Passive speaker crossovers

Discussion in 'DIY' started by auri, Apr 9, 2017.

  1. auri

    auri Almost "Made"

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    Looking for some of that magical SBAF non-bullshit in the realm of passive speaker crossovers.

    At the moment I am personally planning on a simple 2-way circuit with 2 caps, 2 coils, and an L-pad (variable initially, fixed resistors eventually) for a set of B&C DE250 in SEOS-12 horns and Beyma 12" woofers crossed at ~1khz. Options for the present and future include baffle step EQ and Zobel networks for the woofer and a shelf filter from 2-5khz for the horns. Any tips here would be welcome - for now, I have a decent calibrated mic setup and want to see what actually happens before throwing in more components. I want to do everything possible for these speakers to scale up to the combo of a Gumby and a First Watt F5 (DIY).

    In addition to the above, my biggest current questions are in component choice, where to spend money to get the best effect.

    Capacitors - My current impression is that the capacitor in the signal path of the high pass is the most important component. The Capacitors thread rates the white Audyn Reference and the Jantzen Z-Superior caps as being very good for speakers - I've also heard the basic Mundorf Supremes would be good, and all of these choices are somewhat reasonable at $30-50 for a 10uF cap. Any more I should look at? Is the quality of the series wired cap in the woofer low-pass important, or can I get away with something cheap like a Dayton or Audyn Q4 with little to no ill effects?

    As for inductors and resistors, admittedly I have done little research. I have some 18awg Jantzen air cores in my cart at the moment, which seemed reasonably priced.

    Any comments or advice would be greatly appreciated!
     
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  2. auri

    auri Almost "Made"

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    Also, could anyone help me understand what's going on in a design like this? I recognize that a different slope is being used on the high pass, partly to fix the phase as the leads on the high pass aren't reversed, but specifically I was wondering about the placement and values of the resistors. I would just look at trying to copy it and seeing what happens, but my woofers are 3.5db less efficient and I wouldn't know what to change.

    [​IMG]
     
  3. jhaider

    jhaider Acquaintance

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    You cannot do a simple circuit with a horn-loaded compression driver and expect passable sound quality. You also can't do one without measuring the drivers in the intended cabinet in a nice reflection-free environment.

    Worry about getting a respectable transfer function before obsessing over parts brands. That requires measurement, simulation, listening, and then starting over at measurement.

    If you can't do that, my best advice is to outsource to someone who can.
     
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  4. auri

    auri Almost "Made"

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    Could you help me by at least telling me how to modify the L-pad circuit - or replace it with a variable unit - in the schematic in my second post?

    I guess all I'm wondering is if R1 and/or R3 are part of the L-pad circuit and would need to be changed as well.
     
  5. jhaider

    jhaider Acquaintance

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    I can't see the image - sorry. But just "modifying the L-pad circuit" won't get you to a high-fidelity crossover. I don't know what drivers are used there, but clearly at least one is different from the ones you're using.
     

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