7
front panel
controls
1 Standby
When the amplifier is plugged into a live
wall socket and the POWER switched is
turned ON, it will power up in "standby"
mode and the LED (Light Emitting Diode)
in the STANDBY button will glow red. In this
mode the internal circuitry of the MA 240 is
powered up, but disabled so that it consumes
very little power and is isolated by relays at
its outputs.
When the STANDBY button is pressed
the amplifier circuitry will be activated
and the LED will flash green. After a few
seconds delay the loudspeaker outputs
will be connected to the amplifier and
the LED in the STANDBY button will glow
green continuously. (The mute delay in
the MA 120 is about 4 seconds, but in the
MA 240 and 360 it is about 8 seconds to
allow for the longer settling time of the
larger amplifiers’ circuits.)
PLEASE NOTE:WHEN THE POWER AMPLIFIER
IS REMOTELY ACTIVATED FROM ANOTHER
UNIT,THERE WILL BE A BRIEF DELAY BETWEEN
THE CLOSING OF THE OUTPUT RELAYS OF THE
TWO UNITS. THIS IS NORMAL AND NO CAUSE
FOR CONCERN.
When the STANDBY button is pressed again
the amplifier will be returned to standby
mode. The LED in the STANDBY button will
change back to red.
CAUTION:WHEN IN STANDBY MODE THE
INTERNAL CIRCUITRY OF THE MA 120, 240 OR
360 IS STILL LIVE, SO ALL SAFETY PRECAUTIONS
MUST BE FOLLOWED.
loudspeaker
output protection
and muting
When the amplifier is in standby mode the
loudspeaker output terminals are isolated
from the amplifier by a high quality relay.
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 relay is used
to protect both the amplifier and your
loudspeakers against possible damage. If any
one of a number of fault modes is detected
(loudspeaker outputs short circuit, amplifier
overheating, amplifier DC fault) the
loudspeakers will be disconnected from the
amplifier to protect both. In the case of a
short circuit or DC fault the loudspeakers 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
heatsinks to cool sufficiently to allow the
loudspeakers to be re-connected (probably
between five and fifteen minutes depending
upon the room temperature and ventilation).
The amplifier will cool more quickly if it is
switched to standby mode, or if the POWER
is switched OFF.
6
MA 360 only
The three channels in the MA 360 may be
assigned in a variety of ways in Home
Cinema systems. The two most common are:
channels 1 and 2 for left surround and right
surround, with channel 3 for front centre
(using an MA 240 for left front and right
front) or, channels 1, 2 and 3 for left front,
centre and right front (using an MA 240 for
left surround and right surround). In each
case make sure all loudspeakers are wired
“in phase” as described above.
6 Line inputs – normal (unbalanced)
The NORMAL unbalanced line inputs can
be driven from the line outputs of any good
quality stereo preamplifier (such as the
Myryad MP 100) or any other suitable line
level source. High quality phono-to-phono
(RCA-to-RCA) interconnects should be used.
MA 240 only
Note: when using the NORMAL line inputs
the two XLR jumper links (“U”-shaped gold-
plated links)
must
be inserted into the
BALANCED input sockets on each channel
(between pins 1 and 3 as indicated on the
rear panel). The MA 240 is always shipped in
this condition. Failure to insert these links
will result in reduced input sensitivity and
possibly some background hum, but it will
not endanger the amplifier.
7 Line outputs – normal (unbalanced)
Each channel’s line output is directly
connected to its line input – without buffering.
The line output allows power amplifiers to be
“daisy-chained” so that bi-amp, tri-amp and
multi-room systems may be built. For a more
detailed discussion of bi-amping, tri-amping
and multi-room installations please refer to
the Appendix. Only unbalanced line outputs
are fitted.
8 Line inputs – balanced (MA 240 only)
The BALANCED line inputs can be driven
from the balanced line outputs of any good
quality stereo preamplifier (such as the
Myryad MP 100) or any other suitable line
level source. High quality XLR-to-XLR
balanced interconnects should be used.
In order to use the BALANCED line inputs
the two XLR jumper links ( the “U”-shaped
gold-plated links plugged into the
BALANCED input sockets) must first be
removed. Take care of these links and store
them in a safe place. They will be needed
again if the amplifier’s unbalanced inputs
are to be used.
9 Bridged mono switch (MA 240 only)
The MA 240 is shipped with this switch in the
STEREO position, with the button pressed
in almost flush with the rear panel. In this
mode the MA 240 operates as a conventional
stereo amplifier as described above.
If the button is pressed to release it to the
“out” position, the MA 240 is switched to
BRIDGED MONO mode. The amplifier
then operates as a single channel “mono”
amplifier to drive just one loudspeaker, but at
a much higher power level (up to 400 watts
into 8Ω). A second power amplifier is needed
for stereo operation in this mode.
When operated in BRIDGED MONO mode
the following rules must be applied:
• Connect the line input signal to the LEFT
channel input, either NORMAL
(unbalanced) or BALANCED.
• Connect the loudspeaker between the two
RED (“+”) loudspeaker output terminals,
with the red or “+” terminal of the speaker
connected to the MA 240’s Left “+”
terminal and the black or “–” terminal of
speaker connected to the MA 240’s Right
“+” terminal.
CAUTION:WHEN OPERATING THE MA 240 IN
BRIDGED MONO MODE THE MINIMUM RATED
LOUDSPEAKER IMPEDANCE IS
8Ω.
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