Tempest Vented Box Dimensions

Discussion in 'Archived Threads 2001-2004' started by Randy Noel, Nov 19, 2002.

  1. Randy Noel

    Randy Noel Stunt Coordinator

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    I'm trying to finalize my plans for a Tempest in a vented box, and have been playing with the box dimensions some more. If I built my box with outside dimensions of 26" x 26" x 26", using 1" thick material, the internal volume is very close to the Adire Alignment. This does not take into account the difference in displacement of the bracing. What adjustments would I need to make for this size to work? I am a novice, so I have no idea how to model this setup. Would my port lengths need to change? BTW, I'm seriously considering the new plate amp Adire is bringing out next month - the DT300. Thanks for your help.
     
  2. Darren_T

    Darren_T Second Unit

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    I adjusted the dimensions for the Adire Alignment to suit my needs and kept the exact internal volume to ensure good performance. I figured the area of the braces and subtracted the area of the holes in the braces. You will also need to figure the area of the driver and take that into account also, if you want to get real picky you could figure the area of the plate amp but I didn't bother.

    Darren
     
  3. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    Gross Internal Vol = 24 * 24 * 24 = 13824 in^3
    Driver Vol = 305 in^3
    Bracing Vol =~ 10% * 13824 = 1382
    Net Internal Vol = 12137 in^3 = 198.9L

    This is within 10% of the Adire alignment. If you just use the porting specified in the Adire alignment you'll be fine. Tuning will be slightly higher than the Adire but appropriate for this cabinet volume.
     
  4. Randy Noel

    Randy Noel Stunt Coordinator

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    Thanks for your help. How do they come up with 214L net on the Adire? Using the same method you used, on the Adire, 20.5" x 20.5" x 32"=13448"^3, minus 305"^3 for driver, minus 1344 for bracing,=11799"^3. Just wondering- I'm still trying to learn.:b
     
  5. Darren_T

    Darren_T Second Unit

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    Did you account for the mutiple holes cut out of the braces? Just a thought [​IMG] Polyfil also increases the perceived internal volume. There is 64oz of polyfil in the Tempest Adire Alignment sub.
     
  6. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    Well, first you've got to convert units from in^3 to L.

    11799in^3 * ft^3/(12in)^3 * 28.3L/1ft^3 = 193.2L

    Hmm. That isn't exactly 214L, now is it? It looks like you'd have to completely neglect the bracing volume to get 214L.

    13448in^3 - 305in^3 = 13143in^3 = 7.6ft^3 = 215L

    I'm not sure how to reconcile this except to say that your plans call for virtually the same volume as the Adire plans ... and despite the fact that its not really 214L, this sub has made many DIYers happy.
     
  7. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    "The Adire design is a net 214L cabinet, tuned to 15.4Hz. It is stuffed with 64 ounces of polyfill."

    I suppose Darren could be right about the polyfill. But if that's the case then they should have said its a effective net 214L cabinet. Usually the term "net" doesn't take into account the effect of the polyfill.
     
  8. Darren_T

    Darren_T Second Unit

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    This is the very problem I encountered that confused me. I figured 214L net volume meant just that but my calculations of the original design fell a bit short of 214L so I built my enclosure to match the actual net volume of the Adire Alignment, figured that was the safest route. I even went through the trouble to subtract the volume of the holes in the braces and all cutouts etc... still didn't get 214L...sounds great though!

    Darren
     
  9. Randy Noel

    Randy Noel Stunt Coordinator

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    Glad to hear I'm not the only one confused by this! How much you wanna bet someone comes up with the answer for us?
     

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