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Reload Thread: Conflict with Box Calculations (sealed)

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    shamb1s's Avatar
    shamb1s is offline Junior Member

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    Conflict with Box Calculations (sealed)

    I recently purchased 2 Alpine Type S 12" with the Dual 2 Ohm Voice Coils.
    I started doing my calculations on how much air space I'm going to require.
    I started by calculating how much air space I'm going to need based on the recommended Qtc of .86 from the manufacturer, and i get a volume of 2.04 ft/3.
    But my trouble comes from the fact that the manufacturer lists 1.25 ft/3 as the optimum air space to get a Qtc of .86
    I calculated this by hand and with an online calculator using my Theile/Small parameters for my driver. Is there something I'm Missing Here? I'm listing the Theile/Small parameters below if anybody wants to double check for me and let me know what I'm doing wrong

    Fs 30Hz
    Vas 61L
    Qms 12.64
    Qes .63
    Qts .60
    Xmax 12.9 mm
    Power Handling RMS/Peak 300/900W

    Any help would be greatly appreciated.

  2. #2
    Canaan's Avatar
    Canaan is offline Beatin' the block down

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    Re: Conflict with Box Calculations (sealed)

    My guess is Aline ran that sub's specs given the use of polyfil in a 1.25cuft box.

    I ran the #'s in BBP6 w/ 'Typical' dampening and got 0.84 Qtc.
    2cuft w/o fill or 1.25 w/ fill should give you similar results.

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