4th order bandpass build

[pyrospent]

I am trying to build a 4th order bandpass for a freind in his audi a4 he has two sundown nightshade v.2 15" and thanks to somone earlier in this forum I found out I need 2 cu ft per driver on the sealed side but need 8 cu ft on the ported side but no matter how i try to figure it I can only get 4.8 cu ft on the ported side I can get the port to tune to 35 hz for that size box but is it going to be a problem since I cant get it to 8 cu ft like the driver calls for on a vented enclosure what can happen? I only have 37.5" wide by 33" deep by 16" high was looking to iso mount subs toward front with the sealed section across the rear and the ported section across the front.port on the front on one side. Any help or advice is greatly appreaciated.

[Triticum Agricolam]

35 Hz is way too low for a bandpass box, you won't have any mid bass.

How did you come up with 2 cu ft sealed and 8 cu ft ported?

Assuming 3/4" material you only have 9.5 cu ft gross. That's going to be a tough fit.

[pyrospent]

It was on the sundown site under discontinued woofers

http://sundownaudio.com/index.php/products/discontinued/item/nsv2-series

sorry i ment 4 cu ft on the sealed side 2 per driver and 8 on vented side 4 per driver, yeah thats what im worried about only 4.8 cu ft on the vented side is tighter than i wanted but since the subs play into the sealed side im not sure how much the small vented side is going to affect performance or if they will even play right. we modified the rear seat frame to make room.

[pyrospent]

I can tune it around 45 hz with no problem its actually easier forme to go higher