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    zimmer82's Avatar
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    Box Help: port sizes

    ive decided to get my box custom built for my alpine type r 12". It's going to be in a 2.1ft^3 box (3ft. long +8in. port, 14in high, and 13in wide). I got these specs from an anonymous person. (idk if he wants to be named)

    Although, he doesnt know the exact length of the port but does know that it is tuned to 31Hz.
    My Question: Would one of those box building computer programs be able to calculate the proper length of the port for it to be correctyl tuned to 31Hz?

    Anyone with experience with these programs, could you let me know? Im trying to get this box made ASAP before my speaker comes in next week.




    2000 GMC Z-71 Ext.Cab

    SET-UP:

    HU: pioneer deh-7700mp
    front: stock (but decent)
    rear: Stock
    sub: Orion P-Series 12"
    sub amp: orion 600d
    box: ProBox Downfire
    Need $$$ for Upgrades




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    Re: Box Help: port sizes

    just use this formula:
    Lv = Av*1.84*10^8/[Vb*1728*(Fb/0.159)^2] - 0.823*sqrt(Av)
    where:
    Lv= port length
    Av= port area
    Vb= box volume (in cuft)
    Fb= Tuning frequency.

    But I think Win ISD can also.

    *edit*
    is that 2.1 cuft with the port / woofer dispalcement? or with out.
    *edit x2*
    are those dimensions the dimensions of your port area?



    Car: 1999 Plymouth Neon

    Head Unit: Alpine CDA-9853
    Components: RE RE comps in some custom kick panels.
    Subs: 1x Alpine Type R 1242D In a vented 33 hz 3cuft box. (redesiging)
    Sub Amp: 1x Alpine MRD-M301 mono amp (400 rms/14.4volts @ 2ohms)
    Speaker Amp: Infinity 7520a (97 rms x2 /14.4volts @ 4 ohms)

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    Re: Box Help: port sizes

    if you use 2 2" ports they would need to be 6.93" long to be tuned to 31hz




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    Re: Box Help: port sizes

    Quote Originally Posted by exteremespl1122
    if you use 2 2" ports they would need to be 6.93" long to be tuned to 31hz
    That might be correct on some enclosure calculator, but 2" x 7" is not enough port area.



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    Bought From TeamPSI,ace_800, Zxcvtypo,bjfish11,atoz350,timbre-audio,Derrick824, lastcall,eclipsefool,rtillaree,PioneerPimp,6spdcou pe,ctmike,Thieroff


    Quote Originally Posted by bumpin buick View Post
    /yourself
    Quote Originally Posted by elmor001 View Post
    I don't think I'm the dumb one here. You just told someone to go divide themself.

    H/U Alpine 9887
    Mids Seas ER18RNX
    Tweets LPG 25NFA
    Subs 2 10" Memphis Audio Shallow Mount Subs
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    Re: Box Help: port sizes

    Quote Originally Posted by ameduece
    That might be correct on some enclosure calculator, but 2" x 7" is not enough port area.
    even if you used 2 ports, still not enough.



    References

    Sold to jamesdean,jonny101abc,LowLinc,bumpinaintEZ,TurboDu devr4,SVT RELAMPAGO,mk_ ,Burnout956,bonesninja,yenwen,bhsdriller,dalucifer ,BoondockSaints,WillyG4444, alfmoney,btnhfan,dB Dom

    Bought From TeamPSI,ace_800, Zxcvtypo,bjfish11,atoz350,timbre-audio,Derrick824, lastcall,eclipsefool,rtillaree,PioneerPimp,6spdcou pe,ctmike,Thieroff


    Quote Originally Posted by bumpin buick View Post
    /yourself
    Quote Originally Posted by elmor001 View Post
    I don't think I'm the dumb one here. You just told someone to go divide themself.

    H/U Alpine 9887
    Mids Seas ER18RNX
    Tweets LPG 25NFA
    Subs 2 10" Memphis Audio Shallow Mount Subs
    Mids/Tweets Amp Kicker ZX850.4
    Sub Amp Kicker ZX1000.1

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    Re: Box Help: port sizes

    yeah thats true they will need to be rather long with any bigger diamiter than 2"




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    ruckus's Avatar
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    Re: Box Help: port sizes

    ok noob question port area is that width and height of the port?




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    Re: Box Help: port sizes

    yes if its a square port H*W. If its a round port its Pi*R^2.



    Car: 1999 Plymouth Neon

    Head Unit: Alpine CDA-9853
    Components: RE RE comps in some custom kick panels.
    Subs: 1x Alpine Type R 1242D In a vented 33 hz 3cuft box. (redesiging)
    Sub Amp: 1x Alpine MRD-M301 mono amp (400 rms/14.4volts @ 2ohms)
    Speaker Amp: Infinity 7520a (97 rms x2 /14.4volts @ 4 ohms)

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