I want to build my on center channel speaker using a planar tweeter. Then I want to build some main speakers using a Heil air motion transformer out of an old pair of ESS Monitors, I really like the presence of the AMT but it is a little light on the midrange and the bass is muddy. I solved the bas problem with a good subwoofer so I was thinking of designing a dual 6.5 in speaker that would cover from 60 hz to 2000 hz in a 2 way system. the current crossover is at 400 hz and the speaker has a 10 in woofer with a pasive radiator in a sealed enclosure. Any recomendations on books to start my trek?