[linux-audio-user] noise from soundcard

[Paul Winkler]

On Fri, Oct 17, 2003 at 11:08:34AM +0300, Tommi Sakari Uimonen wrote:
> > I tried putting everything on the same power strip and I still get the
> > noise.  I have a mixer and an amplifier that the signal is going
> > through, and I get the same noise going:
> 
> Then you should have all the equipment physically connected to each other
> from their cases, like grounding them together. ** BUT BEWARE, THIS MIGHT
> BE DANGEROUS. ** I don't know where you live, but in Finland the
> electricity system is pretty darn safe and I wouldn't have any hesitations
> to do so. There might be high voltage differences between the cases, so
> all equipment should be disconnected from the outlet before grounding them
> together. And take life insurance first :) And don't sue me if something
> blows :)

There's a lot of info available on proper grounding techniques.
E.g. there's some here:
http://www.cs.uu.nl/wais/html/na-dir/AudioFAQ/pro-audio-faq.html

> > > It appears to be system load based, it might be an internal voltage
> > > interaction when your CPU goes from idle to active.  I've seen
> > > this before.....   try to run this at a bash prompt:
> > >   while true; do yes > /dev/null ; done
> >
> > This takes away a large part of the noise.  There is still some noise
> > that sounds different, and I can still hear my mouse move.  When I move
> > my mouse vigorously, it starts sounding closer to what it sounds like
> > when that shell script is not running.

There are various suggestions for this kind of problem in the old
Audio-Quality-HOWTO:
http://www.linuxdj.com/audio/quality


-- 

Paul Winkler
http://www.slinkp.com
Look! Up in the sky! It's MIGHTY CHAIN WOMAN!
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