Can a sonosub be made that is 16 or 17 inches in diameter? Does the tubing come in that diamter? The reason I ask is that I would like a sub to fit in the right front corner of my room, and I only have 17.5 inches of clearance between the right wall and the front speaker stage. I've looked online at some of the wonderful DIY sub jobs, and everybody seems to be using tubes that are 20 or 24 inches in diameter. Is it even possible or desirable to build a sub that'll fit this space. If not, I'll have to consider other placement options. Thanks!