I just drew up a box for an 18 SX because my brother really wants one....well he wants something loud and this is what I reccomended. Either way though, I'm using 4.71 ft^3 after all displacements (driver, port, port walls), tuned to 37Hz with 81in^2 of port area.
Does anyone see any problems with this? Is 4.7 cubes too little or will it work out okay? Thanks for any help.
EDIT: I'm well aware of the 18" basket situation, he's willing to wait though so that's not a problem.
EDIT #2: Here's a quick sketch in paint of what I'm doing, can someone check it out or double check my calculations.