Sound System Design 131734.5.5.4 Anticipating and Preparing for Problems
These techniques can help troubleshoot DSP problems
and other problems but this kind of troubleshooting can
take time. Thus, it’s better to anticipate potential prob-
lems in the system and prepare to solve them quickly.
Keep spare cables, spare components, and troubleshoot-
ing equipment nearby. Plan what to do if a critical sys-
tem component fails. This includes the system mixing
console and any all-in-one DSP units. Some facilities
with critical sound requirements keep a smaller mixer
and a second, programmed DSP ready to swap in case
of failure. Finally, when possible design the system to
minimize problems resulting from the failure of a single
piece of equipment. For example, replace the all-in-one
DSP with networked amplifier DSP units. This way, the
failure of a single DSP cannot cause the entire sound
system to fail.
34.6 Applications
34.6.1 Portable and Tour Sound Systems
Portable systems range from voice-only paging systems,
as might be used at a local county fair, up to the giant
tour sound systems used for outdoor rock music festi-
vals. The design criteria for a portable system build on
the criteria discussed for permanently installed systems,
adding to and modifying the system to take into account
such obvious considerations as travel and less obvious
considerations such as the potential for abuse by an
inexperienced operator or an overexcited audience.
34.6.1.1 Packaging
Portable systems must be rugged to survive travel. They
must be packaged efficiently in order to fit into as small
a travel vehicle as possible and so that setup and tear-
down are quick and efficient. Even large tour sound sys-
tems are normally designed to fit efficiently into
standard-size trucks (48 foot or 52 foot semitrailers in
the United States). Efficient packaging leads to lower
ownership and operating costs from the ability to use
smaller vehicles (or fewer large vehicles) and from the
requirement of fewer hours for setup and teardown.
Rugged packaging for all components of the system,
from loudspeaker systems to electronics to microphones
and accessories, also reduces system maintenance costs
and improves reliability.
34.6.1.2 Loudspeaker SystemsIn the past, a county fair might rent a portable system
consisting of a group of 70 V paging horns, matching
electronics, and one or more paging microphones.
Today, most portable systems use packaged loudspeak-
ers or line arrays and the largest tour sound systems may
even use proprietary loudspeaker systems designed and
built by the tour sound company itself.
For efficient arraying, most portable packaged loud-
speaker systems are trapezoidal in shape. Manufactured
packaged loudspeaker systems are usually two-way or
three-way designs. Proprietary, tour-sound packaged
loudspeaker systems are commonly three-way or even
four-way systems.
Although some four-way proprietary tour-sound
systems include subwoofers, most popular music appli-
cations use separate subwoofers. Separate subwoofers
mean the main packaged loudspeaker systems can be
smaller. Putting subwoofers on the floor reduces the
size of any suspended array.
Smaller portable systems may use a single type of
packaged loudspeaker. For example a weekband band
may use a two-way or three-way, 90q design and find
this fills its needs for nightclubs and smaller dance
halls. Larger systems will benefit from more than one
type of packaged loudspeaker system. For example, a
mid-sized tour sound system might include both 60q
and 90q packaged loudspeaker systems along with sepa-
rate subwoofers.
In the past, tour sound systems used separate compo-
nents (horns and woofers) in place of today’s packaged
loudspeaker systems. While systems using separate
components took longer to set up and tear down, they
provided increased versatility because the operator
could choose from multiple horn patterns and design a
custom array for each venue.
A designer of a portable system today could bring
back some of this versatility by including both 60q and
90 q packaged loudspeaker systems, by using separate
subwoofers and by packaging a few component
long-throw (40q by 20q) horns to cover the upper seats
in an arena or the far rows of an outdoor theater.
Many tour sound companies are now using line
array-type systems. These systems utilize specially
designed loudspeaker systems and sophisticated DSP
electronics to create precisely controlled vertical direc-
tivity patterns that can reach the back of an audience
with good sound quality while maintaining a reason-
able level in the front.
Selected models of line arrays and packaged loud-
speaker systems are available in self-powered versions