Re: [LAU] debugging hiss

On Fri, Mar 14, 2014 at 6:41 PM, Fons Adriaensen <fons@email-addr-hidden> wrote:
> On Fri, Mar 14, 2014 at 05:39:08PM +0530, Rustom Mody wrote:
>
>> Of late I am getting some amount of hiss from my speakers.
>> I believe its a software problem because it is absent at startup and
>> audibly starts sometime during the boot process.
>>
>> My system is fairly vanilla h/w -- ordinary Intel desktop with builtin
>> soundcard, ordinary speakers.
>>
>> The only non-vanilla things maybe some things I installed when playing
>> around with a TASCAM
>
> How on earth can anybody help you if you give so little information.

Sorry not sure what else I should have given...

lspci ?
aplay -l ??

>
> * Do you have active speakers (built-in amplifier) or is there an
> amplifier in between the sound card and the speakser ? If so, which
> input are you using ? How are things connected ?
>
> * Using ALSA/Jack/Pulse ??

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
---------------------------------

>
> * TASCAM is a brand name. They are hundreds if not thousands of
> different things with that name on it. So what is 'a TASCAM',
> and what did you install for playing around ?

Yeah I know :-)
I guess the TASCAM reference is a red-herring.
I tried it more than 2 years ago.
There was no (hiss) issue then.

Dont have the hardware right now so dont know the number/spec.
The hiss has started after some recent debian upgrade -- couple of weeks

>
> Apart from that, hiss is usually the result of either
>
> - something broken,
> - or using the wrong inputs,
> - or a volume control set too high.
>
> Another cause could be the mic inputs of your sound card
> routed to the outputs. Check the mixer.

Are you asking for hardware or software checking?
Hardware: There is only one connection -- the speaker into the soundcard.
No mic, no line.

Software: I will need to know how to check.

For now, I checked with xfce4-mixer.
If I turn down master or front-mic the hiss reduces
However then musescore (my main use right now) also becomes too soft

Interestingly there was a musescore upgrade just a day or two ago
And now I am seeing segfaults with this message:

$ Alsa_driver: pcm_drop(play): Input/output error
pcmStop failed
Segmentation fault

Dont know that this has anything to do with the original hiss question.

>
> Ciao,
>
> --
> FA

Thanks for the tips

Rusi
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Received on Fri Mar 14 16:15:02 2014