How to control speaker balance or disable one speaker?

Question

I have a laptop with two speakers: one is blown and playing unpleasant distorted sound.

How do I permanently deactivate it or control it using balance?

A terminal command is preferred, I reckon.

Also, I use Gnome's basic sound settings and PulseAudio Manager. The latter is used to maximize volume, because the former does not allow me to go beyond 150%. But when I use PulseAudio Manager, it automatically rebalances the speakers to 50%/50%. So, any solution must be permanent enough so PulseAudio Manager cannot alter the balance.

Thanks.

Answer 1

I don't know any way to lock a control with ALSA or PulseAudio, but this little hack should work:

stdbuf -oL alsactl monitor | \
while read; do
    amixer -D pulse sset Master 0,-
done

It watches for volume changes using alsactl monitor (you can run this command yourself and change the volume to see what it does), and every time a change is made, it resets the volume of the left channel to 0.

You may need to change:

• pulse to something else if you're using a different audio device.

• 0,- to -,0 if you want to keep the right channel muted instead.

• Master to something like Speaker,0 if you want a secondary control (e.g. headphones) to work as normal.

You can make the script run at startup by:

1. Putting it in a file, e.g. ~/.bin/alsa-fix,
2. giving the file permission to be run: chmod +x ~/.bin/alsa-fix, and
3. adding the line ~/.bin/alsa-fix & to ~/.profile.

The script should use virtually no CPU or RAM, but if you want to make it even more efficient, you can probably run it with dash by adding the line #!/bin/dash to the top of the file.

Answer 2

There is a right and left balance control in the GUI interface for sound. Your question seems to indicate you prefer a terminal command, and so if that's the case I can't help you. However if you are merely determined to mute one of your speakers you should be able to configure that in your sound settings. Merely click once on the speaker icon at the top of your screen and click on sound settings.

Answer 3

usual command for amixer to set levels has one value used for all channels, but can use two different values

for example: I set line in capture for a mono mic on my hardware with

amixer set -c 0 Line 42,0

use amixer command or alsamixer to find device id number for -c option
and name of ALSA mixer element to replace 'Line'

Can use percentage or dB values too
In this case Values of '46%' or '0dB' instead of '42' get same result

If Pulseaudio still causes changes in ALSA level
Use Pulseaudio Volume Control pavucontrol
go to Output Devices tab
click padlock to unlock channels to set channel levels