"Nice - thanks again John for another great post."
no problem. I made one correction (speakers in a field have no reflections off walls of course) and the spell check seems to has changed 'haas' effect into 'has' effect.
"So, I'm guessing that acoustic panels on reflection points on the wall and ceiling can help with reflections but not completely eliminate them?"
acoustic panels and dealing with all those "first reflections" is a much bigger problem when working with an omnidirectional radiator than a controlled directivity speaker. most of the cues with respect to imaging are in the 1khz region and up. again, not sure why, it just is. those frequencies are largely controlled by the horn, so acoustic panels don't help much with them. you'll notice that both linkwitz and cowan employ controlled directivity speakers but otherwise have no room treatments. they aren't really necessary.
cookgeek, here is a stylized picture of a jtr speaker in horizontal mode. a listener off axis will have a different distance to each woofer. when that distance is 1/2 of a wavelength, the frequency will be completely cancelled out. the closer the woofers can be put together and the lower the crossover point where only the center unit is emitting sound, the less problematic it will be. for the noesis, the cancellation point would be quite far off axis, so unless you were sitting way off to the side and close to the screen, it should be ok, more or less, to run them sideways. the d'appolito arrangement was actually specifically designed for this purpose by the way as a way of putting the off axis cancellation point right on the walls in order minimize reflected energy. turned vertically, it helps minimize ceiling/floor bounce.Edited by LTD02 - 10/16/13 at 3:43pm