Datasheet

Maximum Wire Run Cable Length (ft.)
Wire Loss In
Central Amplifier Systems
Once you have an idea of how many speakers are to be wired
together in a run, estimate how long the wire run will be from
the first to the last speaker in each run. Include the lead-in wire
length from the amplifier to the first speaker in each run in your
overall run length. For each run, sum up the speaker power
and cable lengths.
With that information, refer to the Wire Loss Chart to ensure
that the wire gauge is sufficient to support the power and cable
length for the run. It may be necessary to increase the wire
gauge, split the speaker loads, or shorten the wire run lengths
if they exceed the chart maximums.
Wire Loss Chart*
(10% of Power Lost in Wire)
Voltage Drop Chart
Wire
Gauge
16 10,000 7000 4600 2300 1400 700 350
18 9000 4500 2800 1400 830 415 205
20 5500 2700 1800 900 540 270 135
22 3400 1700 1100 550 330 11560
24 2100 1000 700 350 210 105 50
Load Power Per Wire Run (Watts)
5
1
0
1
53050
1
00 200
Wire is an important but often ignored component of a paging
system. Because all wire has resistance, some of the voltage
at the source is lost or dropped in the wire before it reaches
the target destination. The amount of voltage lost in the wires
is affected by the resistance or gauge of the wire and the cur-
rent flowing in the wire. This is classic Ohm’s law in action.
If the drops in the cables are not anticipated, the final vol-
ume level at the passive speaker may not meet the require-
ment or, for a self-amplified speaker, there may not be
enough DC voltage available to the speaker to allow the built-
in amplifier to operate cleanly, or at all.
There are different charts for centralized and self-amplified
speakers to determine the maximum cable lengths that
should be allowed. In the case of central amplifier systems,
try to keep the system power lost in the wires to 10% or less.
However, less power at the speaker is the only negative effect
larger losses have on the system. Clarity, intelligibility and
frequency response are unaffected by larger losses in the wiring
of centrally amplified systems.
Self-amplified systems are particularly sensitive to losses in
the wire, especially the amount of supply voltage that is lost
in the wires on the way to the self-amplified speaker. When
the drop in the wiring becomes too large, the speakers may
begin to distort or stop functioning altogether. For this reason
it is important to adhere to the maximums shown in the
tables below.
Voltage Drop In
Self-Amplified Systems
The most important wiring consideration with
self-amplified speakers is to ensure that there will
be enough voltage available at each device to
allow its internal amplifier to operate correctly. If
too much voltage is dropped in the wires leading
to a speaker, this may not be the case.
Once you have an idea of how many speakers are
to be wired together in a run, estimate how long
the wire run will be from the first to the last
speaker in each run. Include the lead-in wire
length from the power supply to the first
speaker in each run. Also sum up the CU ratings
of all the speakers on the run.
With that information, refer to the Voltage Drop
Chart to ensure that there are not too many
speakers loading the wire used in the run or
that the wire gauge is sufficient to support the
power and cable length desired. To stay within
the chart length limits, it may be necessary to
either create a shorter run containing less speak-
ers or double up on conductors in the cable to ef-
fectively lower the gauge of the supply wire.
The Reducing Gauge Chart can be used to de-
termine what effective gauge is achieved by
doubling or tripling up on pairs in the cable.
Wire
Gauge
(AWG)
Maximum Wire Run Cable Length (ft.)
www.bogen.com
75
SYSTEM DESIGN GUIDE
WIRE-RELATED LOSSES
*
Use for 70V Speaker Systems Only