[LAU] Re: Buzzing noise from speakers when no audio app is loaded

Chris Jölly <ml-lau-cj-bHtGYZb/[email protected]> writes:

> Hello,
>
> although it is not a linux audio related issue, maybe some of you guys
> have experience with it anyway :)
>
> I have a laptop, connected external speakers which use an external
> power supply.
>
> Furthermore I have an external monitor, which is connected to the
> power plug.
>
> Furthermore I have a desk lamp and a Roland SH-201.
>
> All devices are connected to the same power bar. Nothing fancy, it
> just has a switch to convieniently switch off everything at once.
>
> As audio system I use Pipewire.
>
> As long as no audio app is using the "Build-in Audio Analog Stereo"
> sink where the external speakers are connected to, there is a buzzing
> noise.
>
> I tried to figure out from where that noise originates, by pulling
> plugs, rearrange plugs, pulled plugs of the TV and the internet cable
> modem in the other room (which is anyway not linked to the same
> circuit/fuse), but the noise does not go away. In some situations it
> got even louder.
>
> As soon as I start an app that connects to the audio sink, like
> Ardour, a browser with a sound playing, a decend "pop" can be heard
> and the buzzing noise is gone. Audio arrives at the speakers just
> fine, no buzzing noise.
>
> Once the audio app disconnects, a few seconds later the buzzing noise
> is back.
>
> Some years ago I almost used the same equipment, same room, only the
> SH-201 was added, and the laptop connected to a docking station. That
> time that noise did not happen.
>
> What might be the issue?

Some autogain cranking up power?  The line getting switched to
high-impedancy (or stereo microphone input mode with plugin power?)
without proper load on it?

-- 
David Kastrup
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