M2D-SUB AMPLIFIER COOLING SYSTEM
The M2D-Sub loudspeaker uses a forced-air cooling system with two fans to prevent the amplifier module from overheating. The fans draw air in through ducts on the front of the cabinet, over the heatsink, and out the rear of the cabinet (Figure 2.6). Because dust does not accumulate in the amplifier circuitry, its lifespan is increased significantly. The front grille helps to filter the air and should always be in place during operation.
Figure 2.6. Airflow through the M2D-Sub
CAUTION: When operating a weather- protected M2D-Sub loudspeaker always
be sure the rain hood is fully open. Leaving the hood closed or partially open will limit the airflow through the amplifier, which could cause it to overheat and shut down.
The variable-speed primary fan runs continuously and is inaudible at its slowest speed. The primary fan's speed increases when the heatsink reaches 42˚ C (108° F). The fan reaches full speed at 62˚ C (144° F) and is still barely audible near the cabinet, even without an audio signal.
In the event that the heatsink temperature reaches 74˚ C (165° F), the secondary fan turns on and is clearly audible without an audio signal. The secondary fan turns on in response to:
Primary fan failure (check status immediately)
Very high signal levels over a prolonged period
Accumulation of dust along the cooling path
The secondary fan turns off when the temperature decreases to 68˚ C (154° F).
NOTE: In the highly unlikely event that the secondary fan does not keep the
temperature below 85˚ C (185° F), the M2D- Sub automatically shuts down until AC power is removed and reapplied. If the M2D-Sub shuts down again after cooling and reapplying AC power, contact Meyer Sound for repair information.
Despite the M2D-Sub loudspeaker's filtering, extensive use or a dusty operating environment can allow dust to accumulate along the path of the airflow, preventing normal cooling. To prevent this, you should periodically remove the grille frame and amplifier module and use compressed air to clear dust from the grille, fans, and heatsinks. Make sure that the air ducts are clear.
CAUTION: Be sure to unplug power to the unit before cleaning the amplifier.
