2. tech-talk
  3. 1226109115

Ground Loop Hum

Hello, I am looking for help eliminating the hum I get in my subwoofer. I have a Rel B1 and am using the high level inputs. The Amp I am connecting it to is a BAT VK-600. Based on the documetation this should be treated as dual mono blocks so I have the two hot wire connected and the ground going to my pre-amp ground. I have tried different grounds including the one on the power conditioner. I have tried all the normal tricks of moving where the cable runs, unpluging all other componets, etc.

Any thoughts would be appreciated.
mabrooks51
infinity_audio
186 posts
 
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
xti16
1,525 posts
 
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.
mabrooks51 OP
3 posts
 
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.
shadorne's avatar
Ag insider logo xs@2x
shadorne
7,477 posts
 
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.
cyclonicman
693 posts
 
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.
More to discover