Ground Loop Hum

Hi, don't know if this will help, but I had a similar problem with my subwoofer until I changed my analog interconnects from my power amp to the subwoofer. Once I removed the Nordost SPM interconnects to the subwoofer and replaced them with Audioquest SubX subwoofer interconnects
my subwoofer was completely silent.

You could also consider a Jensen transformer between the preamp and amp ( I don't like to add transformers because they distort but it is an option that may work for you - Jensen are high end transformers). I hope you are using only XLR connectors? If you use RCA then hum is not uncommon. A trick with RCA is to use an unshielded twisted pair - as ground loops are usually picked up on a shield.

Thank you for your feedback, I will go to Radio Shack and get the isolator. The Rel is in one power conditioner and the BAT is in a different one designed for high current. When I ground to the BAT chasis, the hum is much less then when I use the pre-amp chasis ground so there is some interaction even when nothing is hooked up.

Is the REL plugged into the power conditioner or the wall? If the wall the conditioner may be isolating the ground causing the hum. I had a hum from my cd player and lifting the ground fixed it.

i hooked my PC up to my HT and I had a hum. I unplug the CABLE IN (the ANTENNA WIRE) to my cable box and the hum went away. My hum was caused by a uncommon-ground (ground loop) caused by the ground of the antenna cable for the cable tv. I plugged a Radio Shack ground isolator before the line level in to my receiver and it fixed my problem. Check the following out:

http://www.radioshack.com/product/index.jsp?productId=2062214

oh, DO NOT FLOAT THE GROUND. NEVER! If an electronic is designed with a power cord thats 3 prongs with the ground, it is because by code it required so. FLOATING THE GROUND IS UNSAFE! I wonder what the insurance company will say if something happens to your house if the malfunctioning unit catch on fire or something ... DON'T USE THE CHEATER PLUG TO FLOAT THE GROUND IF YOUR UNIT HAS A 3 PRONGS POWER CABLE!

unplug your cable box from you system to see if it goes away. If yes, its a ground loop the cable box has created. visit axiom speakers website and get a ground isolator make sure its wide bandwidth if you have a HD cable box. you may also try the line level ground isolator Radio Shack offers.

Subwoofers often generate ground/hum loops.
To fix it, only one component in your system should be grounded through the AC cable. The remaining ones should float through 3 prong to 2 AC adapters, otherwise there will be a ground loop.
For safety reasons, I suggest that you ground the BAT amplifier through the AC cable, it is your component that draws the most current.

Also, disconnect the ground wire between subwoofer and preamp, it forms a ground loop, because the ICs carry signal ground from one component to the next.

Also: if your amp is a bridged design, the speaker (-) lead is floating and should be left floating. DO NOT ground the subwoofer high level (-) input.
I hope this helps

try floating the ground with a 3>2 converter on the AC. Or to quote Mary Cardas build a new house.:-)

Rick