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View Full Version : is my box design equation right? 3qf for 2 15l7?



SQ is the SQUAD
08-25-2005, 08:30 PM
car: 2001 chevy impala (big trunk)
subs: 2 kicker 15l7
amp: kicker 1200/1

i am trying to make my own box and i want to make sure i got everything correct before i start cutting my materals
i measures my trunk space as H=17.5" w=37" d=14" so i figured to make my box with everything 1 ince smaller (will assembel in trunk)

these are the measurement i am planning on using
h=16" w=36" d=12"

using this equaiton is my cubic feet correct?

(h-2*.75)*(w-2*.75)*(d-2*.75)/1728

(14.5)*(34.5)*(10.5)= 52526.25/172 = 3.039

does this make my box a 3 cubic ft box?


my next big question is this is going to be a ported sql box, am i supposed to be using seperate chambers or one open chamber? most likely the speakers will be wired in together through one output so i would guess just one chamber.

i really dident understand the info i found for calculating the port size so i am gonna need some help with that. dont know much about ports so i am open to any ideas

fo0manchu
08-25-2005, 08:41 PM
i got the same numbers for volume. good luck

SQ is the SQUAD
08-25-2005, 08:52 PM
just a lil more info

i picked up to big sheets (about 4x10) sheets of 3/4 MDF, i got a big bottle of gorilla glue (already had it) i also hot somt little square wood pegs in 3ft lenghts to use as supports for insode my box. i am not sure if i am going to need the peg supports but i brought them anyways. the screws that i got where 8*2, i couldent find any 8*1 3/4, i shouldent run into any problems should i? i also stopped by autozone to pick up a fibreglass repait kit. i work at circuit city and a kid who works in the 12volt told me to fiderglass that inside seems to make them stronger. is this a good idea? i never heard of anyone else doing this. i am still searching the forum ti find alont of my answerrs, just trying to get a lil help on the way

SQ is the SQUAD
08-25-2005, 08:52 PM
Your calculations are correct, but it's readily apparent that you have absolutely no idea what you're doing ...


y dont you tell me what i am doing wrong insted of just leaving me in the air

SQ is the SQUAD
08-25-2005, 09:07 PM
ok thanks,
so the only way to really get more displacement is to add more depth i can come out more if needed but i can add any more to the with or hight. let me try to recalclate with more depth, how many cubes should i be aming for?

SQ is the SQUAD
08-25-2005, 10:02 PM
here are my new calculations after a million searches

h=16"
w=36"
d=20"
3/4 mdf
2 4" ports @9" long

5.36 CF before
4.65 CF after
port tuning hertz = 33
port area in square inches = 25.13

am i getting closser

still trying to find the suggested Cf for a ported 2 15l7 enclosure

SQ is the SQUAD
08-25-2005, 10:13 PM
i might just splurge the $10 to have you design the box, eventhout i am almost there. i am just not sure how about making the slotted port. anyways let me looking into it a lil more and ill get back to you.

thanks alot for all the help, its really appreciated

jiggy2dmax
08-25-2005, 10:52 PM
I would say two of those subs need around 7 cu ft intotal to get the best preformance out of them. I experimented alot with my L7's before I decided on a box. I hated how they sounded in a small enclosure.

SQ is the SQUAD
08-25-2005, 11:01 PM
and what is everyone opininon on filling the box with the cotton ploy stuff