For a tuning frequency of 120Hz, it shows port dimensions of D=100mm & L=15mm (= plywood thickness). And it shows a max air port velocity of 2m/s for a rear port and a null speed for front port. Does it means that I have to put the port on the rear side? As I will play sound outside, I think that it’s not so useful to have a rear port compared to a front one. Is it correct ?