Re: [LAU] ground loop hell

From: David Christensen <dpchrist@email-addr-hidden>
Date: Mon Feb 16 2015 - 21:21:50 EET

On 02/15/2015 04:50 PM, Roger wrote:
> On 11/02/15 13:58, David Christensen wrote:
>> On 02/10/2015 05:43 PM, Len Ovens wrote:
>>> Right now there is a TS plugged directly into a TRS mixer
>>> output which means the signal minus is grounded.
>> I wouldn't plug a TS cable into an balanced TRS output. First, you
>> are shorting one half of the balanced driver output circuit. Second,
>> you are injecting chassis ground noise into the audio circuits.
> Agreed. If you run balanced -> unbalanced, it's probably best to run
> shielded twisted core from the output and just leave the shield
> disconnected at the input. It's discussed in those Rane docs I posted.

Those are good documents -- I finally finished reading through them last
night.

Some output driver circuits/ chips can handle shorting the signal
negative pin to the signal ground pin. Others cannot. If you are
certain your sending equipment can do this, then a custom cable might
work. If you're sending equipment cannot handle this, or if you are not
certain, then you either need an isolation transformer or a suitable
balanced-to-unbalanced converter circuit.

David

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Received on Tue Feb 17 00:15:02 2015

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