Hey guys i have a bmw 530i 2002 with 2 lanzar opti 1232s and a old kicker 750.1. Yes i know not the ideal setup, but its what i have and im just tinkering with it. I made a box recently with two 4 inch round ports and 1.8 cubic feet per subs(also one 4 inch port per sub with subs in separate chambers) and the box sounds very good and extremely responsive to any music. Got a lot of complements at a recent event, but on the term lab sealed legal it got around 138 dbs. I blame my lack of port space that may have boosted responsiveness, but let me jump to the point. I have some extra wood and want to see what one of these twelves at 4 ohms would do on the 750.1. I want to use more air space to maximize the power Im guessing around 2.5 cubic feet. Any ideas on tuning if i plan to use two 4 inch round ports for the 1 12" sub at 2.5 cubic feet? And with the previously noted dual 12 box tuned to 40hz the termlab showed a peak at 41hz. I used win isd to tune...who knows...thanks for any information.
for anyone familiar with these cars there is a steel wall behind the seat.. i trimmed out the armrest portion and directed my ports through this hole.