The part I'm concerned about it the switching on and off with a
switch not designed for this. Could it be damaging the amps?
No.
Power amps are turned on and off by relays all the time. What turns them off makes no difference. Though I consider the use of a 120v
switch undesirable and we wouldn't install a new
system based on that method of control, if it works for you then leave it. It's more a matter of a preference and practicality than of anything else. Functionally, it works.
About the buzz, we are going to be running new
speaker wire soon that will be balanced and using
xlr to output from the
console to the amps, I'm hoping that will
clear it up.
Again -- could be a
ground loop issue, could be a
gain structure issue. It could also be a lack of balanced lines, but let's
clear something up. The only signal that needs to be balanced is the
mixer output into the
power amplifier. This should be 3-conductor +/-/Gnd. Used to be these were 1/4" or screw
terminal terminations, but more and more they're
XLR's or
XLR and 1/4" combo connectors. Either way, this is the signal that needs to be balanced for best results.
The output of the
amplifier should be 2-conductor. If the connectors are banana, 1/4", NL2, NL4, screw-terminal -- it doesn't matter.
Before anything else, I'd look at the
gain structure. If you didn't have a problem with hum in the
system previously, I'd consider an improper
gain structure to be the likely culprit as the
gain structure was probably not rebuilt when the new amps were put in. If there's always been a hum, it could be a group loop, but for that matter maybe there never was a tuned
gain structure over the last couple decades.
Consider getting a
UPS (uninterrupted
power supply). They will condition your
power against surges, spikes, times of lower voltages,
etc. They will also provide for a good way to shut the equipment down during
power outages. Their cost isn't that different from a
power conditioner.
I'd discourage this. Every time you go to kill the amps via the 120v
switch, the
UPS will go into backup mode and try to keep the
system turned on. It'll probably start beeping loudly too to alert you to the fact that there's been an electrical event. Those inconveniences aside, it's unnecessary. Many
power amplifiers these days are designed to be operated off of generators or in the middle of a football field. At worse, they'll turn off and go into a self-protect mode. All in all, I wouldn't worry because a church is a fairly controlled environment. If the
voltage dips down enough to turn the amps off, you've probably experienced enough of a brown out to also take down your
mixer, any computers, and anything else that may be powered in the room.
----
If you don't currently have balanced lines run to your
amplifier from your
mixer, an easy test to do is to temporarily run a couple cables from the
mixer into the amps as
XLR cables. You can run them straight down an aisle if you'd like. If the balanced lines don't make a difference, another test you can do is to take the
mixer and place it on
stage.
Plug it into the same
power source as the amplifiers and see if that resolves the situation or not. If you've ruled out balanced v. unbalanced and a
ground loop issue, then the last likely culprit you have control over is
gain structure. If not that, then you likely have equipment that's just plain noisy.
I'd recommend you verify that the lines running to your
amplifier from your
mixer are, in fact, unbalanced. It sounds like you've confused the lines that need to be balanced with the lines that go to your loudspeakers -- the inputs to the
amplifier should be 3-conductor, the outputs from the
amplifier should be 2-conductor.