[linux-audio-user] Horrible buzzing sound from speakers when PC switched off

fons adriaensen fons.adriaensen at skynet.be
Mon Mar 6 14:40:54 EST 2006

On Mon, Mar 06, 2006 at 10:07:57AM -0800, baldobe wrote:
> I have just put back my Audiophile 2496 SC into my DAW and when I shut down
> the system I get a terrible bizzing sound comng from the speakers.
> The AP2496 is connected to an A&H analogue mixing desk and the speakers are
> Mackie 824s. 
> I am running various distros and it happend on all them. The buzzing goes
> when I switch the pc on.

The distro probably doesn't matter when the PC is off ;-)

What type of input are you using on the mixer (mic / line / high-Z) ?
What type of cable and connectors ?
What happens when you disconnect at the PC end, or at the mixer end ?

A shielding or earth loop problem could give this type of
trouble. When the PC / audio card is powered up, its output
impedance will be very low and that could hide the problem.

Anyway it isn't really wise to switch the PC on or off with
the mixer channels open. If without the buzzing you could
get a loud bang.


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