# Thread: Need help with my sub box

1. ## Need help with my sub box

I'm going to build my sub box which isn't the problem. The problem is finding the right volume for my Alpine SWR 1222D (JUST ONE) which it say's should be 0.071 cubic feet front mount and for reverse mount( magnet out) 0.085 cubic feet which I'm debating. I used the sub calculators and only can calculate a wedge box which you can see in the blue. So I got that interior volume that is in my drawing. I want my box to look like it does in the drawing. What do I need to do? Never done this before so if it's a stupid question then sorry. Thanks for any info

2. ::

But 3/4" MDF. Cut it with a table saw. You're going to need miter cuts for the angles you need for a box of that shape.
Use a jigsaw to cut out the opening for the sub.
Use wood glue and screws to connect the panels you've cut.

3. It's not a stupid question. It's just algebra.

You've left a dimension out, and it can't be accurately calculated without that. In the revised drawing attached, what's the distance DE, which is marked with a question mark?

To calculate the volume (assuming your dimensions are the inside dimensions), find the area of rectangle ABDG, (AB x BD) and subtract the areas of triangles CDE (CD x DE / 2) and FGH (FG x GH / 2). Multiply the result by the interior width of the sub box, and you have the interior volume in cubic inches. Divide by 1728 to get cubic feet.

If we assume DE=7, the calculations runs like this: ((18 x 14) - (7 x 7 / 2) - (9 x 11 / 2)) x 14 / 1728 = volume, so (252 - 24.5 - 49.5) x 14 / 1728 = 1.44 cubic feet.

I moved the front view so it makes the drawing easier to understand.

4. Use a regular shape container of the same volume of the required volume of the box and fill it with polystyrene filler balls (the filler used in bean bags) then pour it into the sub, U may adjust by shifting the back piece H-A in rdholtz's diagram... Hope this helps.

5. Originally Posted by KOoLkOnDuCt
Use a regular shape container of the same volume of the required volume of the box and fill it with polystyrene filler balls (the filler used in bean bags) then pour it into the sub, U may adjust by shifting the back piece H-A in rdholtz's diagram... Hope this helps.

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