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ommended. When the loudspeaker's internal temperature
cools to 60° C (140° F), the amplifier returns to normal oper-
ation.
TIP:
When CAL is connected to a computer
running the Compass control software, the RMS
tab provides additional feedback and warnings, if
encountered, on the loudspeaker's operating temper-
ature.
LIMIT LEDS
Limit
Limit LEDs
When source levels for CAL exceed the maximum input lev-
els for its drivers, limiting is engaged and is indicated by the
two Limit LEDs on the CAL user panel. The left LED indi-
cates limiting for low-frequency channels while the right LED
indicates limiting for high-frequency channels. When
engaged, limiting not only protects the drivers, but also pre-
vents signal peaks from causing excessive distortion in the
amplifier channels, thereby preserving headroom and main-
taining smooth frequency responses at high levels. When
source levels return to normal, below the limiter's threshold,
limiting ceases.
CAL performs within its acoustical specifications when the
Limit LEDs are unlit, or if the LEDs are lit for 2 seconds or
less and then turn off for at least 1 second. If an LED
remains lit for longer than 3 seconds, the loudspeaker enters
hard limiting where:
■
Increases to the input level have no effect.
■
Distortion increases due to clipping and nonlinear driver
operation.
■
Drivers are subjected to excessive heat and excursion,
which will compromise their life span and may eventually
cause damage over time.
CAUTION:
The Limit LEDs indicate when a
safe, optimum level is exceeded. If a CAL loud-
speaker begins to limit before reaching the required
SPL, consider replacing it with a CAL model with
more amplifier channels, or consider adding more
CAL loudspeakers to the system to achieve the
desired SPL without exposing the loudspeakers to
excessive levels and possible overheating.
LOGIC I/O PORTS
The Logic I/O connectors provide a range of control and
monitoring for CAL, including changing presets, overriding
and muting the input signal, monitoring loudspeaker faults,
and providing voltage output. The Logic I/O connectors are
optically isolated from the CAL loudspeaker circuitry. The
three COM pins are isolated from each other to set the refer-
ence voltage for their associated logic pins. A logic pin is
triggered when it receives a voltage of 3 to 20 V DC greater
than its associated COM voltage.
CAUTION:
Do not send voltages greater than
20 V DC to the Logic I/O pins as this may dam-
age the input circuitry.
Presets 1–4
1
2
3
4
a2
a1
Preset
com
NC
Fault
Contact
NO
Preset Pins
CAL presets recall loudspeaker settings for beam control
and processing (5-band parametric EQ, gain, and delay).
Presets are edited in the Compass control software. An
unlimited number of presets can be saved and stored on
your computer but only four presets can be stored in the
CAL loudspeaker. When CAL is not connected to a com-
puter, presets can be selected by sending control voltages
to the A1 and A2 pins.
Table 1 illustrates the logic for selecting presets with control
voltages.
Table 1: CAL Preset Selection Logic
A1
Preset 1
0
Preset 2
1
Preset 3
0
Preset 4
1
For example, to select preset 2, a voltage of 3 V DC is sent
to the A2 pin while 0 V DC is sent to the A1 and COM A2.
NOTE:
The A1 and A2 pins are triggered when
receiving a voltage of 3 to 20 V DC greater than
their associated COM voltage.
CAL OPERATING INSTRUCTIONS
A2
0
0
1
1
17
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