, yet will be just slightly delayed in the Right mic channel.  Vice-versa for the right side.  Doing that for arrays designed to be flown above an orchestra, with sound sources arrayed in a semicircle all around the recording position, one gets a deep triangular a Decca tree like arrangement, but from a recording positions further back, one gets an increasingly shallow but wide-based triangle.

This mode of thought concerns time-of-arrival alignment for the direct sound. When recording from further back that becomes easy to achieve when all mics are arranged more or less in the same plane.  Significant forward center mic spacing in that case may benefit from time-alignment in post by the addition of a slight center mic delay.  Play around with it.  Also consider Griesinger's 5-mics-in-a-row technique with no forward spacing of the center microphone at all works very well.   



OCT and Williams arrays are thinking more in terms of stereo image, but it's a fine-line in the real world between that and time of arrival as both work similarly.   If familiar with the OCT setup, consider that it's Stereo Recording Angle is tuned by varying the spacing between the L/R sideways facing supercards but the forward spacing does not change.  Basically the further away the recording position, the wider the L/R supercard spacing used, narrowing the SRA appropriately to accommodate the more distant perspective.  William's 3-channel MMAD extension of the Stereo Zoom is similar here, which is all about seamlessly linking the two Stereo Recording Angles (SRA) - that of the left/center mic pair and that of the center/right mic pair with out excessive gap or overlap.   I sometimes use Williams' MMAD charts when deciding on a good approximate forward spacing distance of a center mic between the omnis. 


From typical taper positions further back in the venue, I think increasing the forward spacing of the center microphone more than described above (possibly in combination with compensating alignment delay in post) may prove useful as a way to increase the distance between the three mics when it's otherwise difficult to space the outer microphones far enough apart, achieving good diffuse-field decorrelation (DFC) with a somewhat more compact overall foot-print than would otherwise be possible.  This is all about minimizing conflicts like comb-filtering between multiple mic sources (what the 3-to-1 rule is about, but in a different situation) as well as improving the sound of the ambient/reverberant content of the recording. One could also space the center higher than the omni pair instead of further forward of that pair to achieve this, which would retain good timing alignment for forward arriving sound without any need for timing compensation in post.

Title: Re: Oddball microphone techniques
Post by: Gutbucket on August 25, 2017, 07:55:31 PM
OCT-

I think the OCT also looks pretty cool.

Love it outside where it's a primary basis of my current outdoor oddball setup.  Fantastically good imaging using 3 front speakers, and a really cool intense forward "presence" when mixed in to 2-ch stereo.  The 180 degree sideways-opposed facing supercards optimally reduce crosstalk reducing the need for a super-wide Left/Right spacing.  Because of that one can get away with spacings normally used with just two omnis of a just meter or less.  Just be careful indoors where those mics may be facing a reflective wall. I've had good results indoors from the sweet spot a few times but have not used it indoors extensively.  It was less good onstage for jazz trios in a small reflective room, where Williams 3-mic arrays using supercards pointing more at the on-stage sources worked better (sort of like a mini directional Decca tree arrangement).  I've considered increasing the L/R supercardioid spacing and angling them forward at something like a 90 degree angle between mics indoors to compensate, but haven't tried that extensively.

Quote from: thatjackelliot
For that OCT layout . . . what does "omni directional" mean?

Also, on the left side we have two mics with complementary 100Hz high and low pass filters being summed. No such setup on the right side, just the "omni directional" mic. The asymmetry puzzles me. Perhaps that arrangement on the left side creates a single "omni directional" mic and we see it simplified on the right. It baffles science.

Same on both sides, just shown on the left.  The omnis are intended to extend the bass response of the supercards, arranged coincident with them and low passed at the point where the supers loose sensitivity.

I make a few oddball variants on standard OCT-
1) I use a center supercard instead of a carioid.  That increases center mic isolation from audience noise and room sound (more SBD-like direct sound from the center mic), and theoretically allows for a slightly narrower L/R supercard spacing to produce the same SRA linking.  Of these two aspects, the increased forward directivity thing with less side pickup is the most important aspect for audience taper positions by far.

2)I like the omnis spaced twice as wide (about 1.5 to 2meters), and don't  low pass them.  That makes for more involving wide-spaced omni stereo bass which I dig, and a more open pickup of ambient content.  I EQ and mix the omnis in to taste which contours their mid and high frequency contribution, EQing for both bass timbre and appropriate ambient air and room sound.  This wider spacing is difficult to achieve on a single stand with typical omnis, but is achievable using lightweight miniature mics.  The supercards and omnis are all in one plane so they can be arranged along one (long) bar.  For surround use I send the mids and highs from the wide omnis to the surround channels.

3) I add a backward facing center cardioid or supercardioid.  As mentioned above I like to have mix control over venue and audience ambience and a rear facing directional mic allows for that (the omnis pickup fantastically good ambience, but too much direct sound to provide really good mix control over the ambient balance). I figure a cardioid here is optimal for achieving maximum rejection of the direct sound arriving from the front, but the supercards I've used for this seem to work just as well if not better, so I now use identical miniature supercards all around for Left/Right/Center/Rear.  This keeps timbre the same all around and also makes the entire 6-mic array completely front/back symmetrical, producing both front and rear facing OCT arrays.

[edit]- the OCT surround array specifies two rear facing cardioids, spaced apart and a bit further back than the single rear-facing mic I'm using.  That's probably a better setup for both 5-channel and 2-channel mixdowns as long as one is capable of dedicating two recording channels to backwards facing mics, because it spreads that ambient surround content in the playback image out to the sides making it less likely to conflict with the forward facing center channel information.  In my oddball variant, in addition to using the omnis to provide stereo bass extension below the limits of the OCT supercards, the wider-spacing of the omnis than the supercards (the omnis are essentially spaced twice as wide) allows the omnis to serve as surround channels in combination with the single rear-facing mic.  The spacing between L/R supercards and L/R omnis is essentially insignificant at low frequencies where the wavelengths in question are long and the omnis are meant to extend the frequency response of the supercards, but significant at shorter wavelengths where the increased spacing serves to decorrelate the omni mids and highs (routed to the surround channels or mixed in to 2-channel as ambience) from the mids and highs from the L/R supercardioids.  So the omnis end up serving dual purpose as bass extension and as ambience/surround channels, and arguably do a better job in both rolls in this configuration as well as being more easily managed since they are positioned further out along along the same telescopic bar(s) as the L/R supercards.
 
Title: Re: Oddball microphone techniques
Post by: Gutbucket on August 25, 2017, 08:08:27 PM
The Double MS looks interesting, I assume the three mics would be coincident, would the body of the reverse facing cardioid interfere with the front facing one in anyway (reflections, baffling, etc)? I guess you would just use the front facing M as a center channel in a 5.1 scenerio?

Double MS is very cool for 2-channel coincident stereo.  All three mics need to be as coincident as possible.  It is Ambisonics without height - think SoundField or TetraMic but horizontal plane only.   It's primary advantage is it's very compact size, and the ability to change the microphone configuration in post, both of which have obvious advantages for tapers. Point virtual mics of any pattern from omni to 8 in any direction in post!  That makes it super useful for tapers where setup is rushed and one can't monitor during setup.  Place it in a good spot and tune it to any coincident configuration later.

Drawback is that it's limited to coincident mic configurations only.   It works for surround but isn't optimal for more than 4 channel playback as it doesn't provide enough separation between channels.   You need spacing between mics to optimize for that.. and maybe for 2-channel stereo as well depending on your feelings about coincident verses near-spaced mic configs.

I think it would be best combined with spaced omnis.  Use it like a super configurable center pair.  You also get a rear facing mic at the same time if you want one.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on August 25, 2017, 08:18:42 PM
^ That requires 6 channels total, same as my OCT+ variant.  I'm considering setting up a second rig using the TetraMic + spaced omnis into my old DR-680 mk1.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on August 28, 2017, 12:25:07 PM
I was only able to get the omnis spread about 20 inches, and the figure 8 was only a couple inches in front of the omnis (there's a picture in the Rig Pictures subforum). 

Not being able to get the microphones spaced as widely as desired is probably the most common taper problem with omni setups using more than 2 microphones, in which case the introduction of a center mic can make the stereo recording overly monophonic.  But that doesn't mean it shouldn't be tried or can't be a helpful addition - I listen first to the omnis alone to determine how well they work on their own just with some EQ, then compare that to mixing in some center mic.  To my way of thinking, EQing the omnis alone first is important when making this comparison so as to minimize the timbrel influence of the center mic addition.  That's because I feel the center mic should be helping in ways other than just in terms of simple frequency balance which could be alternately be achieved just with EQ.  Comparing after EQing helps remove timbre from that decision process, since it is one of the more most predominant aspects I immediately notice before more subtle things like stereo image width, depth, solidity, precision. 

If I can't mount the omnis as wide as I'd like, I look at tweaking the mounting to get as much spacing as possible with the current setup.  Can I clip the mics to the ends of the bar instead of to the top of it? I'll also angle the omnis outwards, which often increases spacing by a few inches more and introduces some directional difference at high frequencies.  If I have a center mic, I don't hesitate to point the omnis fully sideways 180 degrees apart (just like the L/R supercards in the OCT setup) even if they are spaced widely enough.  That "makes perceptual room" for the direct high frequency stuff from the center mic in the middle of the stereo image, and also makes the ambient room sound more open.  A directional mic with a more-narrow front pickup angle such as a bidirectional or hypercardioid helps with less than ideally-wide-spaced omnis as well.  Another strategy is to use subcards or cardioids in place of the omnis, and point them 180 degrees apart.  The opposite pointing directionality helps counter the minimal spacing with level differenece substituting for timing differences, and the forward pointing center mic takes care of the direct arriving HF information.

[edit] Another thing which can be tried with an overly-narrow spaced omni pair to do some Mid/Side stereo widening on it, especially when mixing in a center mic.  That increases the difference information so that the addition of the center mic doesn't make the recording overly monophonic / Mid-channel dominant.

Title: Re: Oddball microphone techniques
Post by: Moke on August 28, 2017, 12:40:49 PM
Give up on spacing them... baffle them, instead. 
A baffle gets the omnis close enough together that they can very well be thought of as a coincident pair.  The baffle provides amplitude differences that are substantial enough to give great imaging. With the spaced mic timing issue drastically diminished with the baffle, that gives a lot more control over omni's.
Title: Re: Oddball microphone techniques
Post by: heathen on August 28, 2017, 12:48:45 PM
Give up on spacing them... baffle them, instead. 
A baffle gets the omnis close enough together that they can very well be thought of as a coincident pair.  The baffle provides amplitude differences that are substantial enough to give great imaging. With the spaced mic timing issue drastically diminished with the baffle, that gives a lot more control over omni's.

Most of the instances I'm recording is in an audience with people behind me, and I don't feel great about blocking their view more than already occurs with a normal setup.  From what I've read, a baffle needs to be a pretty decent size to be effective.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on August 28, 2017, 01:05:39 PM
^Moke makes some really tiny baffles work well, but that's really achieving an entirely different thing than what one gets from spaced omnis.  At high frequencies it is essentially the same as pointing a pair of mics further apart rather than spacing them more.  Normal baffles don't have any effect at all at low frequencies, where only mic-spacing or pattern directivity works.  Pointing full-bodied omnis 180 degrees apart is very much like using a tiny baffle- the mic diaphragm itself, mic-housing and amplifier-body effectively act like a small baffle.

Baffled omnis are are near-spaced or coincident setups and have some similar qualities to those setups.  But the omni pattern lends a naturalness that differs from many near-spaced cardioid setups.  Perhaps the best comparison with baffled omnis are other nearly-omnidirectional near-spaced or coincident setups in terms of overall room sensitivity, such as Blumlein 90-degree crossed bidirectionals, which are fully omnidirectional with respect to the room.


Title: Re: Oddball microphone techniques
Post by: heathen on August 28, 2017, 01:10:29 PM
I'm going to try running omnis in a DIN config for the fun of it this week.  Maybe closely-spaced omnis will become the real oddball technique  ;)
Title: Re: Oddball microphone techniques
Post by: Gutbucket on August 28, 2017, 01:18:23 PM
^ That can work well, but will definitely benefit from a baffle if you can rig one.

.. and perhaps some Mid/Side widening too.  Blumlein's original stereo technique before bidirectional microphones were made available to him used baffled head-spaced omnis + Blumlein difference shuffling, which is basically Mid/Side widening.  Jorg Jecklin also experimented with difference shuffling in his re-adoption of Blumlien's original baffle technique 40 years later.
Title: Re: Oddball microphone techniques
Post by: Moke on August 28, 2017, 01:21:40 PM
Give up on spacing them... baffle them, instead. 
A baffle gets the omnis close enough together that they can very well be thought of as a coincident pair.  The baffle provides amplitude differences that are substantial enough to give great imaging. With the spaced mic timing issue drastically diminished with the baffle, that gives a lot more control over omni's.

Most of the instances I'm recording is in an audience with people behind me, and I don't feel great about blocking their view more than already occurs with a normal setup.  From what I've read, a baffle needs to be a pretty decent size to be effective.

I don't want to highjack this thread, but, here is a show where my smallest baffle was tested against a pair of Schopes in a near-coincident array, in extremely loud conditions (Widespread Panic).  The miniature baffle held its own.
How much audience site blocking is that thing going to do?
I run baffles in front of the most discerning audiences in music in the classical/chamber world.  I've never heard a single utterance of blocking views.
Regarding what "they" say about baffle size, don't believe a word of it without trying it for yourself, especially not anything that Jurg Jecklin might have to say on the matter. I've proven him wrong on all of his stringent standards with my own parallel baffled omni experiments dating back to the mid-80's.

First two images: mini baffle at WsP concert
last three images: Large baffle for large diaphragm mics. Why? Because Jecklin said it would not work.
Title: Re: Oddball microphone techniques
Post by: heathen on August 28, 2017, 01:30:09 PM
Thanks for the info Moke.  That small baffle definitely seems unobtrusive.  Is it just a piece of foam or is there more to it on the inside?  I'd appreciate more info so I could give something like that a try.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on August 28, 2017, 01:35:05 PM
Mr Jecklin isn't actually much of a stickler for conformity at all.  I've corresponded with him about baffles and shuffling.  He has simply related what has worked for him, and actually modified his setup considerably over the years.

I think it's others reporting what he's done in an overly specified manor, reporting whatever the dimensions of his setup are as some sort of gospel instead of the more important concepts underlying them, just because that's so much easier than understanding and translating the underlying principles at work.  I feel it's somewhat similar to Tony Faulkner being branded with the oft-reported super-specific spacing of the "Faulkner Phased Array" (near-spaced parallel bi-directionals) which he himself dismisses in every interview I've ever seen or heard when hes asked about it.  He understands how things work and shifts things around until they do.  It's others who attempt to saddle what he does with exact measurements and other specifics.

All that said, tiny omni baffles most definitely qualify as odd-ball!

[edit] extra-credit for identification of the TS member in green in Mokes first photo above, but only to new member's here (say joined post 2010).  Hint- it's not Moke, and he doesn't live anywhere near him.
Title: Re: Oddball microphone techniques
Post by: Moke on August 28, 2017, 01:38:55 PM
Its just foam.  THe mount is a piece of scrap aluminum flat stock, and screwed together with some construction screwws, and silicone adhesive. If I spent an hour at it, it meant that I took a fifteen minute break half way through it.
Truth,... Its the middle of a seat from a PortaBote (one of those 12' folding boats). THe seats ahve that foam on them, for floatation requirements.  I cut the foam out, and replaced it with those throwable float/seat pads.  This met my requirement for a throwable preserver on board, and saved that room in the small boat.
The foam consistency is of a fairly large air pocket, and the foam is firaly rigid, but still flexible. 
I've got to dig out the pics (in folders on my desktop after the rescuing them from Photobucket)
I'll post them here.

did I say that I can highjack a thread, or what?
Title: Re: Oddball microphone techniques
Post by: Moke on August 28, 2017, 01:42:32 PM
Mr Jecklin isn't actually much of a stickler for conformity at all.  I've corresponded with him about baffles and shuffling.  He has simply related what has worked for him, and actually modified his setup considerably over the years.

I think it's others reporting what he's done in an overly specified manor, reporting whatever the dimensions of his setup are as some sort of gospel instead of the more important concepts underlying them, just because that's so much easier than understanding and translating the underlying principles at work.  I feel it's somewhat similar to Tony Faulkner being branded with the oft-reported super-specific spacing of the "Faulkner Phased Array" (near-spaced parallel bi-directionals) which he himself dismisses in every interview I've ever seen or heard when hes asked about it.  He understands how things work and shifts things around until they do.  It's others who attempt to saddle what he does with exact measurements and other specifics.

All that said, tiny omni baffles most definitely qualify as odd-ball!

[edit] extra-credit for identification of the TS member in green in Mokes first photo above, but only to new member's here (say joined post 2010).  Hint- it's not Moke, and he doesn't live anywhere near him.

Lets just call it,... Monday Morning Surliness.

When I first read his works, his was entirely stringent.  That was back in the early-mid 90's at a time when I was having to repair the cancer stricken circuit board of my MKE2002 pair (circuit board peeling and lifting; eventually solved by point to point wiring). I was having to face the reality that my old binaural comanions were dying, and I started into looking into alternate baffled omni theories beyond HRTF/Binaural.
At any rate,... Moke might be a little surly this morning. Sorry to all.
Title: Re: Oddball microphone techniques
Post by: Moke on August 28, 2017, 01:48:57 PM
Mini Baffle
This baffle is roughly the same size as a CD (slightly larger than a cd), only square. Why square? Because round is a PITA to mount, and I'm lazy. I'd rather listen to music than build a baffle.
The cables weave through the disc face to reduce cable tension, which also helps locate the mics to the face of the baffle, and keepping them there.

The mini baffle, in different profile angles, below
Title: Re: Oddball microphone techniques
Post by: heathen on August 28, 2017, 02:00:25 PM
Thanks Moke!  Any chance you could share a sample of a recording made with that setup?
Title: Re: Oddball microphone techniques
Post by: Moke on August 28, 2017, 02:07:08 PM
This is the handiest of my baffles.
This sort of started the quest to see how small you could go with a baffle.
I did this, and was astonished at the sound in the house; Sarge was where she was supposed to be in a binaural sense, the washing machine was grinding off in the distance to one side,.... 
I then went walkabout up this horsetrail, and across to a park, just recording a meandering walk.  It was a nature recording in a city'ish area. But, airplanes became pinpoint placed overhead, birds to left and right, cars whizzing by, all in glorious two channel stereo. I must've looked a bit odd, but,.. thats not that unusual. You ought to see me when I'm out dousing (water witching).

Plankton,... well, he displays the stealther attitude.

edit: fixing the autocorrect corrections.
Title: Re: Oddball microphone techniques
Post by: Moke on August 28, 2017, 02:24:33 PM
Thanks Moke!  Any chance you could share a sample of a recording made with that setup?

Thats a challenge.
I've got to review the pictures, to see where to look for the files.
Let me say, that I settled on an 8" baffle, that I felt worked really well with my 4060 mini omni pair.

The WsP is long gone now, from my collection. But, its out there, I think, if you know that community.
I did, and still do, do far more recordings with my larger, but, still small scale baffle. That slightly larger baffle is 8", and I found that to be a really sweet size with the miniature omni pair.
I was searching for an image of my 8" baffled omnis, with a DPA 4028 sub-card over it as a three channel recording. The band had commandeered one of my pair of 4028 to be used as a close mic source for a very quiet intimate native american flute concerto premiere. They couldn't hear the flute over the backing ensemble. So, I volunteered one of my mics as that onstage close mic (direct to a small amp via my also onstage recording bag and Grace preamp).
At any rate, I ran three channels; two as baffled omnis, and one as a vertically aligned sub-card at 0º, hoping that maybe, some day, somebody as kind, wonderful, helpful, and a dear friend, like Gutbucket, might help talk me through a mix. (sucking up enough, Lee?)
Title: Re: Oddball microphone techniques
Post by: Gutbucket on August 28, 2017, 02:30:41 PM
This raises a good point that we may all prefer somewhat different things, that real-world practicality is so often far more important than our ultimate preference based on sonics alone, and that we tend to stick with what has worked for us previously.

That a tiny baffle works perfectly well and is eminently more practical than a larger one plays directly into that.  Jecklin stuck with a 12" diameter baffle for a long time, simply because his first baffles were built around an old LP record.  He eventually found he preferred a slightly larger diameter baffle with a bit more spacing between the mics, but he was doing studio and orchestral recording where he had freedom of control and the ability to tweak the setup for subtleties, rather than taper recordings like we are doing where we don't have control and practicality trumps subtle acoustic niceties. 

I think Blumlien's original baffle was something like 8" in diameter (but thicker making it more head-like, although I'd have to check the patent to be sure) - so he's somewhat closer to the Moke-tiny-baffle-camp.   After all, Blumlien is mostly thought of as the father of coincidental microphone techniques.  At the opposite extreme, we've all seen photos of Ray Kimber's gargantuan ISO-Mic baffles which take a crane to lift.

I mostly gave up on typical J-disk baffles as being less than practical for the size I felt I wanted them to be for the effect I wanted to achieve.  Spacing tiny omnis further apart was easier for me, less intrusive, and gave me more of what I wanted from them, and flush-mounting them in small balls combined with spacing ended up serving a similar purpose in a more practical way. 

I've used columns, tree trunks, menus and other things as baffles.  Its the concepts behind them which are important, rather than the particulars of the baffles themselves.

Quote
..hoping that maybe, some day, somebody as kind, wonderful, helpful, and a dear friend, like Gutbucket, might help talk me througha mix. (sucking up enough, Lee?)
I owe you so much my friend. I originally came to TS asking about baffles back in 2006 and was immediately directed to you as resident expert!  More than happy to lend whatever expertise I can.

Title: Re: Oddball microphone techniques
Post by: Gutbucket on August 28, 2017, 05:08:39 PM
A few comments on the Omni Cross and IRT Square configurations shown in that Sanken link of surround configurations-

These 4-channel configurations are common formats for recording ambiences.  The IRT Cross is especially popular for things like location sound used for broadcast or film since it is relatively compact.  It can be done using either cardioids with a bit more spacing or supercards with a bit less between each mic.   Consider that it is basically four DIN setups pointing in all four cardinal directions, sharing a microphone at each corner.  It has a bit more spacing than DIN to narrow the SRA of each pair to 90-degrees so that each imaging quadrant links with the next without excessive overlap or gap- this is the Williams Stereo Zoom thing, arrayed for seamless 360 degree coverage using four microphones.  For TV and film use the four channels are routed Front-Left/Front-Right/Surround-Left/Surround-Right, reserving the center channel for dialog and main channel content.

I consider the Omni Cross to be similar to Decca Tree, just rotated 45degrees, with a rear microphone added, and reassigning the channels from Front-Left/Front-Right/Surround-Left/Surround-Right to Left/Center/Right/Back.  Call that a Decca Diamond setup if you like.  That's the four channel setup I ran for years using ball baffles on the omnis partly as a way to minimize the need for excessive spacing.  I initially tried to space all the mics about a half-meter out from center, so both L/R and C/B spacing was about a meter in total.  Center/Back omni spacing often ended up being less than that as determined by practical considerations.

I found I wanted more left/right spacing, didn't need or especially want much spacing of the center mic forward of the left/right pair, and typically ended up not with a right-triangle shaped diamond configuration but rather a flatter diamond shape which was much wider than it was deep.  That played into spacing the L/R omnis 1.5 to 2 meters apart and changing the center and back mics to directional mics only spaced minimally fore and aft.  That then evolved into the OCT derivatives with the addiion of left/right facing supercards placed between the center and omnis.

I think of all these arrays as being linked by the same underlying acoustic principles.  So when I look at my oddball OCT+ array, I also see at it's core a 4-channel IRT cross rotated 45 degrees with it's channels reassigned, in a way similar to rotating an Omni Square configuration by 45 degrees to form a Decca Diamond.  I also see a simple 2-channel wide spaced omni pair, and a wide omni plus directional center three-microphone configuration.  I find a certain engineering beauty, elegance and welcome redundancy in the common aspects shared between these arrays and finding ways of combining them in this way without conflict.

Title: Re: Oddball microphone techniques
Post by: Moke on August 30, 2017, 03:01:32 PM
Thanks Moke!  Any chance you could share a sample of a recording made with that setup?

http://taperssection.com/index.php?topic=183411.msg2239027#msg2239027

5" mini omnidirectional baffle sample
https://archive.org/details/Miniature5BaffleDPA4040

Sample:
All acoustic string quartet and lute soloist
DPA 4060 mini omni pair -> DPA MMA6000 power -> Grace Lunatec V3 48khz ANSR ->  Sony PCM-M1 Dat Oade 7-Pin digi-in
The mics are fairly low, at a level equal to the seated Lute players instrument.

I feel that this quality is very evident:
The string quartet is cleanly placed in the aural image as being in a semi-circle around the Lute, who is centered to the ensemble; and the mic array is centered to all of that.
The bass is well placed to the right, but, does bleed over a bit (there are actually two bassists in this quartet, one deeper into the semi-circle than the other.). It does retain its proper positioning in the captured aural imagery.
Title: Re: Oddball microphone techniques
Post by: heathen on August 30, 2017, 10:18:53 PM
Moke, I think that recording sounds great.  I'm not much of a classical music guy (I like it well enough, but rarely listen to it), but I've listened to this a couple times already.  I definitely want to try out a small baffle like that now (though sadly I don't have access to recording anything other than PA shows...which seem to be mostly mono anyway).
Title: Re: Oddball microphone techniques
Post by: 2manyrocks on August 31, 2017, 12:30:43 PM
Maybe try a local college because they tend towards classical.

What practical difference does it make whether the baffle is square vs round?  Square much easier to make and mount just as Mike said.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on August 31, 2017, 12:59:47 PM
^ not much.  What is most significant is the area of the baffle, the reflectivity of the surface and how far the mics are mounted from it.  With a small baffle, the mics need to be closer to the surface to keep it effective.
Title: Re: Oddball microphone techniques
Post by: thatjackelliott on August 31, 2017, 01:37:29 PM
Two omnis and a little baffle. Neat idea. For music festival application I wonder how this would work compared with the setup I'll be using at our next event?

What I'm Gonna Do: Use a M-S configuration on the stage lip with a bipolar mic for Side and an omni for Mid + a time-aligned mono feed from the SB to bolster the omni Mid signal with detail and fill in the stuff that isn't loud onstage but boosted in the PA.

But What I Could Do: Use this mini-baffle setup + the time-aligned feed from the SB.

Mono-compatibility is essential for the broadcast (our FM stereo generator is turned off right now), and both the M-S setup and this dual-omni/mini-baffle setup provide that.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on August 31, 2017, 03:55:00 PM
^ You'll get best mono-compatibility the way you are doing it (Mid/Side, using only the mid for broadcast), along with more full-frequency-range stereoness in your stereo recordings, where you can bias the Mid/Side to L/R conversion matrix towards as much bidirectional Side as is necessary.  And that's likely to be advantageous given the fully mono PA feed.

Moke's IMO excellent sounding sample was made in what is probably the optimal situation for such a mini-baffle, or pretty much any baffled omnis.  That is, relatively close in to complex acoustic instrument sources.  The stereo image heard live from that perspective in the room will be wide due to the proximity to the group, so a mic setup which maximizes or otherwise emphasizes stereo width is unnecessary.  The stereo interest is mostly in the midrange and higher, and the relatively minimal stereo width at low and lower mid-range frequencies serves to solidify the overall image.  The omnis nicely capture all the detail, nuance, and frequency extension of the un-amplified acoustic instruments as well as a very natural sounding ambiance, and there is no audience or room noise problems to worry about.  That kind of situation is ideal for baffled omnis at the stage-lip or on-stage.

Two quite different situations to my way of thinking, except for being on-stage/stage-lip.

Title: Re: Oddball microphone techniques
Post by: Moke on August 31, 2017, 09:03:31 PM
Moke, I think that recording sounds great.  I'm not much of a classical music guy (I like it well enough, but rarely listen to it), but I've listened to this a couple times already.  I definitely want to try out a small baffle like that now (though sadly I don't have access to recording anything other than PA shows...which seem to be mostly mono anyway).

In louder music, you'll likely find a bit larger of a baffle size to be more fitting.  High amplitude bass can/will overwhelm a smaller baffle.  In my time in playing around with baffles, I found that I really liked a 8" baffle, and mics small enough to be flexible in placement in relation to the disc face; IOW, to be scaled correctly for the smaller baffle. Smaller baffle, closer to disc face spacing.
I still carry the 5" baffle in my recording kit, but don't use it much.
Title: Re: Oddball microphone techniques
Post by: Moke on September 02, 2017, 06:28:04 PM


Quote
..hoping that maybe, some day, somebody as kind, wonderful, helpful, and a dear friend, like Gutbucket, might help talk me througha mix. (sucking up enough, Lee?)
I owe you so much my friend. I originally came to TS asking about baffles back in 2006 and was immediately directed to you as resident expert!  More than happy to lend whatever expertise I can.

Lets test your patience :)

I've been looking for this recording since I mentioned it. Its not exactly as I remember it (from 2009), in terms of mic placement, but its close.  I've done this setup a few times now, and later eforts were with better time alignment than these images.  The center mic is about 5 or 6" in front of the omnis, as this was the only way that I could get it in close to the baffle, and centered, for this impromptu rigging.
Rigged as three mic recording:
DPA 4060 baffled omni stereo, with mics intentionally closer to baffle face for isolation (in hopes of doing something like a figure-eight response, and possible m/s rendering in post-edit).
DPA 4028 compact sub-card at 0º

I've found that if I invert the polarity of either 4060, that the sound opens up.
What seems to be happening, without the phase inversion, is the the 4028 is bringing the whole right side of the ensemble to center, and leaving the left side of the ensemble in a more stereo width spread. It seems to phase cancel the right side to a degree, bringing it to center.
If I invert phase on either 4060 track, one one track only, it opens back up again, bringing full stereo width, and proper right channel placement.

So, to set these tracks up for a quasi-m/s mix, which 4060 track should be phase inverted? It doesn't seem critical for a generalized mix, so, lets get it right for a possibe m/s rendering.
problem for me, and a proper m/s...
I'm a computer klutz, and, doing a proper m/s rendering is eluding me.  YOu've mentioned setting something like this up for a quasi-m/s rendering.
How? please and thank you.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on September 05, 2017, 11:01:38 AM
A few things you can try-

1) First I'd try keeping both omnis in positive polarity, and do some stereo widening on the omni pair before mixing with the center subcard.  The Subcardioid center mic is going be be providing plenty of monophonic mid signal, so by changing the balance of the omni contribution so that it is providing mostly Side info, the combination of the three mics should be much more open and well balanced.  Otherwise you end up with too much Mid buildup, sounding overly closed and narrow, as baffled omnis are relatively Mid-heavy through much of the spectrum to begin with and mixing in a dedicated center mic doubles up on the Mid content.

Widening is a Mid/Side type manipulation, typically done to a Left/Right stereo signal.  Depending on what editor you use, it might be available right on the channel strip as a simple knob twist (in Samplitude you can do it that way at the object level or at the stereo-track level in the mixer).  If not, here's a good free VST plugin for Mid/Side adjustment- http://www.voxengo.com/product/msed/ (http://www.voxengo.com/product/msed/).  It can also be used to convert from Mid/Side to Left/Right or vice-versa like most Mid/Side matrix plugins, yet this one has two M/S matrices available in series, so you can input Left/Right stereo and it will convert it to Mid/Side, allow you to readjust the balance ratio between Mid and Side, then covert back to Left/Right at it's output.  Using that, try increasing the wideness (more Side, less Mid) of the omni pair.  Both the input to the plugin and the output from it will be Left/Right stereo, and the Mid/Side adjustment will made entirely within the plugin.  Make the omnis as wide as it will allow- that is all Side and no Mid from the omnis, and mix that to taste with your center subcard.  This is doing a Mid/Side mix without having to do any mixer routing stuff, and such a mix should limit phase-cancellation issues since all the Mid is coming from the center mic, and all the Side from the omnis. 

Extra credit- You can also try widening the omnis to a somewhat lesser degree, in which case you'll be mixing some Mid contribution from the omnis with some from the center mic.  You'll probably want to use less center mic level that way, and it's possible you might get some phasing, which might be good or bad sounding.  But try it with the omnis "fully widened" first and compare against that.



2) You can do the routing manually.  Which is actually the same thing as above, but done a different way.  We're turning the omni pair into a dipole, at least partially, in place of a figure-8 bidirectional Side mic.  This is similar to what you are doing by inverting one omni channel or the other, but does so in a more balanced way by inverting one omni channel, summing them, mixing that sum with the center channel to produce stereo-Left, and mixing the polarity inverse of that sum with the center channel to produce stereo-Right.

To do that, first mix the Left-omni signal and the polarity inverted right-omni signal together.  Listen when you do that and carefully adjust the level of one channel or the other until you find the greatest degree of cancellation of bass frequencies in the resulting sum.  The greatest cancellation of bass frequencies indicates the most optimized and balanced di-pole sum.  Save the resulting mono mix of left-omni and polarity-inverted right-omni.  You now have two saved mono channels to work with- the center mic (the Mid-signal), and the sum of the omnis with one channel inverted (the Side-signal).

Now open your mixer screen with three channel strips.  Put copies of your omni-sum mono-mix on two of those channels, and your center sub-cardioid mic on the third.  Pan the center mic channel to center.  Pan one of he omni-sum channels fully Left.  Pan the other omni-sub channel fully right and invert it's polarity.  Then bring up all three faders.  You now have control over Mid verses Side balance (center mic fader level verses that of the other two channels in combination) and over left/right balance (the difference between of the two omni channels, without changing the center level).

Notice that in doing this you are inverting polarity twice- once in creating a mono-dipole Side signal from the two omnis. and once again in the Mid/Side to Left/Right matrix.  Other than the part about "balancing the level of the two omnis to find maximum cancellation", that's the significant difference between these techniques and what you have already tried by inverting polarity of one omni channel and then mixing the three original microphone channels directly.   This way you'll gain similar openness, but without the bass being reinforced on one side and cancelled out on the other, and with potentially improved imaging.



Both of the above techniques will only be effective at producing and preserving stereo information above the frequency at which the Jecklin disk begins working.   The addition of the center mic facing forward potentially provides more pickup of direct sound with increased presence and clarity (good) yet doubles up on the monophonic Mid information which decreases stereo width over that provided by the omnis alone (bad).   These techniques essentially reduce the Mid contribution from the omnis to make room for the center mic contribution.  To further increase the sense of openness and low frequency stereo-ness, you might try cutting the bass of the center subcard while boosting the bass of the omnis, in a complementary way so that the overall bass level remains the same.  That will increase the difference signal at low frequencies, similar to using a larger baffle, which should increase the overall sense of openness.
Title: Re: Oddball microphone techniques
Post by: Moke on September 11, 2017, 01:13:01 PM
Busy times here, getting ready for the fire season to erupt (brush clearance, fire fuel abatement touchups).
Hopefully your head is above water, and you're out of the wind.

Apologies for not replying sooner. I'm still trying to wrap my head around the complex way off doing this mix.  I've tried the simple method of just flipping polarity in the right channel, and then making micro-adjustments to all tracks, and have found a nice place.

So, I looked at the concert program for this particular show, and, followed that up with a search for one of the bass soloists, Andres Martin, and I found a video (two parts) on Youtube that shows the same show that I'm working on in this mix. And, in fact, you see my DPA4060 pair, and 8" baffle, and my partners Royer ribbon. The ribbon is at the stage lip, and my baffle is back at first row, about 4' or 5' apart.
You cannot see the DPA4028 up in front of the baffle, as it is out of view in that perspective.  But, it gets you an idea of what I' looking at in part of the mix. In the second half, I have two old school jazz players, sax and drums, on stage. So, I have a very strongly populated center image to deal with and sort out.
This is from the first set, and is a Bottesini bass duet/ w surrounding Hutchins players. I do not know the audo source; its better than most vid cam sound tracks. Nope, its brickwalled.
https://www.youtube.com/watch?v=aNSHWxe72yA
This is the baffled mic array in the video: http://taperssection.com/index.php?topic=96009.msg2239276#msg2239276

Challenge:
In the first set, getting mid-range players into the mix, while maintaining articulation of the bass duet soloists.
In the second set, having a tenor sax and drum player in the center field, both as acoustic players, articulation between those two solists, and surrounded by the frequency range sweep of the consort.
Its been a fun experiment.

my view of the same concert in the vid, below:
Title: Decorellation
Post by: Gutbucket on October 24, 2017, 06:34:10 PM
I haven't posted much in this thread recently.  I've drawn conclusions and logical extensions from each of these oddball techniques, all of which has informed the next incarnation to try out.  I still have variants I want to play around with, but for the most part I've settled down to what works best for me, and feel like I have a pretty good grasp of "why" this stuff works.  Yet I keep realizing more about the "why" part- both the technical aspects and the more philosophical angles, and I've had something of an "ah-hah" technical realization recently which is exciting to me because it fits a lot of the puzzle pieces together for me logically.

So much of recording is finding the right balance.  Here's a list of a few things which need to be in balance:

Tonal spectrum
Recording levels (neither to high, nor too low)
Loud/Quiet dynamics
Left/Right channel balance
Front/Back ambience
Near/Far psychoacoustic balance
Flat/Deep sonic perspective
Direct/Reverberant-diffuse sound balance

Also balancing things like:
Cost/Value
Effort/ROI
Enjoyment/Hassle
Simplicity/Complexity

I see finding an optimal balance for each of these things a key to success. I suppose its a basic philosophical tool that applies broadly in life-  Finding the good middle way.  The trick is realizing what needs to be balanced.

Recently I've realized a fundamental technical balance aspect which is pivotal to what I feel makes for a really excellent recording.  An aspect I've talked around, listened around, and designed microphone techniques around, but never really conceptualized directly in terms of "finding the right balance".  It has to do with the listening experience, and finding a balance between sonic immersion and sense of space on one hand and solid/sharp/clear directional imaging on the other.  On one hand we have the "I am there" experience, a sort of a right-brain experience gestalt thing, and a big part of the actual live music experience.   On the other we have the solid and clear stereo image aspect, presenting a seamless soundstage sonically in front of us with sources we can point to in specific places, a more left-brain experience, and one where most studio recorded material excels.

The "ah-hah" was realizing that the key to achieving both of those aspects is finding an optimal balance between the correlated and de-correlated components in a recording.

I've talked a lot about the importance of achieving low diffuse field correlation in a recording.  It's something I feel is critical and is a big part of what makes a recording sound ("feel") open, big, spacious, enveloping and "real", much like a live experience.  What I haven't realized as directly is that I've been finding an optimal balance between what should be corellated and what should be decorrelated to achieve an optimal balance of "there-ness" and "sharp-imaging", achieving lush depth with good closeness at the same time.

[Edit- Here is an excellent paper on the topic I recommend to anyone interested in digging deeper into the effects of decorrelation on stereo signals - The Decorrelation of Audio Signals and Its Impact on Spatial Imagery - Gary Kendall (1995)[/i] - http://www.garykendall.net/papers/Decorrelation1995.pdf (http://www.garykendall.net/papers/Decorrelation1995.pdf)]


More on this tomorrow and it's connection if I find time..


Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 25, 2017, 12:34:18 PM
Correlation is mysterious.  I'm talking here of audio signal correlation as a relationship between audio channels.

It's a measure of the phase relationship between signals.  Two signals might be identical in every way except for their phase relationship, in which case those two signals will sound identical when listened to individually.  Individually they have no particular correlation and they cannot have any correlation, the term is meaningless in isolation.  Phase correlation and all the attributes influenced by it are emergent properties having to do with the relationship between two or more signals.  It takes two to tango and this aspect simply does not exist at all until there is another signal present with which to compare the first.

This is different from most other audio signal aspect we think about - level, frequency balance, dynamics, direct/diffuse balance of the content - all attributes which exist in a single channel signal.  Correlation only comes into being when another signal interacts with or is compared to another.

Okay, how does that apply to microphone configurations and mix choices? We effect the correlation relationship between channels by choosing a microphone configuration.  We can also manipulate correlation during mixing.

What does correlation or decorrelation between channels sound like? Plug in your headphones and head over to this sample player on the hauptmikrofon site- http://www.hauptmikrofon.de/audio/diffusefield.html (http://www.hauptmikrofon.de/audio/diffusefield.html)

First listen to each of the samples using only one ear.  Just put the headphones on in such a way that you can only hear through one ear or the other, doesn't matter which.  Switch through the various samples, all of which were made using Scheops microphones. Astute listeners might notice a slight difference in low-frequency pickup between samples which relates to the pickup pattern of the microphones used.  The MK4 cardioid X/Y sample has a bit more very low bass content then the MK41 X/Y sample (and the M/S sample) which have a touch more low bass than the Blumlien sample (MK8).  But other than that each sample otherwise sounds essentially identical, does it not? (This step is to prove to yourself that the only significant difference is the low bass extension)

Now listen again with the headphones on normally through both ears.  The samples will sound very different from each other.  The difference is not subtle.  Its pretty amazing how similar the samples sound through one ear verses how different they sound through ears.  What you are hearing are differences in phase correlation between channels.

What's best? What's the take away from this?  The samples linked above are all of totally diffuse ambient content.  Its pretty clear that microphone configurations which produce low correlation between channels convey a more realistic sounding 3-dimensional sense of enveloping space.  That's a rather important attribute in a live music recording.  But is optimizing for that quality alone the best choice?  What's the trade-off, and what's the appropriate balance to try and find? 

In short- a correlated stereo signal, otherwise identical in each channel is heard as a narrow, sharply defined phantom image in the center of the stereo soundstage between the two speakers.  An entirely decorrelated signal is heard as a broad, diffuse, and open "cloud" of sound filling the entire space, possibly extending out beyond either speaker.  In both cases the content is essentially the same other than those imaging and spatial aspects. 

When we choose a microphone configuration we are manipulating this relationship, in addition to other relationships.  By using clever microphone arrangements with more than two channels we not only gain control over signal correlation so as to be able to optimize that aspect separately from other stereo aspects, we can also gain control over which portions of the sound are recorded with high correlation and which are recorded with lower correlation.

More on that next.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 25, 2017, 06:15:18 PM
There is a generally accepted convention that coincident microphone configurations produce "sharp imaging" yet can sometimes be sort of "flat and boring sounding".  And conversely that spaced microphone configurations produce "lush open sounding ambience" yet can sometimes be "loose and phasy with diffuse imaging".  There are elements of truth in that which I'm taking advantage of, but its important to note that its more complex than that over simplification.  I have spaced omni recordings which exhibit clear and distinct imaging, and the examples linked in the previous post provide a good example of some coincident configurations sounding very open and ambient. 

Ideally we'd like to have control over which sounds produce correlated signals and produce decorrelated signals in the recording.  It would be great to record the direct sounds which arrive through an imaginary front "window" which encompasses all the direct sound of interest (like the Stereo Recording Angle or SRA in William Stereo Zoom terms) in such a way that it is correlated and produces sharp imaging, while the sounds arriving from everywhere outside that window are recorded in such a way so as to be as decorrelated as possible.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 25, 2017, 06:15:37 PM
Obviously we can choose stereo microphone configurations and microphone pickup patterns which alter these things, but it's all tied with other things which may be more important to the recording.  Is is possible to find a way to tease these things apart in order to optimize and better-balance these elements with a bit more control?

Each of the samples at the hauptmikrofon link above were made with coincident microphone configurations, yet produce vastly different ambient impressions.  For those who may be thinking, "but there is no direct sound to judge the imaging aspects of the configurations used to record those samples", that's the entire point of the demonstration.  One of the most important things to balance is the ratio between direct and reverberant sound pickup of course, primarily by choice of recording position but also by to a lesser degree by choice of microphone pickup pattern and stereo microphone configuration.  While it is true that when used in a normal recording situation these microphone configurations will be picking up plenty of direct sound (hopefully in a good balance with the indirect diffuse sound) these examples are illustrative precisely because they specifically avoid direct sound, allowing us to clearly hear the differences in diffuse pickup without distraction. 

Like different coincident techniques producing various degrees of correlation in their pickup of the diffuse field, spaced techniques produce various degrees of correlation in their pickup of direct sound.  Direct sound arriving at both spaced microphones simultaneously will produce a correlated signal in the two channels which images sharply in the center on playback.  But that only holds true for central sounds arriving from along the center median plane.  The reproduced image of those center sources will be sharp and clear, even though the sources located off to one side or another may be are reproduced more diffusely.  For this reason, the well-known "hole in the middle" problem from overly-wide spaced omnis is something of a misnomer, the problem can be more appropriately described as "small island in the middle" between two other islands at the speakers locations.  This off-center decorrelation is frequency dependent as well as being dependent on the angle of incidence.  Low frequency content arriving from not overly far off the center line will be more correlated than higher frequencies arriving from the same location.  The specific shape of that frequency/correlation curve is determined by the microphone spacing and the angle of incidence.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 25, 2017, 06:35:53 PM
When we use a center microphone and mix it's signal to both left and right channels,  that signal has identical phase and is fully correlated across the left and right channels.  In combination with an otherwise overly-wide spaced or angled left/right pair, that addition can help "fill the hole in the middle" or rather "extend the boundaries of the center island" so that we get a more solid, clear and upfront soundstage.  Call it a sand-bar I guess.  We get the nice solid middle across the front and a wide, diffuse ambience at the same time.   Works very well and sounds much like the live experience.  This is why I like and commonly suggest 3-microphone techniques around here.  Its still pretty simple, but solves many problems and works really well.   A spaced omni pair plus a directional center mic goes a long way.  Or a less-widely spaced pair of directional microphones angled widely apart plus a directional forward facing center mic.

Nakamichi understood this way back when.  I know think of their 3-point stereo recording system essentially leveraging a simple way to manipulate the balance between the correlated and decorrelated elements of the sound.


Yet it's not perfect and won't satisfy rabid fans of pin-point stereo imaging. 

If we turn that center mic into a stereo pair, and choose a configuration for that which provides high correlation for all the direct sound arriving through the breadth of the SRA window, we can fill that window not just with clear upfront sound which also has with sharp directional imaging.  To do that we ideally need some uncluttered space to fill (a slight hole in the middle) and clear sharp-imaging correlated material to fill it with.  A wide spaced omni pair fits the first requirement and a narrowly directed coincident X/Y or M/S pair fits the second.   Four channels total.


Title: Re: Oddball microphone techniques
Post by: voltronic on October 25, 2017, 07:28:24 PM
Thank you so much for explaining this concept in a down-to-earth way.  I feel that I understand DFC more clearly after reading your mini-treatise.   :coolguy:

A few points in response:

1. I never understood the pinpoint imaging devotees.  In my experience, live music does not ever sound like that unless you are conducting or performing with the ensemble (sometimes not even then either; I've performed in really awful rooms where I can't hear the people 5 feet away).  There is always some degree of blur from even a close audience perspective, and DFC partly explains why certain arrays sound more "real" than others.

2. It should be emphasized that careful placement is equally as important as what array to choose, if not more so.  Manipulation of the direct / diffuse ratio in this way (preferably with knowledge of the Critical Distance of the room) is job 1.  I used to accept being forced outside of that zone; no longer.  It's just too, um, critical...
  :tomato:

3. It's good you mention that these common arrays don't necessarily work the same in all situations.  My recordings with the best balance of reasonably sharp imaging combined with very good ambiance have been from a simple pair of spaced omnis, set close, but narrowly spaced (i.e. the "European" model).  There still seems to be a lot of reluctance to doing that on this side of the pond.  Since being converted, I find that I can cover even very large ensembles this way, with no holes / blobs in the image.  Your 3-mic suggestion or dual-array setup with wide omnis is great (a lot of the classical orchestra guys do exactly that) but I would encourage those who can go close with AB omnis to try narrow spacings (40-60cm) as well.  I'm not sure how much correlation does or does not have to do with that.

Thanks again for sharing the knowledge and furthering intelligent discussion on this board.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 25, 2017, 08:09:16 PM
Good observations, I agree.

1) Yeah, the most important thing for me in a good live recording is a convincing spatiality and "sense of I am there".  Actual live music experience is far more about that than imaging.  If I have to make a choice I want realistic spatial capture over pinpoint imaging.  But what I really want is both!  And that's what a coincident pair in the center can provide.  Sort of the best of both worlds as long as you can get the blend right so the alternate aspects get along well and don't fight with each other.

2) Amen.

3) Nothing wrong with narrow-spaced omnis as a two channel technique in the right place.  To my mind that represents a sort of compromise, as do near-spaced configurations like ORTF, NOS, DIN, or what have you.  What do I mean by that, lumping omnis with near-spaced configurations?  Each of those is a somewhat different solution for balancing a whole lot of different things.  They are either coincident, nor wide-spaced and get some of both aspects going.  But that also means they don't achieve either in a fully exemplary way.  They can't provide fully decorrelated diffuse pickup and the direct pickup isn't fully correlated either, but represent an optimized compromise using only two channels.  Their strong point is simplicity and purity.  Straight two channel.  Two mics through to two speakers.  An argument for similarity to HTRF head-spacing can also be made for near-spaced configurations.  What I'm trying to do is move beyond the imposition of those compromises by combining techniques and using more channels.  More complex, yes.  Worth it to my ear.

But for most TS music tapers the problem is not being able to get a pair of omnis spaced far enough.  Its just a practicality thing.   I've seen plenty of near-spaced omnis in the section used on standard near-spaced mic-bars.  Too far away for that to work well IMHO.  On-stage, maybe.   Back in the audience even big mic bars can only go so wide with typical mics flown from a single on one stand.  That's wide enough for a stereo pair of omnis, but not really optimally wide with a center mic or pair.  Miniature omnis make sufficiently wide spacing a bit easier as you know.

I feel what I'm describing here is different than the general wide-space classical thing with a center pair and wide flanking mics to cover an orchestra.  This is more of a single array using multiple channels.  Than an addition of wide flankers and typically used at greater distances.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 25, 2017, 08:13:42 PM
Here's another way to do it using just 4 channels, which gives up some of the pin-point imaging but substitutes even more realistic "you are there" spatial qualities-

Instead of making the center mic an X/Y pair or M/S pair, use a center rear-facing directional microphone in addition to the front facing one.  Yes, I'm going through previously discussed oddball variants here, but I have a twist this time, which is what motivated all this discussion about correlation and decorrelation.  Mixing in a touch of that rear facing microphone sent to both left and right channels at the appropriate level does a lot to further improve the "you are there" spatial quality.  Others have tried it and reported the same positive results.  We've talked about this previously, both in this and in other threads here at TS.

I always wanted to somehow "stereoize" that rear-facing contribution so it was spread out a bit and didn't clutter up the middle.  I've thought about and experimented a few times with the most obvious solution- using a pair of rear facing microphones instead of a single one, but find it hard to justify the investment in yet another microphone, recording channel for it and all that.  Plus I have higher priority uses for additional channels.  This lead to thinking of various ways of decorrelating that center rear-facing channel signal in the mix-down stage, diffusely spreading out it's contribution across the soundstage.  There are various ways to decorrelate duplicated copies of the signal which are routed left and right.  Running it through a stereo reverb is the most common way, or some other pseudo-stereo effect, but that goes against the ethos of not modifying the sound in an obvious way.  Maybe it could be done subtly enough, but philosophically it rubs me wrong. 

I started looking into the particulars of methods of decorrelation, wondering how the manufacturers of matrix surround decoders and up-mixers do it.  I found lots of pseudo-stereo techniques.  Meh.  Older analog channel matrix surround decoders use decorrelation to help spread a single monophonic or two-channel surround signal across multiple surround speakers, and modern digital surround tech like Dolby Atmos, DTS-X, and Auro use decorrelation to up-mix to numerous surround speakers without localization to any one speaker.   This seemed the most promising.  The basics of the old analog matrix techniques are published at least.  I couldn't find much on their proprietary techniques but generally it involves symmetric left/right channel phase rotations using all-pass filters to altering the phase of one of the duplicate channels by 90 degrees and the other by -90 degrees (270 degrees?) making the two copies 180 degrees out of phase and providing full decorrelation.  Sometimes by some other amount but remaining symmetric (+/- 50 degrees say, retaining partial correlation).

How about just flipping polarity on one copy.  Old Halfler-surround difference-signal stuff.  Inverts the phase which reducing the correlation coefficient to zero.  Mixed back in with L/R the low bass would be attenuated on the inverted side and emphasized on the non-inverted side.  I've long thought the ideal way of doing this will involve duplicating the single channel and finding a way to alter the phase of one copy by 90 degrees and the other by -90 degrees (or +/- 50 degrees or whatever works best).  I have a phase manipulation Voxengo plugin to do experiment with this, but haven't gotten around to messing around with it enough.

Then I went the easy route..
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 25, 2017, 08:49:49 PM
I just ran the front and rear facing center directional channels thorough a Mid/Side decoder.  Forward facing channel as Mid, rear facing as Side.  Dialed in whatever width works best by ear.  Works great! 

This (or a narrow x/y center mic configuration) is what I suggest to most folks do who want to try this stuff-
Most 4 channel recorders have built-in Mid/Side decoders.  Record the front and rear facing mics to an adjacent channel pair on the recorder such that the front facing center mic will serve as the Mid channel and the rear facing one the Side channel.  Listen right off the recorder, balance playback levels of the wide-spaced pair alone first with the center channels muted.  Then unmute the center channels and switch in the Mid/Side decoder with it adjusted to 100% Mid / 0% Side and bring up the Mid/Side level until it balances appropriately with the wide mics.  What you have is the basic configuration of a wide spaced pair plus a center facing directional mic. The basic 3-microphone configuration providing the aforementioned advantages with lots of after the fact adjustability.

Next mute the wide-spaced pair and play with the Mid/Side width control.  As your bring up the rear-facing Side channel you 'pseudo-stereoize' the monophonic forward facing center with rear-facing audience reaction and hall ambience.  Find a nice sounding ratio setting.  Notice that this is not stereo in a Left/Right directional imaging sense.  There is no pinpoint imaging, there isn't even fuzzy left/right imaging, but an ability to make the sound either more direct and center-focused or more broadly diffuse and ambient.  Cool.

Okay, now note your preferred Mid/Side ratio setting, revert back to 100% Mid, and unmute the wide pair.  Bring up the center again to balance well with the wide mics like we did originally.  Notice that you now have Left/Right stereo again.  Mentally compare that to the mid/side pseudo-stereo.  Now the kicker- slowly adjust the Mid/Side ratio away from 100% Mid.  What you have essentially is a blend control between center and sides which does not reduce image width as it is increased like a further increase in Mid level will do.  It affects the smoothness of the blend between across the front between center and sides.  It simultaneously acts as a sort of depth-control going from up front and flatter (all Mid) to very deep and overly ambient (all Side).  Find the best compromise setting.

Note that the preferred setting is likely to be less wide than when listening to the Mid/Side pair alone.  You only need a little Side as you are getting sufficient stereo interest (and difference information) from the wide mics, but that little bit goes a long way.

I love this.  I've been going back through my four-channel LRCB recordings (Left/Right/Center/Back) and listening this way.  Its relatively simple, easy to do and fantastic sounding.
Title: Re: Oddball microphone techniques
Post by: voltronic on October 25, 2017, 09:06:22 PM
(You had two more posts as I was writing this, so pardon me if some of these points have been addressed.)

3) Nothing wrong with narrow-spaced omnis as a two channel technique in the right place.  To my mind that represents a sort of compromise, as do near-spaced configurations like ORTF, NOS, DIN, or what have you.  What do I mean by that, lumping omnis with near-spaced configurations?  Each of those is a somewhat different solution for balancing a whole lot of different things.  They are either coincident, nor wide-spaced and get some of both aspects going.  But that also means they don't achieve either in a fully exemplary way.  They can't provide fully decorrelated diffuse pickup and the direct pickup isn't fully correlated either, but represent an optimized compromise using only two channels.  Their strong point is simplicity and purity.  Straight two channel.  Two mics through to two speakers.  An argument for similarity to HTRF head-spacing can also be made for near-spaced configurations.  What I'm trying to do is move beyond the imposition of those compromises by combining techniques and using more channels.  More complex, yes.  Worth it to my ear.

You're absolutely correct that the single pair of narrow-spaced omnis is a compromise, but I'm just lucky that it seems to work for what I record.

I applaud you for pushing the envelope and innovating.  You should have some arrays named after you like a few of those people on GS.

But for most TS music tapers the problem is not being able to get a pair of omnis spaced far enough.  Its just a practicality thing.   I've seen plenty of near-spaced omnis in the section used on standard near-spaced mic-bars.  Too far away for that to work well IMHO.  On-stage, maybe.   Back in the audience even big mic bars can only go so wide with typical mics flown from a single on one stand.  That's wide enough for a stereo pair of omnis, but not really optimally wide with a center mic or pair.  Miniature omnis make sufficiently wide spacing a bit easier as you know.

I totally acknowledge that what I'm recording is in the extreme minority on this board, and narrow spaced omnis in the section would be not much better than just a single omni mic.

Early in my teaching career when I new next to nothing about recording, I used a pair of omnis maybe 20-30 ft from the stage, but on tall stands spaced 20-25 ft apart.  I recently pulled up some of those old recordings of student jazz bands and they sounded surprisingly good.  That's definitely not practical for typical TS recording!

I feel what I'm describing here is different than the general wide-space classical thing with a center pair and wide flanking mics to cover an orchestra.  This is more of a single array using multiple channels.  Than an addition of wide flankers and typically used at greater distances.

For sure.  I'm just drawing comparisons with the classical / acoustic side of recording.  What you're describing reminds me a bit of the Faulkner 4-mic array in that one of the goals is to compensate for farther distance with multi-channel forward pickup.


Since very wide set omnis are logistically impractical in taper situations, I can now see how your spidery multi-DPA setups with APE spheres make sense within the current discussion.  Correct me if I'm wrong, but it seems you're getting greater decorrolation to work with by using the rearward pointing mics, combined with the fact that they are all spaced some distance apart, with the benefit of adjusting the amount of it in your mix.  Drawing another parallel with classical recording, I once saw a video of a professional engineer setting up to record a pipe organ album in a large Gothic cathedral.  He used an array of 4 DPA 4006s all on the same bar with the diffuse grids.  One pair pointing straight ahead about 50 cm wide, the other pair a bit wider but facing to the rear and angled 45deg outward off center.  That setup obviously had other goals, such as fully capturing the acoustic.

The ultimate, I suppose, would be getting everything you're describing into a physically compact setup.  Perhaps the multichannel systems developed for surround ambiance could be adapted to music recording.  The 8-channel Schoeps ORTF-3D setup certainly looks like a good candidate, but I imagine the typical taper doesn't roll up with an $18k+ mic setup!

Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 25, 2017, 10:10:49 PM
Early in my teaching career when I new next to nothing about recording, I used a pair of omnis maybe 20-30 ft from the stage, but on tall stands spaced 20-25 ft apart.  I recently pulled up some of those old recordings of student jazz bands and they sounded surprisingly good.  That's definitely not practical for typical TS recording!

Not practical but its been done plenty of times.  Numeous examples of those kids of wide splits for Grateful Dead taping, and a taping aquaintence used to do the same at the Spirit of the Suwannee Music Park ampitheater in Live Oak, FL (where I've developed a lot of these techniques) with stands at either corner of the SBD area.  IMO it works without an egregeous hole in the middle because the PA content is predominantly mono (yes even the 'good stereoised' Dan Healy Dead mixes) and as long as the time of arrival distance is about the same from the PA stack on each side to the mic on each side, that mostly monophonic content will translate as correlated material filling the center of the playback image.  I speculate it may enhance any stereo PA effects content such as stereo verbs, choruses, double-mic'd leslie cabinets etc, and it should completely decorrelate all the venue ambience and audience reaction down to the very lowest frequencies.

Quote
What you're describing reminds me a bit of the Faulkner 4-mic array in that one of the goals is to compensate for farther distance with multi-channel forward pickup.

Quote
Since very wide set omnis are logistically impractical in taper situations, I can now see how your spidery multi-DPA setups with APE spheres make sense within the current discussion.  Correct me if I'm wrong, but it seems you're getting greater decorrolation to work with by using the rearward pointing mics, combined with the fact that they are all spaced some distance apart, with the benefit of adjusting the amount of it in your mix.  Drawing another parallel with classical recording, I once saw a video of a professional engineer setting up to record a pipe organ album in a large Gothic cathedral.  He used an array of 4 DPA 4006s all on the same bar with the diffuse grids.  One pair pointing straight ahead about 50 cm wide, the other pair a bit wider but facing to the rear and angled 45deg outward off center.  That setup obviously had other goals, such as fully capturing the acoustic.

Yes, there are definite parallels with the phased-array stuff.  And with David Greisinger's 5 mics in a line across the front of the stage technique.  At some point I'll post thoughts about all that.  There is phase-array antenna theory and is Hass-delay presence and clarity enhancement stuff going on, especially with the bigger 6 channel arrays I've posted about, but I think its also a factor with just 3 points/mics in a line.  Besides being far more practical, I've found going wide with additional mics is better than going deep, that is to say adding mics out to the sides rather than a pair further behind the main pair, perhaps because it preserves arrival transients from frontal direct sound instead of smearing them out.  One can always slightly delay the ambience/surround/rear-facing mics if necessary, which also servers to further decorrelate them from the main channels.

Quote
The ultimate, I suppose, would be getting everything you're describing into a physically compact setup.  Perhaps the multichannel systems developed for surround ambiance could be adapted to music recording.  The 8-channel Schoeps ORTF-3D setup certainly looks like a good candidate, but I imagine the typical taper doesn't roll up with an $18k+ mic setup!

I've pulled a lot of ideas from various surround ambience recording arrays.  One way to think of the 4 directional mics at the center of of my 6-channel setup is as a bastardized IRT-cross turned 45 degrees so it faces front/left/back/right instead of left-front/left-back/right-back/right-front.  I've gotten this thing very physically compact using low voltage DPA miniature omnis and supercards powered by PFAs mounted on the folding the telescopic antennas. Since its all wired up and ready to go I can typically set up and break down considerably faster than most 2-channel tapers who break everything.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 25, 2017, 10:13:37 PM
Getting back to a few final thoughts on the 4-channel setup with center front and rear facing mics run through the Mid/Side decoder-

So what is this bastard Mid/Side decode thing actually doing?  It's decorrelating the rear facing channel by mixing a phase-inverted copy into the left and right channels.  The Mid/Side ratio control simply makes for an easy way to balance it against the forward facing mic.

So I have the primary wide microphone pair providing open decorrelated ambiance along with some correlated information- enough correlated information to provide left/right directional imaging, but preferably set a bit wider than I'd want from that pair if used alone (more of a dent than a hole in the middle).  I have the forward facing center directional microphone channel which maximally focuses on the direct sound arriving though the front 'window' of primary interest and excludes the audience and hall ambience as much as possible providing only correlated information (its signal is routed to left and right identically).  And I have the rear facing directional mic channel information fully decorrelated, clearing it out of the center of the playback image and acting as a blend and depth control between the wide ambient omnis and the up-front present center mic.
Title: Re: Oddball microphone techniques
Post by: voltronic on October 26, 2017, 06:03:56 AM
Getting back to a few final thoughts on the 4-channel setup with center front and rear facing mics run through the Mid/Side decoder-

So what is this bastard Mid/Side decode thing actually doing?  It's decorrelating the rear facing channel by mixing a phase-inverted copy into the left and right channels.  The Mid/Side ratio control simply makes for an easy way to balance it against the forward facing mic.

So I have the primary wide microphone pair providing open decorrelated ambiance along with some correlated information- enough correlated information to provide left/right directional imaging, but preferably set a bit wider than I'd want from that pair if used alone (more of a dent than a hole in the middle).  I have the forward facing center directional microphone channel which maximally focuses on the direct sound arriving though the front 'window' of primary interest and excludes the audience and hall ambience as much as possible providing only correlated information (its signal is routed to left and right identically).  And I have the rear facing directional mic channel information fully decorrelated, clearing it out of the center of the playback image and acting as a blend and depth control between the wide ambient omnis and the up-front present center mic.

Could you accomplish something similar by replacing the front/rear center mics with a single forward-facing fig8?  It would be like a double-MS but rotated 90 degrees.
Title: Re: Oddball microphone techniques
Post by: thatjackelliott on October 26, 2017, 09:54:57 AM
Instead of making the center mic an X/Y pair or M/S pair, use a center rear-facing directional microphone in addition to the front facing one. 

Instead of using two mics in the center -- one directional forward-facing mic and one directional rear-facing mic -- would a figure-8 work?

(EDIT: Looks like voltronic beat me to the punch on this question.)
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 26, 2017, 11:45:04 AM
A single figure-8 in the center should work, but not in the same way. Probably fine if there is minimal ambient sound in back and you are limited to 3 channels. 

I've considered trying that, partly as a way of getting the narrowest front directivity possible with maximum rejection to either side.  But my main concern is that it gives up the exclusive forward focused directivity that a forward-facing center mic provides and which I feel is such a valuable core component in these setups.  Over the years of playing with this, I've moved from omni (sphere-mounted) to cardioid to supercardioid as the forward-facing center microphone to get the most forward focused directivity possible, other than moving to a shotgun mic.  After all, this is about distance recording even when I have it setup FOB in the center of the action or closer, and that center mic is the only one I'm pointing directly towards the stage.  Its forward focus excluding audience and room as much as possible is important.  It functions as sort of a "direct SBD-substitute" in the array.   Even with the 6-mic array, that center mic is the only one actually facing forward! (Although with all microphones basically spaced along a line, the sideways facing mics and wide omnis all contribute to the overall forward directivity of the entire setup in a "phased-array" sense)

The problem is that a figure 8 in that position is equally sensitive front and rear, you give up the ability to adjust how much rear facing stuff gets picked up, and the rear-facing information cannot be not spread out and decorrelated.  It's inseparable from the front focus stuff and imposed upon it.

If one has a figure 8 available, I'd use it in the center mounted coincidently with another microphone to form a Mid/Side pair in one of two ways-
1) Mount it facing sideways along with a forward facing directional microphone as mentioned previously, to provide center blend control between the wide pair and the center mic.  Center mic should be a cardioid, supercard, or a shotgun.  I'd feel somewhat less hesitant to use a shotgun mic in the center if I had an 8 coincident with it, due to this blend advantage.  That's because a shotgun is tighter-focused at high frequencies (good here, but blend may become more important), commonly has off-axis coloration issues (mitigated in this case by the other mics in the array providing ambient content and hiding those anomalies), and likely has a significantly different timbre than the wide pair, so I suspect making it blendable via Mid/Side would be especially advantageous.

2) Do it as I think you are suggesting voltronic, by mounting it facing forward, coincident with an omni (you need the omni to make this work).  You then have a "Strauss Packet" omni/bi-directional arrangement and can dial in whatever forward-facing and rear-facing directional patterns you like.  It acts as a front/back facing Mid/Side pair so you can choose the directivity of both the front facing virtual microphone and a rear facing one.  If versed in Mid/Side decoding, you could even use a different Mid/Side ratio for each and dial in whatever works best, say a supercard-ish forward-facing pattern (for maximum forward focus) and a cardioid rear-facing pattern (for maximum front rejection in the rear facing microphone).  Disadvantages of doing that compared to using two directional mics is that you need to Mid/Side decode it, a figure-8 is more wind noise sensitive, and there is no spacing between the front and rear facing microphones.  Jury is still out on how much front/back spacing matters.

I can do that in a similar way by putting the TetraMic in the center, which makes for an attractive variant.  I tried this years ago in my initial tests with the TetraMic between spaced omnis, before I started using it pretty much exclusively on-stage, and now think I may to revisit it as a second main rig.  Would make for a 3-point arrangement with the TetraMic between spaced omnis.  Need four recording channels for the TetraMic, so even through there are only three mic positions that's 6 recorder channels including the spaced omnis.  The TetraMic is ambisonic (3D Mid/Side basically - essentially three virtual figure-8's + omni) so I could dial in a number of virtual coincident mics adjusting the pattern and angle to whatever works best aferwards- say a narrow-angled forward-facing supercardioid X/Y pair, and a wider-angled rear-facing pair.  This will be a good test of how much spacing matters, as my primary rig has the four spaced supercardioid pointing in the cardinal directions.

Title: Re: Oddball microphone techniques
Post by: heathen on October 26, 2017, 01:36:00 PM
I can do that in a similar way by putting the TetraMic in the center, which makes for an attractive variant.  I tried this years ago in my initial tests with the TetraMic between spaced omnis, before I started using it pretty much exclusively on-stage, and now think I may to revisit it as a second main rig.  Would make for a 3-point arrangement with the TetraMic between spaced omnis.  Need four channels for the TetraMic, so even through there are only three mic positions that's 6 recorded channels.  The TetraMic is ambisonic (3D Mid/Side basically - essentially three virtual figure-8's + omni) so I could dial in a number of virtual coincident mics- say a narrow-angled forward-facing supercardioid X/Y pair, and a wider-angled rear facing pair.  This will be a good test of how much spacing matters, as my primary rig has the four spaced supercardioid pointing in the cardinal directions.

To this point, could you duplicate the B-format TetraMic tracks and make a separate virtual coincident configuration for the rear?  So basically, you'd create your virtual pattern that faces forward, then do it again for the rear?

Forgive me if this is an idiotic question...I'm way out of my depth here but can't resist the curiosity.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 26, 2017, 02:55:40 PM
Yes, exactly.  That's basically what I just described.  You can derive as many virtual mics as you like pointing in any direction from that one point in space.  Diminishing returns beyond 4 virtual mics, due to all of them being coincident in one point in space (plays into the "how much does spacing matter" question).  But no more than that is needed for this.  Most often I'm just deriving a single stereo pair.  In this case I could make a single forward facing mic and rear facing mic to emulate the setups I'be been talking about, but might as well turn those single and rear facing mics into stereo pairs.

There are different ways to convert the native 4-channel A-format from the mic to universal Ambisonic B-format or directly to usable virtual microphone outputs.  No need to duplicate B-format tracks to do that.  I run the A-format through a conversion program which allows me to set a microphone angle (pointing in any direction) and pattern (any first order pattern from omni through bi-directional) for any number of virtual microphone outputs.  That program outputs those virtual microphones to individual or stereo files which I then use in the mixdown.  This bypasses the need to convert to B-format first that way, although that format is best for archiving the files.  Alternately there are VST plugins which work within your mixing software.
Title: Re: Oddball microphone techniques
Post by: heathen on October 26, 2017, 03:02:00 PM
Figures that I was being boneheaded.   :facepalm:  I was locked into thinking about converting B format to just a stereo pair...but of course you're correct that it's not that limited! 
Title: Re: Oddball microphone techniques
Post by: thatjackelliott on October 26, 2017, 03:23:04 PM
Well, this is interesting. Gutbucket, in my music festivals stage-lip setups, where mono-compatibility is paramount, and I'm using a Mid-Side (forward-pointing hypocard mid and sideways-pointed figure-8) arrangement augmented by a direct sound board feed, could this oddball rear-facing directional mic technique be of benefit? I'd like to try in next Summer Festival.

I have up to six mic inputs available, but need to do the mixing in real time. I dematrix (or is it matrix?) the Side mic discretely by splitting the its signal into two paths, flipping polarity on one with an inline xlr polarity-swapping adapter, putting those into the mix with pans hard left and right -- a standard method. I then have level controls for soundboard, mid, and left/right (ganged). Can your rear-mic / mid mic matrixing trick be used in real time with a similar wiring trick?
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 26, 2017, 05:31:24 PM
Quote
  I then have level controls for soundboard, mid, and left/right (ganged).

The rear-mic / forward-mic matrixing trick I'm doing is pretty much the same thing you are doing.  It just substitutes the rear-facing microphone for a bi-directional Side microphone.  In either case the output of that channel is routed Left/Right and polarity-inverted in one channel in the mix, and will null when summed to mono, cancelling out its contribution.

Sure, you could likewise use an audience facing microphone in place of the sideways-facing figure-8.  You'd get more audience reaction and sense of ambient depth in the stereo mix rather than the Left/Right stereoization you get from the figure-8 in your stereo mix.  And that additional audience reaction and ambient depth would be absent in the mono FM feed, just as the stereoization provided by the Side mic goes absent in the mono FM feeed with your current arrangement.

Currently you select how much audience sound you get in both the stereo and mono version by choice of mid pattern.  You used an omni and the audience level balance should remain about the same in the stereo an mono versions.  If you want a less audience, yet want what audience you do get to remain the same level in both the stereo and mono outputs, stick with your current setup and switch to a sub-cardiod or cardioid Mid.

Title: Re: Oddball microphone techniques
Post by: kuba e on October 26, 2017, 05:47:31 PM
I just ran the front and rear facing center directional channels thorough a Mid/Side decoder.  Forward facing channel as Mid, rear facing as Side.  Dialed in whatever width works best by ear.  Works great! 

This (or a narrow x/y center mic configuration) is what I suggest to most folks do who want to try this stuff-
Most 4 channel recorders have built-in Mid/Side decoders.  Record the front and rear facing mics to an adjacent channel pair on the recorder such that the front facing center mic will serve as the Mid channel and the rear facing one the Side channel.  Listen right off the recorder, balance playback levels of the wide-spaced pair alone first with the center channels muted.  Then unmute the center channels and switch in the Mid/Side decoder with it adjusted to 100% Mid / 0% Side and bring up the Mid/Side level until it balances appropriately with the wide mics.  What you have is the basic configuration of a wide spaced pair plus a center facing directional mic. The basic 3-microphone configuration providing the aforementioned advantages with lots of after the fact adjustability.

Next mute the wide-spaced pair and play with the Mid/Side width control.  As your bring up the rear-facing Side channel you 'pseudo-stereoize' the monophonic forward facing center with rear-facing audience reaction and hall ambience.  Find a nice sounding ratio setting.  Notice that this is not stereo in a Left/Right directional imaging sense.  There is no pinpoint imaging, there isn't even fuzzy left/right imaging, but an ability to make the sound either more direct and center-focused or more broadly diffuse and ambient.  Cool.

Okay, now note your preferred Mid/Side ratio setting, revert back to 100% Mid, and unmute the wide pair.  Bring up the center again to balance well with the wide mics like we did originally.  Notice that you now have Left/Right stereo again.  Mentally compare that to the mid/side pseudo-stereo.  Now the kicker- slowly adjust the Mid/Side ratio away from 100% Mid.  What you have essentially is a blend control between center and sides which does not reduce image width as it is increased like a further increase in Mid level will do.  It affects the smoothness of the blend between across the front between center and sides.  It simultaneously acts as a sort of depth-control going from up front and flatter (all Mid) to very deep and overly ambient (all Side).  Find the best compromise setting.

Note that the preferred setting is likely to be less wide than when listening to the Mid/Side pair alone.  You only need a little Side as you are getting sufficient stereo interest (and difference information) from the wide mics, but that little bit goes a long way.

I love this.  I've been going back through my four-channel LRCB recordings (Left/Right/Center/Back) and listening this way.  Its relatively simple, easy to do and fantastic sounding.

Gutbucket, thank you, it is great. Do you think we can use this configuration even in a small clubs with good acoustics or is this method only for outdoors and big halls?

I also would like to ask if the forward and rear microphones must be coincident? If the  forward and rear microphones are spaced, can we neglect the comb filtering in Mid-Side mixing? Or is there need for minimal spacing?
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 26, 2017, 06:05:48 PM
Sure, it can work in small clubs.  And no the mics don't need to be coincident.  Mine aren't. In the rigs I've talked about here I have about a 12" to 15" spacing between the front and rear facing mics.  That could probably be less without issue.  As mentioned I'm not sure if coincident would be quite as good, but front/back spacing isn't nearly as important as left/right spacing.  It works great on my stealth recordings made with 4 baffled omnis pointing in each direction. Front/Back separation is probably 8" in that case, left/right about 20", but the omnis are made directional by the baffling so the narrower left/right spacing works fine. Part of the coolness is you dial in as much rear mic as is appropriate using the width control. If you want none in there no problem, but even in small clubs I usually want some.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 26, 2017, 06:26:42 PM
Perhaps the multichannel systems developed for surround ambiance could be adapted to music recording.  The 8-channel Schoeps ORTF-3D setup certainly looks like a good candidate, but I imagine the typical taper doesn't roll up with an $18k+ mic setup!

[edit] ^ except Mike Grace recording Phish at Red Rocks.[/edit]

I can't really image the stretch to recording and reproducing height information as well, except maybe binauraly via headphones. But most folks consider me crazy recording 6 channels for horizontal surround!   I have a few ideas about what I feel would be more productive use of 8 recorded channels and have done a few tests, but still with a playback target of standard 2-channel, or 5 to 7 channel surround playback.  I think I'm reaching the point of diminishing returns now, but I've thought (hoped?) that in the past before moving this far, yet the further additions were always too compelling to dismiss once I figured out how to take advantage of them.

I suppose if virtual binarual 3-D playback really takes hold and these kind of setup become available at reasonable cost in easy to use formats - plug a future low-cost ORTF-3D blimp competitor into your phone or something.  But outside of the film and TV world where these tools are justified professionally, its hard to sell a quality system like the Schoeps ORTF-3D on the consumer market, when a smaller, more compact, far less costly and complex systems are available, even if the results aren't truly comparable.  Small, low-cost and simple wins over quality most every time in the consumer world.  People generally want something they can just plug in or stream to their phone.  Convenience trumps quality.

But even if Schoeps ORTF-3D is totally over the top for tapers, you raise an interesting point.  8-channel ORTF-3D is basically two 4-channel ORTF-surround setups, one angled down, the other up.  In turn, ORTF-surround is basically two back-to-back standard 2-channel ORTF setups.  It's a straight geometric progression from 1D to 2D to 3D.  Similarly IRT-cross is nothing more than two back-to-back DIN setups forming a square.  It could also be extended to an 8-channel 3D cubic array.

Here's the prototype ORTF-3D setup as a cubic array, prior to squashing to something more compact and marketable (notice that it's using two standard IRT-cross mounting bars)-

(http://www.hauptmikrofon.de/images/2014_01_ORTF3D_026_.jpg)


A motivated taper could rig that up with inexpensive AT or CA mics into an F8 at around the same cost of a top-quality 2-channel Schoeps setup.  These setups get costly because of channel count using quality microphones, but as logical extensions of the basic near-spaced 2-channel mic techniques, they aren't difficult to understand.  We now have the recorders available at reasonable cost.

What that prototype really needs for music recording is a SchoepsCMIT shotgun extending forwards!  I joke, but it's true.  That thing takes care of the ambient stuff in a fully open and airy 3-D better than an ambisonic mic can (due to the more optimal spacing).  Mix it with the SBD and or add a forward facing directional mic for the direct sound component to make it more music suitable.

But then you start optimizing for music recording with a preferred axis and that nice symetric cube becomes more and more stretched and distorted- the front mics point further to the sides to work correctly with the added center mic and so as not to not be overly dominated by the direct sound.  You then approach the geometry of music oriented horizontal-surround configurations like Williams MMAD or OCT-surround setups.. or these odd-ball mishmash combinations of all these approaches.


I'm surprised I've not heard of any tapers dabbling in surround by simply pointing a second near-spaced stereo pair backwards behind their favorite forward facing near-spaced setup, especially the DMB tapers a decade back or so who were messing around with 4-channel surround and producing DTS encoded files.  Just clamp a second DIN rig on the same stand facing backwards and run it all into a 4-channel recorder.  No extra gear needed.  Easy entry to quad surround and should be far better than the few DMB DTS surround attempts I've heard with SBD sent to the front speakers and AUD to the surrounds.  If they had SBD, then route that to the center channel if they wanted to extend from quad to 5 channel in an acoustically optimal way, or stick with quad and mix the SBD in with the forward facing near-spaced L/R pair.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 26, 2017, 06:47:10 PM
I have a few ideas about what I feel would be more productive use of 8 recorded channels and have done a few tests, but still with a playback target of standard 2-channel, or 5 to 7 channel surround playback.

Namely, this involves placing front/back facing bi-directionals coincident with the wide-spaced omnis.  I could then do the "strauss packet" Mid/Side thing on each side and have control over front/back direct/ambient balance in each of the spaced omnis.  Split the output to the front and back speakers as appropriate.  That's probably more useful for surround playback than 2-channel, where I could effectively have a pair of wide spaced rear facing cardioids feeding the surrounds which exclude direct sound pickup from the front as much as possible.  That's motivated by the excellence of the wide omnis as surround feeds, except they typically have about 6dB too much direct sound in them to be able to raise the surround level to what would be optimal.  Subsequently I've gone back to using the sphere attachments on the omnis and pointing them rearwards.  Still works fine in the 2-channel mix but doesn't' quite achieve the 6dB difference I'm seeking.

The obvious and simpler answer is to stick with 6 channels and switch to rear-facing wide-spaced subcards instead of omnis. Could do that with the discontinued and now elusive AT 853 subcards.  Anyone have a pair for me?

Practically its very hard to support anything way out there on the ends of the TV antennas except miniature mics.  A miniature light-weight low-voltage figure-8 doesn't exist.

Title: Re: Oddball microphone techniques
Post by: kuba e on October 26, 2017, 07:06:16 PM
Sure, it can work in small clubs.  And no the mics don't need to be coincident.  Mine aren't. In the rigs I've talked about here I have about a 12" to 15" spacing between the front and rear facing mics.  That could probably be less without issue.  As mentioned I'm not sure if coincident would be quite as good, but front/back spacing isn't nearly as important as left/right spacing.  It works great on my stealth recordings made with 4 baffled omnis pointing in each direction. Front/Back separation is probably 8" in that case, left/right about 20", but the omnis are made directional by the baffling so the narrower left/right spacing works fine. Part of the coolness is you dial in as much rear mic as is appropriate using the width control. If you want none in there no problem, but even in small clubs I usually want some.

Thank you very much, I'm looking forward to trying this. I will write how it will turn out.

Audience recording is so creative field - microphone arrays, stealth four baffled omnis, ortf-3d with shotgun ...The theory that is behind is also very interesting.
Title: Re: Oddball microphone techniques
Post by: thatjackelliott on October 26, 2017, 08:36:41 PM
Quote
  I then have level controls for soundboard, mid, and left/right (ganged).

The rear-mic / forward-mic matrixing trick I'm doing is pretty much the same thing you are doing.  It just substitutes the rear-facing microphone for a bi-directional Side microphone.  In either case the output of that channel is routed Left/Right and polarity-inverted in one channel in the mix, and will null when summed to mono, cancelling out its contribution.

So lemme see now. (Begins to count on fingers.)
Now I can adjust the ratio of dry soundboard and wet stage sound for the mono-compatible signal. Two faders so far.
On to Stereofication:
Now I have a means to adjust stereo spread without munging the center/mono signal.
That's four faders.
Then, the final frontier of . . . is there a name for this? Magically Delicious Decorrelated Ambience?
A grand total of six faders.

Is this accurate? Totally sounds like wiring geek fun.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 27, 2017, 09:44:06 AM
^ Shure.  No need to choose one or the other when you can have both.

Quote
The Rear-facing mic is treated just like the Side mic: split, invert one side, bang into two ganged channel strips with hard left/right pan.

Care to go further down the rabbit hole Alice? If you decide you want some of that rear-facing audience stuff in the mono sum, you can unbalance the levels of those ganged channel strips a bit (just make sure you don't make its contribution overly lopsided in the stereo output), or make some other change between these two channel strips, such as a subtle stereo delay or verb which is different on each side, or a complementary EQ which alternately boosts one side where the other side is cut, simple to do on a graphic by alternating sliders slightly in opposite ways for each side up and down the spectrum).  Whatever difference you impose between the original and the polarity inverted copy won't cancel out in the mono sum.  Bigger difference = more of it in the mono mix.  No difference with perfectly matched levels = none of it in the mono mix.
Title: Re: Oddball microphone techniques
Post by: thatjackelliott on October 27, 2017, 10:30:49 AM
Got it (echo echo echo from the bottom of the rabbit hole*). The split/inverted rear mic signal nulls out if summed 1:1, so imbalancing it will let some rear mic bleed into the mono mix. This can be used to fade the audience during soft songs, and bring them back in for applause. Me very likee. What mic pattern for the rear? I have cards and subcards. Stage lip setup. Probably to help reject the PA stacks I'll try a card.

I monitor live with headphones. They are noise-canceling, which is helpful when trying to listen to the mix, but they are headphones and when it comes to stereo spread and imaging, I prefer speakers. All I can do the first time I try this is to make a guess about the right amount of decorrelated rear/audience/room to add to the main mix. However, I will be recording the mics separately for later mixdown, so after the festival when I get a balance that I like on the speakers, I will see what the mix looks like on a goniometer/vectorscope plugin and use that as a rough guide for the next live broadcast.

This stuff is fun.

* Or is this the bottom? Deeper layers of mic geekery?
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 27, 2017, 10:48:09 AM
Wonderland is bottomless AFAIK. Avoid tousles with the red queen.

Yeah, you'll want to try and reduce pickup of the PA and stage in that mic as much as possible.  An audience facing cardioid is probably the ticket.
Title: Re: Oddball microphone techniques
Post by: thatjackelliott on October 27, 2017, 11:58:30 AM
How coincident to the Mid/center mics would the rear-facing mic want to be?
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 27, 2017, 12:41:47 PM
Don't need to be coincident.  Think of it like room ambience mics.  Only need coincidence for the M/S front facing pair intended to provide left/right stereo imaging. 

From a few posts back in the context of my array-
I also would like to ask if the forward and rear microphones must be coincident? If the  forward and rear microphones are spaced, can we neglect the comb filtering in Mid-Side mixing? Or is there need for minimal spacing?

Quote
..the mics don't need to be coincident.  Mine aren't. In the rigs I've talked about here I have about a 12" to 15" spacing between the front and rear facing mics.  That could probably be more or less without issue.  As mentioned I'm not sure if coincident would be quite as good, but front/back spacing isn't nearly as important as left/right spacing.

Title: Re: Oddball microphone techniques
Post by: rocksuitcase on October 27, 2017, 12:46:21 PM
Sure, it can work in small clubs.  And no the mics don't need to be coincident.  Mine aren't. In the rigs I've talked about here I have about a 12" to 15" spacing between the front and rear facing mics.  That could probably be less without issue.  As mentioned I'm not sure if coincident would be quite as good, but front/back spacing isn't nearly as important as left/right spacing.  It works great on my stealth recordings made with 4 baffled omnis pointing in each direction. Front/Back separation is probably 8" in that case, left/right about 20", but the omnis are made directional by the baffling so the narrower left/right spacing works fine. Part of the coolness is you dial in as much rear mic as is appropriate using the width control. If you want none in there no problem, but even in small clubs I usually want some.

Thank you very much, I'm looking forward to trying this. I will write how it will turn out.

Audience recording is so creative field - microphone arrays, stealth four baffled omnis, ortf-3d with shotgun ...The theory that is behind is also very interesting.
When we have been running the center rear and fwd facing mics, we have tended to use cards (ck61's) and they have been anywhere from 8-16 inches apart. We have tried the center fwd using AKG ck8 "shotgun" then using a ck61 for the rear.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 27, 2017, 01:13:06 PM
Kyle, try the front/back Mid/Side thing, I've had you in mind. 

Somewhat more confident in my smaller club recommendation after discussing your variants.  My primary hesitation in small clubs are the omnis and the rear mic..

But may give the 6-channel outdoor-intended rig (with wide omnis and rear) a go at Magpie Salute in a medium sized indoor club tonight.  Partly because that rig is all setup and I'll be pressed for time, meaning its easier to run than reconfigure for what I'd normally do in that room.  May be a good test even if the omnis aren't ideal in that space (my suspicion).

What I'd normally do in that room as a small-club variant of all this is run 4 channels with the Gefell supercards replacing the wide omnis, spaced around 2' apart and angled around +/- 45 degrees (more or less pointing outside of stacks) with a M/S pair in the center (DPA 4098/Naiant X-8S), without a rear-facing microphone.  That spacing is what works with the mounting system I use there.  Its also more compact aloft, more forwardly directional, and more tailored in low-frequency pickup to typical indoor club applications.
Title: Re: Oddball microphone techniques
Post by: kuba e on October 28, 2017, 06:01:23 AM
When we have been running the center rear and fwd facing mics, we have tended to use cards (ck61's) and they have been anywhere from 8-16 inches apart. We have tried the center fwd using AKG ck8 "shotgun" then using a ck61 for the rear.

Rocksuitcase, was it a big change when you used ck8 as the forward microphone?

My primary hesitation in small clubs are the omnis and the rear mic..

I'm going to record in a small club in a month and a half. I'm sending pictures of the club. There is a beautiful sound. Do not be fooled by the big windows, they were able to solve the acoustics. For me it's a mystery how they did, but they have the best sound in the city.
I do not record often there. But when I am taping, I usually do an audience recording by the soundboard in the back of the room. (For some reason, I have never made a good balanced stage lip recording and sbd feed sounds little strange there). It is a great sound by the soundboard, I can record with an omni pair there. PA is slightly stereo, but it's negligible in the room. Here is an example of recording - naks omni, spaced 1.5', by sbd.
https://drive.google.com/file/d/0B0lpmTYweTrEVFhYbFozcTktdms/view?usp=sharing

I have Chris Church omni and I can make a greater spacing. I also have nak300 cards and SPC4 hypers. Would you recommend some configuration? Do you think Gutbucket's configuration is going to work here or should i stay with one pair only?
Title: Re: Oddball microphone techniques
Post by: Moke on October 28, 2017, 07:45:21 PM
Happy Birthday, Lee!
Title: Re: Oddball microphone techniques
Post by: heathen on October 28, 2017, 09:43:00 PM
But when I am taping, I usually do an audience recording by the soundboard in the back of the room. (For some reason, I have never made a good balanced stage lip recording and sbd feed sounds little strange there). It is a great sound by the soundboard, I can record with an omni pair there.
Have you tried a matrix with aud and the sbd? 
Title: Re: Oddball microphone techniques
Post by: kuba e on October 29, 2017, 11:26:11 AM
Happy Birthday, Lee!
Happy Birthday too!

Have you tried a matrix with aud and the sbd? 
You are right, sbd and aud is great. And I like audience recording on one's own too, it has it's magic. That's why I like to try other new configurations, try to do a bit better audience recording step by step. I do not record often, but I like this recording theory, making it much more fun.
Title: Re: Oddball microphone techniques
Post by: rocksuitcase on October 29, 2017, 04:03:16 PM
When we have been running the center rear and fwd facing mics, we have tended to use cards (ck61's) and they have been anywhere from 8-16 inches apart. We have tried the center fwd using AKG ck8 "shotgun" then using a ck61 for the rear.
Rocksuitcase, was it a big change when you used ck8 as the forward microphone?
OK- first to one major topic- Lee and I have discussed the possibility of using the 4 channel oddball technique indoors and kindms and I have done so about 5-6 times BUT this is still not highly recommended and IMO a "lesser" feature or usage for the 4 channel and certainly the 6 channel oddball technique. IMO- to be successful indoors, the PA must be very high quality and run by an FOH who knows his equipment (e.g. we did Phish at MSG twice using a 6 channel approach, great results because they give a shit about their PA).

The decision to use AKG ck8 vs a cardiod or hypercardiod was based on Lee's discussion of using a "directional as you can" mic in the middle in certain situations. Kindms and I often record at the Cap Theatre in Portchester NY and have decided the PA is so wide and the roof is so tall there is a pronounced hole in the middle, As in we feel we hear it as lacking punch and vocal presence for several of our attempts there. So, we thought let's try the ck8 in the middle. First we tried it as the mid mic in a MS take, using his 414XLSII for the side fig8. Better than our previous 2-3 channel efforts in that room; certainly brought out more center vocals being the main quality difference. Then we ran it indoors a couple of times in less than great PA rooms and really have no reference good or bad. At that point I'd rather run a two channel rig or SBD/2xAUD if possible. For each of these let's stipulate this was loud Rock n Roll with VG to EX PA's.

Then we had good fortune to run 4 days in a row at Greyfox 2016 and tried most of our configs we could. We even ran the ck8 at the same time as a ck61 facing fwd JUST to do this comparison. During the mix down of this evening I chose the ck61 (cardiod) twice and the ck8 once (looking for LMA links if any(the only one up used the ck61's-Elephant Revival https://archive.org/details/erevival2016-07-16.ck22ck61-photos added). As to why I chose the ck8 in that instance I can say it was more presence in the vocals and mids than the 61. It really does show you that even with the same PA and recording configuration that program material/instrumental make up also plays a choice when mixing this stuff down (or in any decision as to which config to run)
Since then we have run the 4 or 6 mic AUD only variation at least a dozen more times, mostly outdoors and have used ck8 2-3 of those times. I have also had the good fortune to record 10 in a row series of noon free shows at the Egg using the 4 channel variant adding SBD to the mix with 8 of those (again no ck8). https://archive.org/details/adamezra2017-07-05.akgck2261-24

edit to add mic details for those playing along: (2 rigs, the outside AKGck22 Omni's spread 100 cm, AKGck8 0'; akgck61 naiant PFA 0' (4 mics into a DR680); then two AKG c414 XLS-II > HDP2 on this day ran in Omni what we called the "omni shootout")
edit2 to add third pic with umbrellas and windscreen on the ck8
 
Title: Re: Oddball microphone techniques
Post by: kuba e on October 29, 2017, 05:38:46 PM
Thank you for your detailed explanation. Gutbucket, you and Kindms have done many experiments. It can be seen that a lot of work has been done for the oddball technique. It's big help for us. I understand, the oddball technique can be useful where there is great acoustics, this is especially true indoor. It is also very interesting to read about your comparison of ck8 and ck61 as the forward microphone.

I like a lot Elephant recording. It's a very quality recording, very delicate.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 30, 2017, 11:50:46 AM
^ That's Kyle (Rocksuitcase).

OK- first to one major topic- Lee and I have discussed the possibility of using the 4 channel oddball technique indoors and kindms and I have done so about 5-6 times BUT this is still not highly recommended and IMO a "lesser" feature or usage for the 4 channel and certainly the 6 channel oddball technique. IMO- to be successful indoors, the PA must be very high quality and run by an FOH who knows his equipment (e.g. we did Phish at MSG twice using a 6 channel approach, great results because they give a shit about their PA).

Alright, partly exploring using the outdoor oddball techniques indoors, I busted out two different open oddball rigs indoors last weekend.  Both in the same medium-sized room- Revolution Live in Ft Lauderdale, FL with decent but not super-great sound, generally too much subs; same recording location- back of pit, just in front of the board, DFC, AUD only (room sweet spot is about 15' forward at the center of the pit floor); same music genre- Southern rock-ish; two different but setups.  The first a 4ch indoor oddball setup I've run there in the past, the second my now-standard outdoor 6 channel oddball setup which includes the wide omnis.

Will post some some details, setup photos, and thoughts about it when I get the chance. Spoiler- The wide omnis were great, and I miss them in their absence. I'm no longer reluctant to run the main outdoor oddball setup indoors, except for when the wideness of the physical setup doesn't work for practical reasons (no problem with that here, as the coming photos will illustrate).

Fun weekend.  For Magpie Salute Marc Ford sat in a chair (somewhat Houser like) nursing a recently dislocated rib.  Good energy and guitar interplay a la Black Crows, and a fun time with friends I'd not seen in a long while.  And The Marcus King Band impresses me more each time I see them, part Allmans, part DTB, real southern soul and phenomenal talents.  Catch them if you can.  The future of music is safe with these cats doing their thing.  Really good in so many ways.


Happy Birthday, Lee!

Hey thanks, says this couple days older, wiser, happier guy!
Title: Re: Oddball microphone techniques
Post by: rocksuitcase on October 30, 2017, 12:38:16 PM
I have Chris Church omni and I can make a greater spacing. I also have nak300 cards and SPC4 hypers. Would you recommend some configuration? Do you think Gutbucket's configuration is going to work here or should i stay with one pair only?
IMO, (and hopefully Gutbucket will post his opinion): Go with the wide omnis (3 feet minimum if possible) and the hypercard pair in a narrow X-Y (60' or less) in the middle. Lee has extolled his reasoning for this variant which can be summarized as: Using the Hypers X-Y gives you a semblance of a "fall-back|normal config" pair in the middle with the omnis outside to add to the mix. We have run this method a few times using our AKGc460b pre-amps with ck3 hyper capsule. It is becoming my go-to config for 4 channels in avg to normal spacing from stage (FOB, 40-60 feet from stacks)
edit to add mic config info:
2xAKG ck22 Omnis on 460 pre-amps using A60 knuckles|adapters spread 100cm; 2xAKGck3 X-Y 60' on 460 pre-amps -> Tascam DR680; 2x AKG c414XLS-II in sub card-> Tascam HDP2 
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 30, 2017, 01:02:56 PM
^Yep. I concur.

Your sample of the 1.5' spaced Nak omnis sounds quite good.  Good spacing for an omni pair used on its own in that situation.

The addition of the center pair of PAS-angled X/Y supercards will heighten vocal clarity a bit more (which is already pretty good for omnis inside at that distance), and you'll want to space the omnis more to give that center pair room to do its thing in the middle.

Narrow-angled X/Y cardioids instead of the supers would also work and might be better.  I say that because even the omnis alone are providing decent clarity and presence so you don't need as much directionality as possible at the possible expense of timbre and smoothness.  You aren't fighting the room so much, so it probably depends more on the sound of your supers verses the sound of the cardioids and which you prefer.. I should clarify that your preference in combination with the omnis may be different than your preference for the cards or supers used on their own.   The omnis will fix/cover some of what you might not care so much for when either directional pair are used alone.

If your first test of this setup is encouraging, you might try the other pattern in the middle the next time and see which you prefer.

How deep is the room behind the recording position?  Is there anything behind the board or is it up against the back wall?
Title: Re: Oddball microphone techniques
Post by: kuba e on October 30, 2017, 05:09:38 PM
If your first test of this setup is encouraging, you might try the other pattern in the middle the next time and see which you prefer.
Lee and Kyle, you are right, I must try and compare. I have all information for start. Kyle, your rig is cool. It inspired me, I will try to find solution to mount two coincident pairs in the center to see how they work with omni.


How deep is the room behind the recording position?  Is there anything behind the board or is it up against the back wall?
The room is half for seating and the back is for standing. I place stand near the board which is located about 2/3 of the room. People usually stand behind board. But if there is a smaller visit, this place is empty and the board is against back wall. I do not estimate distance, but it could be about 15'-20'. I am going there to see Medeski. He is coming to Prague with Kirk Joseph, Will Bernard and Julian Addison. It's great to see them live and moreover in my most favorite club in town.

Fun weekend.  For Magpie Salute Marc Ford sat in a chair (somewhat Houser like) nursing a recently dislocated rib.  Good energy and guitar interplay a la Black Crows, and a fun time with friends I'd not seen in a long while.  And The Marcus King Band impresses me more each time I see them, part Allmans, part DTB, real southern soul and phenomenal talents.  Catch them if you can.  The future of music is safe with these cats doing their thing.  Really good in so many ways.
I heard Magpie Salute recording from their current tour. Old good music. And I would like to see Marcus King live too. I hope that sometimes these bands will come to Europe.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 30, 2017, 07:22:52 PM

How deep is the room behind the recording position?  Is there anything behind the board or is it up against the back wall?
The room is half for seating and the back is for standing. I place stand near the board which is located about 2/3 of the room. People usually stand behind board. But if there is a smaller visit, this place is empty and the board is against back wall. I do not estimate distance, but it could be about 15'-20'. I am going there to see Medeski. He is coming to Prague with Kirk Joseph, Will Bernard and Julian Addison. It's great to see them live and moreover in my most favorite club in town.

In that case I suggest you also try the variant with one forward facing and one the backward facing mic in the center, which would substitute for the center X/Y pair.  One of my considerations upon initial listens to the recordings made over this past weekend was that I wish I'd used a rear facing mic to see how useful it would be there.  I'd figured that was less useful in a smaller room (and the room I was in is probably less open to the rear than yours, yet there are people behind the board, see the pictures in the next couple posts) so I used the bidirectional to make the front center mic a Mid/Side pair instead.  I actually could have done both on Friday, running 5 channels instead of 4, but I was pressed for time and didn't bring the extra microphone.

I'm speculating, but for the folks who cannot accommodate a wide omni split, a backwards facing mic might end up being more useful than the X/Y or Mid/Side forward facing center pair.  A narrower omni split means less space to fill in the center so less center-width-blend-control is needed, and will be slightly less open and wide sounding, so the additional depth from the rear facing mic may be advantageous.  Theoretically based on pattern alone, I'd use a supercard facing forward and cardioid facing rearwards, but it really depends on how the specific mics sound and behave.  Again, the only way to know is to try it an see if you like it or not.

[edit- I will say this, given the choice I prefer the addition of the sideways facing supercardioids over making the center a Mid/Side pair with the bi-direcitonal.  But that's 5 channels total, or 6 if using the rear-facing microphone.]

Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 30, 2017, 07:25:38 PM
Alright, partly exploring using the outdoor oddball techniques indoors, I busted out two different open oddball rigs indoors last weekend.  Both in the same medium-sized room- Revolution Live in Ft Lauderdale, FL with decent but not super-great sound, generally too much subs; same recording location- back of pit, just in front of the board, DFC, AUD only (room sweet spot is about 15' forward at the center of the pit floor); same music genre- Southern rock-ish; two different but setups.  The first a 4ch indoor oddball setup I've run there in the past, the second my now-standard outdoor 6 channel oddball setup which includes the wide omnis.

1) Friday night- The Magpie Salute. 

After the recent discussion of indoor use, I was going to take the already-wired-and-ready-to-roll outdoor 6-channel oddball rig, but chickened out.  Partly because an old friend who used to tape was going and I know he'd be excited by the Microtech Gefells, so I decided to use those along with a cool clamping arrangement which has worked well for me  in this  room previously.  And partly because its been a while since I was there and wanted to run something I could be sure would fit in the space without the 5 or 6' spaced omni spread.

Oddball 4-microphone 3-point stereo array variant (spaced supercards + center M/S pair) consisting of:
Pair of Microtech Gefell 310 supercardioids spaced about 2' apart, angled about +/- 45 degrees (pointed outside of stacks + center Mid/Side center pair- Microtech Gefell M94/MV692 cardioid Mid / Naiant X-8S bidirectional Side, about 15" forward of the supercardioid pair.

Visually, one of the more interesting things about this setup is the "3-pointed star mic bar" and its angled clamping arrangement.

Mics are arranged in a 3-point triangle formation, dictated by the unique mounting arrangement I was using, which consists of an inverted tripod foot base as 3-arm mic bar with  mics attached where the 'feet' would be (I've covered this earlier in this thread I believe, definitely in the on-stage recording thread where it is used right-side-up on the stage). Its a common 3-leg steel folding light-stand base, which comes provided with a tapped 3/8" hole near one foot. I bought it bundled with the telescopic extension arm it's in use with here and drilled/tapped identical holes in the other two legs so I can attach mic-mounts to each 'foot'. Here is is basically just fliped upside down and clamped to the staircase handrail with a super-clamp.  The soundboard is at the top of the staircase, which is roped off to block access from the pit floor.  The angle of the staircase handrail cantilevers the mics up and out into the room over the staircase somewhat.  Mics are approximately 8' above the pit floor.  Looks large and imposing in these flash photos, but its actually not very visible in the venue- out of sight-lines for these in front below, as well as those in back watching from above.

Initial headphone listening assessment via Senn HD650 direct out of DR-680's monitor mix - Good. Mid/Side width setting on DR-680 for center pair at about 20 (with a range of 0=100% mid to 100=100% side, and the Side channel recording level set for about the same modulation as Mid channel and L/R supercards).  Needs EQ to reinforce the bottom in addition to general sweetening, and probably benefit from some multiband compression.  Sort of wish I had the omnis going too with this, but from experience I know I can EQ the Gefells to get much of the bottom octave impact.

Spyder9 also recorded and his mics are also visible in some of these photos atop the high pole past the other side of the staircase, flying over the board rather than under it (his preferred standard location there, which is better protected and isolated from audience chatter).  Spyder ran a Nakamici 1000 cardioid pair, near-spaced PAS (approx. 6" / 25 degrees), mics high above the floor.

Check out the rakish clamp angle, rather cool in a 'Klingon Bird of Prey' kind of way-
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 30, 2017, 07:28:30 PM
Can only get one photo per post to attach for some reason..
View from the bottom of the staircase looking up and back at the mics-


Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 30, 2017, 07:30:24 PM
Top of stair looking forward at stage (flash on)
Sight-line of folks beside/behind the board is above the mics-

Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 30, 2017, 07:35:56 PM
Detail showing the Naiant X-8S bidirectional gaffer-taped to the Microtech Gefell M94/MV692 cardioid to form the Mid/Side front facing pair.

In the photos above the X-8S is immediately beneath the M94 in the center, both sharing the same windscreen.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 30, 2017, 07:53:01 PM
2) Sunday night-The Marcus King Band.  (Go see the Marcus King Band if you've not heard of him yet, a phenomenal talent!)

Figured I'd bring out my current standard outdoor 6-channel oddball setup this time, but switched the rear-facing supercard to a bi-directional coincident with the center supercard to make it a Mid/Side pair as mentioned previously.  Partly to minimize comparison variables by doing basically the same as Friday night but with different mics and minor geometry changes.

This was a 5-point stereo, 6-microphone setup, consisting of:
Wide-spaced omnis in APE spheres, angled +/- 45 degrees, spaced somewhere between 5' and 6'  DPA 4098 supercardioids about 2' apart maybe a bit more, angled about +/- 45 degrees (just outside of stacks + Mid/Side center pair of DPA 4098 supercaridoid & Naiant X-8S bidirectional about 8" forward of the supercardioid pair.

Setup geometry is actually generally similar to Friday except for the addition of the wide omnis, the DPA 4098 supercardioids instead of the Gefell supercards and cardioid, and the whole thing shifted back about 3' towards the back of the staircase (but approximately the same height as Friday night).

Initial headphone listening assessment via Senn HD650 direct out of DR-680's monitor mix - Better than the Gefells I think.  Mid/Side width setting on DR-680 for center pair at only about 12 (with a range of 0=100% mid to 100=100% side, and the Side channel recording level set for about the same modulation as Mid channel and L/R supercards).  Needs EQ to shape the bottom but the omnis are big and convey the impact and power I was missing before.  Not afraid to use them again like this there.  Previously I'd run a single 4060 along with the supercards in this position to help the bottom end, but didn't find it very useful, but the wide omnis are a different story.  They add a nice ambient air as well as a nice solid bottom.


Spyder9 also recorded- This time with a DPA 4011 carioid pair, near-spaced PAS (aprox. 6" / 25 degrees), mics in his same preferred location as Friday, visible on the high clamped pole in front of soundman in the background behind my mics.

Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 30, 2017, 07:57:05 PM
Since this rig is all prewired to a compact Manfroto stand, I kept the stand legs folded in tight and used a giant twisty-tie to tie the stand it to handrail.  Kept it vertical with no rakish forward angle this time.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on October 30, 2017, 08:00:18 PM
Photo taken at extended arms length above head looking across the array. The right omni in APE sphere is in the foreground, the right DPA 4098 is in the mid-ground angling right at ~45 degrees and upwards towards the hanging PA, with the center pair angled upwards behind that.  The center pair is the same Naiant X-8S under another DPA 4098.  Both mics in their own windscreens here.  You can see how the whole linear array sort of tucks in below the board and drink rail behind preserving full visibility for the folks behind.  I tried to take a few photos from the audience in the pit looking back at the board but you can't see my setup in those photos at all, it completely dissapears.

BTW, the windscreen pointing at the ground just behind my stand visible in this and the first photo of this setup is the rear-facing 4098 supercardioid on its telescopic arm, folded down and out of the way while not in use (benched by the last-minute substitution of the X-8S). 
Title: Re: Oddball microphone techniques
Post by: lsd2525 on November 01, 2017, 10:56:53 AM
Interesting set up! That looks like a great venue to tape in
Title: Re: Oddball microphone techniques
Post by: rocksuitcase on November 01, 2017, 11:44:50 AM

How deep is the room behind the recording position?  Is there anything behind the board or is it up against the back wall?
The room is half for seating and the back is for standing. I place stand near the board which is located about 2/3 of the room. People usually stand behind board. But if there is a smaller visit, this place is empty and the board is against back wall. I do not estimate distance, but it could be about 15'-20'. I am going there to see Medeski. He is coming to Prague with Kirk Joseph, Will Bernard and Julian Addison. It's great to see them live and moreover in my most favorite club in town.

In that case I suggest you also try the variant with one forward facing and one the backward facing mic in the center, which would substitute for the center X/Y pair.  One of my considerations upon initial listens to the recordings made over this past weekend was that I wish I'd used a rear facing mic to see how useful it would be there.  I'd figured that was less useful in a smaller room (and the room I was in is probably less open to the rear than yours, yet there are people behind the board, see the pictures in the next couple posts) so I used the bidirectional to make the front center mic a Mid/Side pair instead. 

I'm speculating, but for the folks who cannot accommodate a wide omni split, a backwards facing mic might end up being more useful than the X/Y or Mid/Side forward facing center pair. 
kuba e: I would second this. The #1 configuration for us has been the fwd and rear facing cardiod ( I label them as 0' (fwd) & 180' (rear). As kindms puts it, even though it is subtle, muting the rear channel during a 4 track mixdown always removes some of the depth. If you're mixing the rear channel in, just hit mute on the rear; once you can tell a difference when muting the rear but barely then you are mixing it properly.

Specifically, for that room pictured the fwd/rear cards should offer you good mixdown potential. (caveat here is without a middle X-Y "safety" pair you are "stuck" with the two omnis and fwd/rear- less mixdown options BUT more dimensionality and psycho-acoustic stage width)
edit to add pics of both a 4 channel with fwd/rear (AKG ck22 Omnis spread 100 cm|460b preamps; ck61 cardiod fwd 0'|ck61 cardiod rear 180'|naiant PFA's) and a 3 channel with rear only (AKGck22 spread omni + akgck61 cardiod fwd 0' - also digigal's neumanns? with pink dead rats)
Title: Re: Oddball microphone techniques
Post by: Gutbucket on November 01, 2017, 05:38:43 PM
kuba e: I would second this. The #1 configuration for us has been the fwd and rear facing cardiod ( I label them as 0' (fwd) & 180' (rear). As kindms puts it, even though it is subtle, muting the rear channel during a 4 track mixdown always removes some of the depth. If you're mixing the rear channel in, just hit mute on the rear; once you can tell a difference when muting the rear but barely then you are mixing it properly.

Specifically, for that room pictured the fwd/rear cards should offer you good mixdown potential. (caveat here is without a middle X-Y "safety" pair you are "stuck" with the two omnis and fwd/rear- less mixdown options BUT more dimensionality and psycho-acoustic stage width)

Spot on, all of this.

I partly suggest X/Y or M/S in the middle because it seems less crazy and tends to be easier to convince other tapers to try that than a rear-facing mic. It is more useful than just a single forward-facing center mic, and one of the obvious options for populating the 4th recording channel, but I prefer the rear-facer most of the time, especially using the Mid/Side mixdown technique.

The rear-facer is the first option I'd  try myself there. You're getting pretty good sound with just the omni pair, and the center mic will do the most to improve that. The rear-facer is gravy.
Title: Re: Oddball microphone techniques
Post by: kuba e on November 02, 2017, 03:11:56 PM
I'm speculating, but for the folks who cannot accommodate a wide omni split, a backwards facing mic might end up being more useful than the X/Y or Mid/Side forward facing center pair.  A narrower omni split means less space to fill in the center so less center-width-blend-control is needed, and will be slightly less open and wide sounding, so the additional depth from the rear facing mic may be advantageous.  Theoretically based on pattern alone, I'd use a supercard facing forward and cardioid facing rearwards, but it really depends on how the specific mics sound and behave.  Again, the only way to know is to try it an see if you like it or not.
Yes, that's exactly what I'd like to try. In the previous post, you mentioned that by mixing the rear microphone, we can create a similar effect like playback with halfler rear speaker. I tried Halfler's rear speaker and I was very surprised how it changed the sound compared to the classic stereo playback. I felt like I was in the middle of the audience, the stereo has spread a lot. If I could get this feeling at least a bit into the recording by mid/side mixdown of rear mic, it would be great.

Quote
[edit- I will say this, given the choice I prefer the addition of the sideways facing supercardioids over making the center a Mid/Side pair with the bi-direcitonal.  But that's 5 channels total, or 6 if using the rear-facing microphone.]
Please, how do you mean this configuration? Two spaced omnis + two coincident  sideways facing supercardiods in the middle + one forward mic?

Quote
Visually, one of the more interesting things about this setup is the "3-pointed star mic bar" and its angled clamping arrangement.
Great idea to use stand legs as mics bar. Thanks you and Kyle for photos too. It is very helpful to get an idea of the configuration.

kuba e: I would second this. The #1 configuration for us has been the fwd and rear facing cardiod ( I label them as 0' (fwd) & 180' (rear). As kindms puts it, even though it is subtle, muting the rear channel during a 4 track mixdown always removes some of the depth. If you're mixing the rear channel in, just hit mute on the rear; once you can tell a difference when muting the rear but barely then you are mixing it properly.
I'm looking forward to trying it out. I have five mics and dr680. I can try 1 meter spaced omnis, coincident hypers in middle and one rear card. I hope it will not be difficult to mix. I guess I can always make it easier when i mix coincident hypers to mono. Maybe I'll have chance to try it next week. I'll let you know how it turns out and i will make photos too.

Title: Re: Oddball microphone techniques
Post by: rocksuitcase on November 03, 2017, 02:26:37 PM
Medeski and those guys should have no problems with recording AUD as long as the room allows it you should be AOK!
I'm just a bit jealous as I haven't seen Medeski in a couple of years and always enjoy his side projects (sometimes more than MMW)
Title: Re: Oddball microphone techniques
Post by: Gutbucket on November 05, 2017, 12:55:00 PM
Please, how do you mean this configuration? Two spaced omnis + two coincident  sideways facing supercardiods in the middle + one forward mic?

All covered earlier in this thread. I'm at a tradeshow and can't post a link at the moment. Left/Right facing supercards are spaced about 20" apart or so. In a more challenging acoustic room I might angle them +/- 45 degrees as in the photos recently posted above, but ideally they are pointig +/- 90 degrees, directly to the sides. Front/back are spaced too but can probably be coincident.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on November 05, 2017, 02:03:46 PM
On mixing it-  It can sometimes be advantageous to reduce the low frequency content of the forward facing center mic via EQ curve or even a high-pass filter. That let's the omnis take care of most of the bottom, with all the mics contributing as frequecy rises. The typical resonse of many supercards (usually designed for speech pickup) sort of does some of that automatically, but it's something to play with when mixing for best effect.

Generally I EQ each channel or channel pair to sound as good as possible on their own before  mixing them together. That bottom-end attenuation of the center mic is something of a further modification to that. Further, a loudness curve scooping some miss and emphasising the bottom and top can work well with the backward facing mic.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on November 06, 2017, 05:42:17 PM
Yes, that's exactly what I'd like to try. In the previous post, you mentioned that by mixing the rear microphone, we can create a similar effect like playback with halfler rear speaker. I tried Halfler's rear speaker and I was very surprised how it changed the sound compared to the classic stereo playback. I felt like I was in the middle of the audience, the stereo has spread a lot. If I could get this feeling at least a bit into the recording by mid/side mixdown of rear mic, it would be great.

What the Halfler playback technique does is send the difference signal (L-R) to the additional rear speaker or to a pair of rear speakers.  That difference signal is the Side in Mid/Side stereo and tends to be made up of the reverberant/ambient content in the recording.  So what you are doing is a Mid/Side stereo playback modification, spreading the Side information out around the sides and back.  BTW, using two speakers works better than just one as that spreads out that stuff more diffusely in the playback space.  You reproduce the Mono sum of both channels (Mid) as a phantom image between the Left and Right speakers, Left and Right signals eminate from Left and Right speakers, and the difference sum from the rear speaker(s) with a 6dB difference between each adjacent quadrant.  In essence you have 4 channel LRCS reproduction of a 2-channel L/R stereo signal.  This is similar to the basis on which matrix surround decoding works, such as Dolby ProLogic/PL2/PLX and all the other matrix surround techniques, but without the additional tricks intended to forcibly steer surround information, so Halfler can sometimes work better for straight ambiance retrieval and doesn't mess with the purity of the left and right signals sent directly to those speakers.

What comes out of that rear Hafler speaker(s) is whatever content in the recording is different on each side.  So anything panned full left or right will not only be reproduced in either the Left or Right speaker but also the rear speaker(s).  More importantly for live recordings, besides level differences, phase and polarity differences are also reproduced from the rear channels.  So any content with inverted or randomized phase between Left and Right stereo channels gets more diffusely reproduced throughout the room, and much of that tends to be the audience and ambient content in the recording.

One of the things spacing the omnis far apart enough does, which is further enhanced by having the front/rear mics non-coincident and located in different positions in space, is randomize the phase of the diffuse ambient/reverberant content which ends up in the recording.  When that stuff gets reproduced in such a way such that it is spread more evenly throughout the room it leads to the open and immersive listening experience you've noted of feeling like you are in the middle of the audience. 

This is a direct tie-in to the low diffuse field correlation stuff I was talking about a week or so back when I revived this thread.  The Halfler technique is a method of leveraging this on playback more than 2-speaker playback can do on it's own.  The oddball microphone techniques help in leveraging it on the recording side more so than two channel recording typically does alone, in addition to also leveraging other things.  The Mid/Side mixing technique for the rear facing microphone routes reproduction of the rear facing microphone content to the far sides and to the Hafler speaker(s) in back if it is in use.  Without that Mid/Side mixing technique, that rear facing mic content is still good and useful in the mix, but will tend to be reproduced from the front of the room between the Left and Right speakers along with the stuff the forward facing microphone picked up rather than from the far sides and rear.
Title: Decorellation of Audio Signals and Its Impact on Spatial Imagery
Post by: Gutbucket on November 09, 2017, 02:38:37 PM
Before we moved on to other stuff, I'd revived this thread with a discussion of decorrelation, starting with this post about 4 pages back - https://taperssection.com/index.php?topic=96009.msg2244172#msg2244172 (https://taperssection.com/index.php?topic=96009.msg2244172#msg2244172)

Here is an excellent paper on the topic I recommend to anyone interested in digging deeper into the effects of decorrelation on stereo signals - The Decorrelation of Audio Signals and Its Impact on Spatial Imagery - Gary Kendall (1995) - http://www.garykendall.net/papers/Decorrelation1995.pdf (http://www.garykendall.net/papers/Decorrelation1995.pdf)
Title: Re: Oddball microphone techniques
Post by: kuba e on November 13, 2017, 05:01:53 AM
I tried the oddball technique for the first time. It's great technique, it gives us plenty of options to influence the final sound of the recording. The ability to change the ratio of direct sound and ambience, and add depth is perfect.I'm sure more people will start using this configuration. I'm not good at post processing, but I see this mics configuration is big help to achieve great results. Last weekend I made a trip to Munich in Germany for the Gov't Mule concert. The music was great and there were six tapers too. It was great to meet them. They were interested in this technique too. I sended them a link to this thread.

Unfortunately I came late to the club, the lights were off, no photo went well. At least I took the picture of the club at the end of the concert when they turned on the lights. And I took the picture of the microphone stand at home later. We were setup at sbd about 50 feet from the podium. The mics configuration was:
the forward & rear cards: nak300, spacing 13 inch
spaced omni: ca11, spacing 4 feet.
https://drive.google.com/drive/folders/1MKdygDhUAO1tSdNMz6pkwXxuCXRUsrBO?usp=sharing (https://drive.google.com/drive/folders/1MKdygDhUAO1tSdNMz6pkwXxuCXRUsrBO?usp=sharing)

Post processing is very difficult for me. I'm not sure at all. It was difficult to mix the recording, but I believe it will be better and easier next time. What surprised me very much was when I mixed the front and rear microphones in M/S. The result is very good. M/S is dominant in the final mix, omni are only slightly added there. When I added more omni, it did not sound good. Maybe I spaced them too much. Could I add more omni in the mix if they are less spaced?

I'm sending a sample. In the end, I did not choose it well, omni stereo is not well balanced there. (In the first set it was better balanced, maybe the stand was moved little. I balanced the second set omni by the gain and short delay of the left channel when mixing the final mix.) But I hope it would be enough to illustrate. There is sample of Hans's recording too. He had the stand right next to me with MBHO cards, din. It's for comparsion how it sounds single pair.
https://drive.google.com/drive/folders/1MLNWhfUh9eTgUgE22V2rcJH6QsG_Zpch?usp=sharing (https://drive.google.com/drive/folders/1MLNWhfUh9eTgUgE22V2rcJH6QsG_Zpch?usp=sharing)

Gutbucket, thank you for your explanations and for reference to the theory. I love to read it. It will take me a while, but then I will write back. I was thinking about the little thing relating to the theory when I was processing M/S. When there is a large part of S and M is weak, then much of the signal in the right and left channels is in the opposite phase. Is the partial opposite phase in the left and right signal what makes special sound in M/S (maybe blumlein too)?

Medeski and those guys should have no problems with recording AUD as long as the room allows it you should be AOK!
I'm just a bit jealous as I haven't seen Medeski in a couple of years and always enjoy his side projects (sometimes more than MMW)
I also like very much their side projects. It would be difficult to make decisions when I could choose. But I would probably go to Medeski and friends, Wicked Knee or Wood Brothers than MMW. Perhaps this is because their side projects can be seen in small clubs and in a very relaxed atmosphere.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on November 13, 2017, 10:54:37 AM
Glad you got a chance to try these techniques and are enjoying doing so.  And thanks for the report, photos and samples.

Post processing is very difficult for me. I'm not sure at all. It was difficult to mix the recording, but I believe it will be better and easier next time. What surprised me very much was when I mixed the front and rear microphones in M/S. The result is very good. M/S is dominant in the final mix, omni are only slightly added there. When I added more omni, it did not sound good. Maybe I spaced them too much. Could I add more omni in the mix if they are less spaced?

I've downloaded your samples and will play with them myself when I get the chance. [question- in the front/back pair recording which is in the left and which is in the left channel?] I did a quick listen to each source on this computer and I don't think less omni spacing would make for an improvement or allow you to use more of them in the mix.  Listening to the omni pair alone I don't hear any problem with excessive spacing, but do want to make some significant EQ corrections.  I suspect that's mostly what you are hearing more than an effect from the microphone spacing. 

I typically start mixing that way with the omnis- EQ and level balance the omni pair alone to best effect, then add the center pair.  But you can also do it the other way around if your recording is stronger that way- make the Front/Back, Mid/Side pair primary and bring in the omnis in support of that.  The EQ on the omnis might then be somewhat different, possibly with less mid emphasis (getting more of that from the M/S pair), rather than boosted lows and mids with a carefully cut "mud and boom" region in-between, typically centered somewhere around 300Hz. Omnis can be tricky and commonly need some EQ manipulation to work around the room resonances in that bass region when indoors in a strongly PA amplified room. The top end EQ often depends more on the characteristic of mics and how smooth they sound up there.  I'd have to play around with your samples before commenting there and expect your omnis may want only a bottom and mid emphasis with some top end reduction and the aforementioned cut around 300Hz.

Quote
I was thinking about the little thing relating to the theory when I was processing M/S. When there is a large part of S and M is weak, then much of the signal in the right and left channels is in the opposite phase. Is the partial opposite phase in the left and right signal what makes special sound in M/S (maybe blumlein too)?

Yes, there are definite parallels there.  One of the interesting things to me is how sufficiently randomized phase of the diffuse room sound (via sufficient mic spacing) sounds similar to having inverted polarity in each channel (via Blumlein or Mid/Side with sufficient Side content), even though one relies on spacing and the other is coincident.

Thanks for the post!
Title: Re: Oddball microphone techniques
Post by: Gutbucket on November 13, 2017, 12:10:49 PM
Embedding kuba e's mic setup photos in the thread-


Title: Re: Oddball microphone techniques
Post by: Gutbucket on November 13, 2017, 12:11:41 PM
Front/back pair detail-

Title: Re: Oddball microphone techniques
Post by: rocksuitcase on November 13, 2017, 12:42:00 PM
kuba e: my input regarding mixdown:
Mostly follows Gut's input. I usually load all four channels into the Processing software (I use Audacity). then I focus on the stereo pairs. With the Omni pair, recorded in an indoor room, typically do a lot of listening (speakers, headphones, car speakers) then decide on a EQ scheme. Often, the boominess inherent with the Omni needs some low frequency reduction. that 300Hz region typically needs reduction, I tend to start the reduction at 400Hz then down all the way to 20 Hz. The main idea here is to make the Omni pair sound good with less low frequency boominess. I typically don't worry about anything above 3KHz with the Omni pair as those frequencies get emphasized with the middle card pair.
I then change the card channels to two channel mono labeling the front and rear channels properly (I am NOT dealing with MS option here). I then take the rear mic and lower it by 6-10 dB as compared to the front facing mic. Then I start blending the front and rear into the mix, setting the balance between omni sides and front/rear using the solo or mute buttons. You then have a 4 channel mix with the omni pair EQ'd and can either apply EQ to the front/rear channels as you see fit, OR mix down to two channels then EQ the resulting mix.
I don't do the MS mixing I leave that explanation to Gutbucket.
Title: Re: Oddball microphone techniques
Post by: morst on November 13, 2017, 02:11:37 PM
The term "MID" is used for two different things in this conversation - the M in M/S and also Midrange. Please be sure to specify, if you don't mind, these new techniques are a bit confusing to read about anyhow!

If I get into this, I'll want more than 4 channels soon enough... may have to fire up the laptop and MOTU 828 again!?

.....I typically start mixing that way with the omnis- EQ and level balance the omni pair alone to best effect, then add the center pair.  But you can also do it the other way around if your recording is stronger that way- make the Front/Back, Mid/Side pair primary and bring in the omnis in support of that.  The EQ on the omnis might then be somewhat different, possibly with less mid emphasis (getting more of that from the M/S pair), rather than boosted lows and mids with a carefully cut "mud and boom" region in-between, typically centered somewhere around 300Hz. .....
Title: Re: Oddball microphone techniques
Post by: kuba e on November 13, 2017, 03:09:07 PM
Thank you for help with eq and mix, it's very useful for me. Post processing and eq are very demanding, and there is also a need for sound sensitivity. The recording sounds bad in the speakers but I could not fix it. At least it sounds good in the headphones. I have to learn step by step. I'll try another try.

[question- in the front/back pair recording which is in the left and which is in the left channel?]
I think front mic is in the left channel. I'm not sure about one hundred percent. When I set my microphones, I did not mark it. I'll mark it next time.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on November 13, 2017, 03:36:28 PM
The term "MID" is used for two different things in this conversation - the M in M/S and also Midrange. Please be sure to specify, if you don't mind, these new techniques are a bit confusing to read about anyhow!

Yes, good point! I'd try to say midrange when referring to frequency.

.....I typically start mixing that way with the omnis- EQ and level balance the omni pair alone to best effect, then add the center pair.  But you can also do it the other way around if your recording is stronger that way- make the Front/Back, Mid/Side pair primary and bring in the omnis in support of that.  The EQ on the omnis might then be somewhat different, possibly with less midrange emphasis (getting more of that from the M/S pair), rather than boosted lows and mids with a carefully cut "mud and boom" region in-between, typically centered somewhere around 300Hz. ..... [edited]

And agreed with rocksuitcase, except that when dialing in that upper bass/lower midrange cut (which is often significant indoors and can range anywhere from 120 to 500Hz), I almost always carefully boost the lows below that range to restore the deep bass which is a big part of the realism I feel the omnis uniquely provide.  I may cut the very lowest frequencies if its only non-musical noise, but I'm probably boosting between there and the upper bass/lower midrange reduction, else the overall solid bass which the omnis are supposed to contribute gets anemic.   With a cut on either side, that range gets pulled down along with its neighboring regions and needs a boost to bring it back to where it should be.

Of all the raw tracks you posted, that the Mid/Side mixed front/back pair sounds best to me prior to any other manipulation, so using that as your starting point here seems apt. I often bump the 2-3kHz area of my omnis for clarity and that seems relatively common for most omnis.  Its the frequency range above 3kHz where different mics seem to behave quite differently and its harder to make general statements about what to expect there.  Quite frequently I'm reducing the omni content in that region if the center mics are taking care of it nicely, yet bring the omni level back up in the high treble around 14kHz or so to get some nice open diffuse ambient air.  But that really depends on the mics and situation.  Might make sense to smoothly reduce all the highs from the omnis above 3kHz if they are bright sounding to begin with or if that content conflicts with the same frequency range provided by the center pair.

Quote
If I get into this, I'll want more than 4 channels soon enough... may have to fire up the laptop and MOTU 828 again!?

One of the keys to not going crazy with complications is keeping things manageable.  If you can do that with a laptop and interface, great.  Everyone needs to find their own comfort level, and even 4 channels is more than many tapers want to have to manage.  Nothing wrong with that.  The only way I can do 6, 8 or more channels is to set most of it up beforehand so I can pretty much just roll at the event.  For the last two open-setup recordings I posted about above, the first using the 4 mics took me about 4 times as long to arrange and setup at the show, and also break-down afterwards, compared to the 6-channel pre-wired miniature mic setup I ran a couple days later.  For that one I just popped up the stand and pointed the mics, fired up the recorder, adjusted levels and rolled.  Quick and easy on the recording side of things.  More to manage on the back side once recorded, but that's the nature of these setups.

Quote
I think front mic is in the left channel. I'm not sure about one hundred percent. When I set my microphones, I did not mark it. I'll mark it next time.
 
Thanks.  I may be able to tell by listening.  You'd think it would be obvious, but it can be amazing how similar the different channels can sound in isolation. It's the interaction between them where identity arises.  And yes, always keeping the forward facing mic in the left channel and rear-facing in the right is good practice, and it makes Mid/Side decoding straight-forward.

I've found that as the mic count increases, its extremely helpful to do a mic check either just before or just after the performance, all setup in place, snapping fingers or speaking directly into each mic to ID which channel in a short separate recorded file-set.  More often than I would have expected or care to admit, I've found accidental left/right channel pair swaps or even messier channel mis-routings I did not intend and might not have noticed otherwise.  That's another complication pre-wiring everything helps me avoid, yet I still like to do the check.  I actually keep a dog-clicker in my bag which helps with those mic IDs in loud environments.
Title: Re: Oddball microphone techniques
Post by: heathen on December 03, 2017, 11:12:12 AM
I'm not sure if this counts as an oddball technique, but I tried a Straus packet setup over the weekend.  I had AT4031s set up PAS, then I took Countryman B3s and taped them to the ATs so each B3 was coincident with each AT.  Unfortunately I didn't take  a photo but hopefully that makes sense.

So far I've only processed the opening band, but for that one I ran the B3 source through a LPF at about 200 hz, then mixed that with the AT source.  I had the B3 source at -10 dB in Audacity.  Here's the opener: https://archive.org/details/Genetics2017-12-01.AT4031.B3.flac16/Genetics2017-12-01.AT4031.B3.t03.flac

The main act had their own sound guy, and their mix was a bit better, so I'm not sure if I'll do things exactly the same for the headliner.  I had it set up the same at the show though.
Title: Re: Oddball microphone techniques
Post by: rocksuitcase on December 04, 2017, 10:14:29 AM
Another "classic OMT" I finally just upped to LMA: http://taperssection.com/index.php?topic=184505.0
                                                                 24 bit    https://archive.org/details/adamezra2017-08-16.akgck22ck1-24           

recording Info:
location: 40 feet from stage 8 feet up
ch1|2 AKG ck22|460 omnis spread 100cm
ch3|4 AKG ck1|460 cardiod naiant active fwd 0'|rear 180'
Tascam DR680|SD

Three pics- two of the show set-up. The third is when the band came out into the audience, directly below the rig and I twisted the stand around to center on them.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on December 04, 2017, 10:35:48 AM
^ Looks like a cool venue right on the edge of the lake.

I'm not sure if this counts as an oddball technique, but I tried a Straus packet setup over the weekend.

I tried that a few times with the DPA omnis gaffer-taped onto my Gefell cards or supercards, but never really got it to work very well.  Always worked much better for me to not try and place them coincident but to space the omnis further apart than the directional mics.  Fun stuff to play around with regardless.
Title: Re: Oddball microphone techniques
Post by: heathen on December 04, 2017, 11:12:31 AM
I mostly just did it as an experiment.  At least for the headliner, I didn't feel like the AT4031s needed any "help" so I didn't mix any of the omnis in.  Listening back, the omnis may not have been necessary for the opener either.

Re: further spacing... This was just an experiment, and it was pretty easy to set them up like this rather than rig up another thing to accommodate the greater spacing of the omnis.  Outdoors I'd definitely want to space them further in the future.  Indoors, I just don't know that I will find it necessary to run the omnis at all.  Maybe if I come across a venue that sounds good enough that I want more room sound than I'm already getting...but indoor venues that nice are not where I typically find myself taping.
Title: Re: Oddball microphone techniques
Post by: Gutbucket on December 04, 2017, 11:28:20 AM
When I tried it, it was inside and sort of a last minute thing each time, and I wasn't setup to space the omnis further anyway so it was easy to just tape them to the near-spaced cards/supers.  But it just made for a boomy mess for me and was better without the omnis.  I hesitated after that to use wider-spaced omnis inside for the same reason, but they seem to work much better for me.
Title: Re: Oddball microphone techniques
Post by: heathen on December 04, 2017, 12:14:42 PM
Perusing an old thread, I came across a comment that seems appropriate for this thread:

Quote
The not at all simple alternate answer which potentially could help adjust for being off-center has to do with adjusting the microphone configuration in combination with rotating the stand.  It's probably far more trouble than it's worth, would be hard to do precisely in the field, and is not something most tapers would want to try, but is interesting to me technically.  I won't go into it here in too much depth, but it has to do with adjusting the angle of each microphone so they are no longer in a symmetrical arrangement with the center axis of the microphone array.  Essentially, one microphone is moved forwardof the other, and that accomplishes something similar to the delay thing I described previously, "at the microphone array" itself.

That's based on the work of Michael Williams which explores the inter-relationship between pickup pattern, angle, spacing and position of a pair of microphones.  It's how he goes about "linking" multiple microphone pairs together to form multichannel surround recording arrays which are capable of seamless playback imaging between across each microphone/speaker pair sector, without gaps or overlaps.  His papers on Multi-Microphone Array Design (MMAD) explain this in depth, but are more technical than most tapers here will care to get into.

This was in the context of a question about what to do when setting up off-center from the sound source.  The bolded part has me most intrigued.  I find it really distracting when I'm listening and the whole sound is noticeably off-center.  Obviously sometimes we can't set up at the center line for whatever reason.  I've found that just raising the level of the more "distant" channel is often unsatisfactory...maybe because the volume level doesn't make up for time of arrival differences in the channels?  So, I'm curious about the practical application of the idea hinted at in the quote above.  If we're talking about a near-coincident stereo pair, would putting one of the mics closer to the sound source help mitigate being off-center more than simply raising the gain of one channel?  I'm guessing that the mic on the more distant side would need to be moved closer.  How much of a change in location are we talking about, though?  If we think of it in terms of just a simple PAS config, would each of the mics be pointed at the stacks after adjusting the forward location of the one mic?  Or before making that adjustment?
Title: Re: Oddball microphone techniques
Post by: Gutbucket on December 04, 2017, 01:40:55 PM
Yes, level balancing afterwards is always helpful but can only do so much.  The practical solution at the show is to close your eyes and rotate your head to find the most balanced auditory center direction by ear, then rotate the entire mic-stand to match.   Don't trust what your eyes tell you, as often the acoustic center will not match the visual center.  Perhaps counter-intuitively, this technique will tend to point the microphones toward the louder PA, or more toward the near-side PA stack when located off-center - that is to say it will point the mics further away from the visual center and not towards it.  The result however will be a much more acoustically balanced recording.

I think this is the William's paper in which he discusses the microphone offset technique- http://www.mmad.info/Collected%20Papers/Multichannel/4997%20New%20York%201999%20(31%20pages).pdf (http://www.mmad.info/Collected%20Papers/Multichannel/4997%20New%20York%201999%20(31%20pages).pdf), as one technique of several used to achieve "critical linking" between the individual recording angle segments in multiple microphone arrays - the idea being to have each segment align with the next along it's shared Stereo Recording Angle edge without excessive over-lap or a gap between them.  Obviously that's a rather involved process to figure out, but sheds light on what's going on acoustically.  You can see how simply rotating the entire microphone array to point at the apparent auditory center is sort of doing something similar, if less extreme.

^ That paper and many of his others is made generously available for non AES members via Michael William's website- http://www.mmad.info/ (http://www.mmad.info/)