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Thread: port sizes for 2242 ?

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    Your Memory Lives On RIP Tom Loizeaux's Avatar
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    port sizes for 2242 ?

    I have an existing cabinet around 8.5 to 9.5 cu.ft. (depending on port volume, extra bracing, etc.) and would like some port areas and volumes that would tune a JBL 2242 to around 32 to 38 hz. I just want a moderate extension to use this with a small PA system as a subwoofer to help with the lowest octave.
    Your suggestions will be appreciated!
    Thanks,

    Tom
    Last edited by Tom Loizeaux; 09-09-2004 at 06:46 PM.

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    Re: port sizes for 2242 ?

    9.0 cu ft @ 32 Hz = two 6" dia ports x 9.4" ducts
    9.0 cu ft @ 38 Hz = two 6" dia ports x 4.6" ducts

    10.0 cu ft @ 32 Hz = two 6" dia ports x 7.8" ducts
    10.0 cu ft @ 38 Hz = two 6" dia ports x 3.4" ducts

  3. #3
    Your Memory Lives On RIP Tom Loizeaux's Avatar
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    Giskard

    Giskard to the rescue as always...thanks!
    Since I'm still not quite sure what my final internal volume will be, would you please also post the port lengths for an 8 cu. ft. cabinet? That way I know I'll have all my possible volumes covered and can extrapolate my fine tuning from there.
    Thanks again for a quick and concise rsponse.

    Tom

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    Ok.

    I see you changed the volume range from 9.0 to 10.0 to 8.5 to 9.5.

    The last pair of 9.0 cu ft enclosures I built for the 2242/2245 had 1.2 cu ft of volume displacement due to the driver, ports/ducts, and bracing. Practically all of that displacement was gained back with the addition of 2" OC fiberglass on each side panel and the back panel. In other words, I started with a 9.0 cu ft gross physical volume and ended up with a 9.0 cu ft net effective volume. Cool eh?

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    8.5 cu ft @ 32 Hz = two 6" dia ports x 10.4" ducts
    8.5 cu ft @ 38 Hz = two 6" dia ports x 5.3" ducts

    9.5 cu ft @ 32 Hz = two 6" dia ports x 8.6" ducts
    9.5 cu ft @ 38 Hz = two 6" dia ports x 4.0" ducts

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    The previous answers were via BB6P

    Here's via the old JBL tuning formula

    8.5 cu ft @ 32 Hz = two 6" dia ports x 11.375" ducts
    8.5 cu ft @ 38 Hz = two 6" dia ports x 6.25" ducts

    9.5 cu ft @ 32 Hz = two 6" dia ports x 9.5" ducts
    9.5 cu ft @ 38 Hz = two 6" dia ports x 4.875" ducts

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