Testing for DC presence on AC mains

Posted by madisonears (A) on January 12, 2007 at 17:46:17

Is there a method to test for the presence of DC on my AC mains supply? There is considerable hum coming from the toroidal transformers of my monoblock power amps. The hum is barely audible when they're first unmuted in the morning (they're always powered), then increases throughout the day while playing music. One amp hums louder than the other. Both are on the same dedicated line with Flavor 4 Power Cords. At night, I can hear the hum quite distinctly from 18 feet away! Next morning, it's almost gone again. I can live with a low level of hum, but not this.

Do I need AC conditioning or new transformers? Or new amps? I've added vibration damping to the insides of the cases and tightened the clamp plates on the transformers without improvement. No other amps in my home (every price, every quality level) have ever hummed like these babies do. I've contacted the manufacturer, and he says it's DC that's galling me.

Peace,
Tom E

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Topic - Testing for DC presence on AC mains - madisonears 17:46:17 01/12/07 (19)

Failing power supply filter caps can also cause amplifier hum. N/T - Ugly 16:52:08 01/15/07 (0)

Thanks, I am willing to try this... - madisonears 00:35:43 01/14/07 (5)

From your response we now see you are just whinning. nt - Norm 06:44:29 01/15/07 (0)

Not trying to start a flame but.... - bluelobster 17:30:06 01/14/07 (1)

Re: Not trying to start a flame but.... - djk 04:00:50 01/15/07 (0)

Did you read this one? - jea48 16:27:48 01/14/07 (0)

Re: Thanks, I am willing to try this... - jea48 08:31:57 01/14/07 (0)

Re: And CI Audio have a nice quality DC blocker due soon the XDC-2 - HumanMedia 16:49:44 01/13/07 (0)

Suggestion for testing - lipmanl 15:34:11 01/13/07 (0)

Re: Testing for DC presence on AC mains - kenster 15:29:43 01/13/07 (0)

Sounds like either your transformer's design... - Thomas Martens 14:42:30 01/13/07 (0)

Re: Testing for DC presence on AC mains - jea48 09:01:21 01/13/07 (0)

Re: Testing for DC presence on AC mains - quirck 23:16:22 01/12/07 (2)

DC blocker - djk 23:54:30 01/12/07 (1)

Registration - djk 00:00:54 01/13/07 (0)

Yes. - Poindexter 18:43:32 01/12/07 (1)

No - djk 00:09:12 01/13/07 (0)

Bryston - djk 18:40:40 01/12/07 (1)

Re: Bryston - madisonears 18:47:08 01/12/07 (0)

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