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Ground Loop Question

Just curious about this....

What exactly is a ground loop and why does it affect the stereo like it does? What exactly is happening to cause this? I'm a little rusty on electrical but i know the basics and terms. I would assume a ground loop is actually where a ground gets fed back into itself and maybe oscilates and causes the hum? or am i totally reaching here?

My buddy's ol man has a pretty decent mid-level system that is PLAGUED by this Hum. He has a MONSTER 3600 stage 3 power filter and the hum is still there.

Better yet, when he turns on the lights the hum gets WAY worse. (not a dimmer switch either) Normally i would attribute this to bad power, but shouldnt the stage 3 filter be clearing this? Does this sound like it could be a ground loop?

What are some common causes of ground loops and some common fixes?
slappy
mgattmch
570 posts
 
I had the same problem with my HDTV system using a Krell HTS connected to a Pioneer Elite DV-38 CD/DVD player and a Pioneer Elite PRO-730 RPTV. The CD/DVD player was connected to the TV via a component video cable (RGB). Absolutely terrible hum when the HDTV cable box was connected. The hum was coming from the HDTV cable box, to the TV, then the CD/DVD and eventually pre-amp/amplifier. The problem was eventually eliminated by replacing the copper coax digital interconnect between the Krell HTS and Pioneer Elite DV-38 with an optical interconnect, no hum at all now. I also had some success using a #XA-63400 ground breaker ($7.45 from www.hometech.com ) between the cable box and TV.
lawdog
1 posts
 
I purchased used a Pioneer Elite Receiver VSX 95 that has a hum throught the speakers and the headphone output. This hum is present with all other source components disconnected. The hum does not increase in volume and becomes masked by the music. The AC plug is two pronged and does not seem to have an effect when placed in one way or the other in the electrical outlet. There are no dimmers in the room and this problem occurs in no matter what room outlet the Receiver is plugged into.

This seems like a grounding problem. Is there a simple fix or complex fix that can be done by someone with limited to mayber moderate experience in tinkering with electronics.

Thank you for your time and assistance in helping me. My email address is: lawdogesq@excite.com
rudd
51 posts
 
check to see if your receiver has 3prongs instead of 2. If so, the 3rd prong maybe pulling in the 60 cycle hum from your cable TV...regardless if any of your componens are switched on or off. As a test try uppluging your cable TV and see if the problem goes away. If disconnecting the cable does the trick then a group loop isolator will solve the problem. The part number for the isolator is VR-1FF. I puchased one (49.95) on ebay last month and it worked like a champ....good luck!
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