Is the hum coming from the speakers or the amp's transformer?
General things to try:
1. Float or lift or disconnect the ground on all electrical lines to all audio components. This includes a tv if shared with the audio components or even the vcr if the vcr audio outs go to the preamp. I'm sure you don't but you never know.
2. All of your components should share the same ground or no ground at all. You could have half of your components grounded and half not grounded. But just make sure the ones that are grounded are sharing the same ground.
3. If you narrowed the hum down to the amplifier's transformer, try to determine which circuit the amplifier is running off of. Then check the circuit breakers in the service panel.
Chances are that your amps' circuit is on the opposing phase of some or all of your other audio circuits and therefore generating some AC noise thats affecting the transformer.
Have an electrician move all of your audio circuit breakers in the service panel to the same phase of 115 volts.
Just for grins I moved my amp's circuit over to the opposing phase where my other dedicated audio circuits are to see what sonic improvements I may find. No sonic improvements that I could tell but it instantly cured my amp's transformer hum and the transformer has been almost dead silent every since.
-John
General things to try:
1. Float or lift or disconnect the ground on all electrical lines to all audio components. This includes a tv if shared with the audio components or even the vcr if the vcr audio outs go to the preamp. I'm sure you don't but you never know.
2. All of your components should share the same ground or no ground at all. You could have half of your components grounded and half not grounded. But just make sure the ones that are grounded are sharing the same ground.
3. If you narrowed the hum down to the amplifier's transformer, try to determine which circuit the amplifier is running off of. Then check the circuit breakers in the service panel.
Chances are that your amps' circuit is on the opposing phase of some or all of your other audio circuits and therefore generating some AC noise thats affecting the transformer.
Have an electrician move all of your audio circuit breakers in the service panel to the same phase of 115 volts.
Just for grins I moved my amp's circuit over to the opposing phase where my other dedicated audio circuits are to see what sonic improvements I may find. No sonic improvements that I could tell but it instantly cured my amp's transformer hum and the transformer has been almost dead silent every since.
-John