View Full Version : [Help Needed] Ground Loop Hum
03-27-2010, 01:45 PM
I added a separate amp to my system and now I have a 60 hz hum. The hum disappers completey if I disconnect the front speaker pre-outs from my receiver to the HT bypass inputs on my pre-amp. I tried numerous different scenarios using different circuits, trying everything on the same dedicated circuit, different cables, unplugging everything, cheater plug, etc. Depending on what I did, I could increase the hum or lower the hum but never get rid of it entirely unless I either unplugged the RCA cable from my reciever to the HT bypass input on the pre-amp, or used a cheater plug on the new amp. Doing either of these would give me dead silence but of course I would like to use the HT bypass and I am not sure it's safe to run the amp with a cheater plug. I guess I was somewhat surprised that when I had all components connected to one power center on one dedicated circuit I still got a slight hum. Any ideas on how to fix this?
03-27-2010, 01:49 PM
The hum is more than likely related to a video source. Start disconnecting them one by one, Satellite, cable, playstation, etc to see where the issue(s) are.
03-27-2010, 02:14 PM
Try unplugging the coax cable from your cable TV box and see if it clears up. If so, you may need to grab a Jensen ISO-MAX VRD-1FF. Did the trick for my system.
03-27-2010, 02:16 PM
Yep, I forgot that I had the cable feed running through the power center. I disconnected it and 99% of the hum went away. So now now I can either not have cable, not be able to use HT bypass, or run with a cheater plug on my amp :D
03-27-2010, 02:17 PM
Good idea on the Jensen, that's sounds like my best option. Thanks guys!
03-27-2010, 03:39 PM
No prob. Don't know if you use Bing Cashback but I found a new Jensen on Ebay for around $45 plus a few bucks for shipping and used Bing to get 8% cashback.
Here's the listing I bought from. No affiliation.
BTW, he has best offer but I made 3 offers and they were all automatically rejected. My highest offer was $40 and at that point, I got more savings from using Buy It now with the cashback.
03-27-2010, 04:17 PM
Just to add to the above suggestions, I've had ground loop issues in the past that were resolved with better ICs all around. This is especially true of using a step-up transformer in the turntable path. Although this wasn't so much a ground loop hum it was a 60 cycle hum and I was able to eliminate it using MIT Shotgun S3s and with Joe Abrams' suggestion of twisting 8 twists into the pair really got rid of the hum.
03-27-2010, 04:20 PM
I used this to solve the cabel hum
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