Yes a BFM design table tuba. It is only good to 30hz I am pretty sure. http://billfitzmaurice.net/
I am also on the fence if I want to build 4 of these so I can smoothe out any room modes I may have. http://www.avsforum.com/avs-vb/showthread.php?t=1238398
I hope its ok to link other project sites in here. It isn't that I don't think the Pi subs are a good choice but just isn't what I am looking for build wise. I like something more different.