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Thread: RIAA phono preamp

  1. #1
    Junior Member
    Join Date
    Jun 2021
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    1

    RIAA phono preamp

    Hi,

    I wonder if its possible to filter / deemphase / equalise the RIAA curve digitally as a filter using the audio board (Teensy 3.2)

    I can't find any resources.
    Thank you in advance,
    best regards,
    FS

  2. #2
    Senior Member
    Join Date
    Jul 2020
    Posts
    1,042
    Yes, you can configure a AudioFilterBiquad as three 1st-order sections for the 3 poles/zeros needed - you'd
    use setCoefficients explicitly.

    The RIAA curve has a lot of attenuation at high frequencies so you'd expect the noise floor to rise up at the
    high end due to quantization - don't expect 16 bits effective across the spectrum!

  3. #3
    Member
    Join Date
    Sep 2014
    Location
    South Dundas, Ontario, Canada
    Posts
    44
    There is also the need to properly load the phono cartridge of your turntable for flat response. The Moving Magnet (MM) cartridge may need 47K with 250pF termination. Does the audio preamp have the ability to provide this load? Also, you need to assure you have the proper gain for optimum signal transfer, as MarkT alluded to.
    If you are interested in playing 78RPM records, then the RIAA isn't accurate as this format came after the 78RPM era, and its needle profile.

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