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    moparerrnocar's Avatar
    moparerrnocar is offline Senior VIP Member



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    Wana check my numbers

    I want to build a center slot box for two 12's using .75 material, the subs qts is .106. I want the box to be 36x13x22 tuned @ 32. How wide will the port need to be?

    Using RE's calculator (I heard doesn't account for port displacement) it says if my port is 3.75" I'll be @ 31.08 with a box vol of 4.104. If I change 36 to 35 (for estimated sub displacement) it accounts for .137 and changes the tuning to 31.61.

    I don't know how much volume the port will take up. Would it be tuned close to 32 after port displacement, or is that already accounted for?
    Last edited by moparerrnocar; 12-31-2012 at 10:34 PM.







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    SMS's Avatar
    SMS
    SMS is offline CarAudio.com Elite



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    Re: Wana check my numbers

    3.75+ 1.5= 5.25-width, height=11.5?, length of port = ?
    multiply those three and divide by 1728




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    Re: Wana check my numbers

    Quote Originally Posted by SMS View Post
    3.75+ 1.5= 5.25-width, height=11.5?, length of port = ?
    multiply those three and divide by 1728
    Im a bit confused with the formula you posted....

    I think I figured out my port volume. I took 17.5x1.5x11.5 = 301.875 converted it to ft3 and got .175. Port and subs equal .281

    Changing the box width from 36 to 34 is a .273 difference which puts me at 32.171 Hz according to RE. That is if they don't account for port displacement.



    Edit: I get what you mean now. I have to factor the port area as well as material volume. If so, then my port displacement is .611

    So then .611+.106 = .717 of total displacement? If I change the width to 31 that's a difference of .682 and puts me @ 34hz.

    Does this sound right?




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    Re: Wana check my numbers

    Ok Im just confusing myself, but hear me out. I figured out the volume of my box 11.5 x 34.5 x 20.5 = 8133.375 / 1728 = 4.7068.

    4.7068 - .611 = 4.0958

    RE says 4.082??? Close, so they obviously factor port area. Now I just need to know if a 3.750-3.875 port puts me within 32hz.




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    Re: Wana check my numbers

    I can't answer your question but it would probably be easier to download the Torres box calculator to design your box. It's a great little program.



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