\ Audio Fixes for Dell / Compaq / HP Machines

Audio Fixes for Dell / Compaq / HP Machines

Many Skywave Linux users with Dell, Hp, and Compaq hardware have the “no sound” issue. It stems from pulse and alsa not doing a good job of automatically finding and configuring the particular soundcards used on those computers. It is an irritating problem that has existed for years and particularly bothersome on Skywave Linux due to the need to specify sinks and plugins for the audio processing chain.

If you have hardware which does not have functioning sound on initial boot of Skywave Linux, consider doing a persistent USB or full installation where system changes are not lost at shutdown.

As a first step, check the volume control / audio settings. If there are visible "outputs" then audio may be awakened by unmuting or adjusting levels. Use Alsamixer or Pavucontrol.

If there are no outputs listed in the audio settings applet, the audio failure may be due to a device misconfiguration. Use the "audio switcher" script to specify different audio devices in pulseaudio's defaults. If switching devices doesn't stop audio subsystem crashes, then consider modprobing a different kernel module or changing options for the module in use.

For more in depth troubleshooting, make note of the cards and subdevices on your system. In a terminal, enter the command aplay -l. Some systems have only one card, 0, while others may have a second card, 1. Subdevices are on those cards, and HDMI audio is output is often the first, or 0, subdevice.

Pulseaudio is configured to use the device sysdefault and a chain of processing plugins. If there is an issue with the driver then audio won’t run properly on device sysdefault, but there are work arounds. You could edit (as root, use sudo gedit) /etc/pulse/default.pa and change the device in line 47 from device=sysdefault to device=hw:0,0 or pethaps device=hw:0,1 if HDMI happens to be on “hw:0,0”. The audio switcher script can do all of this with a couple of mouse clicks.

The snd-hda-intel driver should, but often does not, properly configure sound when the computer is made by one if the previously mentioned manufacturers. Here is an extensive list of model options for the snd-hda-intel driver:

http://lxr.linux.no/linux+v3.2.19/Documentation/sound/alsa/HD-Audio-Models.txt

After noting which option to use, open a terminal and execute commands to remove the default driver and insert the driver with a specific model option. For Dell laptops, try this:

sudo su
modprobe -f snd-hda-intel
modprobe snd-hda-intel model=dell-m6
alsa force-reload
alsamixer

For many HP machines this works:

sudo su
modprobe -f snd-hda-intel
modprobe snd-hda-intel model=auto
alsa force-reload
alsamixer

The last command above brings up Alsamixer. Use F6 to select your sound card then set levels. The “m” key mutes / unmutes channels. “Esc” to exit alsamixer. Save the mixer settings, switch to user skywave, and start pavucontrol:

alsactl store
su skywave
pavucontrol

In pavucontrol, check the levels again, making sure the speakers or headphone output is unmuted. You should hear sounds doing a speaker test. Another speaker test, from the command line, sends a tone to the left and right speakers.

speaker-test -t sine -c 2
You should hear a tone alternating between the left and right channels.
Tags:Pulseaudio, ALSA, LADSPA, Dell / Compaq / HP No Audio
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