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CHAPTER 1
If voltage drops below the low boundary of its safe
operating range (brownout), the UPM-1P or UPM-2P
loudspeakers use stored energy to continue functioning
briefly, and shut down only if voltage does not rise above
the low boundary before storage circuits are depleted.
How long the loudspeaker will continue to function during
brownout depends upon the amount of voltage drop and
the audio source level during the drop.
If the voltage increases above the upper boundary of either
range, the power supply may be damaged.
NOTE:
It is recommended that the supply
be operated in its rated voltage window at
least a few volts away from the turn on/off points.
This ensures that that AC voltage variations from the
service entry – or peak voltage drops due to cable
runs – do not cause the amplifier to cycle on and off
or cause damage to the power supply.
Current Requirements
The UPM-1P and UPM-2P loudspeakers require
approximately 3 amps rms max at 115 volts AC for proper
operation. This allows up to five loudspeakers to be
powered from one 15-amp breaker.
The UPM-1P and UPM-2P loudspeakers present a dynamic
load to the AC mains, which causes the amount of current
to fluctuate between quiet and loud operating levels. Since
different cables and circuit breakers heat up at varying
rates, it is essential to understand the types of current
ratings and how they correspond to circuit breaker and
cable specifications.
The maximum long-term continuous current is the
maximum rms current during a period of at least ten
seconds. It is used to calculate the temperature increase
in cables, in order to select a cable size and gauge that
conforms to electrical code standards. It is also used to
select the rating for slow-reacting thermal breakers.
The burst current is the maximum rms current during a
period of approximately one second, used to select the
rating of most magnetic breakers and to calculate the peak
voltage drop in long AC cables according to the formula:
V pk (drop)= I pk x R (cable total)
The ultimate short-term peak current is used to select the
rating of fast reacting magnetic breakers.
Use Table 1.1 below as a guide when selecting cable gauge
size and circuit breaker ratings for your operating voltage.
6
Table 1.1: Current Ratings for UPM-1P and UPM-2P
Current Draw
115 V AC
Max. long-term
1 A rms
continuous
Burst current
1.3 A rms
Ultimate short-
2.9 A pk
term peak
Idle current
0.13 A rms
NOTE:
For best performance, the AC cable
voltage drop should not exceed 10 volts, or
10 percent at 115 volts and 5 percent at 230 volts.
Make sure that even with the AC voltage drop the
AC voltage always stays in the operating window.
The minimum electrical service amperage required by
UPM-1P and UPM-2P systems is the sum of each
loudspeaker's maximum continuous rms current. An
additional 30 percent above the minimum amperage is
recommended to prevent peak voltage drops at the service
entry.
CAUTION:
In the unlikely event that the fuse
!
trips, always replace a fuse with the same
rating and type of fuse. The UPM-1P and UPM-2P
loudspeakers use a quick-acting 3.15-amp current,
250 volts low breaking capacity fuse.
Power Connector Wiring
The UPM-1P and UPM-2P loudspeakers require a grounded
outlet. It is very important that the system be properly
grounded in order to operate safely and properly. Use the
AC cable wiring diagram shown in Figure 1.3 to create
international or special-purpose power connectors.
Figure 1.3. AC cable color code
230 V AC
100 V AC
0.5 A rms
1.2 A rms
0.65 A rms
1.5 A rms
2 A pk
3.3 A pk
0.065 A rms
0.15 A rms
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