Whether or not to absorb or diffuse first reflections is a matter of the time of arrival. In my case, my speakers are fairly close the the left and right walls. Impulse response measurements show that the reflections from the side walls are delayed by only 2ms, which is short enough and loud enough to cause the haas effect to break down. Without absorption, stereo imaging is smeared and incoherent, with absorption it sounds so much better. Contrary to popular belief, toole has never stated that early reflections are always ideal and should be left untreated. It really depends on the room and purpose of the setup. If the direct sound is significantly louder than the reflected sound, and the reflected sound is sufficiently delayed, absorption may not be needed.
I currently use Auralex 2” wedgies for HF reflection absorption. They’re effective down to about 500hz, and they actually work better than something like 2” rigid fiberglass. A steep angle of incidence, as is often seen with side wall/ceiling reflections is a problem with flat absorbers in small rooms. The multiple angles of the wedge design of the Auralex solves this problem. For problems below 500hz, I just use eq. Bass traps can certainly help, but the size required or distance from the wall must be 1/4 wavelength of the lowest frequency one is trying to absorb. Even at 50hz, this is about 5 feet. Multiple, carefully placed subs and eq is more practical.
