All material © 2010 Martin Audio Ltd. Subject to change without notice
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3
Protection
3.1
Turn-On-Turn-Off muting
For about four seconds after turn-on, and immediately at turn-off, the amplifier outputs are muted.
3.2
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 the event of a short circuit condition, the red LED
will be illuminated. The amplifier protection has an auto reset mode which will attempt of reset the amplifier
for normal use after 2 seconds. If the short circuit is still present the amplifier will attempt to reset every 2
seconds until the short is removed.
3.3
Thermal protection
The MA 1.4 amplifier uses a continuously variable speed fan to assist cooling (the fan speed changes in
response to the amplifier's cooling requirements). If the heatsink temperature reaches approximately 75°C,
the "TEMP" LED illuminates and the output power is reduced to prevent damages to the output stage. If the
temperature rises above 85°C the thermal sensing circuitry will mute each channels power section. Once the
heatsink has cooled below 85°C the amplifier will automatically un-mute but the TEMP LED will remain lit
until the temperature has dropped to 75°C. It is possible to reduce the temperature reducing the output
power.
3.4
DC fault protection
If DC or excessive subsonic energy appears at a channel output, an instantaneous protection circuit will
mute both channels of the amplifier. The amplifier shutdown is used instead off of speaker relays, thereby
improving the damping factor and reliability of the MA1.4.
3.5
Input / Output protection
An ultrasonic network decouples RF from the outputs and keeps the amplifier stable with reactive loads.
