I have been thinking about a dedicated theatre for about 15 years and I am finally ready to get started. My home was built in 1948 and space is limited. The portion of the basement I have in mind is about 21 feet long and 12 feet wide. The back 4 feet or so would be taken up with a hallway, to access the back door and the rest of the basement, as well as an equipment room where I would project from. Ceiling height is 7'3" from concrete floor to the bottom of the joists. I am working on a diagram...