Tony,
My VP150 is mounted on a shelf directly above my 65" Mits. It is 5.5' above the floor, 12' in front of the main listening area. I have the speaker angled down to compensate for it's relatively high placement. It is angled down so the tweeters are pointed at ear level.
After reading your post, I used my RS analog sound meter to make some measurements. Using my receiver's built-in white noise tones, with the sound meter pointed at the ceiling, I adjusted the volume of the receiver until the meter showed 75 dB (C-weighted, slow response) while I was in the middle of the listening area. I've got a 7' couch, and I moved the meter to the left and right edges of the couch while playing the white noise. The meter dropped 1 dB at the left and right edges. The drop-off was linear, in other words it seems to drop off steadily. I would estimate it reaches the 1 dB drop-off at approx 15 degrees off-center. I've got a chair that is quite a bit off-center (I would say it's about 45 degrees), about 10' away from the speaker. At this chair, there was a 3 dB drop-off.
I was curious to see if the angle of the speaker made any difference. So I placed the speaker flat on the shelf, so it was no longer angled down to the listening area. I noticed a 2 db drop-off in the center of the listening area and a 3 dB drop-off at the edges of the couch, so the net effect was the same as before.
HTH,
Jason
