I asked this question in a few other threads. Frankly, I'm a bit surprised no one on this site - particularly the home theater guru's to which there are a few - mentioned the following...

As I begin to do my "homework", I come to realize there is significant material on the Internet and elsewhere that can help guide one through proper placement.

Apparently, the use of a mirror to find the reflection point on the side walls and ceiling is the way to go.

As for bass corner traps, I understand it is preferable to place the corner trap at the ceiling as opposed to the floor. Ideally the trap runs ceiling to floor, but starting from the ceiling is better.

Beyond that, I found a mathematical formula. See attached image.

Comments, feedback, etc. welcome.

Hey, GDHAL

I've always used mirrors to locate first reflection points.. always open to better ways.

Rick

GDHAL,

Sorry, GDHAL, I missed where you asked how to find the primary reflection points. I used the mirror trick with some help from my Wife to find the best location for my acoustic treatments. The ceiling would probably be pretty tricky. With multiple treatments, I was able to provide treatments to the primary reflection points for multiple positions.

Cheers,

T Cobe

Yes to all, the mirror method is the tried and true standard.

No one has proven to me that bass traps perform better on the ceiling than on the floor, acoustic engineers I've spoken to shrug off that idea. (We use them on the floor in the corners in GoldenEar trade show systems when they are in hotel rooms.) These days, room correction/EQ and multiple subs seems to be the preferred method of controlling low frequency in-room issues.

Moderator wrote: ... No one has proven to me that bass traps perform better on the ceiling than on the floor, acoustic engineers I've spoken to shrug off that idea....

Okay then. Thank you for that feedback. In fact, coming from you (GET Moderator) I intend to heed that advice and place traps at both the ceiling and floor. I was just meaning to indicate that based on data available via the Internet, the pundits claim that given a choice between ceiling and floor, the ceiling is priority.

Thanks to all (no apology necessary T Cobe ) for confirming the use of a mirror.