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Midwest Audio Fest

It’s that time audio enthusiasts! Registration for the 2019 Speaker Design Competition is now open! Visit midwestaudiofest.com 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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Can someone model this crossover..??

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  • Can someone model this crossover..??

    It is with a Vifa BC25SC06-04 tweeter and a 2 uf cap in line and a .3 mH inductor paralleled across tweeter. It also has a 5.1 ohm Resistor in series with cap and after cap on speaker load side.

    So a "T" shape Cap left, resistor Right, and Inductor across.

    Level seems nearly perfect as is, but not sure how the inline resistor is shaping frequency response on the high end.


  • #2
    In the model, the top end is not affected at all.
    The inline resistor mainly affects around, 2-3K .
    Blue is measured response in box, red is w crossover.


    Click image for larger version

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    Click image for larger version

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    • #3
      Originally posted by donradick View Post
      In the model, the top end is not affected at all.
      The inline resistor mainly affects around, 2-3K .
      Blue is measured response in box, red is w crossover.


      [ATTACH=CONFIG]n1329526[/ATTACH]

      [ATTACH=CONFIG]n1329527[/ATTACH]

      Thanks Don!

      I tried the software a while back and had issues with it. Maybe time to try again!

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      • #4
        Additionally: Your values attenuate the tweeter about -5 to -6dB, leaving it around 91dB w/a -6pt in the 6k-8k range. Seems awfully high - for nearly any application.
        W/out the resistor, the "knee" rises about +1dB, around 4k it rises about +3dB, and the top octave rises about +4 to +5dB.

        Upping the 2uF cap to 6uF leaves the tweeter level about the same but lets it reach down to near 2.5kHz (about the lowest useful Fc for this one).
        Listen to some test tones in the 4k-5k range. If there's a "hole", then I'd suggest lifting that cap value a bit (3uF, 4uF) 'til it fills in.

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        • #5
          Originally posted by Chris Roemer View Post
          Additionally: Your values attenuate the tweeter about -5 to -6dB, leaving it around 91dB w/a -6pt in the 6k-8k range. Seems awfully high - for nearly any application.
          W/out the resistor, the "knee" rises about +1dB, around 4k it rises about +3dB, and the top octave rises about +4 to +5dB.

          Upping the 2uF cap to 6uF leaves the tweeter level about the same but lets it reach down to near 2.5kHz (about the lowest useful Fc for this one).
          Listen to some test tones in the 4k-5k range. If there's a "hole", then I'd suggest lifting that cap value a bit (3uF, 4uF) 'til it fills in.

          Chris, thanks! In this application, I was using a few extra Vifa BC25's I had laying round, to replace two JBL retail tweeters, in a goodwill find, and using the stock crossover as is.

          The Stock Speaker, uses a 6.5" woofer and is actually crossed at 4.5 khz according do the diagram for the speaker.
          I Know a bit high for a 6.5" but the stock tweeter was cheap and small. doubt it could have gone much lower.

          I realize the Vifa should go lower for sure, but "Oddly enough" it sounds fairly decent on first listen.
          I am sure there is some break up with the Stock woofer, but it was not nearly as bad as I had thought.

          So if I drop the Vifa Tweeter to around maybe 2.5-3 khz, I would then have to give the woofer some changes to avoid overlap.

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