The subs are 15" Dayton Quatro's, and a Rythmic 350watt plate amp. I am impressed with the combo. Link Removed Sorry for the "Pop Ups"!Wes great HT setup.
Paul, did you still want people's DIY on your site? I just recently did a Sonotube which I'm very happy with ( Link Here but you mentioned that you want something different and Sonotubes are pretty well documented.
PS: Fantastic site you have done there!