AVM evolution m3ng Руководство по эксплуатации - Страница 4
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Печатать страницуPeople who concern themselves with music know that the human ear reacts much more sensitively to signal
falsifications than any measuring instrument. One of these falsifications occurs when an amplifier operates
too slowly: An insufficient slew rate leads to erosion of the edges of the signals. The human ear orientates
itself on the first wave front (in other words the first rising edge of an impulse) to locate the source of sound.
Amplifiers with insufficient speed very often produce an unprecise image and some instruments do not
produce clarity. To avoid this only an extremely fast circuit technique, current control and field effect
transistors (FETs) in the output are considered.
Fast circuits can also cope far better with a second form of signal falsification: Harmonic distortion.
Instruments produce their tonal quality through the harmonics that exist alongside the fundamental tone.
These harmonics are responsible for ensuring, for example, that we can instantly distinguish the tone of a
flute from that of a trumpet.
If an amplifier produces such distortions then they are often not as harmonic as their name suggests. This
has to do with the fact that the amplifier must reproduce signals simultaneously from several instruments.
Besides harmonic waves in octave bands (distortion) there also arise blends of sound (intermodulation) that
sound inharmonic and disturb the enjoyment of the music. Especially the high frequency distortions sound
unpleasant to the ear because the height of tone has separated itself unnaturally from the original signal and
is therefore instantly identifiable.
Can it really be said that a distortion-free amplifier is musical? Experience has shown us that this is not so. A
certain level of artificially produced harmonic waves, correctly composed helps the ear to identify instruments
better and results in a much more lively sound. This is related to the fact that when listening to music from a
hi-fi unit the support afforded by visual impressions is missing. For this reason a visit to a concert provides a
genuine live experience - even when your point of listening doesn't provide optimal acoustics.
With due regard to its almost distortion free circuitry and following extensive periods of aural testing with
different loudspeakers we have enhanced the quality of listening by installing "musical" distortion
characteristics which almost approach the ideal of "live performance" - regardless of the model of
loudspeaker.
1.3 Details about the circuitry
The M3NG has two separate supply units with discrete, independent transformers. One transformer
exclusively supplies the input- and driver stages as well as the protective circuitry. The second is solely
responsible for the delivery of power to the output stage.
The toroidal transformer of the main power supply unit can deliver a continuous power output of 500VA and
contains two galvanic separated windings. One transformer winding is responsible for the positive, the other
for the negative supply voltage. The total available capacitance of the M3NG exceeds 60.000 µF. The
extravagant construction of the power supply components and the high filter capacitance of the voltage
supply ensure that even complex signals, large phase shifts and low-impedance loudspeakers do not
detrimentally affect the exactness and low disturbance levels of the input- and driver stages through
reactions from the power section. The mono amp retains its well balanced and permanently well defined
sound impression under all prevailing conditions.
A highly precise, extremely fast operational amplifier is installed in the input. This input receiver is
responsible for impedance conversion and the conversion of balanced signals (received through the XLR-
socket) into unbalanced signals.
Then a circuitry adds a certain portion of harmonics to the signal. The amount of added harmonics can be
controlled externally by the user.
The subsequent power amplifier circuitry incorporates two voltage boosters and a subsequent current
booster which provides immunity against stray capacitances. This permitted to incorporate a ground plane in
the pc-board without suffering loss of speed. The ground plane disconnects the individual amplifier stages by
absorbing their stray fields. In this way it was possible to exclude unwanted mutual influences which provoke
parasitic oscillations. To support this the supply voltage was stabilized at strategic, important points through
electrolytic/film capacitor combinations.
Together the output FETs have a current delivery capability of over 60 Amperes. TO-220 types were
deliberately chosen (internally they use the same chip as the mechanically somewhat larger TOP-3 housing)
because a very good electrical contact is provided by the existing metal tag when screwed to the heat sink.
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