4th order bandpass build for 1st gen double cab

So yesterday I started putting together a box for my truck, and i decided to design my own 4th order bandpass box since i didn't want to put a tiny little sealed box behind the back seat, as every 1st gen DC owner knows how much room we have back there. I have a Skar MA-8 and a Skar 5 channel amp on order and it should be here within a week. But here's a pic of the box so far:


The sub will be mounted to the middle wall, with the cone side in the sealed part, and the magnet side in the ported part. It should be tuned to around 30hz, and it should be able to get pretty damn loud based on what i've been seeing with this setup in even simple ported boxes. So we'll see. Stay tuned boys

 

4th orders aren't tuned like ported boxes. That design will hurt your performance drastically. Unless you modeled that actual design with software, paper math will only get you a fraction of the way there. 4th orders have the ported side tuned high because the sealed side picks up the low end. When you play frequencies below the ported side tuning most of the output comes from the sub itself in the sealed enclosure. The ported side is, most times, tuned to take advantage of your cabin gain. Alot of 4ths have the ported side tuned above 40hz. Alot of people live and die on the "ratio" aspect but response modeling is what I prefer to go by.

TLDR: tune your ported side higher with as much port area and as short a port you can get to allow the sub to "act" like a sealed sub on the lower frequencies (32hz and below roughly).