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Thread: crossover experts needed

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    Senior Hostboard Member LOUDER's Avatar
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    crossover experts needed

    So I want to build some n1201-8a for some cabinets. I want to make them bi-amphibole or at the the very least bi-wired. But when I look at the schematic for the n1201-8a I am confused. If you follow the negative leg of the woofer you have a .3 inductor, followed a variabled resistor, to a 8 mic cap and a .77 inductor. How do I replicate this in a bi-amplical situation ?

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    Re: crossover experts needed

    I'm not sure which wiring diagram you're referencing. But, there should be nothing in series with the negative circuit for the LF or HF, it should be a solid conductor from driver to input terminal.

    Even Zilch's "Z-19" maintains this convention.

    Z-19:

    attachmentphp?attachmentid30595&ampstc1&ampd1200899899

    Factory:

    Vintage Altec Model 19 Networkn1201 8aRev

    - - - Updated - - -

    I think your confusion begins in reading the wiring diagram.

    The .77mH choke(in either/both networks) is a shunt across(in parallel with) the HF circuit, it's part of the high pass filter and has nothing to do with the woofer circuit.
    Last edited by bowtie427ss; November 10th, 2020 at 01:23 PM.
    Not all vegetables make good leaders.

  3. #3
    HB Super Moderator
    crossover experts needed


    Altec Best's Avatar
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    Re: crossover experts needed

    Quote Originally Posted by bowtie427ss View Post
    I'm not sure which wiring diagram you're referencing. But, there should be nothing in series with the negative circuit for the LF or HF, it should be a solid conductor from driver to input terminal.

    Even Zilch's "Z-19" maintains this convention.

    Z-19:

    1

    Factory:

    1

    - - - Updated - - -

    I think your confusion begins in reading the wiring diagram.

    The .77mH choke(in either/both networks) is a shunt across(in parallel with) the HF circuit, it's part of the high pass filter and has nothing to do with the woofer circuit.
    Bowtie I get a 404 error when I try to open the image links.


    Altec 9844-8B - Page 8

    Google Image Result
    Last edited by Altec Best; November 10th, 2020 at 12:05 PM.

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    Senior Hostboard Member bowtie427ss's Avatar
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    Re: crossover experts needed

    Thanks AB, i've attempted a fix.
    Not all vegetables make good leaders.

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    HB Super Moderator
    crossover experts needed


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    Re: crossover experts needed

    Quote Originally Posted by bowtie427ss View Post
    Thanks AB, i've attempted a fix.

    No Problem, was just giving you a heads up... Thanks for the fix !

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    Senior Hostboard Member LOUDER's Avatar
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    Re: crossover experts needed

    OK, make it more simpler for me. In the n1201-8a network there's a inductor, L1 .3 mh is it used on the woofer ? why is it there ? Zilch obviously eliminated it. He made the Z-19 cross- over a 12 db per octave slope, on the woofer and a 18 db octave slope on the highs. What was the factory's octave slope ? I see a 24 db octave slope on the woofer, plus the L3 inductor in series with C1 8 mfd cap to get to ground. What is the factories octave slope on the woofer ? And does it make any difference ? Sorry to be a Idiot but I work hard at it ! Thanks in advance.

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    Re: crossover experts needed

    FWIW even though virtually nobody does it except the guy that does some Klipsch kits, but all grounds should go to a grounding bar using ring tongue connectors, flat, lock washers and ideally torqued for the bar material, hardware type.

    Re horn/woofer speaker XOs and especially Altec, I don't get it as I've yet to hear any substantive improvement over using the pot to set woofer/horn tonal balance, then use a by-pass cap [preferably PIO or otherwise well damped or add a 'drain' resistor] to 'let through' the highs to 'taste'. Add a reactance annulled zobel if the woofer has a high inductance.

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