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Classe' preamp ground loop hum. Help!

I just bought a Classe CP-60 preamp. When I hooked it up i got a vicious ground loop hum. I mean a wicked hum, like if I was running cheap speakers they would be toast. Checked all outlets on circuit, perfect ground. Disconnected everything but amp, preamp and source. Still ground loop hum. Hooked up Sony TAe9000ES in place of Classe', ground loop hum goes away. Do i just have a defective preamp? Suggestions? Advice?
ignatz
simply_music
8 posts
 
Is this pre-amp new? Do you have a VCR pluged into the same outlet? Also try lifting all ground except the pre and let me know what happens. Simply Music
ignatz OP
32 posts
 
Simply_music- The preamp is new. I disconnected everything from the outlet and all other outlets on the circuit and still got the hum. I replaced the classe w/ first an Adcom preamp and then an A/V preamp/processor and got no hum with either. This preamp has a separate power supply. I wonder if it could be a problem w/ either the A/C cord or the power line from power supply to preamp?
narrod
1,064 posts
 
Lift the ground on the preamp. The hum should go away.
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