I have a home theater setup with an NAD T762 receiver and a Sunfire Super Junior subwoofer. Whenever the subwoofer is connected to the system, I hear very loud interference when I turn on the system. The noise is fuzzy, but it sounds like I am picking up an FM radio station. I have tried to switch out the subwoofer cable and also to use a different subwoofer input on the receiver -- to no avail. It's not the subwoofer, because the noise occurs even if the the subwoofer is unplugged. The moment I pull out the cable, the noise goes away. Another strange fact -- the noise tends to subside (but doesn't go away entirely) 5 or 10 minutes after the system has been turned on.

I would appreciate some advice -- this has been driving me crazy! Is there anything I can do to make this go away, other then doing without a subwoofer???

I have a home theater setup with an NAD T762 receiver and a Sunfire Super Junior subwoofer. Whenever the subwoofer is connected to the system, I hear very loud interference when I turn on the system. The noise is fuzzy, but it sounds like I am picking up an FM radio station. I have tried to switch out the subwoofer cable and also to use a different subwoofer input on the receiver -- to no avail. It's not the subwoofer, because the noise occurs even if the the subwoofer is unplugged. The moment I pull out the cable, the noise goes away. Another strange fact -- the noise tends to subside (but doesn't go away entirely) 5 or 10 minutes after the system has been turned on.

I would appreciate some advice -- this has been driving me crazy! Is there anything I can do to make this go away, other then doing without a subwoofer???

A) Where is the noise coming from? The sub? The mains?

B) Did this hapenned wheny you first installed the sub? Or after a while?

C) How long is the cable to the sub and what type? (Balanced, Unbalanced, speaker)

This is a solvable problem. Have to take it a step a a time and find the cause.

John -- thanks for responding. The noise is coming from the speakers, not the sub. In fact, (I just double-checked this) the noise exists regardless of whether the cable is even connected to the sub, so long as the other end of the cable is connected to one of the subwoofer inputs. So this seems to have nothing to do with the subwoofer itself.

I have tried two cables. Both are pretty long -- 10 feet or more. I don't know much about cables, but I got them both from professional installers. They are not speaker cable -- they look like cables you would use to interconnect components, except they have two inputs on the sub side and one on the receiver side.

Unfortunately, I can't remember when the noise first became a problem, because I've moved a couple of times since I bought the receiver and subwoofer and had a few different set-ups during that period. I don't think I had this problem when I first installed the equipment, though.

It seems like the cable is acting as a kind of antenna, but I don't understand why the sound would subside after 10 minutes.

A few things to try would be to move your subwoofer interconnect cables away from power cords or other cords that could be causing interference. Also try and get a good quality shielded subwoofer cord if you don't already have one.
You might have a ground loop involving how and where the power cords of the components in your system are plugged in. You could try moving those around and see if that helps as well.