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Dayton RSS315HF-4 12" Reference HF Subwoofer 4 Ohm - box size appears to have a typo

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  • Dayton RSS315HF-4 12" Reference HF Subwoofer 4 Ohm - box size appears to have a typo

    Parts Express usually matches Dayton's numbers.
    But, I think Parts Express accidentally type 1.70 when they meant to type 0.71.
    To make sure, I ran the numbers for both the 4 Ohm Reference HF and the 8 Ohm.
    I am confident that the 4Ohm Reference HF is built for a smaller volume box than the 8 Ohm.
    This leads me to believe that the Dayton website has the correct numbers.

    https://www.parts-express.com/dayton...4-ohm--295-464
    Sealed Volume1.70 ft.³
    Sealed F3 40 Hz

    https://www.daytonaudio.com/index.ph...fer-4-ohm.html
    Sealed Volume 0.71 ft.³
    Sealed F3 70 Hz

  • #2
    If you want a Qtc of 0.7 then neither of those box sizes is correct. 3 cu ft is, giving a 37Hz F3. 1.7 cu ft isn't bad, if you can live with a Qtc of 0.8. 0.71 cu ft gives a Qtc of 1, an F3 of 45Hz, with a 1.6dB hump at 76Hz. That would be OK in a car. Different box sizes for different needs. I don't see any typos, other than the 70Hz F3. You'd need to squeeze it into .2 cu ft to get that, along with a 5dB hump at 110Hz.
    BTW, Parts Express and Dayton is the same thing.
    www.billfitzmaurice.com
    www.billfitzmaurice.info/forum

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    • #3
      Using my (2 yr. old) parms: the RSS315HF-4 in 1.4cf (closed, w/OUT stuffing) yields a "Q" of 0.7.
      Qts = 0.39, Vas = 2.97cf, Fs = 24

      I know PE "updates" these parms (if they change) maybe every other (if not EVERY) yr. now - I didn't check 'em today.

      If you're "designing" a box, you should be using some box sim software ( like WinISD from linearteam.org ), NOT just going w/some written line in the driver description.

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      • #4
        When I run the numbers with formulas I got from Loudspeaker Design Cookbook, my results agree with Chris Roemer's post:
        Originally posted by Chris Roemer View Post
        Using my (2 yr. old) parms: the RSS315HF-4 in 1.4cf (closed, w/OUT stuffing) yields a "Q" of 0.7.
        Qts = 0.39, Vas = 2.97cf, Fs = 24
        I know PE "updates" these parms (if they change) maybe every other (if not EVERY) yr. now - I didn't check 'em today.
        If you're "designing" a box, you should be using some box sim software ( like WinISD from linearteam.org ), NOT just going w/some written line in the driver description.
        Our results are not close to billfitzmaurice's results.

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        • #5
          This is the response from Parts Express:
          I have requested an update. Likely it was just a typo, thanks for pointing it out for us. And thanks for contacting Parts Express. Please let us know if we can be of any further assistance.

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          • #6
            Originally posted by engineeringDynamo View Post
            When I run the numbers with formulas I got from Loudspeaker Design Cookbook, my results agree with Chris Roemer's post:
            Our results are not close to billfitzmaurice results.
            If you used Qts of 0.39 they wouldn't be. When I loaded them into WinISD Qts was 0.489. They must have changed them since then, not for the better IMO.
            www.billfitzmaurice.com
            www.billfitzmaurice.info/forum

            Comment


            • #7
              Originally posted by billfitzmaurice View Post
              If you used Qts of 0.39 they wouldn't be. When I loaded them into WinISD Qts was 0.489. They must have changed them since then, not for the better IMO.
              Thanks for the clarification. So this driver used to have a Qts of 0.489, and it was "redesigned" to become Qts of 0.39?
              My goal, of course, is to use the current numbers, because I have not bought the woofers yet.

              I have some 54L sealed boxes that are 1.5in thick all around, 2in thick baffles.
              I have not cut the holes for the woofers... so I can choose any woofer I want.
              I am shooting for a Qtc between 0.5 and 0.7

              I was thinking this would be a nice choice:
              Peerless by Tymphany 835017 12" Aluminum Cone XXLS Subwoofer, but Parts Express T/S numbers do not match the manufacturers.
              Likely Parts Express "preliminary numbers" are not correct, and the mfg numbers are correct.
              Too bad, because the preliminary numbers are better for me.
              Last edited by engineeringDynamo; 08-16-2018, 01:50 AM.

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              • #8
                Go to the PE home page (I'm guessing at all this, but you'll find your way), then under Resources go to "Woofer Selection Guide". Click (to sort) on top of the Closed Box Size column (or whatever). Then just scroll down to get in the range that your box size is (about 1.9cf?). These will target a Q of around 0.7 - so to get .6 you'll need a larger than opt. size. IF YOUR box is 1.9cf, I'd look for drivers for boxes that are maybe 1.5cf or so? (when put in YOUR box, the Q should drop into the .6 range). This will at least give you some driver choices which you can THEN model in some box software.

                Uhhhh . . . , no one said this driver was "redesigned". It's very possible that it's always had a Qts near 0.44 and that when (Bill F's) data was measured, THAT ("batch") of drivers ran a bit high, and the T/S parms were also calc'd a tad high. MAYbe PE measured one again last yr., and THAT (production run) batch had Qs a little lower than ave., and (for some reason) the T/S parms got measured a bit on the low side as well.

                It's due to driver variations (w/in a batch), and variations from one prod. run to the next, AND (possible) changes made to components (like spiders), (AND the fact that you just can't tell how current ANY driver data is - on the net), and possible "tweaks" to design over time - that having your own measurement rig just seems like the right thing to do (to some of us).

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