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Help needed with Class D Output Filter

Discussion in 'DIY' started by Bassblaster, Jul 15, 2017.

  1. Bassblaster

    Bassblaster Super Member

    Cambridge, Ohio
    I Got a Class D amp with that has filterless outputs but really needs one. I have 130kHz on the speakers and since its also bluetooth i sometimes get some audible HF noise, maybe around 16K?? What parts would i need to make a filter around 12kHz? I figure since im going to be placing a big mouser order for another project why not spend a couple bucks and fix the noise with this bluetooth speaker. Speakers are 4 Ohm. the amplifier IC is a MIX2052 but googling that gives me nothing. after about 5 mins with a scope it appears to be a bridge amp. its in an SO-8 package and there's 2 of them.

    1 Unknown, has 3.1V on it
    2 Unknown, has 1.6V on it
    3 Input
    4 Input
    5 130kHz
    6 VCC (4.2V)
    7 GND
    8 130kHz

    Any ideas with this one?
  2. markn2wae

    markn2wae Mark T N2WAE

    Scotch Plains, New Jersey
    Years ago I used to work on high power class "D" digital amps. and I seem to remember seeing at least two or more toroid coils (wound with very heavy wire!) and two or more "block style" mylar type capacitors, I can't remember much more, but having never needing to replace any parts in this section.
    IMHO, anyone designing switch mode circuitry WITHOUT the proper filtering should be "shot" :thumbsdown: :D
    PS, don't they have the "more smilies" or the machine gum smiley any more?? :(
  3. Bassblaster

    Bassblaster Super Member

    Cambridge, Ohio
    Usually Class D filters are inductors, but im trying to figure out what value inductors i would need
    this 2.1 TPA3116 board has 6 indicators for example.

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