- (2) DD 9512d 4/4 subs
- Each gets 3.5 cu.ft., for 7.0 cu.ft. internal volume
- MTX 81000D run @ 2 Ohms (about 1300W each) on each sub
- Ports tuned to 40Hz
- Total port area = 87.75 sq.in., or 12.5" per cu.ft. of box
- (2) ports: Each 6.5" x 6.25" long and each 14.50" long
- Using 3/4" MDF divider (MANY people said it yields better SQ)

So now I have my final questions, if you could please help:

1) So for internal displacements, I have:

> The .36 cu.ft. for the 2 subs

> I need to add 1.5" per dimension for MDF thickness

> Add .75" to the Ext. Width for thickness of chamber divider

> Other things which I can't figure out.

2) How much port area do I subtract?

3) For the MDF divider displacement, it's just (.75" x Int. Depth x Int. Height), correct?

4) Subtract the MDF of the ports (.75" x Port Length x Port Height). So this is (.75" x 6.5" x 6.25") I think.

5) Anything else I need to subtract, and what are the final internal and external dimensions, allowing room for bracing (how much room do I need)?

Take the internal box dimensions. Outside dimmensions - 2*3/4" in each direction. (length - 1.5) * (depth - 1.5) * (width - 1.5) = box volume

then just substract the divider, drivers, ports(wood thickness and port volume) and bracing.