AVM evolution m3ng Manual de Instruções - Página 3
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Imprimir página1. Basic information
1.1 Technical highlights of the M3NG
• extremely short signal paths for quick reaction. Rise- / fall times below 2 microseconds.
• RCA-cinch inputs as well as balanced XLR inputs. Fully insulated gold plated speaker terminals.
• two independent power supplies for driver and power stages make the circuits free of influences from load.
drive capability down to below 2 Ohms load.
• soft start circuitry avoids large current peaks when switching on.
• 500 VA power transformer, over 60.000 microfarads of capacitance, extremely fast rectifiers make a stable,
quick power supply with huge reserves for powerful bass reproduction.
• protection circuitry overheat and short circuit ensure trouble free operation.
• automatic switch on and switch off circuitry and trigger input make the mono amps easy to use.
• environment friendly 1 watt stand by power consumption.
1.2 Basic principles of construction
A musical/physical guide to circuitry design
In the true physical sense audible music is comprised of variations in air pressure, regardless of space, that
are converted by the ear and brain into a listening experience. Over- and under pressures alternate whereby,
when observed over a long period of time, the energy produced by the over- and under pressures exactly
balance. This means that there is symmetry with regard to the normal air pressure present in a quiet space.
Circuitry that amplifies the electronic image of music (AF signal) should therefore be so constructed that the
symmetry of the music signals described above perfectly matches. The ideal topology of circuitry is therefore
symmetrical to its electrical ground.
Besides the symmetry described above there is a second type of circuit-symmetry. This is achieved by the
use of two amplifiers. One branch transmits the music signal, the other the electronic mirror-image of that
signal. The English terminology "balanced" describes this type of circuitry very well, the common German
term "symmetrical" is misleading. Acoustic pressure does not exist as a mirror-image, the pressures would
equalize themselves out and there would be silence. Concerning musical transmission there is no real
requirement for "balanced" signals unless you wish to eliminate interference along the transmission path, or
compensate distortions (pre amplifier, long cabling).
It is quite normal to find relatively high signal levels in a power amplifier. Through consistent mechanical
assembly (supply unit) significant disturbing influences of the music signal do not occur. A well manufactured
circuit produces such minor distortion that, even from this point of view, a balanced circuit to amplify both the
signal and its mirror-image is not necessary.
Pre amplifiers have to process high-impedance signals mostly at low level. There a "balanced" circuitry
design can offer advantages. This problem does not exist with power amplifiers. Here a "balanced" circuitry
assembly would even produce very grave disadvantages. A simple theoretical experiment helps to explain
this. The output stages of a "balanced" power amplifier deliver the music signal to one of the loudspeaker
connections. The second, on the other hand, is supplied with the electrical mirror-image.
To understand what that means for the individual output stages you can divide the voice coil into two equal
portions, each possessing half of the total impedance. Because both are connected in series this
arrangement gives, in our experiment, exactly the total impedance of the loudspeaker. Therefore when one
output stage supplies positive voltage to the loudspeaker the other is providing an exactly equivalent
negative voltage. At the point where both parts of the voice coil are connected, the signals compensate each
other exactly. From this you can envisage that this point is "ground".
If we now look at the arrangement in a different way the result is that each of the output stages work on a
load that exactly makes half of the loudspeaker impedance and is grounded at the other end. The
consequences of this: The damping factor is halved, distortion increases and the slew rate can deteriorate.
To achieve optimal musical quality in the essential series power amplifiers we use a circuitry concept that is
constructed in symmetry to "ground" but works "unbalanced". A damping factor of over 500 and complete
load stability, even with critical loudspeakers, are two of the essential pre conditions required for the perfectly
natural music reproduction that our power amps produce.
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