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  3. 166032-126

Eliminating Ground Loop Problem

I use a Marantz 7702 MKII processor, ATI 3-channel amplifier to drive my center and rear channels, and my Jeff Rowland Corus preamp with HT bypass when watching movies. I'm using RCA interconnect cables from the Marantz to the ATI, tried balanced XLR cables with no change. I contacted Marantz and they didn't provide any advice. ATI helped me troubleshoot the issue and we isolated the problem to the Marantz. Any advice on how to eliminate the ground loop issue? 
ricred1

Showing 4 responses by oldhvymec

oldhvymec
5,101 posts
 
OP a ground loop is the difference in voltage between two pieces of gear. A ground loop eliminator is BETWEEN the source and preamp/power amp. IF the noise is coming from just the Preamp, no matter the source or the power amp, that’s not a ground loop. BUT it could be a GAIN issue... from another source, don’t be fooled.

Another thing.. routers and Laptop power supplies. UNPLUG them.. Just for now... Noisy thing Especially cable company router box power supplies.. The older the box, the higher the noise level and power consumption.. My old cable box pulled 270 watts.. YUP.. I was floored, It actually required a ground loop eliminator via The Cable Company, Comcast..

Friggen ark welder... LOL

Regards
oldhvymec
5,101 posts
 
There you go OP, Everything has to be plugged into the same circuit and after you verified that by turning on something ELSE, the noise came through the center and rears.. It sounds like they are on a different leg at the main..

One circuit
Unplug routers and PS to laptops
and do some cable art.. My system is dead quiet.. 65 year old C20 preamp point to point.. Talk about an antenna.. LOL Zero noise..

Quiet as a mouse.. Valves in all, there are a slough too.. 30 valves in my system... Quiet as a mouse.. 7 per preamp (2 C20s) and 16 in the ol Cary V12R
oldhvymec
5,101 posts
 
How’s that routing OP? Do you have cables laying over cables?

Cable art.. I should teach a class. It’s fun too.

Make sure nothing is touching, NOTHING. If cables cross make sure there is at least an inch between them and at 90 degrees.

Run them side by side, but NO touching, especially Power Cables (not cords) and Speaker Cables..(not wire).

You can check pretty easy by, lifting and lowering cables.. The sound will Yo Yo..

Regards
oldhvymec
5,101 posts
 
Ok I’m serious now.. I got a feeling If I routed that bunch of cables and inspected the connection including grounds between components, a LOT of the noise would go away if not all of it.
A crap cable can drive YOU nuts too. NOT ME though.. I won't stop until my system is quiet..

At least 10 times I’ve fixed system that supposed PROS didn’t fix because of routing.. You know the Stereo Only, kind of free install they get with a 20K purchase.. LOL.. They leave and you can hear arcing in the back ground.. as you tip them for their BAD work.. BUT you think it’s wonderful..

Can’t find the cat, see his tail sticking out from under one of your new 10k 200 lb speakers.. Still purring..

If the noise is that bothersome, it has to be routing at least partially..
I’m telling you you can stand by my speakers and turn the system up all the way, you have to be within 12" to hear anything.. I can hear valves hiss, ever so slightly.. My kids can’t hear it at all.. Grandson and wife can though.
A lot of valves, too.. 

Regards
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