If I were doing it, and assuming they are good players that know how to balance themselves and that they will be setting up in a fairly tight seating arrancement, i.e., not very far laterally from each other, I would stick with a single pair of SM81 in a near coincident array. I would try to use a more spacing than angle to achieve the stereo representation that I would want as to minimize the off-axis demands placed on the SM81. I would probably start by placing them at head level or a little above.

David's got some good tips for you, Rigby. I'd second his advice, and suggest that you stop over to the Acoustic music forum in the future for more info and lots of good ideas on this sort of thing.

Bass Clarinets are from another planet. You SHOULD be scared. Hehe. ;-) Nah; hopefully it'll be a good group that knows how to balance themselves acoustically.

It was some great advice, the recording went very well.
I kinda veered away a little and decided on a M-S with a sm81 and the apex 415 in a figure 8 pattern.
We used an ortf in the piano lid with two sm81's. The vocals seemed to get mudded out due to the placement of the artists so we threw our last sm81 hidden near the vocalist to get her clearer.
We haven't completed the mix yet but so far so good.
Any thoughts on mixing? other then the normal steps for the M-S.

Rigby_Shacklford wrote: It was some great advice, the recording went very well.
I kinda veered away a little and decided on a M-S with a sm81 and the apex 415 in a figure 8 pattern.
We used an ortf in the piano lid with two sm81's. The vocals seemed to get mudded out due to the placement of the artists so we threw our last sm81 hidden near the vocalist to get her clearer.
We haven't completed the mix yet but so far so good.
Any thoughts on mixing? other then the normal steps for the M-S.

I hope you had a tape measure and made a note of the distances of the microphones from their principal sound sources. When mixing down, you need to delay the spot mic tracks (piano and vocal) relative to the main MS pair by about 1 millisec per foot of distance NOT travelled by the sound. This delay is to get some phase compensation and avoid the mix sounding muddy through having the same sound arriving at different times at the various microphones.

Thanks Boswell,
I think I'm going to start with the M-S mix then I will slowly bring the piano in and nudge it into place, then do the same with the spot mic on the vocalist.
Any tips on any post production that I might need to do? The vocalist can get pretty loud and broad in some spots, would using compression on that track only mess with the cohesion of the entire sound? Or should I just use a master compression to keep everything glued together?

I may be old-fashioned, but I'm of the school that advocates no compression on a concert recording of classical material. There are exceptions, such as when something has gone unexpectedly wrong in the performance. A touch of compression on her mic channel only could be used without upsetting the overall mix. But generally, you just have to cope with things like the vocalist deciding to stand three feet closer to her mic than at rehearsal.

One guideline in post production of live recordings when mixing in spots or flankers (time adjusted) is to bring them up slowly until you can hear them making a difference and then back off a couple of dB. The main thing is to use your ears. See what you like about the recorded sound and try to identify what you don't like.