Well, my school has a variety of old amps... Most of them had torn speakers which were replaced and are now fully working, but there's one Peavey amp - I think it's probably a keyboard amp, but we used to use it for light basswork sometimes. It's 100 watt if memory servers and has a 1x12" speaker. It powers up and runs fine, but if you stop playing music then the buzz is aweful - Really loud so it drowns out even the drums and everything, and it happens whether there's something plugged in or not. Could anyone help me out on this one please??