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Thread: New Equivalent 3145 crossover Network

  1. #16
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    Please post any questions you may have.

    Non of this happened in 5 minutes and there was a lot of thought put into it particularly by Giskard. We should also respect the original work by the designer/ engineer, JBL's Greg Timbers.

    So if you need a few tips or information not posted please ask.

    Ian

    Long Live the JBL 4345, Three cheers for Greg Timbers, Three cheers for Giskard.

  2. #17
    Senior Seņor boputnam's Avatar
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    Great Thread, Ian. Kudos to the design team - all of 'em. I wish I could hear them.

    The black baffle embarrasses me. Let me see what I can do.
    bo

    "Indeed, not!!"

  3. #18
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    Thanks Bo,

    Its an old picture!

    Ian

  4. #19
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    Hi All

    Quote Originally Posted by Ian Mac.
    I think Earl deleted his remarks because he is skeptical or had doubts about the Claritycaps and it was just a shrt question answer thing. . I don't think he has any interest otherwise in this remarkable crossover or the system.
    (A) ( John ) Post Deletions ? Yes ;


    - I deleted two posts because ( as noted above ) they were of a conversational manner, which I knew was off-topic ( to the central N3145 chat ).

    - My intent to delete ( after asking & receiving a reply ), was stated clearly in the first line of each post.

    - Since Ian decided to let his answer stand on record / I guess I was hasty in my deletions . Sorry if that had people looking under stones .

    (B) (Ian ) N3145 ;

    - I actually do have some interest in circuits similar to this ( incorporating 2-pole to 3-pole transitions ) / just not much interest in this one specifically ( as mapped out with these LC values ).

    - Equivalent circuits ( to a tapped autotransformer ) are very interesting. I have to admit, I don't know how to create the "equivalent" pair of inductors ( using a calculator and the posted formulas ). Now, a bandpass circuit consisting of a; series coil followed by a shunt coil followed by a series cap followed by a shunt cap, is an extremely interesting adaptation of a circuit in s far as it "breaks the standard topology rules of passives' arrangement". I wonder how many at LHS members' have listened to this arrangement and it's audible deviations from more "normal" characteristics in circuit dampening .
    .
    - I prefer larger diaphragmed compression drivers without lenses in front of the horn. So that preference precludes directly implementing the N3145 for any of my projects .

    - Last Nov. I spent quite a lot time persuing ( with calculator & empirical RTA testing ) the "best-fit" LC values that would enable the raising of the crossover point up into the 10K range ( for the horn-driver/horn-driver combos ) . I left this effort unfinished. It'll need to remain unfinished for the near future .

    - I fully intend to include a tweeter within my final MTM efforts ( switchable into & out of the hipass circuit since there are a few occasions where I enjoy its' contribution ) .

    - The tweeter driver will be a small format ( small diaphragmed ) compression driver, instead of the usual ring-radiator type. I've had quite good success , ( level matching ), with the inclusion of ( from Italy ) two different polyester diaphragmed drivers. I'm still looking for "THE" small / "efficient" ( @ 1.25" diaphragmed ) driver .

    - At some point I'll want to also tackle minimizing the acoustic nulls in the crossover area caused by the acoustic overlaps.

    - I suspect that a High "Q", series LCR trap ( paralleled across the load ) & set to the correct band-width will help achieve the necessary steep slopes out in the tweeters stop-band. This frequency dependant "trap" can be "hidden" from the amp by putting it behind ( driver side ) any reasonably valued pad. This position will protect the source amp from (seeing & ) having to deal with a frequency dependant short-circuit .


    - The ( horn ? ) will be a simple diffraction slot ( a la the WestLake approach ) but smaller in depth due the octave higher Xover point . The "horizontal" orientation of its' lips can fit into the tight MTM component pack that I have to contend with . My horn "tests" were done with just the metal throat portion from the original 2344 horn . That throat alone provided enough loading for my purposes .

    (C) ClarityCaps, FWIW; Tony G. is auditioning these caps now & will eventually describe his impressions in a 2006 update at Humble HomeMade HiFi .

    - I intend to try them out since I don't own any large value Film & Foils and these seem affordable. Also, I'm terminably curious when it comes to the sound of caps.
    - I was going to order some ( yesterday ) from Ians' Australian contact until I discovered they don't accept online, Visa or PayPal.
    - Shortly, I'll pursue the money-order angle ( Western Union I guess ) .


  5. #20
    RIP 2014 Ken Pachkowsky's Avatar
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    Quote Originally Posted by Ian Mackenzie
    Ken,

    The system is biamped at 290 hertz and the 2122H, the 2307/2308 and the 2405 have a passive crossover. The biamping in the way that I am doing it is superior to full passive operation.

    Ian
    I can appreciate the active 290 hertz x-over from active to passive, but how would you compare the 290 hertz+ passive performance to that of the active x-over?

    Just curious

    Ken

  6. #21
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    Ken,

    I don't know yet as I have no means of a full active sytem at this point.

    I would say it would be difficult to mimic what has been done with the passive crossovers, that is why so often people get a different result when they attempt to plug and play with a active system..its is not that simple

    Ian

  7. #22
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    Quote Originally Posted by Ian Mackenzie
    Ken,

    they attempt to plug and play with a active system..its is not that simple

    Ian
    I would sure second that. As you are aware I have experimented with many different active systems and so far always end up back to the original. Perhaps that will change in a few months .

    Ken

  8. #23
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    Quote Originally Posted by Ian Mackenzie
    I would say it would be difficult to mimic what has been done with the passive crossovers, that is why so often people get a different result when they attempt to plug and play with a active system..its is not that simple
    Often true. Once one gets the voltage drive of the active or line level passive solution identical to the speaker level passive solution one should be good to go. One can't really do that with off the shelf crossover cards in off the shelf production equipment.

  9. #24
    Senior Member andresohc's Avatar
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    I am looking into getting the caps for this circuit and will be checking with E Speaker.com soon. Has anyone tried ordering Clarity Caps from them yet?

    http://gallery.bcentral.com/GID49565...LARITYCAP.aspx

  10. #25

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