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How much poly-fill for sealed subwoofer?

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  • How much poly-fill for sealed subwoofer?

    Hey guys...

    How much poly-fill should I put in a sealed sub box? Should I fill it loosely until it's full or pack it tight?

    Thanks!
    Rob

  • #2
    Re: How much poly-fill for sealed subwoofer?

    General rule of thumb is about one pound (16 oz.) of poly fiber fill per cubic foot.
    Craig

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    • #3
      Re: How much poly-fill for sealed subwoofer?

      Cool, thanks!

      Comment


      • #4
        Re: How much poly-fill for sealed subwoofer?

        Originally posted by nonsuchpro View Post
        Hey guys...

        How much poly-fill should I put in a sealed sub box?
        Enough to get the measured Q down to .8 or so, assuming that it models with a Q higher than that. Unless you have a WT3 to measure Q with the only way to know for sure is if someone else has built the same sub and done the measuring.
        www.billfitzmaurice.com
        www.billfitzmaurice.info/forum

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        • #5
          Re: How much poly-fill for sealed subwoofer?

          Originally posted by billfitzmaurice View Post
          Enough to get the measured Q down to .8 or so, assuming that it models with a Q higher than that. Unless you have a WT3 to measure Q with the only way to know for sure is if someone else has built the same sub and done the measuring.
          I plan on buying WT3, I'm in the dark without it really.

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          • #6
            Re: How much poly-fill for sealed subwoofer?

            Originally posted by PWR RYD View Post
            General rule of thumb is about one pound (16 oz.) of poly fiber fill per cubic foot.
            That's my rule of thumb for FG. However, poly-fill has a much lower specific gravity (i.e. density). Thus it's much harder to cram in 1 lb of poly file into a 1 cu. ft. box than 1 lb of FG. I'd say about 0.8 lbs/cu ft. of poly-fill and be sure to use the crimped stuff; not the smooth, straight polyfill.

            At 0.8 you should have a nicely filled box that's not packed tightly.
            Live in Southern N.E.? check out the CT Audio Society web site.

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            • #7
              Re: How much poly-fill for sealed subwoofer?

              Originally posted by carlspeak View Post

              At 0.8 you should have a nicely filled box that's not packed tightly.
              There's nothing wrong with having the box packed tightly if that's what's required to get the box Q to the desired figure. And that's why rules of thumb don't work where stuffing sealed cabs is concerned. Every driver/cab/damping material combination will have its own specific requirement for best results.
              www.billfitzmaurice.com
              www.billfitzmaurice.info/forum

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              • #8
                Re: How much poly-fill for sealed subwoofer?

                My box is 1.27cft. It has one 10" driver and one makeshift 10" passive radiator. The amp is on one side, the radiator on the other and the back is solid. reason I put the amp on the side is so I can easily get to the controls since it is under my desk. If I have no fill it sounds boxy, if I pack it tight the clarity is great but lacks in sub 40hz. So I just a loose pack somewhere in the middle. not sure how much was used.

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                • #9
                  Re: How much poly-fill for sealed subwoofer?

                  This may be slightly off topic...Whenever I model anything on Unibox, the more fill applied, the earlier the roll off. It seems to hurt low end frequencies with more fill, on paper that is. Can anyone elaborate why?

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                  • #10
                    Re: How much poly-fill for sealed subwoofer?

                    Originally posted by ameuba10 View Post
                    This may be slightly off topic...Whenever I model anything on Unibox, the more fill applied, the earlier the roll off. It seems to hurt low end frequencies with more fill, on paper that is. Can anyone elaborate why?
                    my problem exactly... i would say it's because less air is moving around inside

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                    • #11
                      Re: How much poly-fill for sealed subwoofer?

                      http://forum.sounddomain.com/ubbthre...1110/page/1407
                      "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche

                      http://www.diy-ny.com/

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                      • #12
                        Re: How much poly-fill for sealed subwoofer?

                        Thanks... im assuming that the "fake out" affects sub 50hz, boosting it while clearing up 100-250hz.

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                        • #13
                          Re: How much poly-fill for sealed subwoofer?

                          Originally posted by nonsuchpro View Post
                          My box is 1.27cft. It has one 10" driver and one makeshift 10" passive radiator.
                          That's not a sealed alignment, so you would not stuff it anyway.
                          www.billfitzmaurice.com
                          www.billfitzmaurice.info/forum

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                          • #14
                            Re: How much poly-fill for sealed subwoofer?

                            I was always told that it "fools the woofer" to think its in a larger box. I kinda get the idea now. But why would it model differently?

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                            • #15
                              Re: How much poly-fill for sealed subwoofer?

                              Originally posted by nonsuchpro View Post
                              Thanks... im assuming that the "fake out" affects sub 50hz, boosting it while clearing up 100-250hz.
                              The 1 - 1.5 lb guideline has been around for a while.
                              My primary goal for using "poly" has not been to drop Fs but primarily to attenuate the upper stuff ( like 100 - 250Hz ) where the absorption coefficient of that material becomes effective.
                              "Not a Speaker Designer - Not even on the Internet"
                              “Pride is your greatest enemy, humility is your greatest friend.”
                              "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

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