ORTF and mic placement

Recording a choir is a lot of fun - can also be a lot of work to get it right.
 
A couple of observations...

First - the ORTF configuration is meant to capture both volume and time (read phase) differences. So especially at such a close distance I'd expect phase differences - not issues<G>. I prefer coincident configurations, but when I use ORTF I use it at some distance from the source.
I prefer (at least these days) either Mid/Side or Blumlein configurations for stereo recording. I don't get the same depth of image, but i get great mono compatibility, and very repeatable results.

I also tend to shy away from large capsule cardiod microphones when recording spaces. I've never been completely happy with the results. I do lean towards cardiod patterns, but I prefer small capsules at any distance.

Ultimately, and I don't say this to sound simplistic, it comes down to how the choir sounds in that specific space. Have them sing and walk around the room. Get a really tall boom stand and place a stereo pair (coincident or not) way up high and give that a listen.

Without seeing/hearing the space and the choir I can't get more specific than that, but I can tell you what has worked for me in the past. This was for a 40 plus piece children's choir in a large, stone church.
1) a Blumlein pair using a Royer SF-12 stereo ribbon microphone was placed about 20 feet back, and about 15 feet up (maybe higher, it was as high as my stand would go.)
2) a coincident pair of Earthworks SR-77 microphones was placed about five feet behind the conductor and about 5 feet above her head.
3) I also placed a pair of Sennheiser MKH-405s about 10 feet back and at the extreme sides of the church. I ended up not using those tracks, they didn't provide anything I didn't already have.

Your mileage, of course, will almost certainly vary!!!
 

gswitz
You've got a lot more choices than I have.

 
Choices are good - but keep in mind I've been building my locker for almost 30 years, it helps<G>!
 

gswitz
I'm not a pro, and my mike locker is a little light. The placement of my KM184s is going to be the most important. I don't have a stand that will go as high as 15 feet. I have a stand that might go up 8 feet, but that's about as high as it reaches

Your microphone collection is pretty good, if I were in your shoes I'd invest in a large, heavy microphone stand, and then I'd curse my name every time I take it out of the studio<G>!
 

gswitz
Can I borrow your mics?

 
I don't think you want to drive from Richmond to Philly twice... and while I do loan them out from time to time I'm not a big fan of shipping them anywhere.

gswitz
I was thinking I could use the LDCs to fill in some of the soloists if they are a little light in the ORTF pair.

 
A good plan!
 
Biggest challenge, I think, will be finding a spot for the stereo pair where it sounds awesome. I can't recall the last time I had to use spot microphones - not saying I don't put them up, but if you get that stereo pair in a sweet spot you won't need the spot microphones.
 
Good luck, and have fun!

http://www.soundpure.com/p/k-m-20811-microphone-stand/1006
 
This?

For tall stands on location,  it is very common to see Manfrotto or Calumet light stands instead of microphone booms.  The threads on light stands are 3/8-16 which is the European microphone standard, and will fit the adapter that comes with just about every mic clip in the US.  They are lighter and more economical.  Just remember sand bags.  
 
I am just finishing up 2 album releases of choir music.  One of Bach's mass in B-minor and the other a Christmas album of a local professional choir.    You can see the setup of the latter here.  Basically three omnis in front as a Decca tree, and a NOS cardioid pair as a room microphone about 25 feet back.  I think room mics are important for choir as the washy, faded sound of distant mics help glue the mains together.  What you don't want is individual voices sticking out.  
 
 
I do prefer omnis for choir in an AB pattern but cardoids should be okay.  With directional mics, ORTF and NOS are the best patterns for choir I think.  The former for room, and the latter for clarity.   Though I agree Blumlein is hard to beat.  Just remember that cardoids should be slightly further back than omnidirectional mics, maybe 6-8 feet behind the conductor.  The height should be around 9-13 feet.  Too high and the sound may be too bright.  

I posted one of the songs here...
http://forum.cakewalk.com/Christian-Choir-m3124836.aspx#3124836