alright im designing a box for a Fi BL 15" and its 3.75 cubes and i want to tune it to 35Hz and i want to use 4" flared aero ports and i dont know how many to use for maximum port area or how long they need to be
each 4 inch port is appx.12sq in of port area. using the DD port area formula,16 inches of port per cuft youd need 5-4in aeros 16 in long each to tune to 40hz.then about an inch longer per hz lower,ex 36hz would be 20 in long per tube.hope this is right and hope it helps,its worked for me.4 cubes would need 64 in of port.
