HELP: how to eliminate speaker HUM?

Kr4 is right, but add this: if your cable box is attached to your HT setup, a poorly/non grounded cable coming in to the house could cause ground loop hum. Very Common. At least try removing the cable box from the system.

Hey guys, thanks. After I posted, I took out the Rowland Capri preamp from my HT system (had used for 2 chnl)and that did the trick for all speakers except for the sub. The sub has had hum for a long time, and has been plugged into a Monster 5100 PC and now a separate dedicated Furman. Don't know what the deal is with the sub, however, disconnecting the sub's IC eliminates the hum.

Couple of suggestions on the sub:

1. Lift the ground with a cheater plug on the sub.

2. Check to see if the sub is connected on a different outlet/circuit.

Jeff

The breaker for the outlet that the sub is plugged into may be on the other phase/rail in your main circuit breaker box, or the outlet could be wired out of code. Either of those could cause the hum also. If floating the ground doesn't work, check that all the room's outlets have a black wire to the brass screw and white wire to the nickle screw. If so- and you find that the breaker for sub's outlet IS on the opposite rail from the rest of the system; move it to same rail as the rest of the room's outlets. If floating the ground DOES work: PS Audio offers some nice cords with removable ground prongs, ie:(http://www.musicdirect.com/product/74108) an inexpensive one. If you haven't been using an upgraded power cord, you'll reap some sonic benefits in the replacement process. A cheater plug will take you in the other direction.

The hum might be caused by a component or transformer near your preamp/processor. I had a small 12V transformer slip under my lexicon processor and it created a hum just as you describe. Solution...move the transformer (or other device that causes the hum).