> Hi,
>
> I would like to appeal to anyone with experience in eradicating a
> probable ground loop. I've just done a bit of upgrading in my studio,
> and I've developed a nasty buzzing in my system. I've narrowed it
> down to the interplay between Logic 7 and my analogue synth. Of note
> is that I have not changed anything inside the synth since before the
> upgrade and that the problem exists even when the synth is turned off
> but not when it is unplugged from the wall. In fact, I've just been
> jiggling about with the plug and the buzz come back as soon as the
> earth pin of the plug makes contact.
>
> The problem also only exists when Logic is running but not when i
> run things like iTunes etc. It can also be controlled by the mixer;
> turning down the channel volume or EQing it out work. I've also gone
> around turning off and unplugging everything except the computer,
> synth and mixer, but the buzz remains.
>
> Can anyone help
>
> Yours Aye
>
> Stuadh

We had similar problems when we changed the arrangement of the A-100 demo
system, mixer and computer. The solution we found was the usage of a passive
DI box between mixer and computer.

Best wishes
Dieter Doepfer