Topic: How split do split omnis need to be?

[T-90]

Gutbucket has never split any omnis, don't let him fool ya 

T-90 has never left idle message bomb surprises on recordings during set breaks. 

T's one of the few who was there the first time I stuck a pole in the air at an outdoor amphitheater, changing spacings and scribbling notes between sets (3' was best ) with two 4060s on a telescoping TV antenna gaff taped to a painter pole stuck into the back of my chair. And also one of the few I know who has taken up the miniature omnis on a TV antenna idea.  Smells like validation.

2007 springfest - spirit of the suwanee music park.....this guy comes out of nowhere, opens his camp chair and attaches a painters pole, mounts these two little mics and in no time at all is up and running....then before i can even make my way over to check it out hes gone, like a thief in the night.....i was amazed at the compact and easy set up.....over the past 7 years i have been even more amazed by the imagination and engineering that the mind of lee has produced.

pics that contain images of 2 different configs from his initial test run......in retrospect i should have taken some better pics of the maiden voyage, but how was i to know? in pic 1 he is to the left, in pic 2 his rig is to the right

[T-90]

those 2 setups pale in comparison with his current festi rig, from springfest 2014

[Gutbucket]

Thanks for the documentory photos, T.  After 8 years at that fest it was time to join the tapers. 

That first picture shows a diy Jecklin-like baffle.  In an attempt to make it slightly less visually conspicuous without overly compromising the baffle properties, it's in the shape of an oval  You can see the telescopic TV antennas angling up on either side of it with the miniature omnis mounted on the ends, which illustrates how that arrangement made it very easy to experiment with various microphone spacing options with or without the baffle in the middle.  The second one is unbaffled omnis with a 3' spacing or so.  Those are straight 2-channel omni recordings.

The 6-channel setup from springfest 2014 earlier this year uses a 6' omni spacing with the front and back facing cardioids.  It also adds two supercardioids mounted about halfway out the TV antennas facing directly to the sides, forming a three channel Optimum Cardioid Triangle arrangement with the front cardioid.

[ts]

Here's the practical take away of the technial stuff I posted above-

When the omni spacing is relativley narrow, slight differences in spacing distance have relatively large sonic effects upon the mid and upper frequency range.  The "critically-spaced omni" Oade Dead AUD's from the 80's sound great for a number of reasons but the key phrase, "critically-spaced" isn't meaningless but.. largely critical to the result.

When the omni spacing is wider, like around 2-4' the obvious sonic effects of adusting spacing tend to manifest in the lower-mid and bass range.

There is other stuff going on too but those timbral effects are the most obvious things I hear when adjusting omni spacing while listening.

Thanks for the very detailed responses. I'm going to see if I can rig up at least a 3 foot spread. I'll be using full body mics, so I need something sturdy. Next trick will be rain protection for split mics. Two mini umbrellas?

[ScoobieKW]

Decided to check AB spacing of omni microphones with the Sengpiel Visualizer

http://www.sengpielaudio.com/Visualization-Blumlein-E.htm

Change the type from blumlein to AB
Change the mic type to omni

Notice how the Stereo Recording Angle doesn't change until you get to 5. meters apart.

[lsd2525]

Thanks for the documentory photos, T.  After 8 years at that fest it was time to join the tapers. 

That first picture shows a diy Jecklin-like baffle.  In an attempt to make it slightly less visually conspicuous without overly compromising the baffle properties, it's in the shape of an oval  You can see the telescopic TV antennas angling up on either side of it with the miniature omnis mounted on the ends, which illustrates how that arrangement made it very easy to experiment with various microphone spacing options with or without the baffle in the middle.  The second one is unbaffled omnis with a 3' spacing or so.  Those are straight 2-channel omni recordings.

The 6-channel setup from springfest 2014 earlier this year uses a 6' omni spacing with the front and back facing cardioids.  It also adds two supercardioids mounted about halfway out the TV antennas facing directly to the sides, forming a three channel Optimum Cardioid Triangle arrangement with the front cardioid.

Out of curiosity, what kind of mini-omnis do you run? I'm still trying to track down some rabbit ears so I can do away with that tent-pole setup lol. My X-X omnis are about the size of a jelly bean:)

[T-90]

 I'm still trying to track down some rabbit ears so I can do away with that tent-pole setup lol.

i could only find them on ebay, not even walmart carries such basic antennas anymore

[Gutbucket]

Decided to check AB spacing of omni microphones with the Sengpiel Visualizer

http://www.sengpielaudio.com/Visualization-Blumlein-E.htm

Change the type from blumlein to AB
Change the mic type to omni

Notice how the orchestra angle doesn't change until you get to 5. meters apart.

Interesting. I think you mean the Stereo Recording Angle.  The Orchestra Angle always remains at whatever angle you set it.

Looks like the SRA maxes out at 180 degrees total, equating to an omni spacing of about half a meter or 20".  Any spacing narrower than that shows the same 180 degree SRA.  All the other stuff other than the Stereo Zoom imaging still changes of course.  Subjectively that seems about right to me, 2' is about where I feel the spacing becomes sufficient and not over-narrow.

26" is the best compromise between sound and reasonable set-up, as I can carry a lightweight separator that size. Any longer than that becomes somewhat unwieldy for me to implement.

Sounds like a good practical compromise to me.  This stuff has to be reasonable to rig first and foremost.

[Gutbucket]

Out of curiosity, what kind of mini-omnis do you run? I'm still trying to track down some rabbit ears so I can do away with that tent-pole setup lol. My X-X omnis are about the size of a jelly bean:)

DPA 4060 or 4061. The Niaint omnis are probably very well suited and not that much larger or heavier.

I bought the antennas at RadioShack, which still had them last I looked about a year ago.  They are still used for OTA digital broadcast TV.  I couldn't find individual black finished ones instead of chrome except by buying the entire set-top thing with the base and UHF antenna loop and dismantaling them for the telescopic arials.  Those were about $15-$20.  If they are getting harder to source I should buy some extras.

Next trick will be rain protection for split mics. Two mini umbrellas?

That is a problem.  I worried about that with my new-bought matched 4060s.  With the telescoping antennas I can retract them and angle them up to narrow the spread down to were they are under the edges of a stand umbrella covering the center mics.  I had a funny image of minature cocktail garnish umbrellas popped up over them with the arms fully extended.  I experimented with protecting them with finger cots or unlubed condoms over the miniature windscreens, but rain drops hitting them was like little reverb-less firecrackers going off.  Recently in these outdoor rigs, I'm using a pair of less valuable 4061s (bought a cheap ebay batch of used ones, tested and found a close match of two of them) an now don't worry about those getting wet.  If they get rained on they'll keep working fine until the small windscreens eventually fully saturate. Dry them and they work fine again.  If that happens I rinse them with disilled water that night and dry them.  Fortunately it rarely rains long and hard enough with them setup out there for that to happen.  I either retract them under the umbrella or just break down when the major squalls hit.  It's a pretty strong testiment to the hardiness of the miniature DPAs, but I still wouldn't want to subject the more valuable 4060 pairs to that kind of treatment.

[ScoobieKW]

Decided to check AB spacing of omni microphones with the Sengpiel Visualizer

http://www.sengpielaudio.com/Visualization-Blumlein-E.htm

Change the type from blumlein to AB
Change the mic type to omni

Notice how the orchestra angle doesn't change until you get to 5. meters apart.

Interesting. I think you mean the Stereo Recording Angle.  The Orchestra Angle always remains at whatever angle you set it.

Looks like the SRA maxes out at 180 degrees total, equating to an omni spacing of about half a meter or 20".  Any spacing narrower than that shows the same 180 degree SRA.  All the other stuff other than the Stereo Zoom imaging still changes of course.  Subjectively that seems about right to me, 2' is about where I feel the spacing becomes sufficient and not over-narrow.

26" is the best compromise between sound and reasonable set-up, as I can carry a lightweight separator that size. Any longer than that becomes somewhat unwieldy for me to implement.

Sounds like a good practical compromise to me.  This stuff has to be reasonable to rig first and foremost.

you are correct, SRA was my intended phrase. Will revise my post for clarity.

[aaronji]

A little off topic, maybe, but I have been doing a lot of spaced omni recordings lately using a two Super Clamp set-up with two 122B extension poles.  Usually from a balcony rail, where I can space the mics as far (or near) as I want.  At a moe. show a few months ago, for example, I had a nearly three meter spacing with no problems.  I generally go with about a meter, though, as it is easier to deal with the cables (and, like Gutbucket, I find that to be a good distance).  I have also clamped to a vertical rail in a wide V, which can easily get me a meter or more of spacing (a little trickier to get the mics in the same horizontal and vertical planes, but do-able).  I started doing this because it is hard to find sufficiently wide bars and those that are out there are either heavy, bulky, or pricey...

[Colin Liston]

the bad part of gutbucket's set up is that no matter where you are in the ampitheatre you are always under his microphones and if you start talking he gives you the death stare. Not that anyone ever gets the chance to listen to any of his recordings though....

[Len Moskowitz (Core Sound)]

First off, spaced omnis have a long history of making outstanding recordings both around here and in the professional classical world.  That record speaks for itself.  I needn't defend the technique.

You'll get no argument from me on that. If you like the results, that's all that matters.

When used on stage close to the sound sources, significant level differences from to proximity of sources to one microphone or the other are produced.

That's true. But at a distance you don't get level differences.

I've already stated why I don't think near-spaced baffled omnis are an optimal choice for recording outdoor performances at a big distance.

Again, we agree. I wouldn't use a baffled omni setup at a distance more than roughly twice the width of the sound source. Anything more than that and the location cues are not sharp.

[Gutbucket]

Thanks for the clarification, Len.

Colin, it's the loud conversational tapers who are preferentially targeted with the stare.

[lsd2525]

Bruce Hornsby 06/27/14