Diffusors vs. absorbers room treatment


Hello experts,
I'm trying to toy with room treatments to see how it will improve my system. I just moved my system upstairs to a smaller room and I notice the sound is a little brighter than I would like. Can anyone tell me a basic or rule of thumb on where to use the diffusor and where to use te absorber? Or are they pretty much the same thing? I visited few website from like sonex, auralex, rpg etc. I am thinking about getting sonex classic since I thought they're pretty reasonably priced. Can anyone also recommend me some other that are not toooo expensive? My room is 14' wide by 13' deep. I place my sonus grand piano speakers about 2' from walls. Thanks in advance.
heeengky
Heeengky, Absorbers and diffusers are not the same thing. They are as there names imply. Typically, absorbers should be placed at first points of reflection. Side and back walls are the rule of thumb (even ceiling). Diffusers are usually behind the listening position and deflect the sound waves in various ways. However, I suggest absorbers behind the listening position if very close to the back wall. The idea is to cancel reflections and modes but not over-deaden the room. There's a ton of information available on how to figure placement with mirrors, lights, test cd's, electronics, mics, and your own trusty ears so I won't go into details here. Don't overlook the corners where bass modes accumilate and are potentially the most harmful to your sound. I'd even suggest you start there. ASC and Echo-Busters are very effective and attractive. You can find them here on the Agon occaisionally at good prices, but they are $$$ new. There are many ways to treat your room that are not exspensive. Do the research and learn how sound waves interact with your listening room before you spend any $$$. The education is worth it. Hope this helps and good luck, Dave
Look here for some good info and DIY recipes:

http://www.geocities.com/jonrisch/a.htm
I'm using a TacT RCS 2.0 in my 10' X 17' X 8' room with
excellent results, and minimal diffusion (three
Room Lens clones I built). The TacT allows precise
diagnosis and minimizing of the room nodes, particularly
bass nodes) which are the most harmful to sound quality.
It made a remarkable improvement in my less-than-ideal
sound room.
I agree with the above post as far as placement of absorbers. I've got wall treatments on the sides, rear wall and on the ceiling of my listening room. Many experts will say that diffusors should be placed in the rear of the room and are used to expand your room as they spread out the sound. You really have to experiment to see what suits your room the best. I am using Argent Room Lens clones and CD racks at the rear corners of my room to act as diffusors. Moving the room lenses as little as a couple of inches makes a difference in your soundstage. I've placed the room lenses at the mirror image points to the sides of my speakers and behind each left and right speaker. Both absorbers and lenses are DIY following John Risch's on-line instuctions. You can see pics of my room if you look at my "system".