humming amp

[kurukato]

I hooked up my amp today and ran power to it and when I turned it on it made a humming noise that sounded almost like a loud cooling fan in a computer..
is this normal? It certainly isn't feedback because the sound isn't coming from the speakers its coming from the amp itself. any help would be appreciated.

thanks,
Evan

[KeithGTP03]

Does your amp have a built in cooling fan? If not, sit back and wait for smoke.

[SlowNA06]

My amp makes two noises. The one is a fan spinning. The other occurred when I attached a capacitor and seemed to have a poor connection to power or ground (or both - not sure). I fixed it by removing the capacitor. It never hurts to ensure that you have a really, really clean ground. Sand down the paint around it and cover it all with some liquid gasket, paint or caulk to keep oxidation away.