Selecting and Positioning
Ceiling Loudspeakers
Several key criteria determine the type and
quantity of ceiling speakers to employ in a
job. Specific EVID™ Ceiling Series models
accommodate each job, depending on how
these criteria are specified.
• Room size
• Coverage density desired
• Coverage angle specification of the speaker
• Ceiling height
• Audio program material being played
In the traditional approach to overhead-
distributed systems, loudspeakers are located
in a grid arrangement whose dimensions are
dictated by the room height and the directivity
of the speaker elements. Two basic placement
patterns prevail: square spacing and hexago-
nal (or crisscross) spacing. See Figure 20.
In addition to the spacing pattern, the
designer must choose between three cover-
age density types, designated respectively as
edge-to-edge, minimum overlap and center-
to-center. The greater the overlap, the more
uniform the coverage. The illustration below
shows these various layout patterns.
Ceiling Systems: Size vs. Coverage
In the past, system designers usually speci-
fied 8-inch cone loudspeakers for distributed
overhead systems, at least in part because
they represented the traditional choice. The
EVID systems, however, allow for far more
flexible options.
In many cases, you can achieve excellent
results — at a significant savings — by using
4-inch transducers. This is especially true in
jobs that do not require extended low-end
response or high SPL levels. 4-inch transduc-
ers, such as those used in the C4.2, offer wider
dispersion to allow for fewer speakers to be
employed in the job. For example, due to its
smaller cone diameter, the C4.2 exhibits signif-
icantly wider dispersion (130 degrees) than
the C8.2 (110 degrees) at the -6 dB points.
The effect of this characteristic on an over-
head system is indicated in Figure 21. In
replacement applications where existing
speaker positions are used, the C4.2 (shown
in angle A) offers greater overlap and, thus,
more uniform coverage than an older con-
ventional 8-inch unit (shown in angle B).
When specifying a new system, you can take
advantage of the C4.2’s wider dispersion to
decrease the number of speakers required to
cover a given area. This will result in even
greater savings.
Of course, the C4.2 is somewhat less sensi-
tive than the 8-inch C8.2. The difference is
–7 dB. The C4.2 will also have slightly
reduced low-frequency capabilities below 90
Hz. However, neither of these factors is a sig-
nificant problem in many distributed sys-
tems. The C4.2 is conservatively rated to han-
dle 50 watts of continuous power equal to or
greater than most other brands of 8-inch
units, so its continuous SPL output will be
more than adequate. Moreover, its low-fre-
quency output can easily be augmented with
the addition of the C10.1 subwoofer. For these
reasons, the C4.2 represents a great way for
you to provide good audio coverage while
10
EVID™ Ceiling Series Installation and Operation Manual
Appendix B — System Design Guide
Grid
Edge-to-edge Minimum
overlap
Center-to-
center
He
xagonal
Square
Figure 20:
Coverage patterns
Ceiling
A
B
A
B
Figure 21:
Size vs. coverage
