not sure if there is a minimum size for the port on a sqare ported box. im building a square ported box for 4 12"s. i found a box calculator, but it was only for circular ports; however, i calculated the area of my square port (4"x13.5") and converted it to the diameter of a circle (8.96"). will this work? will the port be big/ small enough?
for round ports for a 12" sub, min is 4" ID no real minimum for slot vents, since they'll be larger by default. with a slot vent, you can wrap it around teh inside of the enclosure to accomodate the length required, so distanec from the opposing plane isn't an issue usually. I'd keep at least 4-6" between the end of the port and the facing inside panel.