I thought it'd be fun to record the bluegrass jam at my local brewery. It'll probably be a circle of ~15 musicians of various skill levels. It was indoors last time (noisy brewery), but I'm guessing it might be outdoors (near a busy street) next time.

I want to be as unobtrusive as possible, and I'm considering one of two options:

• a spaced pair of Schoeps MK2H @ 35cm, or
• a pair of coincident OC-818 @ 90 deg set to omni mid/side (one omni, one figure 8).

Either pair would be centered in the circle, probably just below eye level.

I anticipate not having any time for tweaking placement, just levels.

I'm torn between which pair to use. I like the thought of a spaced pair, but those OC-818 would give me multiple options if I record both sides of each mic (4 channels).

I'm even toying with the idea of setting up both pairs (6 channels), and using the spaced pairs as mains and the 4 OC-818 diaphragms as cardioid spots @ 90 degrees. Might come in handy to compensate for quiet guitar solos and noisy fiddle/banjo solos. It's a lot of gear for an ad hoc performance, but if the cardioid spots give me some flexibility, it would be fun to test that.

What say you experienced folk?

A full circle? I'd go for a classical Blumlein (crossed fig8) setup in the center of the circle.

Well, I wouldn't go for Blumlein if it's a full, unbroken, circle, but it's a good option for arcs of, say, 70 degrees front and back. John Cuniberti has plenty of useful advice on this in his OneMic recordings. The spaced pair of MK2H should sound fine. I included a pair of omnis in my tests recordings of a pipe band in the round, and, though I preferred MS with omni mid, the spaced pair sounded pretty good. You might find my write up useful: it includes sound samples (which you can download) of all the different options of the session - https://drbadphil.com/a-tale-of-two-...rt-2-recording

Cheers,

Roland

Though you may find it too visually obtrusive, one of the most effective things to use for a full circle of players is a Jecklin disc, which provides full, even 360 degree coverage with no phase issues. Point the mics (SDCs) straight up, that way all the instruments will be picked up with the same HF balance. Some high EQ will likely be needed to compensate. DPAs with nosecones probably wouldn't need any top EQ.

I wouldn't use any LDCs in a situation where sound is arriving from all angles.

Yeah, I need to build a disc. It's on my to-do list.

I wonder how it'd sound if I put the pair w/disc ~ a foot above their heads (pointing down) to get it out of the way.

Unfortunately, blumlein's a no-go with a full circle. It was my first thought, and then I read about the phase issues and tested in my garage. Phase is crazy in the -/+ and +/- quadrants.

That'd work perfectly fine.

Yes, with Blumlein you'd be limited to two arcs of players 90 degrees wide, exactly opposite each other; a bit limiting.

Thanks for the info. Reading through your write-ups and listening to samples. Sounds like I'm contemplating something very much like what you did (minus a coincident omni).

I'm still trying to wrap my head around 2-figure-eight mid-side, and how it equates to blumlein, but that's for another thread.

I've heard plenty of Blumlein recordings with the singers/musicians gathered around the mic that sounded pretty good. But I have to admit: I'm using a different setup myself in situations like these, but it cannot be done with the mics at hand. If you don't want to use crossed fig8's you may want to go for Blumlein's small omni AB (±22cm) with a shuffler in post. Sounds excellent.

Blumlein's small omni AB was with a baffle; a crude version of a Jecklin disc.

With non-Classical music, a Jecklin without shuffling can sound perfectly fine.

Think I'd go with the OC818s and four channels.

It maximises your options on mix-down. The HF off-axis response isn't as good as an excellent SDC, but IMO that's offset by the flexibility of the setup:

You'll essentially have the option to "aim" the stereo image wherever you like, although 45-degree steps (XY with any pair, M/S in-between) will be the most straightforward.

Bonus: you'll still be able to tweak the polar patterns in post.


Chris

Without shuffling the low frequency stereo image sounds more narrow than the higher frequencies (also with a disc), especially on speakers. With or without a baffle the shuffler is what gives the good stereo image, with beautiful room bloom. At 22 cm without baffle the system sounds truly fine. The use of the baffle is with a mic distance of 20 cm.

Vertical pointed up spaced Schoeps MK2H stereo pair centered in the performance circle.
Unobtrusive fun way to record them.

This would be objectionable for Classical, but with pop/folk/bluegrass, LF centered in the image is rather typical and expected. In studio recordings of this type of music, the bass instruments are usually mic'd mono and panned to the middle.

As such, it would be recommended to place the lowest-pitched instruments directly in front (and/or directly 'behind') the disc.

These small ABs do always sound better with shuffling, but it's debatable whether it's worth the trouble with this genre of music.

The original Jecklin OSS specification (with 30cm disc) was for a mic spacing of 16.5cm (human head spacing). The later, larger one (with 35cm disc) was 36cm spacing.

I'm researching shuffling now, trying to understand how it works. Can it be done manually using mid-side EQ? Or does it require time-difference processing?

Also, what advantages does a 22cm spacing have over 35cm? Both seem to have an SRA of 180, but it looks as though 22cm would bring the outer sources inward.

^ THIS!

unless you have/can rent a soundfield mic or a double m/s mic system.

Since I'm doing this for free (with limited expectations) for my edification, I'm really leaning toward putting up both pairs. It'll be fun to test the various configs I can muster from the OC-818s alone, and also seeing how they work as cardioid spots for the spaced pair.

My biggest concern is the safety of the mics. I'm hoping it's indoors.

^ THIS!

unless you have/can rent a Josephson C700S (which isn’t ‘as unobtrusive as possible’), or a coincident set of “2 Schoeps MK 8 + an appropriate Schoeps omni”, or the Schoeps ORTF-3D microphone array.


Post production will take you far—if it doesn’t eat you alive.

Ray H.

Footnote: https://schoeps.de/en/knowledge/user...recording.html

i wouldn't use any spaced mic technique other than maybe a pair (or quartet) of overheads, flown high above the ensemble if (the room is high enough and) the ensemble really sets up in a full circle; whether this is the smartest setup is a different discussion though...



[i found the combination of double m/s for horizontal pickup plus double ortf for the overheads to be a highly efficient rig for immersive music production]

Probably ain't going to happen this go-round, but I'm intrigued by double-ORTF. I have four MK-012s that are reasonably well-matched.

The Sengpiel visualizer can't display results for baffled omnis/Jecklin, as the resulting polar patterns vary considerably with frequency.

Thanks D.

I recall recently reading something about Apple Music acquiring a Schoeps ORTF-3 for (pop music) concerts. But—though not specifically disclosed—I suspect it was more for sampling the crowd?

There was more serious research done by S3A. I’d have to dig back to find their thoughts. Their old blog seems to have been taken down.

Footnotes:

https://www.surrey.ac.uk/centre-visi...nal-processing

https://www.linkedin.com/pulse/recor...hilip-coleman/

the schoeps ortf-3d is a brilliant piece of kit...

...but i think i wouldn't use it indoors, except maybe in (very) large halls - and not as main mic system.

for this, i think i'll stick to (double) m/s (and maybe add an omni for lfe) on most occasions (and add a pair of outriggers for pickup of very wide ensembles).


[that said, i'm temped to buy a pair of used mkh twins right now...]

Keep in mind that with players in a full circle, cardioids are going to pick up a lot of sound at 180 degrees off axis, where most cards have very scooped and/or ragged response (even the vaunted MK4).*

One way around this is to use a pair or array that places the mics a bit above the players, pointing down - that way they would all be approx. 45 degrees off-axis.

________

Unless you are recording surround, ORTF-Surround will result in significant combing, since you'll most likely be mixing the front pair and rear pair at equal levels. The cleanest, simplest way to deploy four cardioids for a circle of players (that results in much richer stereo than any MS combo) is with two DIN pairs placed coincidently. Think of it as a 90 degree XY pair aimed 90 degrees left; both recorded on the left channel, and another 90 degree XY pair aimed 90 degrees to the right; both recorded on the right channel. Spacing the two XY pairs 20cm apart will result in two coincident DIN pairs that will mix at equal levels with no combing. Literally, DIN stereo with 360 degree coverage.

As stated above you'll want them a few feet above the players pointing down, so they are all equally off-axis with none at a full 180 degrees.

Myself, I would only bother with four cards if the results with Jecklin were too roomy.

*First image below is the MK-012 cardioid; the second is MK4.

Blumlein does not really work in a folk circle because the angle of acceptance is so narrow. People to the sides drop off in level substantially. But, you can also make sure to place the people who can't play well into those side positions.

A set of four, six, or eight cardioid microphones in a circle in the center is a very fine solution.... then you can pick any two microphones to use after the fact, picking as different pair for each song so that the person in the lead is loudest and everybody else is still audible. (This is for music where there is clearly one person in the lead and everyone else following... not the case for Irish trad music but often the case for bluegrass and old time.)

A Jecklin disc in the center can work too, if the circle is a small one. People off to the side very quickly fall off to the edge of the stereo image but at least they are still at the same level. Point it toward and away from the better performers.

The ultimate solution is a guy in the center with a pistol grip and a pair of hypercardioids which are pointed as needed and I used to do this for folk circles when I was younger and had stronger back muscles. The solution above with the circle of cardioids is really just an attempt to duplicate this process after the fact and do all the pointing in post.
--scott

Not so long ago, in a universe far, far away, I answered essentially the same question thusly:

For a "single mic" recording of musicians in a circle, there are four choices.

1. A single omnidirectional mic. To make this work at all, you'll need to adjust player distances, move amps farther back, add vocal mics, and possibly a few spot mics as well. It takes a lot of experimentation.
2. A planar B-format array. Think of this as a Blumlein pair with an additional omni mic. There's software available that allows you to adjust the pickup angle and rotate the focus towards whomever is soloing at the moment. You can build this with two figure-eights and an omni, four coincident cardioids, or a pair of OC818's (capturing all four capsules). It takes a bit of pre-matrixing to reduce these alternate configurations to B-format, but it's easily doable in a DAW.
3. A full Ambisonic microphone. Same comments as above, but now you can tilt the pickup angle elevation as well. These mics used to be expensive but Rode and Sennheiser both offer cheaper ones now. A second-order Ambisonic microphone gives you better separation at the cost of recording more channels. Core Sound makes the cheapest one.
4. A spherical array microphone. There's been a ton of academic research on high-order spherical arrays but, with the canonical Eigenmic costing about $20k, almost nobody could afford one for music recording. This changed with the availability of micro-machined silicon "chip" microphone elements. Now you can buy a nineteen-element spherical MEMS microphone from Zylia for about $2k. It's effectively a third-order Ambisonic microphone that provides a ton of control. Combining so many lower-quality transducers yields a higher-noise floor, but that's less of an issue when the musicians are close.

David

Yes. There is also a pretty affordable program that does it instantly: https://pspatialaudio.com/download.htm (Stereo Lab Tonmeister, setting: Blumlein Delta.)

No.

The 22cm gives a much better solidity in the image and sounds good on both headphones and speakers. The 35cm spacing version makes me dizzy.

I didn't see anywhere that the OP inquired about "single mic' . . .

It's a recycled answer. By "single mic", the original OP meant they didn't want to mic every player in their (smaller) circle; they wanted to put up a single stand in the middle and capture everybody. If you'd read my answer carefully, you'd have noticed that option 2 actually involved three mics.

Concerning option 4, there's a new version of Zylia's Ambisonic plug in that does automatic source tracking.