All material © 2010 Martin Audio Ltd. Subject to change without notice
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4
Protection
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
Short circuit protection
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
Thermal protection
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
DC fault protection
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
Input/Output protection
An ultrasonic network decouples RF from the outputs and keeps the amplifier stable with reactive loads.
