Midwest Audio Fest

It’s that time audio enthusiasts! Registration for the 2019 Speaker Design Competition is now open! Visit for details and to list your speaker project. We are excited to see all returning participants, and look forward to meeting some new designers this year, as well! Be sure your plans include a visit to the Parts Express Tent Sale for the lowest prices of the year, and the Audio Swap Meet where you can buy and trade with other audio fans. We hope to see you this summer! Vivian and Jill
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High Pass Filter Circuit....???

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  • High Pass Filter Circuit....???

    I believe that the high pass filter section for the tweeter section is a 12dB filter with a crossover freq of 6400Hz. Can someone explain to me what function does the C4 capacitor and R1 resistor parallel circuit serves in the tweeter section?

  • #2
    Looks like a high pass shelf, to raise the level of higher frequencies. The resistor attenuates at lower frequencies, but the cap cuts in to reduce the attenuation. Maybe the tweeter droops a bit towards the high end.


    • #3
      Realistic Mach 2... old school!

      The parallel RC is a shaping filter. It will reduce output below the critical frequency where the cap opens up and you end up with a series resistor. Above that frequency the cap effectively shorts the resistor out.
      Electronics engineer, woofer enthusiast, and musician.
      Wogg Music
      Published projects: PPA100 Bass Guitar Amp, ISO El-Cheapo Sub, Indy 8 2.1 powered sub, MicroSat


      • #4
        It's a contour network.


        • #5
          In a sim (which you can run yourself), using an "8 ohm" tweeter (w/flat Z-curve - like a planar), it effectively attenuates the tweeter an additional -2dB IN IT'S PASSBAND (which is roughly the topmost octave) with little change to the Fc (and below). (In my moc sim, I can actually get the same x-fer fn by just using the 2 ohm series resistor, w/OUT the cap.)