[pulseaudio-discuss] Delayed muting of studio speakers

Chris Mayes cmayes at cmayes.com
Sat Dec 19 21:04:07 UTC 2020

Oh, I didn't realize that pulse was built upon Alsa.  I pulled up alsamixer
and found an "auto-mute" option that was binary but listed as a fader on
the display.  I've disabled it; maybe that'll help.

>From what I've skimmed, it looks like this is to account for, say, a
headphone jack being plugged in.  I rarely do this (almost always
Bluetooth), so switching off this detection is low-risk.  Bluetooth might
not trigger the switch, but I can always just switch off the main speakers.

Thanks for the lead!  I'll send an update if/when this solves the issue.



On Sat, Dec 19, 2020 at 1:20 PM Matt Feifarek <matt.feifarek at gmail.com>

> I'm not following everything that you're writing (including the file you
> mentioned... which I've never messed with, but I find on my system
> as /usr/share/pulseaudio/alsa-mixer/paths/analog-output.conf.common)
> I think, though, that the file you mention might have to do with the alsa
> mixer labels in the ui of the console "alsamixer" program more than the
> lower level wiring, but I'm not sure. There are lots of dark arts in the
> alsa. Personally, I wouldn't mess with that stuff.
> When the speakers drop out, is there anything in your logs? You can check
> with:
> sudo journalctl -u pulseaudio.service
> Are you certain that the software is muting, and it's not just some kind
> of dropout?
> The system can't see what kind of speakers you have, since they're hooked
> up via analog line out. I doubt that impedance is an issue, but I'm not
> very familiar with the analog side of things.
> If you're just using line out, PA should be fine, and you shouldn't have
> to worry about detecting, auto-detecting, or the like. Playing analog out
> through onboard sound is pretty normal, you shouldn't be having any
> trouble... but see what's in your logs.
> On Sat, Dec 19, 2020 at 1:43 PM Chris Mayes <cmayes at cmayes.com> wrote:
>> Hi, everybody!
>> It takes me back to have subscribed via Mailman to an email distribution
>> list.  I'm generally able to solve my issues via Googling, but this one's
>> proven tricky.
>> I recently bought a pair of KRK Classic 5
>> <https://www.krkmusic.com/Classic> speakers to replace a pair of M-Audio
>> Studiophile AV 40 <https://m-audio.com/products/view/studiophile-av-40>
>> speakers that had developed a rapid popping noise in the internal
>> amplifier.  The new speakers sound fantastic, but they have an odd
>> spontaneous muting issue, at least as configured.
>> The issue is that the speakers seem to become muted (first one, then the
>> other, usually L->R) after some time of playing without any issues.  My
>> provisional solution is to crank the volume past 100%, which un-mutes them
>> (though at an unpleasantly loud volume).  This clears up the issue, though
>> it usually happens again a few minutes later once I've brought the volume
>> back to a reasonable level.
>> Based on my Googling, I tried modifying analog-output.conf.common to
>> "ignore" volume.  Here's the PCM block:
>> [Element PCM]
>> switch = on
>> volume = ignore
>> volume-limit = 2.0
>> override-map.1 = all
>> override-map.2 = all-left,all-right
>> Sadly, this didn't seem to make any difference.  What else might I try?
>> I have a passing familiarity with audio concepts, and one difference that
>> I noted is that the new speakers have about half of the impedance of the
>> old pair (which never had this problem).  Do sound cards use impedance to
>> detect the presence of a device?  It's plugged into line-out (lime green)
>> on an Asus Xonar SE <https://www.asus.com/us/Sound-Cards/Xonar-SE/> (the
>> motherboard (Asus PRIME Z390-A)
>> <https://www.asus.com/us/Motherboards/PRIME-Z390-A/> had the same issue).
>> Also, the audio is fed to each speaker separately rather than being fed
>> to a single speaker and bridged to the left via speaker cable.  Maybe
>> that's a factor?
>> The brute-force thing would be to just mark the line-out port as "always
>> on" and to skip attempts to detect whether there's a device connected.  Can
>> PulseAudio do this?  More elegant solutions are also warmly welcomed.
>> Thanks,
>> -Chris Mayes
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