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Thread: How much abuse can a 2268 take?

  1. #1
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    How much abuse can a 2268 take?

    I am planning to put a few of them into something reminding of a horn. I am worried that the extreme pressure in the throat will break the diaphragm.

    Does anyone know how strong the cones are? What are they made of?

    Thanks

    Mårten

  2. #2
    Senior Member RMC's Avatar
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    Hi Marten,

    I didn't find the answers you are expecting. However, it sounds like an adventurous project, the 2268 appears like a nice driver to put at risk with how much abuse it can stand...

    Seems to me you don't really have on-hand the driver for a horn type low-frequency enclosure.

    The 2268 driver Qts at 0.36 is relatively high to load this in a horn type. Usually, JBL woofers designed for horn use have low Qts figure around 0.20, some as low as 0.17 or so. Yours is about double that.

    After reviewing the three basic classes of low-frequency transducers, JBL's John Eargle (note 1) shows typical Thiele/Small parameter values for these three major classes of LF drivers (including for horn type) and I don't see the 2268 having some of those for a more appropriate horn design.

    I don't recall seeing a JBL horn type box using that woofer, but it was used in SRX 718/728/738 being vented enclosures. It gives a clue on intended use I guess.

    In case abuse may involve woofer cone travel capability, I note that Parts-Express which sells the 2268 mentions a Max linear excursion of 8 mm (their other stated T/S are correct so I would assume this one is also), JBL's T/S table Xmax 23 mm, but the 2004 Design Engineer's Specifications (Alex Salvatti) for this driver says "Xmax, damage 23 mm peak before spider bottoms on gap sleeve".

    I hope this can be of some help to you. Regards,

    Richard

    1- Handbook of Sound System Design, P. 100, 106, 108, 112.

  3. #3
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    Thanks RMC.

    It is more a quarter pipe with a back chamber than a horn. The T/S parameters are just perfect for my purpose.

    My only worry is the stability of the cone, Total pressure on the cone will be 800 Pascals according to my Hornresp simulation.

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