How Much DC is OK on a Power Line?


The other night my Classe amplifiers started producing a substantial mechanical hum. Classe told me that it was likely from DC on the power line. The hum was there even when the preamp was switched to standby, and even when I plugged the amps into different sockets.

My questions:

1) how much DC on the powerline does it take to cause problems with audio equipment?

2) How does DC get into the AC signal on the power line?

3) Do the power companies have any spec they need to acheive for maximum DC?

4) Or is it more likely appliances within my house causing the DC.

Thanks, Peter
peter_s
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It matters if you don't want your power supply transformer to hum loudly. If you are trying to be a smart ass, all you have done is made a ass out of yourself.
^^^Give me your address and i will send you a royality fee..sounds like you already own the market for being an a-hole.
6550,

That is exactly the type of response I would have expected from you. Sad, just very sad.