box size

OK, the magice number is supposed to be 1728.  When I use the link you gave, here is what I get...........

33x12.5x22=4.1 cubic feet 3/4" MDF

When I use the calculator, this is what I get, keep in mind I am subtracting 3/4" for the wood..

32.25x11.75x21.25=4.6 cubic feet

What am I doing wrong?  The numbers should be the same whatever method I use.

The 2 main reasons you will want separate chambers are 1) the subs create pressure inside the box which makes it flex. If the box is flexing then you have a loss of bass (applies mostly to a spl setup) by adding a divider it acts as a brace making your box more rigid. 2) In large enclosures you get stagnant waves which results in cancellation. If you divide your box up it creates smaller boxes thus minimizing if not eliminating cancellation.

don't forget to add in your chamber walls to your box size though.  They make the box smaller.  Cut the box into 4 seperate boxes when you are figuring out the space.

If 33" is as wide as you can, 3 10's might be all the room you have unless you want to do a fancy clam shell box (which is not easy for a first time box builder).

You had mentioned that you would put 2 on top and top 2 facing to the rear.  I (as well as others I'm sure) recommend against doing this in most cases.