There is a good chance I might find myself soon mixing a worship band in a room with an
LCR rig. While I am familiar with the concept, I have yet to have any experience in front of such a rig. I have mixed stereo (and
mono, but who hasn't) rigs before, however I feel that this may be a different kind of beast.
It definitely is. Many rooms have what appears to be a left, center, right arrangement but it is actually something physically similar like stereo plus
mono or exploded
mono. So the first thing to find out is whether it is truly L/C/R or not.
If the
system truly operates as L/C/R, then the next question may be how well it works, especially whether each individual
array provides good coverage and imaging for all the listeners. You might want to use
pink noise and pan it left-center, then walk the floor. Do the sound and the imaging stay consistent as you walk the listener area or do they vary? If either varies significantly then you may want to consider minimizing the use of panning anything other than hard left, dead center or hard right.
If you find that it is a well designed and functioning L/C/R
system, then how you pan depends somewhat on the sources. For
mono sources or impulsive sources (drums,
etc.) you basically have to decide if imaging or clarity is more important. Having a
mono source assigned to a single
array (e.g. panned hard left, dead center or hard right) will result in the sound coming from a single source, improving clarity and time coherence. Panning a
mono source between these (e.g. left-center or right-center) will result in multiple signal arrivals at the listener, thus typically reducing clarity and 'smearing' the signal. However, it is also that difference in time and
level of the two signals that provides the imaging information.
Stereo sources are a different matter as they can actually benefit from differences between the left and right signals. However, a L/C/R
system is different than stereo in that the differences the
system produces are between left and center or right and center rather than between left and right. On the one
hand this means the imaging stays a
bit more stable across the listener area than with a stereo
system, if you have a
channel panned left-center then the worst it does is
shift a
bit between left and center throughout the audience rather than between left and right as in a stereo
system. On the other
hand, it was intended to be a stereo source then introducing a center
channel component will differ from the original intent. So for a recorded stereo source you may want to keep it with the left and right channels hard panned. But for a live stereo or two
channel source, you may want to use panning to help place the
image on
stage.
Here's a couple of resources you might want to read:
http://www.rane.com/pdf/ranenotes/Mixing%20for%20Three%20Channel%20Reinforcement.pdf
http://sound-technology.com/media/press_release/Multichannel Mixing AES01.pdf