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How to eliminate system hum?

I have the following
Rotel 1090 amp
Hovland Pre-amp
Sony 777 CD player
Shahinian Speakers
I have this irritating hum/hiss when I turn on the pre-amp. The sound comes from the speakers when the pre-amp is turned on. If the pre-amp is off and the amp is on, the system is totally silent. It seems as if the amplifier is ok. It seems to be doing its job and is amplifying the crappy signal it is receiving.
Thinking my home electric was poorly configured, I had my electrician install a panel and dedicated lines for my system. The problem is now worse!
I don't think the pre-amp is to blame as I had the same problem with my previous pre-amp. I also have a new cd player.
I have read about "floating" the system ground by using 3 to 2 prong adapters on all system power cords. Is that what I should try?
If anyone has any ideas, I'd be very appreciative. Having $20k worth of stuff that sounds bad is no fun!
holzhauer

Showing 4 responses by holzhauer

holzhauer OP
201 posts
 
Sean:
I read your entire noise hum and polarity post. You receive an A+ in my grade book. I think you qualify for the honorary Phd in hi-fi. How long have you been doing this?
P.S. The owners manual for the CAT SL1 ultimate had a similar discourse. Just not as detailed. I bought a VOM today.

A1126lin: 3/2 adapter is a $0.39 hi-fi component at Ace hardware! The female end takes the 3 prongs from your power cord. The male end eliminates the ground and has only two prongs.
Floating refers to having only one of your components hard grounded to the outlet. The others have 3/2 adaptors and ground via the interconnects.
holzhauer OP
201 posts
 
Thanks Judit. I now have 3 to 2 adapters on everything but the preamp and the hum is totally gone! Ah sweet music again!
I guess this is a fairly common problem. But in 22 years of stereo ownership, I haven't had it. I'm thinking the 380 watt/ channel Rotel exacerbated the problem as it amplifies the living day lights out of everything that comes its way.
holzhauer OP
201 posts
 
A1126lin:
Try 3/2 adapter on all 3 prong components except the pre-amp.
holzhauer OP
201 posts
 
I was able to eliminate the hum and still have one ground path. The pre-amp is a good component to ground as it is centrally located. If the surge protector is the only path to ground then you could float all but one plug going into it. If the preamp went straight to the wall outlet,the surge protector can be be floated at the outlet without doing each input individually. I'm not an electrical engineer so I can't tell you if there might be a safety compromise. I can say the technique eliminated all hum from my system and I have had no problems.
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