How to properly stuff a box.

Discussion in 'Home Theater Projects' started by BryanDO, Jan 4, 2005.

  1. BryanDO

    BryanDO Stunt Coordinator

    Mar 22, 2004
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    I wanted to experiment with stuffing my Shiva sub (3cu ft tuned to 19Hz) With polyfill stuffing. I stuffed the box with approx. 1.1 lbs of fill and turned the sub on. The output was terrible. The port wasn't blocked, I left little space from the fill. I'm curious, how do you properly fill a box? I just took a hand fulls of it and jammed it into the box and every crevise between the bracing and port and everything, it was pretty packed in. Is there a special way of doing it? Do you have to keep it away from the sub itself or the port? Any info would be appreciated, thanks.
  2. Patrick Sun

    Patrick Sun Moderator

    Jun 30, 1999
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    Technically, you're not supposed to stuff a ported enclosure, mainly just line the walls with padding.

    If you start stuffing a ported enclosure, the enclosure volume that the driver "sees" gets a little bigger, which will affect the tuning frequency from the port should the port stay the same length as you stuff the enclosure (the tuning frequency would go up as you stuff the enclosure).

    Usually if you wanted to stuff a ported enclosure, it's because you are limited by the enclosure volume, and stuffing it will make it seem larger (20%-30% larger using the 1 lbs/1 ft^3 heuristic below), but you have to design the port tuning length to take into account the additional volume created by the stuffing.

    Also, a good starting point (for sealed boxes), is to stuff the box with stuffing by a ratio of 1 pound of stuff per cubic foot of enclosure volume. Then, you can either salt to taste by adding or subtracting the amount of stuffing for the sound quality you want.

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