Subwoofer Hum

[Greg]

I had the sub on the same power strip as everything else, and it was still humming. I've recently noticed, though, that the humming disappears for a second just when doing things like skipping through chapters on a DVD.

Do ground issues even effect it if it has a two prong power cable?

I think the coax cable I have is like 12', but it kind of needs to be this long to reach behind the couch. It's a decent cable, though.

 

[EricB]

yep. but breaking a ground won't resolve your issue. creating one might resolve it

take a piece of wire. unscrew a screw in the sub. wrap the wire around it and tighten it. touch all of your stereo component's grounds that you have to until the hum goes away. start by touching the outside rca shield of the sub, then the ground screw on your receiver. let me know what you touch that makes it go away. I instruct you from there

you could buy a rca ground loop isolator for car stereo. but do that as a last resort as it take away some sound (although most people can't tell). that what I use because I don't want to use a ungrounded sub. if I take off the ground it will go away but I'm an electrician at heart so I don't go that route

 

[KurrentEweser]

I've recently noticed, though, that the humming disappears for a second just when doing things like skipping through chapters on a DVD.

This sounds more a source problem than subwoofer grounding problem. Does the hum go away when the DVD players audio cables are disconnected?

 

[Greg]

Haven't tried, but it happens on everything. Satellite box, Xbox Media Center, MP3 player, Audiotron, etc.

And thanks Eric, next time I have a minute I'll move my sub and try that out.

 

[EricB]

if you are savvy enough to mess with electrical boxes you can try and install an isolation grounding outlet. these were originally made for hospital but they beat any surge protect and offer superior isolation for computer and audio equipment. they are usually orange

you need and 14/3 wire to the electric box. you round the regular ground to a ground of another outlet, the nuetral to neutral and power to power. they you run the red wire (usually a power wire on a 220 volt circuit) to the ground at the electrical box and to the ground of the plug. this isolates the ground from the regular house grounds

Hospital Grade Duplex Isolated Ground Receptacle

 

[Greg]

Hmm, sounds like a lot. I still haven't tried your first suggestion, though

I should get on that.

 

[EricB]

Hmm, sounds like a lot. I still haven't tried your first suggestion, though

I should get on that.

let us know how that goes. I just moved to another house. I'm going to make 2 isolation circuits

 

[EricB]

Well I just made 1 20 amp isolation circuit. the hum is gone(I don't need tricks like ground loop isolators anymore), plus I got another benefit that I wasn't counting on. the loud crazy thump from my sub isn't there anymore. the living room is next

the orange one is the isolation circuit.

 

[EricB]

here's instructions for the wiring since I've been asked. don't attempt this if you don't know anything about electric wiring

Installing an Isolated-Ground Receptacle

 

[Greg]

Finally went out and bought a ground loop isolator like you suggested, and the hum is drastically reduced to the point of no longer being extremely annoying. I'd have liked to put in the isolation circuit, but I'm not sure I could pull it off since my breaker box is on the opposite side of the house. Thanks for all of the advice