This is a sectional view of a Decware Deathbox. It is a tunable 4th order bandpass for a 10" woofer. You can tune high for loudness at stupid frequencies. Or tune low for great sq.

kind of interesting isn't it

I have most of the decware designs now

Have you built any of these enclosures yet? I stared at the design for a while trying to figure out what is different from a traditional 4th order bandpass, it's down firing and the half moon vent is supposed to ease pressure on the cone, but other than that it seems like a regular 4th order bandpass with a nifty adjustable insert.