Room Treatment for Corners - Recommendations?

Outlier - nice name! You into statistical analysis by chance? I digress . . .

You mention ceiling corners and there's lots of fiberglass-type absorption products you can use, just be sure to leave a healthy (6"+) air space between the wall surface and rear of the absorber so that it works across a broad freq spectrum and doesn't act as a low pass filter which would throw off the timbral balance of the reflections and reflections of those reflections.

Have you considered a hemi-cylindrical diffuser (often called polyfusers or polys for short) for the floor-to-ceiling corner? They're made from Sonotubes used at construction sites for concrete pouring. If you use a 180degree arc then it'll diffuse in about 120 degree pattern and you can stuff the interior with OC701 or 703 fiberglass to act as a bass trap. The curved surface facing into the room should be hard enough to prevent absorption of mid and high frequencies. Use a radius with a minimum of 12" (24" diameter) and finish it off with some kind of Guilford or Maine cloth or what I did with stained wooden veneer:

http://i1126.photobucket.com/albums/l620/kevinzoe/Frontwallhemi-1.jpg

Match the wooden veneer to your speaker's or fireplace bricks or wall colour etc etc. Just a thought and hope it works for you.

Thanks again guys for the tips on the treatments.

Tholt, those Cathedral treatments look intersting and are the right price. I'm curious that they do not align with the three corners in the corner like most corner treatments, but are positioned flat to the side and front walls...

Kevinzoe, I don't think I can attemtp those radical setups ;-) I use a front CRT projector to the front wall too, so I can't accomodate any of those hemispherical acoustic treatments between the speakers.

I do use Shakti Halographs behind the speakers currently, which may provide some value along the lines of what the plant approach provides.

I'll experiment a bit. thanks again.

Kevinzoe, to answer your question on Outlier; it was my section name in business school. Irongically, statistics is one of the few subjects I failed in undergrad - I'm practically scared of stats ;-0 I do like the meaning of the term Outlier though.

I have had a very good experience with GIK Tri-traps in my room and they are quite cost effective to boot.

Yes, what kiwi said.
Also GIK worked with a sketch of my room and helped me figure out what I needed.