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In the Forum: Audio Discussions
In the Thread: It’s mad, mad, mad... electricity.
Post Subject: Ground PotentialPosted by Paul S on: 6/8/2014
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Perhaps the PP in the circuit raised the residual current on the neutral and/or ground line(s)? It doesn't take much resistance to get the front end humming. Of course, the Class D switching broadcasts all kinds of "noise", but this is much higher in frequency than "hum". Still, shielding might still help with "hum" if the shielding was grounded in a way that dropped ground resistance/residual current on the problematic line. This notion still supposes it's a "ground loop" problem; but it also "explains" the roles of the PP and the shielding in "causing" and "solving" a hum problem.
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