A-2 Ver. 2 Integrated Amplifier

Premium Silver/Premium Black

Version 2 is a dramatic evolution based on the knowledge gained from the 3 series.

[Top]

[Bottom]

Simple configuration using non-feedback discrete circuits

The amplifier circuit is a completely non-feedback amplifier with no feedback loop whatsoever. The simple configuration of just a power amplifier with a selector and volume is essential to maintain the freshness of the signal without allowing it to deteriorate.

Parallel push-pull with high-speed and high-power TO3P transistors

The output stage is a parallel push-pull configuration using the same high-speed, high-output TO3P transistors used in the A-3. The output stage transistors are precisely paired with hfe, eliminating the sound bleeding that is a drawback of parallel push-pull configurations.

Super powerful driver stage

The driver stage also uses the same TO3P transistor as the output stage. By passing a large current through the driver, it instantly compensates for hfe fluctuations caused by current changes in the output stage, generating powerful driving force. This is the biggest difference from the original and a breakthrough.

4-stage Darlington circuit

To fully drive the final transistor, a four-stage Darlington configuration using high-frequency transistors is used, and the amount of current for each stage is optimized, providing ample driving power for any speaker.

Newly developed voltage amplification stage

The voltage amplification stage circuit has also been newly developed for the A-2 ver. 2. It has been significantly simplified from the original, and the bias circuit has also been completely redesigned.

Non-impregnated large toroidal power transformer

By lowering the output voltage compared to the original, we prioritized instantaneous current supply capability at low impedance over maximum output at 8 ohms, resulting in a dramatic improvement in the audible power and grip.

Relay switching type balanced attenuator

For volume adjustment, instead of a rotary slider or electronic volume, we have adopted a balanced attenuator system that switches high-precision resistors with SOULNOTE's unique relay. This dramatically improves clarity and creates a three-dimensional sound image. Furthermore, sound quality at low volumes is also significantly improved, eliminating the worry of gang error.

Ideal construction

The input signal line is minimized by concentrating the input terminal, input selector, volume, and non-feedback voltage amplification stage on a single multi-layer board. This eliminates factors that degrade sound quality, such as vibrations and inductance components in the connection cables, and the effects of radiated noise, without using any shielding or filters that would adversely affect sound. This is an ideal construction that could only be achieved with a relay-switching type balanced attenuator.

Uses a 4-layer board with a copper foil thickness of 70 microns

The power block, consisting of 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 of "rectifier capacitor → output transistor → speaker + terminal → speaker - terminal → rectifier capacitor." By eliminating the inductance component of the large-current line, we have achieved extremely excellent frequency characteristics and stability.

Contactless wiring

Not only the signal lines but also the power lines have no connectors, and the cables are soldered directly to the board, making them contactless.

Chimney-type heat sink

The heat sink is a chimney type that has high cooling efficiency and a shape that minimizes inherent vibration.

Sound quality is the top priority

The structure is designed with sound quality as the top priority, with features such as a non-fixed top cover, feet directly below the power transformer to eliminate vibrations from the power transformer, and a non-fixed circuit board.

Power amplifier mode

In power amplifier mode, the microcomputer is powered off, and the selector and volume are bypassed, further improving the signal-to-noise ratio. In this mode, you can also select between XLR and RCA inputs.

4 types of usage available

You can choose from the following four ways to use it.

• Stereo Integrated Amplifier
• Bi-amplifier mono integrated amplifier
• Stereo power amplifier
• Bi-amplifier mono power amplifier