Originally Posted by jim19611961
Depends on the gain and timing of the reflection(s). The term "image broadening" applies directly to what your asking wrt to "bigger". Perhaps this may help.
The space between instruments I would say is more related to soundstage width and depth which constitutes many factors of which reflections is only a part.
The red and green zones are pretty much .. lol .. black and white. But the yellow zone, IME, is psycho-acoustical territory and, also, the land of preference. For my MCH theater, I initially favored an adaption of LEDE. But after a lot of use, I have noticed (and can no longer NOT notice) that the front lobes of the dipole surrounds are collapsed causing a hole between the L&R and their respective surrounds. And, with carpeted walls up to seated ear level (along with the completely absorbent front wall), I "feel" the room is over-damped in general.
And this is what brought me to REW in the first place. I wanted to measure before and after I swapped the rear FRP absorber for skylines, and see if that fixed my concern. I am also prepared to swap front L&R FRP absorbers for skylines as well. But I bumped into one obstacle; what should my target decay be? A helpful chap from THX once told me that they design for a midband decay of 300ms. OK, one "data point." but in all of my questioning on the Acoustical theory thread, none of the resident acousticians would ever divulge what they used as a target ... as if it were knowledge reserved for the gurus.
So, I know how to build and deploy acoustical treatments and measure, and I certainly know how to listen, but I am missing some sort of guide rail. The Q&A of the last few days and, especially, the graph you just posted has helped me. And convinced me that I need to do more research.