Ok I recently got a Orion hcca 12 for cheap. I had a sealed 15" box for a tc sounds 3hp. The tc blew off my amp (massive p3000.1 coils when I got it were burnt badly so the amp finished it off) anyways the box is going to be 3.35 cubes after displacements. I built a 8" areo port out of concrete former tube and bondo. Its going to be tuned at 42hz. Sub is going to be running at 1 ohm on the p3000.1 ( hoping the amp will take it) is the 8" areo to big for it. The box is built out of scrap wood so it kind of looks,ugly but its completely sealed. Hoping for good numbers out of a spare box I had!