5
USING YOUR MXA
1
FRONT PANEL
CONTROLS
1. Standby
When the amplifier is plugged into a live
wall socket and the POWER switch is
turned ON, it will power up in "standby"
mode and the central standby LED (Light
Emitting Diode) in the display window will
glow red. In this mode only a small part of
the internal circuitry of the amplifier is
powered up, so it consumes very little
power and all loudspeaker outputs are
isolated by relays.
When the STANDBY ellipse is touched the
red standby LED will extinguish and the
amplifier will be activated. Power will be
switched to each module location in
sequence and a blue LED will light in the
display window for each amplifier module
installed (up to the maximum of seven
modules). Once all seven locations are
powered, the lit blue LEDs will flash while
the loudspeaker outputs remain muted.
After a delay of about eight seconds the
relays will close, connecting the
loudspeaker outputs to the amplifier and
the blue LEDs will glow continuously. When
the STANDBY ellipse is touched again the
amplifier will be returned to standby mode,
the blue LEDs will extinguish and the
standby LED will light red again.
There are seven blue LEDs behind the
display window and each is lit only if an
amplifier module is installed in the
corresponding location (either a 1x150W or
a 2x80W module). So if a module is
installed in the far left location, then the far
left blue LED will light when the unit is
switched out of standby - and so on. If
modules are installed in all seven locations,
then all seven LEDs will light blue.
Please note: When the power amplifier is
remotely activated from another unit, there
may be a time difference between the
closing of the loudspeaker output relays of
the two units. This is normal and no cause
for concern.
CAUTION: WHEN IN STANDBY MODE
THE INTERNAL CIRCUITRY OF THE MX
POWER AMPLIFIER IS STILL LIVE, SO
ALL SAFETY PRECAUTIONS MUST BE
FOLLOWED
2. Loudspeaker output protection
and muting
When the amplifier is in standby mode the
loudspeaker output terminals are isolated
from the amplifier by high quality relays.
When the amplifier is first switched on from
standby mode the loudspeaker outputs
remain disconnected for a few seconds to
allow the internal voltage levels to settle.
The loudspeaker outputs are immediately
disconnected again when the amplifier is
switched back into standby mode.
The same loudspeaker mute relays are
used to protect both the amplifier and your
loudspeakers against possible damage. If
any one of a number of fault modes is
detected in any channel (loudspeaker
output short circuit, amplifier overheating,
amplifier DC fault) the loudspeaker will be
disconnected from that amplifier channel to
protect both. In the case of a short circuit
the loudspeaker will be re-connected after
a few seconds, but will be disconnected
again if the fault persists. If overheating has
caused the protection system to operate,
then it will take some time for the module’s
heatsink to cool sufficiently to allow the
loudspeaker to be re-connected (probably
between ten and twenty minutes depending
upon the room temperature and
ventilation). The amplifier will cool more
quickly if it is switched to standby mode.
The protection circuit in each channel of
the MX power amplifier is totally
independent of the other channels (even
within a 2x80W module). When a channel’s
protection is activated, for whatever reason,
only that channel’s speaker relay will open
muting only that channel. The only
exception may be with a 2x80W module
overheating as both amplifier channels
share a single heatsink. Each channel has
its own temperature sensor, so one or both
may protect if overheating occurs.
