Anyone have experience w/ LT circuits?

Discussion in 'Home Theater Projects' started by MarkRoberts, Jan 11, 2006.

  1. MarkRoberts

    MarkRoberts Stunt Coordinator

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    I have a couple of Atlas 15" subs I would like to try one out sealed but the recommended cabinets are quite big like 6 cu.ft.
    I was wondering if I could get one of these bad boys in a 3cu.ft. cabinet with a LT circuit. I was looking at the Rythmik Audio site and one of the amps the 350 is offered with a optional LT circuit board. I however have no idea how to get the necessary values for the resistors and caps.Any help would be great.
     
  2. MarkRoberts

    MarkRoberts Stunt Coordinator

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    Thanks for the link Chris!
    I also found a excel spread sheet at John Murphy's web site.
    The only problem is the rythmik audio LT has a 2nd op amp in it so I guess I'll have to contact them to see how to calculate that part of it.
    rythmik LT
    Looks like the spread sheets will do the first part of the circuit.
     
  3. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    Don't forget to check out:

    http://www.linkwitzlab.com/x-filters.htm#9

    A lot of stuff on linkwitzlab is a bit greek to me, but maybe if I took the time I could figure out some of the more technical aspects of active filters.
     
  4. MarkRoberts

    MarkRoberts Stunt Coordinator

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    Chris T,
    Thanks for the link.I checked it out and I have to admit it was a little overwhelming.:b Going to have to look at that some more and read and re-read. Its allot to take in.
     
  5. MarkRoberts

    MarkRoberts Stunt Coordinator

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    Alright I downloaded John Murphy's LT excel sheet.
    If any of you have used it I have a couple questions.

    1.In the notes section it asks for the F and Q of the exsisting closed box speaker.
    This is the Q of the box and Fb or F3, correct?
    Would Unibox's calculations be good enough?
    Or is this simply the T/S specs of the driver?
     
  6. ThomasW

    ThomasW Cinematographer

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    It's best to use the measured Fc and the measured Qtc. That data is more accurate than a computer sim.
     
  7. MarkRoberts

    MarkRoberts Stunt Coordinator

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    ThomasW,
    Thanks for the reply. Well I guess I am SOL as I don't have any measuring gear other than a rat-shack meter.
    [​IMG]
    How much would it cost for a measuring/testing set-up?
     

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