Stevens R. Miller
Well-Known Member
I suspect this is asked (and answered) a lot, but most of the online guidance I've found has been (understandably) a bit vague. I'm hoping, though, that maybe someone has had experience in nearly the same setting as the one in which I'm seeking guidance.
After our last community theater musical wrapped, I made it clear to my colleagues that I have had my lifetime desire to work with badly maintained, curiously wired, largely undocumented dusty humming audio equipment of nostalgic vintage completely satisfied by our latest experience. Accordingly, I am pushing for us to get our own powered speakers, so we can stop using the in-house stuff in the middle schools we use as venues. The response has been cautiously supportive. But the threshold question, of course, is how much will this cost? That, naturally, depends on what we need.
Our typical venue is a middle school auditorium, with a seating area of about 4,000 square feet (roughly 80 feet wide by 50 feet deep), that seats about 480 people. They usually have a single center cluster of three speakers mounted on the ceiling, just above and in front of the proscenium arch. As far as I can tell, it is driven by a QSC CX1102 amplifier. I do not know the impedance of the speakers. If they are 8-ohm, QSC says both channels driven gets you 700 watts (I am not entirely sure, but I think both channels are used in a bridged configuration). If they are 4-ohm, QSC says that gets you 1,100 watts. The masters on the amplifier are down about one-third from their least-attenuation position, and I know we could be driving the amp with higher line levels than we send it, so we have a lot of overhead that, I am guessing, we mostly never use.
So here's my question: if we're going to use a pair of self-powered speakers on stands, instead of the single center cluster on the ceiling, in a 4,000-square-foot, 480-seat middle school auditorium, how much power should each speaker provide?
After our last community theater musical wrapped, I made it clear to my colleagues that I have had my lifetime desire to work with badly maintained, curiously wired, largely undocumented dusty humming audio equipment of nostalgic vintage completely satisfied by our latest experience. Accordingly, I am pushing for us to get our own powered speakers, so we can stop using the in-house stuff in the middle schools we use as venues. The response has been cautiously supportive. But the threshold question, of course, is how much will this cost? That, naturally, depends on what we need.
Our typical venue is a middle school auditorium, with a seating area of about 4,000 square feet (roughly 80 feet wide by 50 feet deep), that seats about 480 people. They usually have a single center cluster of three speakers mounted on the ceiling, just above and in front of the proscenium arch. As far as I can tell, it is driven by a QSC CX1102 amplifier. I do not know the impedance of the speakers. If they are 8-ohm, QSC says both channels driven gets you 700 watts (I am not entirely sure, but I think both channels are used in a bridged configuration). If they are 4-ohm, QSC says that gets you 1,100 watts. The masters on the amplifier are down about one-third from their least-attenuation position, and I know we could be driving the amp with higher line levels than we send it, so we have a lot of overhead that, I am guessing, we mostly never use.
So here's my question: if we're going to use a pair of self-powered speakers on stands, instead of the single center cluster on the ceiling, in a 4,000-square-foot, 480-seat middle school auditorium, how much power should each speaker provide?