Can someone advise how the Gnome Alsa Mixer settings work. in conjunction with the standard System Setting in 18.04. There are the mixer controls which are weird the Mute buttons, which seem to do nothing the many IE958 checkboxes, which I had to turn off to prevent fullvolume audio whfrom s/pdif when using headphones.

Below is a screen shot of it for reference:

Reason I ask is: the settings in the mixer mess with the settings in system settings and it is not consistent, or how they are meant to be used, I use s/pdif out to my Home Theatre, and Headphone Jack to my Headphones, I would use Bluetooth to my headphones but they are only 1 channel bluetooth so I leave them paired to my cellphone and I plug them into my desktop Headphone Jack.

UPDATE: I am wanting to understand the general behaviour of the mixer controls and the tick boxes of the GNOME ALSA Mixer. What effects do they have, and then why do I have so many settings with the same Name "IEC958" /END UPDATE

FYI I tried to use Alsa Mixer in Terminal and it was worse, at least I was able to turn off the dual audio issue.

Ref my other issue I had, where I added my answer to said issue, It could be improved with the right knowledge here.

Stop sound from speakers when connecting headphones

enter image description here

  • The mixer controls shown are exactly those offered by the hardware. You have to read the ALC1220 datasheet (which Realtek does not publish) and to know how it is wired on your mainboard.
    – CL.
    Aug 3, 2019 at 5:43
  • BTW is that a cynical response suggesting that Realtek does not support their hardware? :) Aug 4, 2019 at 8:15
  • 1
    Realtek supports only their customers, which are mainboard manufacturers.
    – CL.
    Aug 4, 2019 at 9:48

1 Answer 1


In short: within the sound architecture of Ubuntu, user interact with Pulseaudio, not with Alsa
If you cannot find an answer to your needs with the Pulseaudio features and tools, then you can remove the Audio server and keep Alsa only

Read https://askubuntu.com/a/427036/77093

 | Audio        |
 | Applications |
 +--------------+                          +---------------------------+
 |              |    Inputs and            |Audio control applications |
 | Pulseaudio   |    Outputs settings      |(gnome-control-center)     |
 | Server       <---+Volume levels   <-----+(pavucontrol, paman,...)   |
 |              |    Mixing                |                           |
 +------+-------+                          +---------------------------+
 | Alsa audio   |
 | driver       | 
 | Audio device |
  • Thanks this helps (upvoted), but I want to understand the individual settings and what they do. Not all of them but the general sections. Settings in application should have descriptive enough names that you know what action will happen, in this case Gnome ALSA Mixer and ALSA Mixer are very difficult to understand. Aug 4, 2019 at 8:28
  • my answer is to say: regarding ubuntu sond architecture, you should better play with pulseaudio settings and keep defaults on alsa
    – cmak.fr
    Aug 5, 2019 at 5:04
  • The original issue I had was: Out of the blue with no changes to any settings I swapped from S/PDIF to headphone port in pulseaudio, The volume went to 120% on the S/PDIF and was not adjustable, only on or off; Most solutions given were to adjust ALSA, and most did not work, hence here I am. I want to understand ALSA settings, as it is pretty obvious they are not setting explanatory. Aug 6, 2019 at 6:30
  • please see my linked issue above. Aug 6, 2019 at 6:32
  • ok. So as i wrote: if you want to tune sound settings with Alsa instead of PulseAudio, you may remove PulseAudio since, for Ubuntu sound architecture, this one is the settings machine for volume control, mixing, input/output settings.
    – cmak.fr
    Aug 6, 2019 at 7:07

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