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INTRODUCING THE A-2000 25
th
ANNIVERSARY SE KT150 PUSH-PULL STEREO POWER AMPLIFIER
The A-2000 25
th
Anniversary upgraded SE (Special Edition) version KT150 Power amplifier is Allnic Audio’s top
of the line, push-pull stereo power amplifier model. Like all Allnic Audio products, the A-2000 SE has Permalloy
(iron and nickel alloy) for its transformer cores. Allnic is grateful to Mr. G.W. Elmen of Western Electric for
inventing Permalloy for transformer core use, and in so doing, providing an enormous service to recorded
music listeners everywhere.
The A-2000 25
th
Anniversary SE is an upgraded version of the original A-2000. It uses the new, powerful and
musical KT150 power tube, a beam tetrode, with requisite changes to transformers and several minor circuit
elements. The A-2000 25th Anniversary SE has the following features:
•
100 watts of high-power output in pentode (beam tetrode) mode, 50 watts in triode. The A-2000 is a push-pull,
pentode/triode switchable stereo power amplifier.
•
Powerful Driving Circuitry. Allnic believes in the importance of using high-quality, low noise and powerful driving
circuitry in all its amplifying devices. Therefore, we employ the 6S4 pure triode tube in the SE version as the
second stage driver tube. The listener can easily hear and even "feel" the differences between this design using
higher loading and more current than other, more conventional, ones. Please imagine, as you listen to the A-2000
SE, its sound compared to the sound of an amplifier using conventional 12AU7 or 12BH7 tubes as drivers.
•
“Full Engagement" Output Transformers. Conventional output transformers use pre-set secondary windings to
accommodate 4, 8 and 16 ohm loudspeaker loads. However, these conventional transformers utilize
only one secondary winding at a time, while the other secondary windings remain "idle". This approach has two
adverse effects. First, the output transformers are not working at their maximum efficiency, reducing their output
relative to their potential. Second, the "idle" windings are not actually "idle"; they are subject to parasitic
oscillations, producing their own "signal". This undesirable electrical information is additive to the transformer's
output, distorting the amplified signal going to the loudspeaker. Allnic's "Full Engagement" transformers address
these issues by having 4 independent, secondary windings that are always fully connected, never "idled". This
means that all secondary windings are always connected to your loudspeakers, regardless of which output switch
position you use (4 ohms or 8 ohms for the A-2000 25
th
Anniversary SE). The result is that there is neither a loss of
transformer output efficiency, nor the introduction into the output signal of distortion from parasitic oscillations
of the secondary windings.
•
Large Nickel/FeSi Core Output Transformers. As with our other models, Allnic uses very large output
transformers (114 mm) with nickel, mixed with FeSi, cores. This provides for higher inductance with fewer
windings than other designs can provide and results in the great benefit of an extremely wide range of output
frequencies.
•
"Soft-start" Circuitry. Allnic uses soft start circuitry that, after sufficient warm-up only, provides the high voltage
supply to the plate of each tube. This protective design results in prolonged tube life and fewer and less frequent
issues with tube performance.
•
Analogue Power Tube Current Monitors. To provide constant current (bias) monitoring for the power tubes, the
A-2000 25
th
Anniversary SE has a separate analogue current meter for each pair of power tubes. The meters
make it exceptionally easy to see the status of each tube at any time and to respond immediately to any
variation in bias by use of the bias control knob for the relevant tube. The meters offer a simple, unambiguous
indication of each tube's status compared to conventional LED bias monitors.
