SmartSMS User Manual
Soft dB inc.
User Manual
p. 21
Note about constant voltage systems:
Each speaker introduces a slight drop of voltage on the electrical line. When the number of
speakers on a line increases, there is a difference of level between the first and the last speaker on
the line.
Figure 14 : Speakers connected in parallel on an electrical line
The level drop depends on the power tap used. If there are 16 speakers on a single line, connected
to the 2-watt tap, there is a 1.2 dB difference between the first and the sixteenth speaker. If the 0.5-
watt tap is used, the level drop is approximately 0.4 dB.
The solution to limit the level variations is to limit the number of speakers to 16 per line. If you have
a large zone with 32 speakers, divide the speakers in two (or more) lines, and connect those two
lines in parallel to the SMS unit. This is valid for taps of 2 W, 1 W and 0.5 W.
Figure 15 : Speakers connected in parallel on 2 electrical lines
If you are using the 4-watt tap, limit the number of speakers to 8 per line.
