View Full Version : box help

06-04-2009, 12:49 PM
i need a little box help. i'm having a hard time calculating the internal volume of my box. i'm thinking it's too small for my 2 12 kicker cvx subs. the top depth is 13 5/16, bottom depth is 17 3/8, height is 16, and the width is 32 3/8. of course all measurements are in inches. the box is constructed of 3/4 inch mdf. the port is a cylindrical port, 7 inches in diameter and about 16 inches deep. the material the port is made of can't be more than 1/8 inch thick. supposedly the box is tuned to 38 hz. any help here on internal volume and tuning frequency? i'm having a hard time with the online calculators because of the cylindrical port and the size of the port.

06-04-2009, 01:20 PM
3.58662 ish before displacements http://www.the12volt.com/caraudio/boxcalcs.asp

try here very helpfull to newbies

06-04-2009, 01:22 PM
port displacement should be about .35634 ft3

06-04-2009, 01:37 PM
so do you add or subtract the port displacement. box designing is a little over my head.

06-04-2009, 04:04 PM
subtract all displacements (sub, port , braces etc...) that 's what displacement means
when you take up air space in side the enclosure it's called displacement

06-04-2009, 04:29 PM
so most 12 inch subs have an average displacement of about .07 cubic feet. is that correct? i read that on bcae1.com. supposedly it's a close approximation for most subs.

06-04-2009, 04:30 PM
what subs r u runnin'???

06-04-2009, 04:35 PM
2 12 inch kicker cvx

06-04-2009, 04:39 PM
the thing is in the manual for the subs, the minimum ported box size is 1.75 cubes per sub. at that size they'll only handle 300 RMS. i think my box is smaller than that. basically, i had the 05 cvr's in the kicker box and i purchased 2 cvx's to take the cvr's out. i'm using the kicker box. the cvr's say the same for minimum size, but the power rating doesn't change from the smallest size to the largest recommended size. with the cvx's, it changes from 300 each to 700 each, smallest to largest recommended size, respectively. i'm only using an alpine mrd-m605 for the subs (dual 2 ohm wired for a 2 ohm load) so i'm giving them 638 watts rms, according to the birthsheet that came with my amp. i'm afraid i'm going to mess them up if i keep playing them with that kind of power going into them in that small of an enclosure. also, my subsonic filter is set to 15 hz 24 db/oct slope. the subs are rated with a 25 hz subsonic filter with a 24 db/oct slope. i've only got 15, 30 or off. with it at 30, i'm missing out on a lot of low stuff.

06-04-2009, 04:50 PM
so what max size ported for the cvx'z

06-04-2009, 04:53 PM
dude heres one i drew for a caprice its aprox 4 ft3 tuned to about 38hz ported up through the rear deckhttp://i668.photobucket.com/albums/vv50/DAPPA5/ltd.jpgignore all that other crap @ bottom i was just showing the kid where his amps and cap could go

06-04-2009, 05:04 PM
that's a pretty neat design. only thing is, i'd really like to keep my spare tire and not port it through the rear deck. i don't want to cut a hole in the rear deck. i could probably do with a box with close to the same dimensions as mine, just wider to add some more cubes. the max for the cvx's is 2.25 cubes per sub. here's a link to the manual
i've got a hu for sale, maybe i'll see if someone local can build me a box for the hu...

06-04-2009, 05:10 PM
what hu?

06-04-2009, 05:13 PM
alpine 9853