ok heres some dimensions i drew up for a box im going to build for a friend of mine for one L7 15"
Using 3/4 MDF
Internal dimensions
L- 21"
W- 20"
H- 21"
Outer dimensions
L- 22.5"
W- 21.5"
H- 22.5"
Port
L- 14"
W- 3"
H- 12"
with my calculations it seems to be 4.6525 cubic feet after port and sub disp. tuned around 32 hz
this sound right to yal? thanks