Audio Mixer
"Eeyore" wrote in message
...
Ron Hardin wrote:
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.
That's the traditional reason for 'hum loops'.
In this case the problem is made worse but the use of switching power
supplies (certainly in the
computer) and in some audio gear (I'm fairly certain the Behringer model
mentioned also has one).
These swiching power supplies have filters on the ac power input that
injects a noise current
into the ground conductor. This messes up your grounding arrangements very
effectively.
I've always been under the impression that the simple presence of a hard
chassis ground was all it took to pretty well guarantee a ground loop, if
there was a second hard chassis ground anyplace in the equipment that was
attached to the PC. IOW, the switching power supply might have made the
ground loop more obnoxious-sounding, but it would be there regardless.
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