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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
 
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!
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
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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.
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