I want to design a box. The dilemma..... - I want to tune it as low as I can (preferably around 20Hz but not higher) - I don't want the box to take up half the home theatre (5 cubic ft is the maximum, no sonotube for this project) - I need the ports to fit in this box without elbows Now I messed around with various port diameters. Question, does pvc tube come in 2.5" diameters? Is a vent mach of 0.13 acceptable or is it too close to the limits? If this is the case then I need to go with 2 wider ports of 3" and yielding port lengths of around 16.5" as opposed to two smaller ports 2.5" wide and only 12" long. In other words... - 2x2.5" ports @ 12" long with vent mach = 0.13 or - 2x3" ports @ 16.5" long with vent mach = 0.09 I need to work out these numbers then figure out my optimum box length, width, and height for this 12" driver.