I am trying to get a box together for my to fi q 12s & I am looking at about 5 cubes net (maybe too big for the subs possibly 5 cubes gross would be better?)  after port, sub, bracing displacement  tuned to about 32hz  powered by saz 3500v2.I am stuck on port area or it was just less than I expected I could put 2 6inch aeros in but the length is what gets me. I was using the torres box calculator 5.57 per cubic foot & that seemed kinda low to me since the specs say 12-16ft per cu ft I know thats a general rule of thumb for slot ports but still. I guess what I need is some help designing a box my max dimensions are 19" Height x 39" Length x 17" depth. This is going in the trunk of my 99 camry facing the rear. I was wanting to try aero ports but a good center slot port is not out of the question. I am trying to keep the depth down so MAX dimensions would be 19 inches Height x 40 inches  length x 25 inches depth. thank you for you input & help I posted on this forum because I always get helpful answers from people who know what they are doing & I learn a little something too which is nice cause I like to learn everything I can about CA plus I don't know it all. 

Edited October 27, 201311 yr by Mike1982

got it figured out

As far as I understand it, the only reason anyone would need more port area is to lessen the port velocity of their enclosure. As you already noted, there are general guidelines to follow, but these are very general. The misconception lies in the idea that there is a ratio between port velocity and box displacement that is universal; regardless of what goes into the box. The speakers used, power supplied, tuning of the box, and box dimensions all play a role. 

 

Modeling software like WinISD can give at least give you an idea of what type of numbers to expect. 

From what I've found searching on the web, you don't want to exceed 20m/s for port velocity. 

http://www.bitpusher.in/?p=portarea

 

you could do external ports if you need more internal volume. 

 

perhaps someone will chime in with a design for you.  but if you're doubting your ability to design it yourself  and no one has time, i would pay someone to design it. i think a few members do that sort of thing for a small fee. 

Edited October 28, 201311 yr by lithium

I was having a problem getting enough port area

But I have decided to have someone design & build it for me.