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Thread: port size help

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    port size help

    I have a box already built it is 2.4 cubic feet and has a cutout for a 12 inch sub it has two 2.5 inch circles for ports how long should i make my tubes

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    Owner BigAl205's Avatar
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    Re: port size help

    The sub and ports take up space in the box, so a 2.4 cubic foot box won't be 2.4cuft when the stuff is installed.

    To know what port size you need, we need to know what kind of sub you're going with (the Thiele-Small parameters), and what frequency you want it tuned to.

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    Re: port size help

    51, 53, 116 on right-hand side might help you.
    http://www.bcae1.com



    The longer the length of the individual port tubes , the lower the frequency
    What is fs of sub you will be using ?
    Your port tubes may have bends to accomodate desired frequency of tuning.
    WINISD , bassbox , et cetera [ enclosure design programs ]
    Last edited by Hic; 12-26-2017 at 10:05 PM.
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    Re: port size help

    Vd [ft3] 0.0198
    Hvc [mm] 31.6
    Sd [m2] 0.052
    Hvc [In] 1.24
    Sd [ft2] 0.56
    VC.Diameter [mm] 48
    Revc [O] dual 2,9
    Eff [%] 0.23
    Levc [mH] (2000Hz) 4,85 (8 Ω) / 1,23 (2 Ω)
    S.P.L. [dB] 95
    Xmax [mm] 10.8
    R.M.S.Power [W] 400
    Xmax [in] 0.4
    M.M.P. [W] 1400
    Zmax [O] 74,19 (8 Ω) / 18,6 (2 Ω)
    Sp. Displacement [l] 1.67
    Nom. Dia.(In) 30
    BI [Tm] 16,2 (8 Ω) / 8,2 (2 Ω)
    Sp. Displacement [ft3] 0.059
    Qts 1.05
    Rms[Ns/m] 3.39
    Qms 13.79
    Mms [g] 166
    Qes 1.02
    Cms [m/N] 7,6 x 10-5
    F0 (in Cabinet) 55.8
    Fs [Hz] 43
    Mg.Wt.[g] 2100
    Q0 (in Cabinet) 1.25
    Vas [l] 32.7
    Flux Density [Gauss] 7381
    Vas [ft3] 1.15
    Hag [mm] 10
    Vd [l] 0.56
    Hag [In] 0.39
    I listen mostly to rap so it probably needs to be tuned arond 35
    Last edited by Dsaulen0902; 12-26-2017 at 10:51 PM. Reason: more information

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    Re: port size help

    https://www.stevemeadedesigns.com/bo...ng-fs-and-qts/

    2nd post [ NDmustang65 ] . With a very high Qts (1.05) sealed box just screams at you.

    http://www.ecoustics.com/electronics...io/214770.html

    Fmods @ parts express are mechanical/electrical sub sonic filters.
    http://www.google.com/shopping/produ...Lw_wcB#sgro=om this sub has a 28 Hz Fs and is 4 ohm. The power of your ZA amp .will work well.
    http://www.jlaudio.com/12w3v3-4-car-...-drivers-92154

    We are talking a low Fs = 26 Hz and we get the 500 bridged watts.
    Last edited by Hic; 12-27-2017 at 06:38 PM.
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    Owner BigAl205's Avatar
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    Re: port size help

    According to WinISD, tuned to 35hz and each port lengths of 8-3/16" would give you a 6db hump around 60hz

    Click image for larger version. 

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    Tuned to 40hz with ports of 1-7/8 would give you a 7.5 db gain at 58hz

    Click image for larger version. 

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    Re: port size help

    Did you figure any boxes with 2 1/2 inch ports ? Port "chuffing" being my concern.

    http://www.rockler.com/2-1-2-clear-p...AaAh2REALw_wcB

    Possibility of pipe for ports ^^^^^^^^^^4
    Last edited by Hic; 12-28-2017 at 10:10 PM.
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    Re: port size help

    Dsaulen0902,

    Getting it sorted ?
    Or , hopelessly confused ?
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    Owner BigAl205's Avatar
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    Re: port size help

    Quote Originally Posted by Hic View Post
    Did you figure any boxes with 2 1/2 inch ports ? Port "chuffing" being my concern.

    http://www.rockler.com/2-1-2-clear-p...AaAh2REALw_wcB

    Possibility of pipe for ports ^^^^^^^^^^4
    BOTH of them are configured with 2-1/2" ports...or more specifically, 2.68" ports, which is the closest size that appears in the drop-down menu of the program. The program also takes chuffing into consideration, and the highest of them shows a vent mach of .15, which is the upper limit. (yet is why the result is green and not red)

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    Re: port size help

    Awesome job , Al. !
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