building a ported box

i have two punch 12 svc's and they need 21 cubi inches of air space. how do you go about finding the deminsions of a ported box and also the size of the port.

thanks

subs usually quote cubic foot requirements, not cubic inches.  cubic feet is measured simply as (in inches) width x length x height, all divided by 1728.  Don't forget to take off the thickness of material for each panel.  So, if you were to build a box out of 0.5" mdf, and make it 12x12x12, it will NOT be 1 cubic foot. 

11.5 x 11.5 x 11.5 = 1520.87 divided by 1728 = just over 0.88 cubic feet.  so don't be fooled!!

ported boxes also require very specific port length/diameter/surface area to be tuned properly.  look up the recommended box size and port dimensions for your sub from rockfords website, and build it to match that....

b

Dude, check your math, you must have a whole pile of resin odours in your store! Your basic calculation shows .25" mdf to give you that total of 1520.87. A small slip up but nonetheless we don't want to send him on the wrong path. While we know what the mistake is, he may not, so no offence Hamilton but here goes.

based on 1/2" mdf  and a box size of 12x12x12  = 11x11x11 (internal volume) = 1331 or .77 cu.ft.

The poster should read bbermans comment so we can point him in the right direction, or if he wants to learn, someone can teach him box calculations

I SEEN A WEBSITE ON ABOUT BOX CALCULATIONS, BUT I CAN'T SEEM TO FIND IT. DOES ANYONE KNOW THE NAME OF THE SITE

THANKS

thats whut happens when you do 3 things at once....my bad for sure.  You're correct....take thickness of material off BOTH sides of each panel, and the rest of your math is correct.  appreciate that being pointed out.  now if we could just get him to lay off the caps (YELLING!) we might be able to show him something  :)

b