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CHAPTER 2
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CHAPTER 2
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Figure 2.4. The M2D loudspeaker’s limit LED indicators
If the limit LEDs are on for no longer than two seconds,
and off for at least one second, the M2D loudspeaker
is performing within its acoustical specications and
operating at a normal temperature. If either LED remains
on for longer than three seconds, this indicates that the
particular channel is incurring hard limiting that can result
in the following negative consequences:
Increasing the input level will not increase the volume.
The system distorts due to clipping and nonlinear
driver operation.
Unequal limiting between the low and high frequency
drivers can alter the frequency response.
The lifespan of the drivers is reduced because they are
subjected to excessive heat.
While the limiters protect the system under overload
conditions and exhibit smooth sonic characteristics, it
is recommended that you do not drive the M2D into
continuous limiting.
NOTE: The limit LEDs indicate when the
safe power level is exceeded. If an entire
system of M2Ds begins to limit before reaching the
required SPL, you should consider adding more
loudspeakers to the array.
The limiters cease operation when the level in the channel
returns to normal. Limiters have no effect on the signal
when the LED is inactive.
M2D AMPLIFIER COOLING SYSTEM
The M2D loudspeaker employs a natural convection
cooling system. A large aluminum heatsink is cooled by
the air owing over its ns.
If the temperature of the heatsink reaches 85°C (185°F),
the On/Temp LED on the rear panel turns from green (On)
to red (Temp) and the limiter threshold is lowered to a
safe level to prevent the system from overheating. Under
high temperature conditions the maximum output level is
reduced 6 dB. When the heatsink temperature decreases
to 75°C (167°F), the On/Temp LED changes from red to
green and the limiter threshold returns to normal.
Optional Fan Assembly Kit
While convection cooling is adequate for most
applications, in situations where the M2D loudspeaker is
driven into continuous limiting under severe temperature
conditions, or where ventilation is restricted, installation
of an optional fan kit is recommended to maintain a safe
operating temperature.
The easy-to-install fan, powered through the 24 V fan
connector on the M2D loudspeaker’s user panel, blows
air directly onto the heatsink. The fan speed increases as
the heatsink temperature rises, which maintains a safe
operating temperature with minimal fan noise. Contact
Meyer Sound to order the fan kit.
Power Supply Fan
The power supply is cooled by a single small internal fan
operates on low speed when the unit is rst powered
up. The fan increases speed as the system is driven
with audio. Since the fan draws air in from and exhausts
through the back of the cabinet, there must be at least
6 inches of clearance behind the cabinet to allow an
adequate air ow.
M2D-SUB INTERCONNECTIONS
The M2D-Sub loudspeaker utilizes two 4-ohm, 15-inch
cone drivers. These drivers feature lightweight neodymium
magnet structures. Each channel of the amplier drives
one low frequency driver.
CAUTION: All Meyer Sound loudspeakers
are shipped with the drivers in correct
alignment. However, if a driver needs to be
replaced, make sure the replacement is reinstalled
with the correct polarity. Incorrect driver polarity
impairs the system performance and may damage
the drivers.
high-frequency
LED (yellow)
low-frequency
LED (yellow)