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Simple configuration with non-feedback discrete circuit
The amplifier circuit is a completely non-feedback amplifier with no feedback loop whatsoever. This simple configuration, which just adds a selector and volume to the power amplifier, is necessary to maintain the freshness of the signal without allowing it to deteriorate.
Parallel push-pull output stage with high-speed, high-output TO3P transistors
The output stage is a parallel push-pull design that uses the same high-speed, high-output TO3P transistors as those employed in the A-3. The output stage transistors are precisely matched for hfe, eliminating the sound smearing that is a drawback of conventional parallel push-pull designs.
Ultra-powerful driver stage
The driver stage also uses the same TO3P transistors as the output stage. By supplying a high current to the driver, hfe fluctuations caused by current changes in the output stage are instantly compensated for, generating powerful driving force. This is the biggest difference from the original and a breakthrough.
4-stage Darlington circuit
A 4-stage Darlington configuration using high-frequency transistors is employed to fully drive the output transistors, with the current flow of each stage carefully optimized. This ensures ample driving power for any speaker.
Newly developed voltage amplifier stage
The voltage amplifier stage circuit has been newly developed for the A-2 ver.2. It has been significantly simplified from the original design, and the bias circuit has been completely redesigned as well.
By lowering the output voltage compared to the original, the large, non-impregnated toroidal power transformer prioritizes instantaneous current supply capability at low impedances over maximum output at 8 ohms, dramatically enhancing the perceived sense of power and control.
Relay-switching balanced attenuator
Instead of a rotary volume control or electronic volume circuit, a balanced attenuator system is used, switching high-precision resistors through SOULNOTE’s proprietary relays. This dramatically improves clarity and produces a richly three-dimensional sound image. In addition, sound quality at low volume levels is significantly enhanced, eliminating concerns about channel tracking errors.
Ideal construction
The input signal path is kept to an absolute minimum by integrating the input terminals, input selector, volume control, and non-feedback voltage amplification stage onto a single multi-layer board. This design eliminates factors that degrade sound quality—such as vibration, inductance in connection cables, and the influence of radiated noise—without relying on shielding or filters that can negatively affect the sound. This ideal construction is made possible only by the relay-switching balanced attenuator design.
Power block construction
The power block, comprising the output stage and main power supply, uses a 70-micron copper-foil inner-layer plane as the power bus bar, minimizing the large-current loop (rectifier capacitor → output transistor → speaker + terminal → speaker – terminal → rectifier capacitor). By eliminating the inductance in this high-current path, the design achieves exceptionally high frequency response and stability.
Contactless wiring
Not only the signal lines but also the power lines have no connectors, with cables soldered directly to the board, making the connections completely contactless.
Chimney-type heat sink
The heat sink uses a chimney-type design, providing high cooling efficiency while minimizing inherent vibration.
Structure that prioritizes sound quality
The structure is designed with sound quality as the top priority, featuring a non-fixed top cover, feet placed directly under the power transformer to eliminate vibrations, and a non-fixed circuit board.
Power amplifier mode
In power amplifier mode, the microcomputer power supply is stopped, and the selector and volume are bypassed, further improving the signal-to-noise ratio. In this mode, XLR and RCA inputs can be selected.
Four selectable operating modes
The following four modes are selectable:
Stereo integrated amplifier
Bi-amplifier
Mono integrated amplifier
Stereo power amplifier
Bi-amplifier
Mono power amplifier
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Product Name: A-2 VER2 SF (Premium Silver) / A-2 VER2 BF (Premium Black)
Output Power: 80 W × 2 (8 Ω), 160 W × 2 (4 Ω)
Total Harmonic Distortion: 0.16 % (1 W, 8 Ω)
Frequency Response: Speaker (8 Ω, 1 W): 3 Hz – 240 kHz (±1.0 dB)
Input Sensitivity / Impedance:
LINE 1, 2, 3 (balanced): 700 mV / 16 kΩ
LINE 4, 5, 6: 700 mV / 8 kΩ
S/N Ratio: 110 dB (IHF-A network)
Power Supply: AC 100 V, 50/60 Hz
Power Consumption: 235 W (J60065), 70 W (idle)
Maximum Dimensions: 430 (W) × 162 (H) × 423 (D) mm
Weight: Approx. 20 kg
Accessories: Remote control, spikes, power cable
JAN Code:
Premium Silver: 4580197838496
Premium Black: 4580197838458
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