NHT Evolution System - Manual (Page 49)

11.5 Orientation Independent Dispersion
The Evolution monitors are optimized for use in
either a horizontal or vertical orientation. This is
achieved by means of the relative placement,
size and crossover frequencies of the drivers.
The very small separation between the
midrange and tweeter drivers allows dispersion
that is very wide and well controlled. When com-
bined with the low crossover frequency between
the woofers and midrange, the resulting sound-
field permits the speaker to be used in a hori-
zontal or vertical orientation without significant
changes in frequency response and imaging
characteristics.