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Thread: adcHighPassFilterEnable();

  1. #1
    Junior Member
    Join Date
    Nov 2019
    Posts
    5

    adcHighPassFilterEnable();

    Hello guys,

    I am doing some audio project with tennsy 3.2 + audio board. Now i've calibrated microphone on audio board and adjuted to show the decibels. I think that works quite fine.
    I also found option "adcHighPassFilterEnable();". If I understand correctly, this function is used by default, even if I don't use it and it cut the low frequency noises?

    Does it works like A-weighting? Can I somehow set the border frequency of filtering (in case if cuts "too much").

    ""By default, the analog input (either line-level inputs or mic) is high-pass filtered, to remove any DC component.""

    Every answer will be helpfull.

    Best regards,

  2. #2
    Senior Member
    Join Date
    Oct 2015
    Location
    Vermont, USA
    Posts
    195
    Personaly, I always disable that ADC filter as I find that it adds unacceptable noise to the system. See my post on this issue here:

    http://openaudio.blogspot.com/2017/0...noise.html?m=1

    If you choose to disable the adc's highpass filter, you will have a small DC offset in your audio stream. You can remove this by adding a highpass filter using one of the filter blocks in the Teensy Audio Library (or using your A weighting filter, which also filters away DC). I have no problem with filtering; I only have a problem with the specific implementation of the HP filter used by default in the ADC.

    Chip

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