How should I mike a choir of 60 to 80 people for sound reinforcement? The choir loft is 26.8 feet wide by 11.3 feet deep by 5 feet high in the back. We have been using 16 mics but it hasn't worked well.
Reply: Here’s our recommendation. Use three mics 8 feet apart, 15 feet off the floor, 2 feet in front of the front row and 2 feet over the head height of the back row, angled down 30 degrees to aim at the center row of the choir.
All the choir will be within the pickup angles of the microphones.
Every time you double the number of mics, you reduce the gain-before-feedback by 3 dB.
If 2 mics have 0 dB of gain,
4 mics have 3 dB less gain than 2 mics.
8 mics have 6 dB less gain than 2 mics.
16 mics have 9 dB less gain than 2 mics.
So, if you used 2 mics instead of 16, the sound system would be 9 dB louder! Also, the fewer mics you use, the less phase interference between mics you get. The result is a clearer, less muddy sound.
Experiment with mics on stands before hanging the mics.
Two Crown choir mics are the CM-30 and CM-31. Both mics hang from the ceiling. The CM-30 has a circuit that fits into an electrical outlet box, and the output is screw terminals. The CM-31 has a regular XLR 3-pin pro audio connector. Both are condenser mics with a supercardioid polar pattern, and both require phantom power from your mixer.
Here’s are links to the Crown datasheets for those microphones: