1256 Chapter 34
large, and with power amplifiers larger and less expen-
sive per watt, many designers now choose vented enclo-
sures because they fit in the smaller spaces provided in
modern buildings. It can be shown mathematically that,
for a given amount of total enclosure volume, a loud-
speaker system using vented enclosures can produce
more total acoustic power than a horn-loaded loud-
speaker system. The vented system simply uses more
loudspeakers and higher-powered amplifiers to achieve
this victory.
34.3.1.3 Compression Drivers and Horns
One class of components is designed specifically for use
on a horn. These components are called compression
drivers, and they are used almost exclusively as the
midrange and high-frequency components of two-way,
three-way, and multiway systems. At these frequencies,
horn sizes are smaller than at the low frequencies used
by low-frequency horns. Because of the efficiency and
dispersion control of the horn, especially in the critical
midrange and high frequencies, mid- and high-fre-
quency horns and compression drivers, Fig. 34-11, are
the midrange and high-frequency components most
often used in packaged loudspeaker systems.
There are several types of mid- and high-frequency
horn designs. These include exponential (radial), multi-
cell, and constant directivity horns. In the past, expo-
nential horns were commonly used in packaged
loudspeaker systems and multicell horns were
commonly used in component clusters and in cinema
loudspeaker systems.
Today, almost all available horns are constant direc-
tivity designs. Constant directivity horns have very
good dispersion control (pattern control) over a wide
frequency band. Although well-designed constant direc-
tivity horns are somewhat larger than exponential or
multicell horns, the dispersion control advantage of
constant directivity horns is so overwhelming that theyFigure 34-9. A horn-loaded loudspeaker system. Courtesy
EAW.
Figure 34-10. A pair of dual 15 inch driver folded-horn
enclosures shown with accessory midrange and
high-frequency horns. Courtesy Klipsch & Associates, Inc.