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| MARK LEVINSON No20.5L |
2,760,000yen( It is 1 set in two sets, 1989 release) |
Monophonic power amplifier which polished up the
tone quality based on No20L, and was developed.
The main changed parts from No20L to No20.5L are enhancements of the circuitry
in the input-stage-voltage amplification stage, and a circuit element,
and one plug-in PC board (card module) is changed.
Two mass toroidal transformers of 600VA are carried in a power-source
part, and it has the completeness ± independent stream composition. Moreover,
the included power amplifier whole page is controlled for the output stage by it
being parallel to an electrolytic capacitor, and connecting to it the quality
polyethylene type which was extremely excellent in the impedance characteristic
with the low-noise, and also adopting a high-speed regulator circuitry with
large capacity.
AP-4 circuit board is adopted as an input stage and the amplification stage.
The voltage amplification stage has AC amplifier composition of two steps of differentials. Moreover, the first rank considers it as the differential circuit by an NPN transistor, and makes the cascode interconnection of the FET.
The 2nd step of differential amplifier serves as an active loading circuitry by a current mirror push-pull operation. And the voltage amplification stage serves as a three-step Darlington stream composition, and the driver stage has triple push pull composition.
The output stage has eight-step parallel push pull composition.
Some candidates who selected from all over the world were tested in the
power transistor again in property, and the bipolar [ which carries out the
prolonged listening comprehension test equipped with what remained out of it ]
model transistor by which even free was taken up is adopted as it.
A
protection network eliminates the relay leading to a tone-quality failure, and
it is coping with it by turning OFF a power source in an emergency.
It
has a XLR (canon) termination besides the CAMAC termination which has
established reputation in an input terminal in the height of a robustness, and
the balance input is also supported.
Moreover, it is also possible to carry
the INVERTING termination and to carry out two-set bridge connection.
There was an upgrade service of descriptions, such as a switching to AP-4 circuit board for No20.5L from AP-3 circuit board for No20L and a switching of a power transistor set. Moreover, there was also a service which exchanges the front panel for the thing of No20.5L entering a model name. (AP-3 circuit board, a power transistor, and the front panel had become the Herman taking over)
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| Form |
Monophonic power amplifier |
| Circuitry |
The complimentary push-pull circuit by whole page
pure class A operation |
| Output power |
400W (2ohm)
200W (4ohms
100W (8 ohm, 20Hz - 20kHz, and less than THD0.1%) |
| Input impedance |
50kohm |
| Power source |
AC100V, 50Hz/60Hz |
| Power consumption |
About 500W |
| Dimensions |
Width 483x height 210x depth of 560mm
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| Weight |
33kg |
| Remarks |
Upgrade to No20.5L from No20L
A circuit boat, a transistor switching (358,000yen)
Front panel switching (110,000yen)
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