Okay - Have been _trying_ to work my way through The Book From Hell. Someone please tell me if I have this right or explain it in plain English, and tell me if it's a good idea or not... Okay - Let's say that I've got a pair of woofs... I stick both of 'em in a box that's vented, fire 'em both in-phase, and I get a decrease in distortion and a bit of added SPL? Then I take that same pair of speaks, set 'em up pointing away from each other (like in a tube), fire one of 'em out of phase, so that they're both essentially moving in the same direction. I get the lowered distortion, but not the added SPL? And I can make the sealed box 1/2 the size that I otherwise would have to, with the tradeoff that the f3 won't be dropping significantly? Have been sorta thinking on a "cheap sub project" and I suspect that another $30-40 for a driver might be better than making a larger enclosure, especially for just music.