need help with square port length
i am building a new truck box for my Diamond audio D3 sub and i really dont know how to calculate port length. my gross box volume is 2.3^3 after sub displacement. well i want to build a 3"x3" port but dont know how long it has to be to get the tuning around 37hz...if possible, i would like it to be down to 32 but then it might be too long.
box specs: 41x18x8(bottom)x6(top)
help would be much appreciated. and if u see anyflaws please dont hesitate to tell me.
and i did try recalculator but they dont do square ports
refs: tapout, justadork2u, plyer3, NisAznMonk, 1000101