KR PORTABLE SYSTEM
Ver. 1.0
24
8.1 AC POWER
The amplifier module and any audio equipment connected to it (mixing consoles, processors, etc.) must
be properly connected to the AC power distribution, preserving the AC line polarity. Every grounding
point must be connected to a single node or common point using the same cable gauge as the neutral
and line cable. Bad grounding connections between speakers and the rest of the equipment may
produce noise, hum or serious damage to the input/output stages in the system’s electronic equipment.
Before applying AC to any K-array self-powered speaker, ensure
the voltage potential difference between neutral and earth
ground is less than 5 VAC.
8. AMPLIFIER
8.2 VOLTAGE REQUIREMENTS
The KMT12, KMT18 and KMT21’s switching power supply accommodates AC mains operating at either
115 V or 230 V. The amplifier will continue to operate safely, without interruption, provided that the AC
voltage remains within this nominal range (operating range 90 - 135 V or 190 - 250 V) at 50 to 60 Hz.
The KMT12 Mark I, KMT18 Mark I, KMT21 Mark I and KMT218’s auto-range power supply feature allows
the amplifier unit to operate safely and without audio discontinuity when the AC voltage stays within a
nominal range of 100 - 240 V (operating range 85 - 265 V) at 50 to 60 Hz.
Please verify that your AC main connections are capable of satisfying the power rating for the device.
CAUTION: Do not connect the system to AC mains power
exceeding 265 V. Doing so will cause significant damage to the
device and create serious risk for users!
8.3 CURRENT REQUIREMENTS
The amplifier presents a dynamic load to the AC mains, drawing additional current as operating levels
increase. Different cables and circuit breakers heat up at varying rates, so it is essential to understand
current ratings and how they correspond to circuit breaker and cable specifications. Maximum continuous
RMS current - measured over a period of at least ten seconds - is used to calculate the temperature
increase in cables, which drives the proper size and gauge cable and rating for slow-reacting thermal
breakers. Maximum burst RMS current - measured over a period of approximately one second - is used
to select the rating for fast-reacting magnetic breakers.
For best performance, voltage drops should not exceed 10% at 100 V or 10% at 230 V. The minimum
electrical service amperage required by a K-array loudspeakers system is the sum of their maximum
continuous RMS current. K-array recommends allowing an additional 30% above the minimum amperage
to prevent peak voltage drops at the service entry.
