Exact measurements become irrelevant when you don't have a bilaterally symetrical room. My system is in a 'sunken' living room. Right side has a large window behind the speaker, and a very large picture window to the right along the wall. Left speaker has an opening, some day a window, otherwise a long drywall surface. So not equivalent. The room opens to a dining room, staircase, etc., so no reflections to deal with. But speaker placement has to be done using the ears, not a tape measure, at least in this case.
I found much better sound as I inched both speakers away from both the back wall and the sides... Just trust your ears!
I found much better sound as I inched both speakers away from both the back wall and the sides... Just trust your ears!