View Full Version : NEED HELP with custom box for BMW

02-04-2009, 06:00 PM
okay heres there situation:

i am building a 3 chamber bandpass box and have it ported into the cabin in my 97 bmw m3. i have 2 oz audio 12 Matrix Elite's powered by a hifonics1606d.
the dimensions are 31in wide, 15in tall and 18in deep. volume is 3.80ft3. these subs require 1.0 sealed and 1.5 ported so i left a good amount of space to work with.

where im stuck is how to seperate the chambers. i was told to have the sealed side smaller than the vented side but how much? my graph shows the the bigger the sealed side the lower the frequncy i can get when tuning.

second is which port should i use square or oval. my ski pass is 9in wide and 12.5in tall. i think its too big to use the whole port so i was thinking maybe something like 9in wide and 8in tall and closed off the extra space or what do you guys recommend?

Is there advantages/disadvantages or have such a HUGE port?
im trying to tune it as low as possible. 30's to 70's.

sorry i have no pics. i only have the outer sides cut anyways. but ill try to get some. the subs are facing the middle chamber.

note: i know ported is better but i had one built to specs and it sounded nice and all but bmw trunks and so sealed that i lost alot of sound. i stuck the subs into my friends lexus is300 with same amp and box and WOW huge difference. they pounded like no other. plus im tired with all the rattle from the trunk and im fully dynamated.

any info or advice would be helpful. thanks in advance!

02-05-2009, 04:26 PM
dang no help huh? thanks for nothing