How to build an car subwoofer box by it's given dimensions?

Question

I have all the dimensions for a vented box for my single 12'' alpine dvc 4ohm type r subwoofer. I understand the external dimensions and how to build the box itself, I just don't understand how to use the dimensions given for the vent to achieve 33-34 Hz tuned, and where the vent goes.

Vent area(dimensions) 15in^2 (12x1.25)

Vent length 22.75in

Vent displacement 0.305 Ft^3

Net internal volume 1.3Ft^3

F3,ripple,Fb 33Hz, 2.5dB, 36Hz

Answer 1

going by what they gave you, the internal box height looks like it would be 12". place the port on one side of the box (the same plane the sub is on) and put the sub on the other side(best to have them as far apart as possible). measuring 1.25" in from the side of the box, place another panel there, this will be your port wall. they say you need to have it 22.75" long to achieve 33Hz. more than likely your box will not be deep enough to place a straigt 22.75" long port in. in this case you will need to bend it and have it follow around the back side of the box. when measuring a port always remember to measure down the center of it.

lets say you box is only 14" deep. you port wall will need to be 14 - 1.25 = 12.75" long. but measuring down the center, you get 13.375" long. you need another piece that will be 8.75" long (this will make the other 9.375" you need) to go along the back side of the box. now, measuring down the center, you should get a total port length of 22.75".