My (yet another) Tempest Sonotube Update

Discussion in 'Archived Threads 2001-2004' started by Aaron D, Jul 1, 2001.

  1. Aaron D

    Aaron D Stunt Coordinator

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    Ok, I'm getting close to building this thing (on the 7th and 8th of July) and I just want to double-check myself. (Sorry to post another one of these.)
    1. Anyway, I'm looking at a 230 L tube (24" dia). My understanding is that the port volume "replaces" some box volume, so I will add some to the tube dimensions to account for the volume of the port.
    2. The tube will be 25% fill (Qa of 30), so for a tube of 230 L, this means I'll add about 2.2 lbs of fill?
    3. Finally, for a tune of 15 hz, I need a 4" dia port of 35.7 cm long.
    I can't help the feeling that I'm forgetting something, so if anyone spots trouble, please say so! [​IMG]
    On another note, I have concocted a quite unique design for my enclosure, but I don't wan't to reveal it yet just in case it won't work!! [​IMG] I will post some pics as soon as I get it built, though.
    Wish me luck, and THANKS!!
    Aaron
     
  2. Julian Data

    Julian Data Second Unit

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    Aaron,
    Be sure to include the volume of the driver which is 5L.
    The port volume is given by using the equation Vol Cylinder = PI(r²)Length
    The result will be in CU³, to get to FT³ divide by 1728. And then to covert to liters from fT³, multiply by 28.325.
    For you case:
    I assume you are using standard PVC and not the "thin wall" type? If so..
    =[3.14(2.15)²(14.055")]/1728 = 0.115386 (28.325) = 3.268L
    So..
    Your NET volume is 230L
    GROSS volume would be adding the port, inside endcaps (2 of them - one on top and bottom : 2(24" DIA * 0.750") and driver in your case. 230 + 5 + 3.27 + 11.12 = 249.39L. If you were doing a box, include the braces.
    Cut the 24" tube to a height of: 33.750" which gives a GROSS Volume of 250.27L.
    As for the fill question, you need need 2Lb for 25% of a 8FT³ box.
    ------------------
     
  3. Aaron D

    Aaron D Stunt Coordinator

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    Julian, thanks once again!!
     

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