CHAPTER 2
LED (yellow) 
LED (yellow)
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 specifications 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 flowing over its fins.
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
Power Supply Fan
The power supply is cooled by a single small internal fan operates on low speed when the unit is first 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 flow.
The
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.
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