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Subwoofer displacement

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  • Subwoofer displacement

    One thing I have not noticed (Maybe I am blind??)
    is how much volume does a Dayton audio um18-22 displace? Need this information to play with box designs

  • #2
    It's 'Vd' on the spec sheet...…

    You don't need the information because your software derives it by multiplying 'Sd' and 'Xmax'.

    It wont ask you for 'Vd'

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    • #3
      Very few manufacturers supply that information. B&C is one that does, shown on their data sheets as Air volume occupied by driver. For their 18TBW100 that's 0.39 cu ft/11 L, the UM18 is probably similar.
      www.billfitzmaurice.com
      www.billfitzmaurice.info/forum

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      • #4
        Not only that, but in a large, closed, stuffed box, the volume used by the actual driver will be way more minor (probably) than variations in its T/S parms (unless you measure your actual driver "in hand"). Even then, it won't end up being very significant.

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        • #5
          Well pe says 3 foot net internal. And this box I made is 3.2?? Actual internal volume 20x20x17 external. So I am probably pretty damn close

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          • #6
            I get that it can do that with Xmas and sd. But what about the volume displaced by the magnet and basket. And that is significant. I find it difficult to fathom how to design a proper enclosure without knowing that information. And since most things are designed now days with c.a.d. it would be a no brainer for manufacturers to include that data

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            • #7
              Originally posted by Bill C View Post
              I get that it can do that with Xmas and sd.
              That's something entirely different and not what you asked about.

              www.billfitzmaurice.com
              www.billfitzmaurice.info/forum

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              • #8
                Close enough is good enough in this case. I usually use twice the volume of the magnet structure, which is usually a pretty simple cylinder.

                Dan
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                • #9
                  Figure 0.2cf if you want. The box sizes are so large that it's inconsequential going sealed OR vented (as I said). Is this auto?

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