Ground loop

pjchappy · « **on:** 3 Jan 2005, 03:11 am »

I switched my system from one room to another. . .since then, I've had a major ground-loop.

My wires are even less cluster-fucked then they were. . . .so, what's the usual culprit?

Thanks!

p

ted_b · « **Reply #1 on:** 3 Jan 2005, 03:24 am »

Ground loop hum is usually associated with cable tv being a part of a home theater system. The cable is grounded back at the main distribution point, but not at the house. It sets off all kinds of problems, usually solved by finding something that reacts well to "lifting the ground" with cheater plugs. This is not the best solution, however, due to safety reasons, but we audiophiles usually look past that. Personally, I've killed two ground loop hum problems; one with a cheater plug, one with a nice ungrounded aftermarket ac cable.

Somebody please give him a better solution.

Oh, here's a decent website about it:
http://www.smr-home-theatre.org/Ground-Loops/

Ted_B

pjchappy · « **Reply #2 on:** 3 Jan 2005, 03:26 am »

I have the same CATV connection that I did before. . . just ran a longer cord. . .

p

ted_b · « **Reply #3 on:** 3 Jan 2005, 03:32 am »

Quote from: pjchappy

I have the same CATV connection that I did before. . . just ran a longer cord. . .

p

Check the cord.....the shield may be bad.

pjchappy · « **Reply #4 on:** 3 Jan 2005, 03:35 am »

I will. . .

p

John Casler · « **Reply #5 on:** 3 Jan 2005, 04:26 pm »

Quote from: pjchappy

I switched my system from one room to another. . .since then, I've had a major ground-loop.

My wires are even less cluster-fucked then they were. . . .so, what's the usual culprit?

Thanks!

p

The two most "usual" suspects are the Cable/Sat TV, or a bad ground plug on an interconnect.

Unplug your whole system, totally. That is each component from each other, and each component from the wall, and work backward, plugging each in.

Start with the speakers to the amp and the amp to the wall "ONLY". Keep adding a single wire and component at a time until you hear the hum.

REMEMBER TO SHUT THE AMP DOWN EACH AND EVERYTIME YOU CHANGE OR MAKE A CONNECTION!!!

ctviggen · « **Reply #6 on:** 3 Jan 2005, 05:07 pm »

I'd still make sure the CATV connection is properly grounded to earth ground of the house. Then, as John says, unplug everything and plug things in one at a time. Also, check that your outlets are actually grounded (you can buy a cheap outlet tester at Home Depot/whereever; these are handy devices, although they sometimes don't catch things). While cheater plugs do work, I prefer to do things the "right" way and find the source of the hum and eliminate it.

bluesky · « **Reply #7 on:** 3 Jan 2005, 05:07 pm »

Hi

I have had ongoing loop problems with my equipment as well. Rod Elliott has a loop breaker circuit that is supposed to deal with this problem as well as a balanced receiver and transmitter if all else fails. Mr Elliott has a long history in the music industry where hum is a big issue with all those rat's nests of wires for bands everytime they play a gig.

The loop breaker circuit is quite simple and consists of a bidge rectifer and a small capacitor to reject the spurious signals on the earth wire inside equipment. Douglas Self also addresses ground loops in his book and this is worth reading as well as he takes a different approach to Mr Elliott.

Cheers

Ian

PM me if want more specific information.

TIC · « **Reply #8 on:** 3 Jan 2005, 05:15 pm »

p,

Unplug the CATV coax from your setup. If the hum goes away, get a ground breaker like the Mondial Magic Block. They sell them at AudioAdvisor for $99. I think RadioShack has a similar device for less money.

Enjoy,

TIC

StevenACNJ · « **Reply #9 on:** 3 Jan 2005, 07:35 pm »

If it is ground loop hum from coax cable get one of these from Jensen

Model VRD-1FF - $59

Definately works well and does not degrade pic quality.

http://www.jensen-transformers.com/iso_vid.html