Powered subs are notorious for problems like this. One mfr used to ship their subs with a cheater plug packed in the box. Bad idea, and does violate NEC.

We often use a car stereo transformer-coupled ground lifter on the subwoofer signal line. I'm sure a Jensen transformer would also work, and offer better frequency response than the $20 car stereo part.

I have used these before. They do work. May not work for you but you can always take it back to the shack.:)


[Link: radioshack.com]

I used this in my own system and it solved the problem:

[Link: tributariescable.com]

100 bucks though... egads!

My latest test is to have the SUB80 connected with shielded RG6 to the receiver , receiver is unplugged from AC and subwoofer is plugged into AC. Still hums. Dang!

Wiring is correct.

I'll try Infinity or Energy, which I have used before with no grounding problems. No more Earthquake for me. Thanks to everyone who responded, this is a great forum.

Spoke to tech support from the vendor and he suggested to "lift" the ground by using a cheater plug, which he claims does not violate NEC.

OK. If the neutral inside the box lifts for whatever reason and you touch the metal on the back of the sub, you run a risk of a shock; you are the ground, the path for that wall current that wants to run like the wind. Very, very unlikely, but a possibility. Considering that kids are usually the ones fooling around the back of the sub chasing their little bouncing balls, a risk I would not take.

I always think of these things after the fact myself, but did you happen to ask the tech what the purpose of the ground was in the first place? Why put it in there if it is only a potential source of problems?

Actually, it might not be NEC that is violated; I would defer to Larry Fine on that one. Without a doubt the UL listing for the sub would be out the window.

This message was edited by Theaterworks on 03/01/05 15:28 ET.

I agree, that ground prong is there for a good reason. Like I said earlier, I'm switching brands. Thanks again for all the input in this forum.

Well actually I'm going to try one more avenue. Something called a cable TV isolator. Anyone heard of this?

A cable tv isolator is a ground lifter for incoming cable tv service. Didn't you say this was a satellite receiver based system? Unless there's cable service coming into the home an isolator of this type would have no application for you.

Cable TV Isolater may be the same as this part that MesaMan mentioned.

[Link: tributariescable.com]

It is the same part.

Company rep says to install this inline between sub and receiver.

I have been using ebtech hum eliminators on subs for years now. Cheap and available at any pro audio store like Guitar Center and obviously online.

[Link: zzounds.com]

Of course this wont do a damn thing if the hum is caused by the electrical groud loop. But it will eliminate any signal wire groud loops.

Good luck with it. I hate ground loops and those in subs can be the toughest to figure out and fix.