::: continuation of a previous legend Assistent 10 / 20 :::
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::: continuation of a previous
legend Assistent 10 / 20 :::
By popular request
of the AudioValve Fan Community, AudioValve proudly presents a succession
model within the Assistent series, the Assistent 50.
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One of the original features of the Audio Valve products is to be found in the utilisation of the valves in such a way that they operate as closely as possible to their ideal reference values each according to its type. One recalls, for instance, the output pentode-triode PCL 805 and most particularly the small beam tetrode with a common cathode QQE 3/12. This valve with a noval (nine pin) base was manufactured formerly by Valvo, Philips and Telefunken etc. (the latter was used in our test amplifier) It has a per plate power dissipation of 7,5 W and may be used with plate voltages ranging from 200 to 300 V. It is ideal in class A and AB amplifiers. This valve, according to Helmut Becker, is ideally adapted to be integrated in a circuit which includes another very innovative concept, an automatically operating grid bias control, refered to as "ABR" and used to great advantage in the integrated amplifier Assistent - 50.
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The amplifying circuit uses 12 valves, but the push-pull output stages are coupled to the ABR circuit for each power tube. This exclusive AudioValve feature, allows a comparison of the reference voltage value with that engendered by the quiescent current and which appears at the terminals of a small value resistance in the return cathode circuit. A small operation amplifier monitors, as comparator, the divergence and deliverers the compensation voltage to the grid of the valve. Each valve, young or old, reaching reference values or not is thus compensated in its Grid bias to operate at a value which corresponds to its optimal quiescent currant. A red LED diode, at the foot of each value lights up preventing the use of inadequate or defect valves. For each channel the input stage and driver stage are served by an almost known noval valve, the double triode ECC 82. |
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The classical chassis has been set into a caisson (a case-like frame). The valves sit in their sockets mounted on a double side printed circuit board. Little columns support the glass cover preventing dangerous hand contact burns or electric shocks could ensue conforming to the CE requirements. The cooling is achieved through the rearsides and topglas. The minimal controls mounted at the front consist of and a volume control the two channels and input selector being coupled in their operation by a remote control. At the back are the cinch input sockets, two pairs of output terminals and a mains switch and connector. |
tech. - features: Type: Integrated stereo tube amplifier |
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