I'm pondering building my own sub for H/T use. I have built many simple, sealed sub enclosures in high school for many of my car audio friends so I have some experience but not nearly as much as most of you here. I am thinking as small a diameter as possible for the shiva driver(I'm pretty positive on the driver since everyone here recommends it). I don't know much about sonotube at all. What sizes does it come in? How thick are the walls? How do you connect those end caps to get a good seal? Where do you get sonotube? I don't mind the height of the sub(my entertainment center is over 5' high), I just want the footprint to be as small as possible, maybe 14" if that will work. Also, I was thinking, would it be the same to build a rectangular enclosure that stood upright with a down-firing sub just like a sonosub but use MDF and make it square instead of circular? I would think this would be easier but may not look as nice, even with a good finish. My objectives: To build a solid sub tuned to 20hz, To have a small footprint, To have it look nice, I pretty much want an SVS 20-39cs. Any help and other opinions on what I should do would be helpfull. Thanks!