OK.. let me admit up front that I have no idea what i'm doing. I got a copy of LspCAD to act as a bit of a crutch since I'm not exactly satisfied with the existing plans out there. That said, here is the subwoofer configuration I am kicking around, presented to you all for ridicule.. This is using the Dayton 15DVC, since apparently the Tempest that I was going to use is out of stock (?). The box is 300 liters (~10.5 ft3), port diameter 6" and length 22". Ql is assumed at 7. According to the model the port airspeed hits a little over 2 m/s at the resonant frequency. I'm going to put that PartsExpress plate amp that was on special (the 250W one at 4ohms with the nifty remote) and cross it over at 80hz. Now, what I wanted out of this design was the impossible... I want my brains to leak out of my skull when there's an explosion in a movie, but to have the sub still have enough class to not embarass itself in the occasional music session. My concerns are for the group delay, while this appears to behave itself by staying under 20ms until 20hz, it does peak. Is this a problem? Will there be an issue with the impedence profile? It also shows a bass shelf response, which is -3db at 30hz until 17hz (from 80hz), I don't know if that's a problem. Also, how would I calcuate the Q for this box? I'm looking for advice to learn from, so please feel free to comment.