Re: [LAU] RF noise suppression?

From: <fons@email-addr-hidden>
Date: Sun Apr 04 2010 - 00:55:33 EEST

On Sat, Apr 03, 2010 at 05:48:43PM -0400, Rick Green wrote:

> I'm using a FOcusrite Saffire pro 26 I/O with ffado, jack, and Ardour to
> make multitrack recordings of live concerts, to my emachines M6810 laptop
> running ubuntustudio. I'm plagued by noise that sounds to me like RF
> interference from the laptop, getting into the audio portions of the
> interface. It's most obvious when I'm at home trying to mix down my
> recordings, as its almost constant in my monitors and most noticable in
> a quiet room, but it also manifests itself sometimes during shows, showing
> up on the input lines to the interface, which are plugged 'half-way' into
> the FOH mixer's channel inserts, so it invades the PA and the performers'
> monitors. WHen that happens, I've no other choice but to abandon the
> recording and shut down the laptop.

Do you mean TRS plugs inserted 'half way' to get the output
of the insert on the plug's tip ? That means:

* the connection is unbalanced, and worse
* the ground of your input probably remains
  unconnected.

This is not even supposed to work.

The least you could do is make some of special cables
that allow the TRS plugs to be fully inserted. But even
that would mean that you are using an unbalanced connection
which in 'live' circumstances usually means trouble.

The real solution is stage box with split outputs, or
a FOH mixer that provides balanced channel outputs.

Ciao,

-- 
FA
O tu, che porte, correndo si ?
E guerra e morte !
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Received on Sun Apr 4 04:15:02 2010

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