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McIntosh hum problem

Any of you MAC people own a MCD 751 CD Transport and MDA 700 D/A Converter combo? I do and both hum, wondered if any others with same problem? The converter hums louder and MAC gave me a new power transformer for it, but did not help. The hum is from the units themselves vs. speaker hum. Any way to reduce the hum. Any advice appreciated.
amwarwick
stehno
1,453 posts
 
If you've narrowed it down to a transformer hum, try to find which circuit the amplifier is running off of. Then check the circuit breakers in the service panel.

Chances are that your amps' circuit is on the opposing phase of some of your other audio circuits and therefore generating some AC noise thats affecting the transformer. Have an electrician move all of your audio circuit breakers in the service panel to the same phase of 110 volts.

I moved all dedicate audio circuits to the same phase and that cured my transforer hum.
amwarwick OP
40 posts
 
Thanks for the advice Stehno and I will check this out.
stehno
1,453 posts
 
Amwarwick, I would be very interested in your findings.

When I made this change, I was simply trying for some/any sonic improvement. Did not notice any, but I was quite pleased to discover that the amp's transformer hum disappeared.

Pleas keep me posted.

-John
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