Dave, your 2" line driver idea has peaked my interest in starting a new project. I already have the Vance D Titanic sub, but wonder if a 6-8" woofer could be easily be added to the bottom of the speaker to the to fill out the lower end a little (see awful diagram below.)
Also, is there any reason why I couldn't make a smaller center channel to match with 16 drivers?
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1----\ 6-8" driver, angled up here or possibly side mounted?