The Raspberry Pi has an on-board audio jack, which is super handy for all kinds of sound effects and speech, just plug and go! However, for when you want better audio for music playback, a USB audio card can greatly improve the sound quality and volume, this tutorial will show you how.

This guide will also show you how to record audio via the headphone jack on the adapter

Pre-requisites

Figure out your chipset

If you have CM108

You may see a lot of stuff happening like the below:

Now you can go down to the update alsa module options section

Raspbian Jessie - Updating alsa options

All we have to do is tell Raspbian to look at "card #1" for the default audio. Card #0 is the built in audio, so this is fairly straightforward.

run sudo nano /etc/asound.conf and put the following in the file and save

This will make the default PCM (audio) output card #1 and the default control also card #1

Raspbian Wheezy - Updating alsa options

If you're using Wheezy, we'll edit the audio system configuration file with

sudo nano /etc/modprobe.d/alsa-base.conf

For all but the most recent Raspbian Wheezy releases, look for the line that reads:

#options snd-usb-audio index=0

Change this to:

options snd-usb-audio index=0

Note we removed the # at the start of the line.

For the latest Raspbian Wheezy versions, look for this line instead:

options snd-usb-audio index=-2

There's no # to remove in this case, just change the index from -2 to 0:

options snd-usb-audio index=0

Testing!

OK now that you've configured ALSA depending on your OS...that's it! Now reboot with sudo reboot and log in again, you can test with speaker-test by running

speaker-test -c2

Which will play white noise through the left and right 'speakers' on the audio card. Once you've got something coming out, try to play an audio file with speaker-test (for WAV files, not MP3)

speaker-test -c2 --test=wav -w /usr/share/sounds/alsa/Front_Center.wav

If you want to play a stream of music, you can try

sudo apt-get install mpg123
mpg123 http://ice1.somafm.com/u80s-128-mp3

If you want to play MP3's on command, check out this tutorial which covers how to set that up

Headphone vs Audio card

Don't forget, you still have the built in headphone jack on the Pi, if you edited alsa confit might be called card 1 now (not the default card 0)

You can run aplay -l to list the devices

If you want to aplay through a specific card, specify card 1 with -D plughw:1,0 or card 0 -D plughw:0,0 etc

speaker-test -c2 -D plughw:1,0

aplay --device=hw:1,0 test.wav


You can set audio levels for both output and input with

alsamixer -c 1

Use the arrow keys and return/escape to set and save the settings. It's a sorta-cute text-graphics system

At least with the CM-Headphone type adapter, you can also record audio.

 arecord --device=hw:1,0 --format S16_LE --rate 44100 -c1 test.wav

Will record signed 16-bit (S16_LE) audio at 44100 Hz (--rate 44100) mono (-c1) audio to test.wav. We've noted that any audio input will be echoed out the speakers as well

You can have a little VU meter show up if you add to the-V mono command line. Press control-C to quit

Once you're done recording you can play back with

aplay --device=plughw:1,0 test.wav

If you're using a Raspberry Pi and notice the output isnt totally clean, some USB Audio adapters don't like USB-1.2 and produce crackling in the output. You can work around the problem by adding dwc_otg.speed=1 to /boot/cmdline.txt and setting the USB ports to USB-1.1 mode.

You can get user access to the audio hardware with other devices by granting access using sudo usermod -a -G audio username