Rather than one microphone per sound source, the object is to pick up multiple sound sources (or a “large” sound source) with one (or more) microphone(s). Obviously, this introduces the possibility of interference effects unless certain basic principles (such as the “3-to-1 rule”) are followed, as discussed below. For one microphone picking up a typical choir, the suggested placement is a few feet in front of, and a few feet above, the heads of the first row. It should be centered in front of the choir and aimed at the last row.
In this configuration, a cardioid microphone can “cover” up to 15-20 voices, arranged in a rectangular or wedge-shaped section. For larger or unusually shaped choirs, it may be necessary to use more than one microphone. Since the pickup angle of a microphone is a function of its directionality (approximately 130 degrees for a cardioid), broader coverage requires more distant placement. In order to determine the placement of multiple microphones for choir pickup, remember the following rules:
- Observe the 3-to-1 rule
- Avoid picking up the same sound source with more than one microphone;
- Use the minimum number of microphones.
- For multiple microphones, the objective is to divide the choir into sections that can each be covered by a single microphone.
- If the choir has any existing physical divisions (aisles or boxes), use these to define basic sections.
- If the choir is grouped according to vocal range (soprano, alto, tenor, bass), these may serve as sections.
- If the choir is a single, large entity, and it becomes necessary to choose sections based solely on the coverage of the individual microphones, use the following spacing: one microphone for each lateral section of approximately 6 to 9 feet.
- If the choir is unusually deep (more than 6 or 8 rows), it may be divided into two vertical sections of several rows each, with aiming angles adjusted accordingly.
- In any case, it is better to use too few microphones than too many. In a goodsounding space, a pair of microphones in a stereo configuration can provide realistic reproduction.