Note that, if the signal is distorted or clipped before it reaches the amplifier,
the clip limiter will not be activated.
Under normal operation the clip limiting is inaudible. The limiter can be turned
On or Off by depressing the relevant clip limit switch (2). Some manufacturers
of loudspeaker processors do not recommend the use of clip limiters in
amplifiers, as they tend to upset the tracking of the processor's limiters.
Apart from this one exception, MARTIN AUDIO recommend leaving the clip
limiters switched "on" (button depressed). NB. As a by-product, when the
amplifier comes out of a protect condition, the output level has a slow rise
time - the effect is like turning the gain up slowly.
Thermal protection
When the amplifier is driven very hard into a low impedance load, the
cooling fans will run at high speed. If these operating conditions continue,
the Protect indicator(s) will illuminate indicating that the amplifier is about to
go into thermal shutdown.
After five seconds the amplifier will go into thermal protect, by muting the
input signal. After 15-20 seconds the amplifier will have cooled down
enough for the amplifier to come out of shutdown and operate as normal.
If the load conditions remain unchanged the thermal protection will be re-
initiated. Thermal protection starts when the heatsink reaches a
temperature above 90˚C.
VHF protection
If a signal of more than 12kHz, at full power, is detected at the amplifier
outputs and lasts for more than five seconds, the VHF protection mutes the
input signal. (This is indicated on the front panel (3) labelled “Protect”).
After five seconds the outputs will un-mute and return to normal operation,
unless the output signal has remained unchanged in which case the VHF
protection will re-initiate. This circuit is inaudible in normal use, however it
can be turned off. If the VHF protection is required to be turned off i.e. for
studio monitors, please consult your supplier, as this is a non-user
adjustment.
Short circuit protection
All MARTIN AUDIO MA Series amplifiers are completely short circuit
protected. The protection circuit permits very high peak currents, but still
holds the output devices within their safe operating area. If a short circuit is
maintained, the channel affected will eventually go into a thermal protect
cycle until the short circuit is removed. The MA1.6 is equipped with ALS™
(Adaptive Limiting System) protection circuitry, which continuously monitors
the supply rails and limits the current going to the output transistors. If the
ALS circuit is activated, the input signal is muted and the "Protect" LED will
illuminate.
Martin Audio – MA1.6 Power Amplifier
E
NGLISH
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