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I need help building a crossover

Discussion in 'Electronic Basics' started by Ryan Richards \(Diesel Breath\), Jun 21, 2004.

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  1. I need to make a crossover.. nothing fancy or anything... I remember in
    college we went over how to make a crossover and I think it had something to
    do with a resistor and a capacitor... Anyway, here's what I'm trying to

    I have a bass rig and the cab only goes up to 5kHz... I have a component
    system; meaning I have a preamp and a separate power amp... I want to insert
    the crossover between the pre and the power so the power amp isn't wasting
    its time with frequencies that the cab doesn't even support... I need it to
    crossover at 5kHz and slope at 18dB/oct... Any help is good help... thanks
  2. JeffM

    JeffM Guest

    Posting the same question independently to multiple groups
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    This practice
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    It also doesn't let everyone know
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    If the query is relevant to multiple groups,
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  3. Bob Masta

    Bob Masta Guest

    It sounds like all you need is a simple low-pass filter,
    and maybe not even that. I'd guess that with a normal
    bass, there would be little enough energy above 5 kHz
    to begin with. However, if you are using effects like
    fuzz, there might indeed be a lot of extra harmonic
    energy. I don't know how serious this would be for the
    amp, but it might sound too gritty for your preferences.
    I would have thought that the preamp had tone controls
    that would accomplish this nicely, but if that is home-built
    or otherwise without them, try adding just about any
    simple low-pass filter. I assume that the 5 kHz limit
    is in the speaker itself, not the power amp, otherwise
    don't bother. Start off with a simple passive R-C filter
    between the preamp and amp. You'll need to determine
    the impedance of the amp and include it in the calculations
    for a proper design, but you will probably be well served to
    just do it by ear: Increase the R or C until you hear some
    loss in the high end with the fuzz active, and adjust to taste.

    The cutoff frequency is 1 / (2 * pi * R * C), where R is in ohms
    and C is in Farads. So for example with a 0.01 uFd cap, you
    would solve for R = 1 / (2 * pi * 5000 * 0.01x10^-6) = 3180 ohms.
    Use the nearest value you have on hand.

    Hope this helps!

    Bob Masta

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
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