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    I'm new to all of this but want to learn so bear with me. I'm going to build a fiberglass box. Half MDF(bottom) and fiberglass(top). I bought a Alpine SWR-1222D Sub and want to mount it with the magnet fasing out. It say's that the recommendations for a sealed box(which I want) to be 0.071 -1.0 cubic feet and for reverse mount(magnet out) which I want. It say's added volume 0.085 cubic feet. What is ADDED VOLUME mean? My other question is it say's the external dimensions of the box should be 13"x13"x12.5". Does it have to be that dimension since i'm reversing the magnet? The box I want to build is (external dimensions of MDF) are bottom 18" wight 14" front side 7" back side 5" and the top will be fiberglass with the height being 13" from bottom of MDF to the top of the Fiberglass. Is this okay or do I need to make the box lenght shorter and if so what would you recommend?

  • #2
    Well from what I got on the sub calculater it is 0.95487 cubic feet will that work I'm using 3/4 MDF


    • #3
      Fill the box with poly fill (quilt batting). It'll make the box "look bigger" to the sub, and possibly give you a little boost in low end extension. (more bass lower frequencies)


      • #4
        The reference to "added volume" means the positive change in the box's volume when the sub is positioned with the magnet facing out. It accounts for the volume of air inside the sub itself.

        In other words, when you build your sub box with the magnet facing out, you will have 0.085 cubic feet more volume than you would with the magnet facing in.
        If just enough is really good, then too much ought to be perfect.

        2006 Scion xB with in-dash Atom & Lilliput 889GL -- Worklog at


        • #5
          so, you don't want to do a simple box?

          The box you had started there was probably your best bet.

          Here's some other links to help you on your way:

          This forum is dedicated to CarPCs and installing them in your car.

          For specific questions related to car audio equipment systems that do not include CarPCs, I would recomend checking out car audio specific forums:

          et. al.

          There is a chance that someone on here might have an answer for you, I would just hate for you to wait around for it when I know you could get an answer much quicker on a dedicated forum.
          2007 Chrysler PT Cruiser TE
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