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

[Nigel Henry]

On Monday 06 March 2006 19:07, 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.

Hi Bal. That sounds like the sort of thing you'd expect from a bad 
ground/earth/return connection. For instance. If only the left and right 
channels were connected, but the screen was disconnected, that is the sort of 
sound (more of a loud hum) that you would expect. It is worth checking that 
the ground/earth connections are good, on both the computer, mixer, and amps 
That is for the 240volt power connections. Also when the computer is switched 
off, try removing the line output from the computer, and seeing if anything 
changes. Then put it back, and remove the line input, and see for changes. I 
presume the screw is in to hold the soundcard in place, but there is so much 
metal in contact, that, that shoudn't be the problem. It might be worth 
trying different cables to connect from the computer to the mixing desk, just 
in case there is a faulty one.

PLEASE. Don't electrocute yourself in the process. Nigel.
>
> If I boot up into windows I get a sharp hissing sound which I sort out by
> not picking the SPDIF I/O.
I get that problem on FC2 with an Ensoniqs ens1371 card until I mute IEC958.
>
> What is going on here???
>
> I have checked in alsamixer and there is nothing there that would indicate
> why I get this sound which only occurs when the machine is switched off.
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