AC100 sound mixer

These netbooks use ALC5632 audio codec plus mixer IC which has quite some amount of knobs and switches. Most of them are available for direct manipulation with alsamixer, GNOME Volume Control and other applications that interact with ALSA mixers.

Analog Audio Mixer Path

Fear not, here's the diagram from the datasheet that allows one to make sense out of all those confusing opportunities:

Understanding it doesn't require any special knowledge, here's a short legend:

  • DAC is Digital to Analog Converter, DACs module gets digital stereo signal via I2S bus from the CPU (VoiceDAC module is left unconnected an ac100)
  • ADC does the reverse and can be used to convert sound from inputs to digital form which is then sent over I2S to the CPU
  • DMIC is a digital microphone, connected to special pins of the integrated webcam
  • A triangle on the diagram means a sound amplifier
  • A square marked Vol is an attenuator that a user can tweak to reduce the volume of the signal
  • A square with M is a mute switch
  • A circle with sigma is a module that mixes all the inputs together
  • A trapezoid is a mux, a module that allows the user to select only one of the inputs to be connected to the output

Common usage scenarious

Here ALSA control names are used, if you're using alsamixer or other similar software you will not see “Playback” or “Mux” in the control names, that is normal.

Stereo playback on integrated speakers

Should be enabled:

  • DACL2HP Playback Switch
  • DACR2HP Playback Switch
  • Int Spk
  • Speaker Playback Switch (i.e. unmute Speaker)

Should be set:

  • SpeakerOut Mux to HPOut Mix
  • SpeakerOut N Mux to RP/+R

Master and speaker playbacks should be unmuted and set to the desired level.

Proper mono sound via MONO mixer or Speaker mixer is impossible to produce on unmodified hardware, see reversed_polarity_of_one_of_the_integrated_speakers for details. Luckily most usage scenarios do not require that anyway. You can swap polarity of connection of one of the speakers but then RN/-R would need to be used for the stereo output.

Stereo playback on headphones

Same as stereo playback on integrated speakers but with Enabled:

  • Headphone Playback Switch (i.e. unmute Headphone)

Set:

  • Left Headphone Mux to HP Left Mix
  • Right Headphone Mux to HP Right Mix

To mute the internal speakers you can disable Int Spk or mute Speaker.

Recording sound from integrated DMIC

This can be used to record sound from the digital microphone integrated in the webcam module, useful for e.g. VoIP Selected for capture:

  • DMIC En Capture Switch
  • DMIC PreFilter Capture Switch
  • DMICL Mix DMICL2ADC Capture Switch

Set:

  • I2SOut Mux to ADC LR

Tweak DMIC Boost Volume and Rec Capture Volume to your needs.

Recording from external microphone

Selected for capture:

  • Left Capture Mix MIC12REC_L Capture Switch

Tweak Mic 1 Boost Volume, Mic1 Capture Volume and Rec Capture Volume to your needs.

Save and Restore different sound settings

Don't frighten you do not need to memorize all the above settings. If you select the settings in alsamixer according to your needs type on the command line:

# alsactl store -f <name>
</code
e.g. 
<code>
# alsactl store -f headphones.state

Now, if you want to switch over to your headphone settings next time simply type

alsactl restore -f headphones.state

Hence, you can save settings for internal speakers, headphones, mute all, etc. If you do not want to type all the above to restore just create a little shell script (name it e.g. setsound.sh) to do that for you.

#!/bin/sh
# Set alsa sound to a predefined state
# save state via 
# alsactl store -f <name>.state
# call this this by
# ./setsound headphones

alsactl restore -f {$1}.state

make the file executable

# chmod +x ./setsound.sh

now you can set sound settings by simply typing

# ./setsound.sh headphone
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