Thread: Audio Mixer
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Ron Hardin Ron Hardin is offline
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Default Audio Mixer

Adrian wrote:
Then you'll find you get enormous AC hum when you connect to your computer,
owing to a ground loop. Put a Radio Shack ground loop isolator in that line
(cat 270-054). I keep a bunch of them around to isolate every different thing
that's plugged in on AC mains.


Is that true even if I utilize the USB link into my Notebook?


Yes, it's a problem in the connecting audio cable. The computer and the audio components
don't have quite the same idea of what ground potential is. The slight difference is made up
by a current down the ground shield of the audio cable. There's a slight voltage drop
across the shield as a result, and this voltage drop is shared with the audio input circuit.

So you hear the slight ground difference in the audio signal, as AC hum.

An isolation transformer breaks the ``DC'' path in the audio cable, so there is no
shared current between power and audio circuits.

No hard trying it without, but if you get a hum, that's why.

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