Thomas A wrote:
"As Toole and others already have said several times:
A: A speaker with a flat on-axis and smooth off-axis is the most preferred, when evaluated in mono with music.
B: The same speaker sound different when in stereo setup playing the same music in mono, because of the stereo system errors (comb filtering).
So if A is true, the same preference for B cannot at the same time be true. You need another frequency response to mimic the mono speaker setup.
Tooles solution is to add a center channel."
Isn't it a bit strange to use monophonic material to evaluate a stereo pair of speakers dedicated to stereophonic music material?
One could argue so. However very much of music content lies in the center of the phantom image, such as voices. There is just no optimal solution other than to add a center channel if you want correct timbre across the whole image. For stereo playback, there are only compromises which questions the optimal response of a +/- 0.0 dB variation of the on-axis response.