Hi, i recently called a sub manufacturer and asked them to help me out with a box design for one of their subs, all was fine untill the tech guy told me to make my port 17" long with an opnening of 17 square inches! At first i did question it, but then when i hung up the phone, i was puzzeled on how big to actoally make the opening of my port!!! Can you guys help me figure this out please, i suck at math!
My box size is 13" high, 19"wide and 19" deep. These are outside dimentions and the 12" woofer is going on the 13" by 19" and i would like to put the port there firing with the sub, thanks in advance.

 

#1 There is no way your going to fit a 12" sub with an external height of 13"
#2 The given dimensions leave you with ~2 cube feet BEFORE any sub or port displacement.
#3 When the tech people told you 17 sq in of port, what they meaning is the total amount of port area inside your enclosure. The given rule is that per cubic foot you should have roughly 12-15 sq in of port area

In turn, your going to have to give up some more space. Are you looking to build a slot port enclosure, or one with an aeroport(s)?

 

slot port, it leaves me with 2.1 cubic feet, and yes a 12" sub will fit! But overall, what's the formula to figuring out what i need to know???

 

You need 17sqin of surface area. Vent opening can be:

17 x 1 = 17 (don't use this one)
8.5 x 2 = 17
5.67 x 3 = 17
4.25 x 4 = 17
4.123 x 4.123 = 17

The depth of the vent does not change as long as the area remains constant.

Oh, and the volume of the enclosure has nothing to do with the area of the vent...