Datasheet

Speaker Wiring Patterns
Because distributed paging systems involve a great
number of speakers and long distances, the manner in
which the speakers are wired is of interest. Deciding on
how to wire the speakers depends on whether separate
zones of speakers are needed, how many lines back
to the amplifier are reasonable, and how easy it will
be to troubleshoot the system in the future.
How you wire a speaker system may require some
tradeoffs. The simplest way is to parallel all the speakers
on one very long run of wire. This approach leads to
some problems. First, the amount of power lost in a
long run of wire may not allow the required amount of
70V speaker signal, or 24V DC voltage for self-
amplified paging systems, to get to the farthest
speakers. Second, if there should be a short on the
wire run, it would take down the entire run. In order
to locate it, you would need to disconnect each speaker
until the failed one is found.
Multiple Wire Runs
A more practical approach is to wire each row of speakers
in an area together and run a lead wire from this row
back to the amplifier. The objective is not to have so
many speakers daisy-chained together that it makes
troubleshooting impossible. Wire runs can be sepa-
rated to determine in which run the problem exists.
SPEAKER PHASING
As the voltage on a speaker changes from plus to minus,
the speaker cone moves from pushing out to pulling in.
If you reverse the polarity, the speaker responds in the
opposite manner.
If a speaker is pushing out and an adjacent speaker is
pulling in, some of the pressure caused by the speaker
pushing out will be absorbed by the speaker pulling in.
These two speakers are out of phase.
In a paging system, all the speakers should be in phase
so that they all push out at the same time. Out of phase
speakers operate perfectly well and will not cause any
harm to a paging system, but will tend to diminish the
bass response in the area around the out of phase
speaker.
The important thing is to wire all the same polarity (+ or -)
connections together. This will ensure that the speakers in
the system all work in unison. All paging speaker connec-
tions have a polarity indicator. It may be a color code, plus
(+) and minus (-) symbols, or a red dot.
Reversed Connections
in 70V System
www.bogen.com
73
SYSTEM DESIGN GUIDE
SPEAKER WIRING