Re: [PLUG] Ground Loops / Hum

[Martin Cracauer via plug <plug@lists.phillylinux.org>]

Casey Bralla via plug wrote on Mon, Mar 24, 2025 at 03:34:30PM -0400: 
> 
> So how should I kill the ground loop?

You should first confirm that it is what you think it is.

Have a headphone amp at the soundcard directly.  Is the hum gone?

Connect just one in-the-wall cable? Is the hum there?
 
> I tried enhancing the earth ground connection to the shielding, but this
> didn't help.

The opposite is appropriate, terminate the shield connection of the
cable on one end.

Another possibility is transformer-based isolation devices.  Same
principle they break ground.

> One thought I had was to separate all the grounds at the distribution box.??
> Each cable run to the distribution box would be grounded only to its
> individual amplifier.?? This means the signal lines will still be shielded,
> but will be floating relative to ground.?? Is this acceptable practice?

Yes.  But only if it is a true ground loop.  Which hum often isn't.

Martin
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Martin Cracauer <cracauer@cons.org>   http://www.cons.org/cracauer/
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