Subwoofer hum

[axionjaxion]

I have a subwoofer hum that I can't figure out. The subwoofer is powered. When connected to the Amp the hum is minimal. When the amp is turned off, the hum gets much louder. If I unplug the speaker cable from the back of the subwoofer the hum disappears. If I unplug the speaker cable from the back of the amp the hum does not change. This is annoying because it forces me to turn off the subwoofer whenever I turn off the amp. Any suggestions?

[TinHere]

I have a subwoofer hum that I can't figure out. The subwoofer is powered. When connected to the Amp the hum is minimal. When the amp is turned off, the hum gets much louder. If I unplug the speaker cable from the back of the subwoofer the hum disappears. If I unplug the speaker cable from the back of the amp the hum does not change. This is annoying because it forces me to turn off the subwoofer whenever I turn off the amp. Any suggestions?

Sounds like a ground loop issue. Try a cheater plug [3 prong to 2 prong].

Good luck.

[F1]

Sounds like a ground loop issue. Try a cheater plug [3 prong to 2 prong].
Good luck.

Or try to plug the sub to another outlet.

[joel2762]

What kind of subwoofer do you have? I have a Quest SW-880. It does the exact same thing...It's supposed to have auto shut-off but it never works..because of the humming I thought. So I brought it to my basement..No humming..It still didn't shut off. Oh well, it was supposed to have crossover too but it's not there ...I unplugged my VCR and the hum lowered noticeably...I don't know..what gives.