I know most would recommend a longer throw driver for HT but I cant help but wonder what an 18 from B&C like the 18TBX100 would be like if tuned for mid to high 20's. Basically a clone of designs from Pro Audio Technology etc. or QSC cinema subs. The goal being 20hz and up efficiency vs 20hz below infrasonics. Not trying to debate which is better. What ported or sealed sub box would work best for a driver like the 18tbx100 ? The big 21 inchers would be "neat" but out of budget. The interview on home theatre geeks with Paul Hales was interesting mentioning the design goals of his subs (low vs ultra low) again Im not trying to start debate, just would like to get some design ideas.