Turn-On/Turn-Off Muting; Short Circuit Protection; Thermal Protection; Dc Fault Protection - Martin Audio MA12K - 2010 User Manual

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4.1

Turn-On/Turn-Off muting

For about four seconds after turn-on, and immediately at turn-off, the amplifier outputs are muted.

4.2

A short circuit protection system safeguards the amplifier's output transistors under short circuits and other

stressful loads. It is completely inaudible when inactive. In case of short circuit, the red LED will be light-up

and writing "PROT" appears in the first line of the display (see Par. 2.2 for a detailed description). The

amplifier will reset itself 50 times every 2 seconds. Once 50 resets have been performed, if the fault still

exists on the output, the unit goes into permanent protection mode. A power OFF/ON cycle is needed to

restart the unit.

4.3

The MA12K & 12K DSP amplifiers use a continuously variable speed fan to assist cooling (the fan speed

changes in response to the amplifier's cooling needs). If the heat sink temperature reaches approximately

80°C, the yellow LED starts to flashing. If the temperature is more then 85°C the thermal sensing circuitry

will mute each power section channels, the LED will light permanently and the power supply will be cut off.

Once the heatsink has cooled down, the amplifier will automatically reset and the LED will go out. The

temperature can be reduced by reducing the output power.

4.4

If DC or excessive subsonic energy appears at a channel output, an instantaneous protection circuit will cut

off the power supply for both channels. Power supply shutdown is used instead of speaker relays, thereby

improving the damping factor and reliability of the MA12K & 12K DSP amplifiers.

4.5

An ultrasonic network decouples RF from the outputs and keeps the amplifier stable with reactive loads.

Protection

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