Subwoofer Hum

Pizdook

I'm using a PSW505 subwoofer and I recently got a new Denon AVR790 receiver and all of a sudden I have some low frequency hum coming from my subwoofer when the receiver is off and the subwoofer is in the auto state (so it doesn't go to sleep after 15 minutes). My old receiver was an Onkyo RT-530 (from a HTIB) and when I got the subwoofer I had the same sort of problem but moving the subwoofer cable away from the speaker cables seemed to help things and the hum went away, but that fix doesn't work with this new denon receiver.

Just some other information...

If I turn the sub into standby mode there is no hum.

When I have the sub plugged into the wall without any cable running to the receiver there is no hum.

When I have the sub plugged into the receiver and the receiver is on there is no hum, but when I turn the receiver off the hum starts.

I do not have cable TV so there is no coax cable plugged into the TV.

I have tried multiple outlets and that changes nothing.

For the subwoofer cable I'm using a 25 foot Belkin Pure AV cable. Would having a short subwoofer cable eliminate the humming? or is the belkin pure AV cable pure cr*p?

I'm not sure if this is a ground loop or electromagnetic interference problem. but if anyone has advice/information it would be appreciated.

ben62670

A real quick test is to try using a cheater plug. They are the ones that adapt 3 prong AC plugs to 2 prong outlets. The Belkin wires seem decent, but that is a long run.

dudeinaroom

http://www.polkaudio.com/forums/showthread.php?t=88698&highlight=ground+loop
http://www.polkaudio.com/forums/showthread.php?t=88461&highlight=ground+loop
http://www.polkaudio.com/forums/showthread.php?t=87755&highlight=ground+loop

This site has an awesome search feature.:cool:

The problem could be coming form a few different places.

A cheater plug works, but there is a reason why they call them a cheater plug.:rolleyes:

Welcome to Club Polk.

Hang around there is a lot to learn on the forum pages here.

Later,
dude


****Edit****

Sorry Ben, I guess you did say as a test.

sTiLlLeArNiNg

If possible i would try a different cable, a shorter one would be better if you don't need the 25' length. I am inclined to say that it is an EMI problem

danz1906

ben62670 wrote: »

A real quick test is to try using a cheater plug. They are the ones that adapt 3 prong AC plugs to 2 prong outlets. The Belkin wires seem decent, but that is a long run.

Agreed,that should work.