how to figure out how much port area a subwoofer needs?

[Jessica]

Hmm, well all i ever hear is 12-14sqin per cuft. But i think it is more important to know the xmax of the sub and then base port area off that.

Let's just assume you want to get the most of these subs and not have a pure spl box. So design the box so that after port displacement you have close to the middle of what the manufacture recommends for volume. As far as port area, i don't know because it all depends on so many variables. What kind of port, i.e, slot (1, 2 or 3 common wall, aero port, pvc tubes) so on and so on. let's assume you have unlimited time and resources and can build 73 different enclosures and have the time to test them in a variety of different configurations. Like 3 to 1 ratio, 2 to 1 ratio. port up port back, sealed off from trunk assuming you ave a trunk, so on and so on and so on.

ok, i'm done here. So, in short. i don''t know and it's unlikely anyone else here does because if you are going to build a 4th order you may be barking up the wrong tree. Because Port area is more than a rule of thumb.

Easiest answer here, and you might not like this, but just build a sealed enclosure per manufactures specs. Then add various ported sides to it with external interchangeable ports and test the ever lovin shiznit out of it.

Of course you would need a term-lab to actually see differences and of course things like ambient air temperature, barometric pressure, voltage at the time of testing, and 1000 other variables could skew your results by like .5db's so you might start second guessing yourself at one point.