User Guide

Sound System Design Reference Manual
Horns may be stacked in a vertical array to
improve pattern control at low frequencies. The JBL
Flat-Front Bi-Radials, because of their relatively
small vertical mouth dimension, exhibit a broadening
in their vertical pattern control below about 2 kHz.
When used in vertical stacks of three or four units,
the effective vertical mouth dimension is much larger
Figure 3-11. Stacking horns for higher directivity at low frequencies
(solid line, horizontal -6 dB deamwidth, dashed line, vertical -6 dB beamwidth)
than that of a single horn. The result, as shown in
Figure 3-11, is tighter pattern control down to about
500 Hz. In such vertical in-line arrays, the resulting
horizontal pattern is the same as for a single horn.
Additional details on horn stacking are given in
Technical Note Volume 1, Number 7.
3-9