# Buzz Hum Problem



## Guest (Feb 9, 2007)

Hi, I was wondering if you could give me some input to a slight problem I have been having? The other day I still noticed the very slightest kinda hum buzz going on in both of my channels. It can only be heard at all if the amp gains are past half way up. If you were not listening for it most people wouldn't hear it. I noticed it after playing my Nakamichi cd player, and switching over to my Harman Kardon CDR-26. The Nakamichi is dead silent. All I have to do is turn on the H/K and I get the noise! I don't even half to be on the H/K's input, just turn it on. I'm sure this is some kind of ground loop, but I don't want to put any signal degrading isolation transformer on the H/K outputs. Any suggestion? I was thinking of grounding the Chassis directly to the my Crown IC-150's chassis. The connecting cables between the H/K and Ic-150 are quite old, but then again so are the one's between the Nakamichi and the IC-150. This is the only component giving my a noise issue. Everything else is dead quite! I tried moving the H/K's power cord to a different outlet with no improvement. My Ic-150 is connected to a Crown XTI-2000 power amp.


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## bobgpsr (Apr 20, 2006)

A bit of a bother but you could "float" your HK CDR with a power line isolation transformer. Can make one by using say two Radio Shack 115/24VAC transformers and wiring the secondaries together. Fortunately a CDR does not need a lot of watts.


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## Wayne A. Pflughaupt (Apr 13, 2006)

It sure sounds like a ground loop, but typically every component connected is affected. Is your Nakamichi connectd via an optical connection? That could be why it’s silent and the CDR isn’t. It could be that the CDR has a problem, or like you said, it could be the cables. Try those cables on another component and see if the problem follows.

By the way, a common ground loop cause is your satellite or cable TV service. If you have any cable or sat boxes connected to the system, try disconnecting them.

Regards,
Wayne


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## Guest (Feb 10, 2007)

Thanks Wayne. I'll try debugging next week. The hum is very low level. The cables I have connected are also very old, and cheap. The Nak is not using optical connections. When I had my Onkyo M504 power amp in the system, I never noticed it, but I'm sure that has something to do with the difference in gain structure.


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## srckkmack (Feb 10, 2007)

If it is a ground loop, there is a quick and easy way to trouble-shoot. Simply use a cheater plug. Plug your various suspect components into the cheater plug before the outlet, one at a time until the hum is gone. Then you know which component is causing your ground loop. You're not supposed to keep the cheater plug in the system as there could be a shock hazard if that component ever has an internal electrical problem and you touch it.


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## bobgpsr (Apr 20, 2006)

srckkmack said:


> You're not supposed to keep the cheater plug in the system as there could be a shock hazard if that component ever has an internal electrical problem and you touch it.


That is why if a cheater plug fixes it, and trying everything else afterwards fails to stop the groundloop, an isolation transformer is a legitimate solution. No path to earth ground with either AC power leg after an isolation transformer is used. Electronic techs often use them while servicing equipment.


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