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Thread: Audio adaptor board - low output level after turning on SGTL5000 audio processor

  1. #1
    Junior Member
    Join Date
    Feb 2021
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    3

    Audio adaptor board - low output level after turning on SGTL5000 audio processor

    Hi, I'm new to the Teensy family so still working my way around the forums and code examples.

    I'm trying to use if I can use the Audio adaptor board rev D + Teensy 4.0 to add bass boost and EQ to line in. The dap_bass_enhance example seems to be the perfect starting point. When I compiled the sketch, I'm getting very low headphone output level through the headphones compared to the PassThroughStereo sketch. The output level is restored after commenting out audioShield.audioPostProcessorEnable();

    I've played around with adding digital gain but I'm getting clipping and generally lower audio quality. Is there a setting I need to set to get the SGTL5000 audio processor output to be the same quality as pass through?

    Thanks,

    Tan

  2. #2
    Senior Member
    Join Date
    Jul 2020
    Posts
    927
    Its probably doing the bass boost by attenuating the other frequencies - simply up the overall gain with the volume()
    and/or lineOutLevel() methods?

  3. #3
    Junior Member
    Join Date
    Feb 2021
    Posts
    3
    Iíve isolated the issue to the audio processor. Adding just audioPreProcessorEnable() or audioPostProcessorEnable() to PassThroughStereo also results the same low output level.

    Even with volume(1.0) the output is too quiet. Without the processor, volume(0.7) is plenty loud.

  4. #4
    Junior Member
    Join Date
    Feb 2021
    Posts
    3
    Found the issue! Setting an invalid bass boost setting caused the SGTL5000 to be in a bad state, even after a reprogram. Hard resetting the board (disconnecting power) completely fixed the issue.

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