Originally Posted by SuprSonik
Hi everyone, I am just about finished painting my theatre room and am ready to do some acoustic treatment. I needed a few things cleared up though...
When finding the first reflection points using a mirror, am I supposed to do this for just the Front R/L speakers, or the center/rears as well?
No. Only the front speakers need to have their early reflections absorbed. This is to keep the front sound-stage tight and accurate. Reflection is good
for the surround speakers.
I read that only the point up to where your ears are should be covered as well, does this mean I shouldn't put any rigid fiberglass above ear level or on the ceiling?
Not necessarily. It depends on how much absorption your room needs. As for the ceiling, sometimes there are early reflections which need to be absorbed there. This depends on the directivity pattern of your speakers, as well as how they are place.
I'm not totally sure why the entire front wall needs to be covered too. It seems like no sound would be bouncing off that area. But if it's recommended, I'll do it.
It may not be absolutely necessary. If you know beforehand that your front speakers do not significantly radiate at medium to high frequencies toward the screen wall (considering toe-in!), you don't need it. It is always a good safety measure, however. In commercial cinemas, where the speakers are located behind a perforated screen, front wall absorption is used largely to kill reflections from the screen back towards the front wall.
Absorption on the front wall also follows the live-end dead-end model (room is live in back, dead in front), which works well for home theater surround sound. The front wall is also generally a convenient, available area for absorption.
However, what about the area with the screen? Should I put the fiberglass up all over the wall first, then put the screen up? Or put the fiberglass around the screen (making the screen appear as though it's impressed into the wall?)
If you are using an ordinary non-perforated screen, you don't need fiberglass behind it.
I'm planning on using 2" thick stuff, and I want to space it out from the wall a bit. What would be the best material to mount between the fiberglass and drywall? Wood?
You could space it out with furring strips. Spacing the absorption from the wall enhances low frequency performance.