Fix cracking PCM sound in pulseaudio

Introduction

Most of the times volume in Linux is crisp and soothing. However there are times when you change the volume it collectively increases the PCM volume level and which in some cases can result in cracking sound. The problem is that after the PCM volume goes up it does not come down when lowering the volume level. In this tutorial I will discuss about a small fix that will help you set only one volume slider when increasing or decreasing system volume. In my case both Master and PCM can change the volume level of output sound. Therefore I would like to change only one of them while keeping another fixed.

Configuration

Copy /etc/pulse/default.pa into .pulse directory of your home directory.

mkdir ~/.pulse
cp /etc/pulse/default.pa ~/.pulse

Next find and change load-module module-udev-detect line to following

load-module module-udev-detect ignore_dB=1

Finally find the commented line that says load-module module-alsa-sink control=PCM. If you want to control PCM, un-comment this line. If you want to control Master instead make it look like following line.

load-module module-alsa-sink control=Master

After making this change, you can kill pulseaudio with

killall pulseaudio

You can reboot or run “pulseaudio” command from terminal. Now when you change the volume you will only effect either Master or PCM (depending upon your configuration above). You can use something like alsamixer to fix the volume of the other slider which you don’t want to change while changing the volume.

References

  1. http://askubuntu.com/questions/15069/how-do-i-change-the-way-ubuntu-adjusts-my-volume-mixer-levels
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