I completed these about two months ago as bi amplified speakers with a DEQX digital crossover, but I finally got around to building passive crossovers so they can be driven by a far more simple arrangement of a source and a two channel stereo amp. I prefer the sound of the passive version. Each tower includes twelve 7" Dayton Esoteric midwoofers and nine BG Neo8 PDR tweeters. The crossover is 2nd order for the woofers and 3rd order for the tweeter array. The dimensions are 18"W, 8'H, 1.5"D. A Dayton Audio 12" Ultimax sub in a 2' sealed enclosure, driven by the Dayton 500W plate amp handles the bass from 100hz down. Sensitivity is in the 93+dB range, and they are easily driven to levels of awesomeness by a 200w/ch Krell integrated amp. For perspective on the size, that area behind them is 8' high. The room is 22' wide by 38' deep, with a 12' ceiling.