A-2000 Power Amplifier

The A-2000 25th Anniversary is an updated version of the original A-2000. It uses the new, powerful and musical KT150 power tube, with requisite changes to transformers and several minor circuit elements.

The A-2000 25th Anniversary has the following features:

• 100 watts of high power output in pentode mode, 50 watts in triode.
• Powerful Driving Circuitry : Allnic believes in the importance of using high-quality, low noise and powerful driving circuitry in all its amplifying devices. Therefore, in the A-2000 25th, we employ the E282F tube in triode mode as the second stage driver tube, with a load of about 5K ohms, and using 20mA of current. The listener can easily hear and even “feel” the differences between this design and other, more conventional, ones. Please imagine, as you listen to the A-2000 25th, its sound compared to the sound of an amplifier with conventional 12AU7 or 12BH7s used as drivers, with a load of about 47K ohm, and using 2 to 3mA of current.
• “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 or 8 ohms or 16 ohms, depending on the factory configuration you have selected). 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 : In order to provide constant current (bias) monitoring for the power tubes, the A-2000 25th 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. 5
• “On-the-fly” Triode/Pentode Switching : Switching between triode and pentode operation can be done “on-the-fly” at any time while the amplifier is in use.
• Beautiful 20kHz square wave response.