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C-Media CMI8738

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The CMI8738 is one of the C-Media cards supported by the cmipci ALSA module.


Initial Setup

Before plugging speakers into the card, check the Master volume control is at a reasonable level, but not at maximum (you might damage your speakers, or worse, your ears).

Also check the following controls are unmuted (and set to reasonable levels):

  • PCM
  • Synth
  • CD


The following is a partial list (it ignores Capture controls):

  • Master
  • 3D Control - Switch
  • PCM
  • Synth
  • Line
  • Line-In Mode

    • Rear Output
    • Line-In
  • CD

  • Mic
  • Mic Boost
  • Phone
  • IEC958 5V
  • IEC958 Copyright
  • IEC958 In Monitor
  • IEC958 In Phase Inverse
  • IEC958 In Select
  • IEC958 In Valid
  • IEC958 Loop
  • IEC958 Mix Analog
  • IEC958 Output

    • on - for digital output
    • off - for analog output
  • PC Speaker

  • Aux
  • Exchange DAC

    • on
    • off
  • Four Channel Mode

The Master control on this card is purely a volume control (it has no 'mute' switch).

Troubleshooting Hints

No Sound from Analog Speakers

If you hear no sound when using this card with analog speakers/earphones, try switching off the following:

  • IEC958 Output
  • Exchange DAC

These can be switched off using alsamixer, amixer or other available mixers. (Tested using Debian 4.0r6, alsamixer v1.0.13 and headphones connected to the SPK jack socket.)

See Also

  • The cmipci ALSA module page contains a lot of useful information on this card (and other C-Media cards).

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Category: Sound cards

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