In my setup, the closer the TV is to the wall, the louder the noise is.
Overall, I got lucky as my buzzing/fan exhaust noise level is pretty low and almost non-existent. If my 150FD was as loud as many have posted, I would return it for another set, and return it for a refund if the second set sounded the same.
My personal opinion is altitude and mounting location play a great part in this problem. I would like to know how many of you at or near sea-level have a large buzzing problem.
The above may have been posted by others... I just thought I'd add to the pot.
Oh yes, I have owned five TV sets over the last 15 years: the 40" Mitsubishi CRT, a 32" Proton, a 20" NEC, a 50" Pioneer FHD-1 and the 60" Pioneer 150FD. EACH buzzed, even when it was new (especially during very bright scenes).
On a separate note, I am getting a lot of the "power-off / flashing blue light" errors. What is the latest on this problem?
Lastly, I still believe the FHD-1 has an awesome picture which was easily attainable without professional calibration. Although the blacks are not as dark as the 150FD, it is still a great plasma capable of dialing in a great (non-calibrated) picture. I was floored by its out-of-the-box picture, and slightly (not hugely as originally typed) disappointed with the 150FD out-of-the-box picture.
Of course, I know each TV is different, the 50" should have a slightly sharper picture because of the smaller screen and dot-pitch size, and that calibration will make the 150FD shine even brighter (as well as other facts, issues and points I'm sure a lot of you will point out but I don't have the time to type right now), but this is just my opinion, having viewed both plasmas side-by-side on the same feed.
I am now content with the picture I have utilizing a combination of D-Nice and Ken Ross' settings, but I spent a lot of time to get to this level.
In a nutshell, I was able to get a spectacular picture on the FHD-1 quickly by utilizing D-Nice's settings and I will need to get the 150FD professionally calibrated to achieve the same picture/feeling of greatness.
Just my opinion.