Grounding; Power Consumption - Martin Audio MA1.3 User Manual

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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
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
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
power equal to 1/8 of full power. The one-eighth power is the maximum
volume music can be re-played without continuous amplifier clipping.
It also corresponds to headroom of 9dB, which is very low for normal
program material.
If operating the amplifier into a sustained 2 ohm load, protection circuits
within the amplifier will limit the long-term current draw, and thermal
protection may occur.
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Grounding

Power consumption

Martin Audio – MA1.3 Power Amplifier
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