practical simple design tips
while i have never built an HT room, as a pro sound & recording engineer i have constructed 3 recording studios and the same rules apply.
*if this is your basement you're limited but, you can't beat height...10' clearance is ideal.
*18' is the minimum distance to properly reproduce 60Hz. this does not mean you cannot hear 30Hz, but you want to reproduce a full 60Hz unimpeded wave length, as opposed to harmonics and reflextions of the fundamental. for this reason there is no such thing as a professional recording studio shallower than 18'.
*the greatest improvement you can make to speakers, expecially JBL's is to flush mount them into the wall, approximately 1" proud of the surface. the boxes dissappear and the room becomes your speaker.
*you can have a symetrical room (almost all studios are) but they incorporate a "reflextion free Zone" in their design archeticture. meaning, all surfaces are gradually sloped with 90 degree corners taken out, or rather sloped out. for example the front wall gradually opens up, similar to a baseball diamond but with at least 2 pairs of slanted angles. this includes the ceiling, very important and while extra work, it is not hard to do.
*it is absolutely imparitive that your opposing rear wall be solid (not just dry wall) or the your stereo image will not be equal as phase shifting results...i found this out the hard way. really only concrete can fix this...
*in a recording studio the rear wall usually has a baffel design to create an "infinite" space simulation, cancel nodes and in some cases act as a bass trap.
*finally, your acoustic ideal is neutral, not sound dead. one simple and esthetically pleasing way to do this is to make several (10-12) rectangular 2" thick baffels incorporating a nice wood frame some insulation and a nice cloth material cover. put a grooved strip of wood along your walls and hang these baffels at different intervals and heights. THIS WILL ALLOW YOU TO TAILOR AND FINE TUNE YOUR ACOUSTICS TO AN IDEAL AND YOU WILL BE AMAZED AND LEARN A LOT ABOUT ACOUSTICS. if you do this you need only paint your drywall as the combination of reflective and absorbative surfaces create your room acoustics and if done right it can also look great. (there is a picture of this...sorry lousy pic...on my website under the heading ADR/foley.
Akira, Soundchaser Pro Audio http://soundchaser.ca