Time and Phase....read what JA has to say about Vandersteen “imaging champs”....
Thanks for the helpful reply. I just read JA's review of the Vandersteen Quatro Wood. His measurements are interesting.
"Fig.5 shows the Vandersteen Quatro Wood CT's horizontal radiation pattern, normalized to the tweeter-axis response and plotted up to 45° to the speaker's sides rather than the usual 90°... The contour lines in this graph are impressively even, implying stable stereo imaging."
"Like its predecessors, Vandersteen's Quatro Wood CT offers a true time-coincident output, due to the stepped-back sub-baffles for the upper-frequency drivers, the first-order crossover slopes, and the fact that all its drive-units are connected in positive acoustic polarity. Fig.9 shows the speaker's step response on the tweeter axis. The initial arrival is an almost textbook right-triangle shape, though the tweeter's output arrives slightly before that of the midrange unit. This confirms that the optimal axis will be 5° below the tweeter axis. Finally, the Quatro Wood CT's cumulative spectral-decay plot (fig.10) is impressively clean."