Outdoor Paging System - Toa BS-1030 User Manual

TOA Electronics Speaker Guide
Using the level change with power input chart (see Figure 5-2 on page 22), we see that 4 W per
speaker provides the 6 dB needed to reach the L
tap above 4 W is 5 W. Add the speakers at 5 W each to yield a total of 60 W. Multiply by 1.2
(120%) to get the minimum amplifier power: 72 W.

Outdoor Paging System

Paging is needed in an outdoor area. The area is 100 x 200 ft (20,000 sq. ft), and the speakers
will be mounted on poles along the center of the area (200 ft). TOA model SC-615T is selected
for its high efficiency and wide area coverage.
From the coverage depth column of the SC-615T coverage and spacing table (page 53), we see
that mounting a speaker 10 ft above the listener's ear level and aiming it down by 10° results
in a coverage area that extends 57 ft from the base of the speaker's mounting surface. This po-
sitioning allows reaching the edges of our outdoor area from poles along the center line.
When mounted 10 ft above ear level (approx. 16 ft high), the rated coverage area of the SC-615T
is 1713 sq. ft, suggesting that 12 horns are needed to cover the space smoothly. Ideally, the
horns should be mounted on the central poles, back-to-back, aiming outward.
Assume the measured noise levels in this outdoor setting are 70 dB (A-weighted). The operat-
ing level should be 90 dB, with 6–10 dB headroom, for a L
From the SC-615Tcoverage and spacing table (page 53), we see that when mounted 10 ft above
ear level and aimed down 10°, it delivers 99 dB SPL to the farthest on-axis listener, at 57 ft
from the base of the speaker's mounting surface. This is based on operation at the maximum
transformer tap of 15 W, and is within our target range. Adding 12 speakers at 15 W yields a
speaker total of 180 W. Multiply by 1.2 (120%) for a minimum amplifier rating of 216 W.
To economize, we could lower the operating level to 96 dB. Using the level change with power
input chart (see Figure 5-2 on page 22), we see that a drop of 3 dB reduces the power require-
ment by a factor of 2, for a minimum amplifier power of 108 W. Since this brings our headroom
down to 6 dB, it is wise to use a paging mic input with built-in compression. This is a good idea
for any paging system in noisy environments, but especially when headroom is limited. The
TOA model M-61S input module performs this function when used with a 900 Series mixer or
mixer/amplifier.
. The speaker's smallest available transformer
req
of 96–100 dB.
req
32
Amplifier Selection