Fill for sealed "sub"

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  • Brandon B
    Super Senior Member
    • Jun 2001
    • 2193

    Fill for sealed "sub"

    I'm (finally) building the enclosures for my 3 bass modules for my 3 main speakers. Each is a Stryke Lambda SB10 in a 3cu' box.

    Am I correct in planning not to stuff these other than some padding at the top and bottom to eliminate reflections? Cabinet is sort of a tall, thin pyramid, truncated on top. Front and back are at slightly different angles. Walls are 2 layers of 3/4" MDF, with 1/8" cherry veneer plywood outside that. They are covering from 250 down to 30 or so.

    Any recommendations for best material for lining top and bottom?

  • Patrick Sun
    Super Senior Member
    • Aug 2000
    • 1380

    Rule of thumb:

    Stuff the sealed enclosure with polyfill.

    Line the walls of the ported enclosure with eggcrate, or other foamy padding, or Black Hole 5 (but it's costly).

    PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs
    PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs


    • JonMarsh
      Mad Max Moderator
      • Aug 2000
      • 15269

      No need to amplify on Pat's comments, really. But while I'm here, what the heck?

      The polyfill stuffing that is fairly dense, used for pillows, works quite nicely for stuffing sealed enclosures, even though some folks will tell you that it attenuates more in the midrange than in the bass.

      You can gauge the affect by checking the enclosure impedance curve, looking for the peak of the resonance; it will drop a little in frequency.

      If your speaker is handling a wide range, such as a sealed two way, then my ultimate preference is long fiber wool, but it is a little more pricey. Considering the drivers you're using and their cost, it's quite in line with the overall system budget.

      For reflex systems, many DIY'ers do as Pat suggests. I prefer lining the enclosures with 1/2" heavy felt, then using polyester batting in a few layers behind the woofer, for some extra midrange damping. This is the batting used for making quilts, not the loose stuff type of polyfill.

      Let us know how your system turns out, and post some pictures for us!



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      • Brandon B
        Super Senior Member
        • Jun 2001
        • 2193

        Fill it shall be then. This is a sealed box. The main reason I was asking is the Stryke site says the driver is intended for use in a 1.5 to 3 cubic foot enclosure, and since filling a box increases it's apparaent volume, this would make it effectively larger than 3, although, this may have been what John J. meant, 1.5 to 3 filled, I haven't asked him or anyone at Lambda.

        Waiting on a wood order to come in, then will start building. Is there a way to post pictures to this site, or do they need to be linked in from somewhere else?

        These are not actually subs per se. I am also building a dual HE15 unit. 2 of the SB10's are for the dedicatewd 2 channel listening part of the system, and so the wool sounds like something I would like to do, if it's going to improve the performance (albeit a tiny amount). Where does one typically buy such stuff?



        • ThomasW
          Moderator Emeritus
          • Aug 2000
          • 10934


          Long fiber wool is expensive, hard to find, and not really necessary for a midbass driver. It's most beneficial for midrange drivers that extend up high.

          But if you really want some try these guys.

          Rio Grande Wool Mill Inc.
          Box B, Tres Piedras, NM 87577
          (505) 758-1818


          IB subwoofer FAQ page

          "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson


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