Re: [LAU] debugging hiss

On Fri, Mar 14, 2014 at 07:16:47PM +0530, Rustom Mody wrote:
 
> No jack (to start with at least when the hiss sound starts)
> I am using debian -- which meant that there was no pulse until recently
> Of late I see occasionally some pulse related messages.
> eg I get these messages when I start audacity:
>
> ----------------------------------
> ALSA lib pcm.c:2239:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
> ALSA lib pcm.c:2239:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
> ALSA lib pcm.c:2239:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side
> ALSA lib pulse.c:243:(pulse_connect) PulseAudio: Unable to connect:
> Connection refused
>
> ALSA lib pulse.c:243:(pulse_connect) PulseAudio: Unable to connect:
> Connection refused
>
> Expression 'stream->playback.pcm' failed in
> 'src/hostapi/alsa/pa_linux_alsa.c', line: 4611
> Expression 'stream->playback.pcm' failed in
> 'src/hostapi/alsa/pa_linux_alsa.c', line: 4611
> Expression 'stream->playback.pcm' failed in
> 'src/hostapi/alsa/pa_linux_alsa.c', line: 4611
> Expression 'stream->playback.pcm' failed in
> 'src/hostapi/alsa/pa_linux_alsa.c', line: 4611
> ---------------------------------

First of all disable Pulse, or get rid of it. Don't know how to
do that on Debian.

> Hardware: There is only one connection -- the speaker into the soundcard.
> No mic, no line.
> For now, I checked with xfce4-mixer.
> If I turn down master or front-mic the hiss reduces

So you are sending the mic signal (which will be lots of hiss when no
mic is connected) to the speakers.

> However then musescore (my main use right now) also becomes too soft

That should not depend on any 'Mic' settings, only on 'PCM' and
'Master'. If it does, that means the upgrade botched your ALSA setup.
Try turning down (or switching off) anything 'Mic'.

Ciao,

-- 
FA
A world of exhaustive, reliable metadata would be an utopia.
It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)
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