Stereo, Mono and LCR in Sound Reinforcement
Stereo, Mono and LCR in Sound Reinforcement

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Learn the best choices to make when building your sound system.
By Ken DeLoria

space, as opposed to the left loudspeakers covering only the left side and the right loudspeakers covering only the right side.

The downside, however, is that there will be a lot more sonic energy reflecting off of the side walls, than if each loudspeaker cluster was to be arranged only to cover its own room section (of course outdoors this is rarely a problem, unless there are nearby buildings that might reflect the sonic energy).
 
Stereo can work, and work well, if the side walls of the room are either (a) not particularly acoustically reflective or (b) occupied by patrons, such as in a wraparound- or horseshoe-shaped concert hall. Patrons can absorb a lot of sound, thereby reducing acoustic reflections. This is especially true in winter weather when patrons tend to wear thicker and heavier clothing. Summer-only venues, beware.

When a sound system is configured in stereo, as described above, it becomes important to pan L & R program sources to hard L & R, or at least very close to hard. You don’t want the same acoustic source to be heard from the left and the right loudspeakers at the same time, as the distance between the loudspeaker clusters will cause time smear, which harms intelligibility and musical clarity.

Sources that are inherently mono, such as acoustic guitars, flutes, woodwinds, brass and others, can often be miked with dual mikes to obtain a stereo source. For example, one mic can be placed by the sound hole of a guitar and another placed near the neck. That will give you two sources to work with, so that there’s less overlap of identical acoustical information.

What Happens If You Have a Mono Source, Such as Vocals?

Because vocals are usually the mainstay of most musical performances, the answer here is to divide the system into a stereo configuration for music and a mono configuration for vocals, or any other non-stereo source.  How to do that? Well, as long as each loudspeaker cluster is made up of a horizontal array of multiple, individual arrayable speakers, with a little extra work it‘s possible to circuit them so that only the two or three individual speakers that cover only their side of the room will receive the mono signal, while the entire array — perhaps four, five, or more loudspeakers — receive the stereo feed. This will require the use of a matrix on the mixing console, and/or an external summing device. It can’t be easily accomplished with a small,


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