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Ground Cheater plug or....

Maybe this isn't a good idea, but I thought I'd ask anyway.

I have what I believe to be a persistent ground loop hum from my amplifier. It's quiet, inaudible if music playing or unless you're standing next to the speaker, but knowing it's there is annoying.

I've heard suggestions to use a cheater plug to defeat the ground, but it seems counterintuitive to stick a 35cent plastic plug between expensive cables and power supplies. My question is, couldn't you accomplish the same thing by disconnecting the ground wire in the outlet, and still exact the benefits of better cables?

I'm sure the fire marshall would disapprove, but I'd like to hear what the hi-fi nuts have to say.

Cheers!
grimace
atmasphere's avatar
atmasphere
12,027 posts
 
Al is correct. This will not be solved by cheating the ground. Grimace, you've not mentioned your speakers; if they have an efficiency of over 100db or if your room is really really quiet this might be perfectly normal.
grimace OP
624 posts
 
speakers are 89db Spendor S8e. I can only hear the hum from the listening position if there is no ambient noise - i.e. the fridge is not cycling - or if I'm standing right next to them, but not when music is playing. I sent the amp in for service and Cary said this was normal, but I'm not convinced. They said they weren't able to duplicate the hum.
podeschi's avatar
podeschi
303 posts
 
great thread, commenting here so it is parked in my threads.
grimace OP
624 posts
 
The plot thickens. I took the amp to a local tech who a) could not duplicate the hum and b) could not find anything wrong with the amp - although he did say it sounded very nice. Not quite believing it, I went and listened for myself, and he was right.

So, since that is now two places - Cary and my local guy - who've been unable to duplicate the hum, I guess that points to something in my AC system causing the problem.

So now what? Dedicated line? turning off the fridge is not an option.
grimace OP
624 posts
 
In addition, I figured out which circuit the hi-fi is on, turned everything else in the house off, as well as unplugging everything else in the room, and the amp still hummed.

I also used a ground tester and the outlets were showing that they were in fact grounded.

grrrr.
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