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T O P I C R E V I E W
DoniSJ
Posted - 01/05/04 : 17:57 SOME MIC TECHNIQUES: x-y technique - The stereo miking technique where two microphones' capsules are placed in close proximity and are splayed at 90 degree to 110 degree angles as in the x-y axes on a graph. 3-to-1 Rule - Stereo mic placement technique that states: For every unit of distance away from the sound source, the mics must be at least 3 units of distance apart. This applies only to equidistant close miking of a sound source. For choir applications, most mics can be postioned 2 to 3 feet in front of the choir and spaced six to nine feet apart.
Mic Placement for Sound Reinforcement. When placing mics to pick up the choir, a critical factor is gain before feedback. To get enough gain, you must to mike the choir much closer than you would for recording. Place the mics about 18 inches in front of the first row of singers, and about 18 inches above the head height of the back row. The mics are raised to prevent overly loud pickup of the front row, relative to the back row. The rows are equidistant from the raised mics, giving a well-balanced sound.
Other Considerations. Monitor loudspeakers can easily feed back into the choir mics. To keep feedback under control, try not to use monitors near the choir. Turn up the house loudspeakers instead. If the choir insists on monitor speakers, don't feed a monitor signal of the choir back to them becasue it will cause feedback with the choir mics. Instead, just feed them some music for accompaniment.
If the choir members complain they can't hear themselves, maybe the piano, organ, or music tracks are too loud in the choir monitor speakers. Have the choir sing a capella, with the air conditioning turned off. Can they hear themselves? Now turn on the air conditioning. Can they still hear? Turn up the piano or organ in the choir monitors. Then turn up the tape tracks. At what point can the choir no longer hear their voices? Turn down the offending sound source.
In some venues the choir mics pick up too much of the organ's sound. In this case, use supercardioid mics and aim them toward the middle row of the choir. Because the mics partly reject sound from the side, they will pick up less of the organ in this configuration. If the organ is still too loud, aim the mics straight down over the choir and filter out frequencies below 100 Hz in the choir mics.
HOW TO MIC A CHOIR Miking a choir or large vocal group is fairly easy and mic placement is not as critical as in other applications as long as a few simple guidelines are kept in mind.
When selecting a microphone, a condenser mic is your best choice since most are able to pick up voices from up to 7 feet away and are more capable of a flat wide-range frequency response. Before positioning your microphones, imagine a 60 degree cone of sensitivity emerging from the front of the mic. Vocalists within that cone will be picked up louder than those outside the area. Also keep in mind that it is not possible to mic all voices evenly. Some voices will be louder than others. Take this into account when positioning your vocalists.
High quality mics will generally pick up about 25 people each, therefore use two microphones for up to 50 singers and add one mic for each additional 25. (For example, a group of 58 would need three mics; a group of 80 would need four.)
If more than the recommended number of microphones are used, partial cancellation may occur. This occurs when the 60 degree cones overlap each other. A voice that is picked up equally by two microphones will not get heard.
When positioning the microphones over the choir, they should be placed one foot in front of the front row and 24 to 36 inches over the heads of the front row. The mic should be pointed at the heads of the back row. This formula is very effective for up to three rows of vocalists.
Microphones may be either set up on mic stands or hung from the ceiling. Your decision depends on how long the system will be in place and how portable they must remain. If the system is a temporary set-up or the microphones need to be portable for other applications, mic stands will be your first choice. If you desire a neat, clean appearance and the system will be in place for a long time, hanging the microphones from the ceiling is the best choice.
