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Thread: Lx5 whithout autoformer ?

  1. #1
    kalkan0
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    Lx5 whithout autoformer ?

    Hello to all the JBL lovers !

    Is it possible to find an equivalent schematic of LX5 (3115) crossover without autoformers ?
    I want to do this crossover for a LE 15A ( 8 ohms) filtered at 500 Hz and for a 375 in a Iwata Horn.
    Thank s a lot for your answer
    Maurice

  2. #2
    Maron Horonzakz
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    What do you have against autoformers?

  3. #3
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Maron Horonzakz
    What do you have against autoformers?
    Can't get 'em, mostly, and the resistors ahead of them are, ummmm, wasteful (see below).

    Former member Giskard once started a great debate about using them in another thread here with the thesis: "Why bother?"

    There were no replies....

    http://audioheritage.org/vbulletin/s...233&#post49233
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  4. #4
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    Quote Originally Posted by kalkan0
    Hello to all the JBL lovers !

    Is it possible to find an equivalent schematic of LX5 (3115) crossover without autoformers ?
    I want to do this crossover for a LE 15A ( 8 ohms) filtered at 500 Hz and for a 375 in a Iwata Horn.
    Thank s a lot for your answer
    Maurice
    Bonsoir Maurice,
    Une suggestion, i give you a suggestion:
    Consult Benny de chez Aqua Bleu (Ant/Be).
    He did a very good musical (and spectacular) X-over for my multihorn concept.
    Bonne chance.
    Salukes.
    Karel

  5. #5
    RIP 2011 Zilch's Avatar
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  6. #6
    Member soundmotor's Avatar
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    Quote Originally Posted by Zilch
    Can't get 'em, mostly,
    You could however fab something nearly equivalent. Autoformer or tapped inductor = the same thing. 4x 1mH laminated-core inductors in series would be ~close, just not on the same core. Connect the switch at each series junction for attenuation.

  7. #7
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    Quote Originally Posted by Soundmotor
    You could however fab something nearly equivalent. Autoformer or tapped inductor = the same thing. 4x 1mH laminated-core inductors in series would be ~close, just not on the same core. Connect the switch at each series junction for attenuation.

    - Techbots' thread on "Tapped Autotransformers" is quite informative by laying out most of the theory behind building a tapped autotransformer .

    - If you so desire, use it to buildup a coil offering a 3 db tap. Follow the logic you've just laid out. The theory in that thread ( does somewhat ) suggest one needs 2 duplicate value coils to successfully create a 3db tap .

    - The results surprised me .


  8. #8
    Member soundmotor's Avatar
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    Quote Originally Posted by Earl K
    - Techbots' thread on "Tapped Autotransformers" is quite informative by laying out most of the theory behind building a tapped autotransformer .

    - If you so desire, use it to buildup a coil offering a 3 db tap. Follow the logic you've just laid out. The theory in that thread ( does somewhat ) suggest one needs 2 duplicate value coils to successfully create a 3db tap .

    - The results surprised me .

    Staggered values make sense so it is really just a question of getting an example coil and putting it on a bridge for DCR & L measurements.

    I'll volunteer as I've access to a lab standard bridge.

  9. #9
    RIP 2011 Zilch's Avatar
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    Adding to the mystery:

    The inductances don't add as assumed:

    http://audioheritage.org/vbulletin/s...ead.php?t=5629

  10. #10
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    Quote Originally Posted by Zilch
    The inductances don't add as assumed:
    - Zilch, Thanks for the link to that thread .

    - I had missed all that info on "asymmetrical summing" . ( All I knew was that they didn't add )

    Cheers

  11. #11
    Member soundmotor's Avatar
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    Quote Originally Posted by Zilch
    The inductances don't add as assumed:

    http://audioheritage.org/vbulletin/s...ead.php?t=5629
    I'd like to measure one of these with a bridge. I cannot think of any reason why it would measure one net inductance in one direction and a different net in the other? A neat puzzle.

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