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Full circle around a Blumlein Pair - a capella

Had a fun recording on Sunday. A vocal group at a college about 90 minutes away hired me to record them for an archival CD for the members. 17 singers - I had them stand in a circle around a Blumlein pair (SPC3) with Oktava MK319s for lead vocal and beatbox. No beatbox on this piece, but ended up with some fun stereo placement quite by accident.

Preamp was a Sebatron VMP4000e into a MOTU 24i into Samplitude.


MadMax Tue, 04/25/2006 - 20:01
I sure hope you acoustic folks don't mind a nasty ol' multitracker in here too much...


I bet that WAS fun!

When I get a gospel choir gig, I like to get the choir to do some stacking with a similar arrangement...

I like to put em' in a circle around my SF12... either with the MP2MH or the DVC. (The VMP sound's great BTW!)

Kind of a rough go sometimes... I've only got 10 pairs of headphones... The choir's got to bring some of their own, but I usually get it done w/o too much hastle. I just drag a 6 channel headphone distro and a BUNCH O' "Y"'s...

It's fun just to watch em' walk around the mic talking... For fun, once I flipped L & R... one poor girl got so disoriented she had to sit down! :twisted:


zemlin Tue, 04/25/2006 - 20:21
No cans for this session. We were on the stage of a smallish auditorium - they were winging it for balance - soloists off the lead mic would step in to bring up their parts a bit - other than that they just checked their distance from the mics and balance by ear.

There were two folks (besides me) monitoring on headphones and providing feeback to the singers.

zemlin Wed, 04/26/2006 - 03:41
Full circle. I'm completely aware that I had reversed left/right imaging on the back quadrants and reversed phase on the sides - that was the whole point of that setup - I wanted a big, wide sound. Mono compatibility is whacked with the voices on the sides - I know - but I seriously doubt this recording will ever see mono playback.

Did you listen to the track? it sounds good to me.

zemlin Wed, 04/26/2006 - 04:25
A little more info and a fuzzy photo:
The blumlein pair is a bit lost in the photo - but singers were in a full circle around the center pair. Lead vocal spot mic at 12:00. Beatbox spot mic at 6:00. Time aligned the lead and beat mics - had to flip phase on the beatbox mic, of course, since it's on the backside of the Blumlein mics.

I guess there were only 16 singers. I didn't count them when I was there - I was told there'd be 17.

Cucco Wed, 04/26/2006 - 07:35
DavidSpearritt wrote: I do hope you mean not all the way round in a circle, because you have to avoid putting anyone in the two out of phase quadrants.

For close-up "vocal in the round" this technique actually works just fine. In situations like this, think less "in-phase" and "out-of-phase" It's really not out of phase. The vocal aiming at the reverse lobe is actually in phase with themselves though yes, out of phase with the person directly on the other side - but that rarely matters in situations like this. Different parts are grouped similarly (SATB all grouped alike) and Soprano is across from Tenor, Alto across from Bass, there really isn't too much to worry about phase wise.

Agreed, the result will sound a tad different than usual, but you'd be surprised just how well it can work. I've done this technique numerous times with a vocal group I record quite often. Usually, their shows are very diverse - they'll go from a full vocal with instrument ensemble down to a quartet and back to full chorus within any given concert. For these smaller quartet recordings, I typically do just that - blumlein with the singers positioned around it. Since you're primarily capturing direct sounds and little to no reflected sounds, there is little issue with phasing.


zemlin Wed, 04/26/2006 - 08:03
The singers on the sides (3:00 and 9:00) are singing into the front of one mic and the back of another, so when panned the cones are doing a push-me-pull-you thing that gives it that very wide sound - and it will cancel when played mono.

It also sounds like total crap when played back with a "stereo enhancement" setup, like SRS or Q-Sound since those are playing with the phase.

I think it sounds good when played through proper equipment though. I haven't tried it in my car yet.

Cucco Wed, 04/26/2006 - 08:13
I guess I didn't get your picture and description.

When I've done this, I group individuals so that they are in fact facing a lobe. It sounds (and kind of looks - although, I don't see a blumlein array in your picture) as though you were doing a true circle...

That can spell trouble as the point you've mentioned - when you're between lobes, you are in fact hitting opposite polarities. If it cancels in mono (which, in this case it should) that means it will also cancel when you are sitting in the sweet spot of the speakers.

Have you thought about doing a double M/S on this one? (Not a TRUE double M/S more like a Mid/Side with a phase-flipped rear...)

I haven't listened to your recording yet, but once I get to the studio, I will.


zemlin Wed, 04/26/2006 - 08:41
I must confess, I had not thought through the total picture here until after the recording session - one of those "it seemed like a good idea at the time" moments. I'm still not sure I have any regrets, but I probably would do things differently if I were to do it again.

I considered MS with or dual MS, but the Blumlein is what I chose.

I'm not hearing cancellation (can you hear cancellation :-? ) with speakers - just a very wide image.

anonymous Wed, 04/26/2006 - 09:15
zemlin wrote: Earlham.

I ask because I recorded an all female a cappella group from Miami University in Ohio only a couple of weeks ago, and MU is roughly 90 minutes from Indy!

I used a pr of Schoeps MK21 in NOS. In a live church, pickup was fairly close. I did the 'balance on the fly' too with soloists and beatbox.

This wasn't by chance "The Cheezies," was it?


zemlin Wed, 04/26/2006 - 10:27
My reply to your post above was a bit defensive, but your message caused me to step back a bit and think more carefully about the phase relationships I had going on. As I said a few messages back, I'm not sure I regret what I did, but I see how I could have done things differently and how my approach may have some problematic side effects (no pun intended). My thoughts about what I was getting were incorrect the day of the recording. Thanks for the wakeup call.

... always learning ...

DavidSpearritt Wed, 04/26/2006 - 11:08
No offence taken. I listened after typing my post, but knew for sure you had problems with the "all round the blumlein array" approach. The 9 and 3 o'clock quadrants are strictly out of bounds for the blumlein pickup, but not for singing into spot mics.

This recording is OK, a lot better than I thought, but I can hear some phase weirdness as well.

We recorded the Ten Tenors in a front/back around two KM120's in Blumlein, and had two spot mics, 1 vocal and 1 for piano, further back in the out of phase quadrants. It worked well because the two groups of 5 singers standing opposite each other were phase coherant, although reversed. The accenting of spots in the out of phase quadrants needed to be up higher than normal, to cancel the incorrect phase cues from the KM120's.

Overall, we got a fantastic blend and balance with minimal channels, this is motivation enough to try this complex technique. But there are lots of traps. I also had to put two long crosshairs in Gaffa on the studio floor, to keep the wild, joking, tenors shenanagans in the bounds of the array, and demanded bare feet, particularly when the soloists had to step round into the out of phase quadrants to sing into the M149.

My inspiration for this technique came from an article in Audio Technology magazine when Simmo interviewed Bob Katz re I Ching recording for Chesky.

Cucco Wed, 04/26/2006 - 11:34
David French wrote: One gripe - I prefer hiss to denoising artifacts anyday.


I still haven't listened to the recording yet...sorry. But, I agree with David 110% The human ear has an amazing noise reduction system. When presented with music and common/natural noise such as hiss or rumble, we can easily filter that out and act as though it doesn't even exist. However, artifacts are very un-natural and thus call attention to themselves.

My take on noise is always - "Embrace the noise." Getting rid of it only causes far worse problems. There are ways to minimize it. For example, I just did a recording in this local hall where the lighting system is cooled by this incredibly loud system which is located just in the right wing of the stage. The orchestra did Williams' Fantasia on Greensleeves where harp and flute have a long portion of the piece by themselves. I was able to filter much of the offensive noise out by a simple high-pass filter at ~100Hz and gently crossfade in and out of this steep filter when appropriate. Sure there's still noise there, but it's easily ignored.

Just some thoughts...

zemlin Wed, 04/26/2006 - 11:48
NR on this was to kill rumbling A/C noise. I actually thought it had come through pretty clean. :oops: I'll need to turn up the volume a bit and listen again. I'll blame some of it on MP3 compression ... yeah, that's it.

I can't tell here at work - my cans are very open and the A/C here is very noisy.

anonymous Wed, 04/26/2006 - 13:31
It sounds like you were happy with the recording until people pointed out the flaws. If it sounds good to you and to the group, who cares about theories and dissertations? All that stuff takes second seat.

One thing ive observed is that there are so many different notions on what sounds good, posting samples for critique(that ive seen) is rarely productive...Noone shares the same ears.

Guy A---man, that sounds great!
Guy B-Man, that sounds like @(!
Guy C-You shouldve used a neve you #**hole

I bet the group loves it. 8-)

zemlin wrote: NR on this was to kill rumbling A/C noise. I actually thought it had come through pretty clean. :oops: I'll need to turn up the volume a bit and listen again. I'll blame some of it on MP3 compression ... yeah, that's it.

I can't tell here at work - my cans are very open and the A/C here is very noisy.

zemlin Wed, 04/26/2006 - 13:47
BigRay wrote: It sounds like you were happy with the recording until people pointed out the flaws.
I am still happy with it. I just have some concerns on how it will translate in different spaces, and I'm always interested in learning and improving my understanding of all this stuff. Comments here have pointed out some issues I hadn't previously considered.

At this point, I'm not planning to change a thing - but there are a few things I'm going to keep an eye on as I finish the project.

DavidSpearritt Wed, 04/26/2006 - 14:10
BigRay wrote: It sounds like you were happy with the recording until people pointed out the flaws. If it sounds good to you and to the group, who cares about theories and dissertations? All that stuff takes second seat.

Well I tend to align with this sentiment too, if it sounds good it is good.

But there are some fundamental requirements that must be met, and that are not just "theories". One is that you don't mount the left mic to receive sound from the right first. Same with Blumlein phasing. Unless you want the out of phase as you are a composer, like in the I Ching project.

ghellquist Wed, 04/26/2006 - 15:05
Great recording I say.

I guess the mp3 coding does not give full credit, seldom does really.

I would add a tiny bit of a good reverb to get some more room. Maybe cut the lowest octave, there is not much energy coming from the singers below, say, 100Hz so most of the energy there is room noise.

It does sound really good on good phones (Dac1 + HD650). Loses quite a lot of the "outside" voices when monoed which might be expected.

All in all though, as most music is listened to on iPods and similar nowadays "headphone" compatibility is more important than mono compatibility.


Simmosonic Fri, 04/28/2006 - 01:12
zemlin wrote: I considered MS with or dual MS, but the Blumlein is what I chose.

Using dual MS for this recording would be like using a hammer to kill a fly...

For recording in a full circle as seen in your picture, MS with an omni for the M capsule would be an excellent choice. It decodes to two cardioids back to back. The front (or + side) of the S mic would determine hard left, the rear (or - side) would determine hard right, so position to taste. Centre would be directly into the side null of the S mic (either side).

With this technique you probably would not have needed to spot the soloists; just get them to step up closer to the side null of the S mic (either side would do, or both if you had a number of soloists), and they'd be in the centre. You'd have no out~of~phase quadrants to worry about, excellent mono compatibility, a full-bodied low frequency response, and there'd be very little (if any) proximity effect on the soloists, allowing them to get quite close if necessary.


Simmosonic Fri, 04/28/2006 - 02:03
ghellquist wrote: It does sound really good on good phones (Dac1 + HD650).

No discredit meant to the recording, but on this topic: I find Blumlein always sounds very impressive on headphones. I think the out~of~phase quadrants and the rear LR reversal tend to create a very spatial effect when heard in headphones. In fact, I find it can be quite misleading on very good headphones (i.e. Sennheiser HD600s, 650s). When using the SF12 and SF24, I have to be very careful or I end up with too much room sound when heard on speakers. It all sounds gloriously lush and enveloping and yummy in the heaphones, but way too reverberant on speakers. Sigh... If only everyone could hear it in all its spatial glory on the headphones.

Which brings me to:

ghellquist wrote: All in all though, as most music is listened to on SPAM! and similar nowadays "headphone" compatibility is more important than mono compatibility.

You're touching on a pet subject of mine these days, and I am assuming that where your post says "SPAM!" you were probably mentioning Apple's little i P o d. (A word that the server here seems intent on replacing with "SPAM!", no matter how many times I write it and preview it. Very Pythonesque!)

Most engineers I know have always had the philosophy that sounding good on headphones is okay, but if it doesn't sound good on speakers then it's not worth bothering with. Binaural recording techniques, for example, have never been taken seriously for this reason. People listen and are amazed, but the pro engineering response was to dismiss it with "Yeah, but it doesn't work so well on speakers".

Things are very different these days, as anyone walking a busy street or riding a bus or train will see - lots and lots of people listening on earbuds to music that was mixed to sound good on speakers. So... I think headphones are equally as important, or perhaps more important, than speakers these days. I am not sure if most mainstream engineers have cottoned onto this yet, but it's worth considering.

One could almost justify ditching the expensive studio monitors and acoustic treatments and so on, and just deciding to mix purely for the i P o d market. Get yourself a good DAC, a pair of high quality headphones for the main monitors, and a pair of Apple's earbuds for the 'real world' NS10-equivalent headphone reference. You can certainly get all of that for less than the cost of a decent pair of studio monitors, and you'll get much better fidelity at the same time. Keep a pair of NS10s on hand to check how your mixes will sound on speakers, and be done with it.

And, while you're at it, revel in all the cool spatial things you can do in a mix that only work in headphones!

IMHO, a speaker/headphone priority shift is imminent...