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    NEED BOX HELP QUICK! Please!

    ok guys the dimensions of my box are 36"x14.5"x15"


    It is an L shaped port, the port is 3"wide the whole way i need it tuned to 28-30 Hz how tall/long does the port need to be?

    Someone please help!!! I am trying to use win ISD but am not sure about how much airspace the port takes up and what not!




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    Re: NEED BOX HELP QUICK! Please!

    Here is a quick pic of my box...Kinda crappy but hey i had to do it quick!
    Attached Thumbnails Attached Thumbnails NEED BOX HELP QUICK! Please!-sub-box.jpg  




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    Re: NEED BOX HELP QUICK! Please!

    you make it as high as your box is internally.

    According to winISD about 33" long,at least I think I am right.

    assuming your port is 3x13 that is

    port=3x13x33




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    Re: NEED BOX HELP QUICK! Please!

    so what is the internal volume of this box after the port?? Before it would be like 3.3




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    Re: NEED BOX HELP QUICK! Please!

    So in order to get 30.3hz in my current setup i need 46.5" of 12 x3 port? what if i cut the port down to like 9 or 10 x 3?




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    Re: NEED BOX HELP QUICK! Please!

    so on winisd when it asks for box displacement you have to put in your final displacement after port and driver displacement correct?




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    Re: NEED BOX HELP QUICK! Please!

    If you cut it down to about 9 or 10 x 3 then it will shorten the port length. But on the other hand it will increase on the amount of port air velocity. if you want to find the total port area then multiply the width ( + .75 ) and height ( + 1.5 )and the total length ( + width )

    so for a 3" x 10" x 40" port you would do this

    WIDTH * Height * Length
    ( 3" + .75" ) * ( 10" + 1.5") * ( 40" + 3" ) =

    Width * Height * Length = Total Port Displacement
    3.75" * 11.5" * 43" = 1854.375 cubic inches

    If you want to convert to cubic feet divide the answer by 1728

    so that would make that 1.073 cubic feet.

    And yes when it ask for the box volume it's asking for the volume after the displacement of the port and of the displacement of the sub.




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    Re: NEED BOX HELP QUICK! Please!

    Thanks a lot man! So would it hurt to drp the port height down? Would that lower my tuning with a 34.25" port? if i cut it down to say 9X3 would that give me the 28hz tuning i am looking for?




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    Re: NEED BOX HELP QUICK! Please!

    Well i didn't plug those into WinISD because i don't have the specs on hand.
    but here is how it works.

    If you make the height smaller while keeping the length the same then you will see a lower tuning frequency, but there will also be a higher port velocity. If you lower the port length while keeping the port area the same you raise the tuning frequency. If you lower both the port length and the port height... it could lower or raise your tuning frequency.. the ony way to tell is by plugging it into winISD or some other program.




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    Re: NEED BOX HELP QUICK! Please!

    well winisd say at 2.48ft^3 with oirt size of 9X3 at 34.04" long tuning will be 29hz so this is about what i am shooting for. what will happen if port velocity is increased?




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    Re: NEED BOX HELP QUICK! Please!

    If the port air velocity goes up so does the port noise. It' can sometimes be very unpleasant to hear. If you look at the rear port Air velocity graph and it's less than 25 or so around there at and above 25 hz or so you should be fine. Just make sure it isn't at like 50m/s.




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    Re: NEED BOX HELP QUICK! Please!

    ok guys i spent all day before work working on this bad boy (its my first ported enclosure) and i chopped it down to 36X13.5X15 (only one inch but gave me a little less air space and allowed me to put it badk in the trunk more so as i still have some trunk space) So before displacement of port and subs it should be about 3.234 ft^3 Correct? Now my port is 12 X 2.75 and 34.25 inches long which should be about .757 ft^3 correct? and sub displacement is about .2 ft^3. So 3.234 - .757 - .20 should be 2.79 ft^3 of airspace after all displacement correct? So according to winisd pro with that port with 2.79 ft^3 of airspace it is about 28.5 hz correct? I think i finally got everything right! I didnt have time to wire it up but i will do that sometime tonight and i will get pics of the box and everything tomorrow! Let me know if my calculations are still wrong!




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