Hum coming from Sub. (Not caused by ground loop)

A friend of mine has an Energy S8.2 sub and a hum comes through when it is powered on. It goes away if I unplug the LFE cable. I don't think it's caused by a ground loop because it only is a two prong connection. I'm thinking it could a couple of things:

* The sub cable could be bad. Going to check it with different cable.
* The sub cable runs right next two power cable of the power strip. (Will need to drill new hole to run sub cable a different route)
* I have heard that cable tv will bring in a hum. I have all audio/video running through receiver to do switching. The cable runs to digital cable box, then is connect via composite to receiver. How would I get rid of cable tv hum?

Also if there are any other suggestions or advice I'm all ears. Thanks in advance.

Quote:

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Originally Posted by Torech Ungol

A friend of mine has an Energy S8.2 sub and a hum comes through when it is powered on. It goes away if I unplug the LFE cable. I don't think it's caused by a ground loop because it only is a two prong connection. I'm thinking it could a couple of things:

* The sub cable could be bad. Going to check it with different cable.
* The sub cable runs right next two power cable of the power strip. (Will need to drill new hole to run sub cable a different route)
* I have heard that cable tv will bring in a hum. I have all audio/video running through receiver to do switching. The cable runs to digital cable box, then is connect via composite to receiver. How would I get rid of cable tv hum?

Also if there are any other suggestions or advice I'm all ears. Thanks in advance.

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So, you don't have hum if nothing is connected to the sub? If so, and you get hum when the LFE interconnect is hooked up, then you either have a bad cable or a ground loop, a classic case.
Just to be sure on this, unplug any cable TV cables to the setup and see what happens :)

My Paradigm PDR-12 had the same problem. Fixed it last week. It was a cracked solder joint on the connector going to the board.

My Quest does the same thing even when the cable is unplugged.....My stuff is all squeezed in one small corner so there's cables everywhere, no way to keep them apart..I brought the sub downstairs and no hum at all :S....I don't have any more suggestions than the ones posted, but btw! Is the sub good? I was looking at that one..

Also, Brian what do you mean by "board"? The receiver amp or the sub amp?
And Joel, the sub sounded pretty good at the store, we haven't had a chance to calibrate and listen to it at his house. I will let you know.

The Sub amp board where the back of the RCA connector ground leg connects.