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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
almarg's avatar
almarg
8,673 posts
 
Did you ever try shorting the amp's inputs, as I had suggested? Doing that would probably have led to the conclusion (which now appears to have been the case) that the hum that was heard while nothing was connected to the amp's inputs did not have the same cause as the hum that was heard while the preamp was connected. Knowing that would probably have led to a much quicker resolution. See my post dated 3-30-12.

Regarding the safety aspects of using a cheater, IMO it's your call. While the risk is very small, assuming that the equipment is in good condition, it can't be said that the risk is zero. And if that very small risk were to materialize the consequences could be very serious.

Regards,
-- Al
grimace OP
624 posts
 
Well again, the power supply - a PS Audio something-or-other - is still grounded. The cheater is between the preamp and the power supply, and the power supply still has a protection circuit, so I think the risk is pretty low. The amp, which is the big power draw, is still grounded.

I might check on the polarity thing though. It couldn't hurt.
jea48
2,944 posts
 
I might check on the polarity thing though. It couldn't hurt.
07-30-12: Grimace

Grimace,

One of the questions I asked in my last post about the power cord used on the power amp.

There have been instances where the AC polarity of an aftermarket PC was reversed at the female IEC connector.

That is why I asked you if you sent the PC you use on the amp with the amp when you sent it to Cary........

You can check the polarity of the PC with a simple continuity test.
.
grimace OP
624 posts
 
I didn't check the cord, but I did switch out my aftermarket PCs with the factory stock, in various combinations, and the hum remained.
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