The audio port in one of my old motherboards starting putting out static in the right stereo channel. I decided to fix this by purchasing a cheap USB sound card and using it instead. The specific model that I purchased is by Sabrent and has a model number of AU-MMSA.

I plugged it into my system, opened Sound Settings, and chose “Audio Adapter Analog Stereo” from the device options. Sound then flooded my headphones with the volume being far too loud for comfortable listening. As I lowered the volume, the sound went from far too loud to completely silent when I moved from around 40% volume down to 35% volume. It was if somebody muted the volume.

After playing around with the settings for a while with no change in loudness or the sound cutting out at low volume, I dug in deeper. I found many different bug reports and suggested solutions to this issue, but only this one by user sen in the Arch Linux forums fixed both problems.

Unfortunately, the solution requires modifying a file as root, which can be a bit daunting, but I believe in you, so let’s modify that file.

First, open a terminal. This can be done by pulling up Ubuntu’s dash (clicking the Ubuntu icon at the top of the icon bar along the left of the screen), typing in “terminal” and clicking the enter key. Next, we need to edit the /usr/share/pulseaudio/alsa-mixer/paths/analog-output.conf.common file as root. This can be done by typing the following in the terminal and pressing enter:

[chris@home ~]$ gksu gedit /usr/share/pulseaudio/alsa-mixer/paths/analog-output.conf.common

You will then be prompted for your user password. Type it in and press enter.

A file editor will open up with the file loaded. Search for the text “Element PCM”. You should see the following text:

[Element PCM]
switch = mute
volume = merge
override-map.1 = all 
override-map.2 = all-left,all-right

Update this section of text to look like the following (changes are in bold):

[Element PCM]
switch = mute
volume = ignore
volume-limit = 0.01
override-map.1 = all 
override-map.2 = all-left,all-right

Note that the value 0.01 can be adjusted as needed to change how quiet and loud the volume is. Making the number smaller reduces the max volume while making the number larger increases the max volume. I tested out 0.05 and found that the max volume was much louder than I would ever use. I also decided that 0.01 was technically louder than I’d ever use. I ended up with a value of 0.0075 (0.005 was too quiet) which I felt gave a good maximum volume and resulted in better overall control over the volume range.

Once you have saved the changes to the file, a couple things still need to be done in order to have this change go into effect.

Inside your terminal window (it should be behind the text editor), run the following command:

[chris@home ~]$ pulseaudio -k

This will force the audio system in Ubuntu to reload. If you had any application that was playing audio, it will go silent at this point. Any application that is now silent will have to be closed and reopened.

You can now test out the change to see if you need to adjust the number down or up to make the volume to your liking. Remember to save the file and run pulseaudio -k each time you change the number.

What Didn’t Work

I found a number of guides that recommended that the /etc/pulse/ file be modified and have the following lines added:

load-module module-alsa-sink control=PCM
load-module module-udev-detect ignore_dB=1

Neither of these worked for me. The first config change had no effect. The second config change did fix the issue with the sound muting at low volumes, but the volume was still far too loud with just 1% volume being what I consider to be an 80-90% volume level.

Technical Details

For those that are interested in the technical details of this USB device, the following information is for you.


Full verbose details (lsusb -vvvv) can be found here. These are the basics:

Bus 005 Device 002: ID 0d8c:000c C-Media Electronics, Inc. Audio Adapter
Device Descriptor:
  idVendor           0x0d8c C-Media Electronics, Inc.
  idProduct          0x000c Audio Adapter
  iProduct                1 C-Media USB Headphone Set

aplay -l

**** List of PLAYBACK Hardware Devices ****
card 2: Set [C-Media USB Headphone Set], device 0: USB Audio [USB Audio]
  Subdevices: 0/1
  Subdevice #0: subdevice #0

Full details.

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