MARTIN AUDIO switch mode amplifiers use primary switching, i.e. the
mains is rectified directly before the transformer, which means that the
power supply is insensitive to the mains frequency and will operate from
DC to 400Hz.
The amplifier is supplied with an approved European AC line connector. If
this connector is not appropriate for your country, it can be cut off and wired
to a suitable connector in the following way:
BROWN
-
LIVE
BLUE
-
NEUTRAL
GREEN/YELLOW
-
EARTH
Once connected to a suitable AC supply, the amplifier can be started with
the power switch. When you power up the amplifier it takes a couple of
seconds to self check (this is known as the "soft start" or "slow start"
sequence). The fans then blow at high speed before going into "idle". The 2
bottom green LED's then illuminate to show the amplifier is operational.
5.4
Grounding
There is no ground lift switch or terminal on this amplifier. The signal
ground is always floating via a resistor to chassis and the grounding system
is automatic. If a potential above 0.6V presents itself between signal ground
and chassis ground, a short circuit is introduced between the two, thereby
enabling electrical protection. If a unit in the system is faulty, its mains fuse
will blow, due to this automatic ground system. If however, you wish to tie
the signal ground to chassis, connect the XLR-connector's shell lug to pin
1. In the interest of safety never disconnect the earth pin on the mains
connector.
For compliance with the EMC directive (conducted emissions), there is an
AC mains filter. This filter needs the chassis ground for reference, otherwise
a current loop is formed via the signal ground. Use the balanced input to
avoid hum and interference.
5.5
Power consumption
There are three ways to define the power/current consumption of the
amplifier:
First, the peak current draw at full power output. Under this condition the
amplifier will operate for less than 2 minutes before thermally limiting.
Secondly, the maximum expected average current under worst case
program material, which corresponds to 1/3 of full power according to the
FTC-standard. At this level the music will be in a state of constant clip and
is therefore the highest power level one can obtain without completely
obliterating the program.
Lastly, the "normal operating power", as defined by EN60065 as a
measurement level for approval and testing to this standard. The normal
operating power is measured using pink noise, with an average output
Martin Audio – MA4.2 Power Amplifier
E
NGLISH
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