I was considering how I might make a powerful and interesting subwoofer out of a 12" long throw subwoofer I have kicking around. The idea of transmission line is intruiging, but generic. I thought perhaps a design in which a speaker was mounted in a transmission line enclosure that was designed such that instead of folding the horn vertically, it would be built concentrically around the driver. Then the end of the line would surround the speaker, and reinforce the forward wave directly around the driver itself. Has anybody tried this? If not, does any transmission line / horn guru have throughts on the viability of such a design?