Software & AppsOperating SystemLinux

How To Set a Default Sound Card with Alsa

Ubuntu 17

In this comprehensive guide, we will walk you through the process of setting a default sound card with the Advanced Linux Sound Architecture (ALSA). This is a common task for Linux users who have multiple sound cards installed on their system and want to specify which one should be used by default.

Quick Answer

To set a default sound card with ALSA, you need to identify the card number of your desired sound card using the command cat /proc/asound/cards, and then edit the /etc/asound.conf file to specify the card number as the default. After saving the changes and restarting your system, ALSA will use the specified sound card as the default.

Understanding ALSA

Before we dive into the process, it’s important to understand what ALSA is. The Advanced Linux Sound Architecture (ALSA) is a software framework and part of the Linux kernel that provides an API for sound card device drivers. It’s the primary sound system used by most Linux distributions.

Identifying Your Sound Cards

Firstly, you need to determine the number of your desired sound card. This can be done by running the following command in your terminal:

cat /proc/asound/cards

This command will display a list of all available sound cards installed on your system, each associated with a unique number. For example, you might see something like this:

0 [Intel ]: HDA-Intel - HDA Intel
1 [NVidia ]: HDA-Intel - HDA NVidia

In this example, 0 and 1 are the card numbers, and HDA-Intel and HDA NVidia are the card names.

Setting the Default Sound Card

Once you have identified the card number, you can set it as the default sound card. This is done by creating or editing the /etc/asound.conf file. You can use any text editor you prefer, but for this guide, we’ll use nano:

sudo nano /etc/asound.conf

In this file, you need to add the following entries:

defaults.pcm.card <card_number>
defaults.ctl.card <card_number>

Replace <card_number> with the number of your desired sound card obtained from the previous step. For example, if you want to set the HDA NVidia card as the default, your /etc/asound.conf file should look like this:

defaults.pcm.card 1
defaults.ctl.card 1

The pcm parameter stands for Pulse Code Modulation, which is a method used to digitally represent analog signals, in this case, the audio signal. The ctl parameter stands for control, which is used for controlling the sound device.

After adding these lines, save the changes and exit the editor. If you’re using nano, you can do this by pressing Ctrl + X, then Y to confirm saving the changes, and finally Enter to exit.

Restarting Your System

The final step is to restart your system for the changes to take effect. You can do this by running the following command:

sudo reboot

After your system reboots, ALSA should now use the specified sound card as the default.

Conclusion

Setting a default sound card with ALSA is a straightforward process once you know the steps involved. It involves identifying your sound cards, setting the desired one as the default, and restarting your system. By following this guide, you should be able to easily set your default sound card with ALSA on any Linux distribution.

Remember to check out the ALSA project website for more information and resources on using ALSA.

How can I check if ALSA is installed on my Linux system?

You can check if ALSA is installed on your Linux system by running the command alsa-info.sh in the terminal. If ALSA is installed, it will provide you with information about your sound cards and their configurations.

Can I have multiple default sound cards with ALSA?

No, ALSA only allows you to set one sound card as the default. However, you can switch between different sound cards manually using ALSA commands or by configuring the sound settings in your desktop environment.

How can I test if my default sound card is working correctly with ALSA?

You can test your default sound card by playing audio using a media player or by using ALSA’s command-line tool, aplay. For example, you can run aplay /usr/share/sounds/alsa/Front_Center.wav to play a test sound on your default sound card.

Will setting a default sound card with ALSA affect other applications?

Yes, setting a default sound card with ALSA will affect all applications that use ALSA as their sound system. The default sound card will be used for audio output unless specified otherwise by individual applications.

Can I change the default sound card without editing the `/etc/asound.conf` file?

Yes, you can change the default sound card without editing the /etc/asound.conf file by using ALSA’s command-line tool, amixer. You can run amixer -c <card_number> sset 'Master' 100% to set a different sound card as the default. Replace <card_number> with the desired card number.

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