Soulnote A-3 Core: Stereo power amplifier boasting unique technology

Japanese manufacturer Soulnote presents the A-3 Core, a top-tier stereo power amplifier that integrates technologies from its range of high-end products. Notably, it features a unique ground separation system, similar to that found in the P-3 preamplifier and the A-3 integrated amplifier. Additionally, the amplifier utilizes a single push-pull output stage derived from the flagship M-3 monoblock.

Soulnote has incorporated the ground isolation feature of the P-3 preamp into the A-3 integrated amplifier. This principle is also applied in the A-3 Core. Each channel, left and right, is powered by its own 700 Watt toroidal transformer. The amplifier employs straightforward non-NFB circuitry along with an optimized design for all components, ensuring that the amplifier cabinet remains ground-free. This design minimizes high-current loops and reduces the necessity for coils.

The M-3 Monoblock has demonstrated that a single-ended and single-push-pull output is crucial for delivering an emotionally engaging musical experience by removing blurring in the microscopic time domain. Consequently, the A-3 Core incorporates the same reliable push-pull output stage, managed by a four-fold Darlington circuit. A TO3 bipolar transistor is utilized to achieve the required high current amplification.

The A-3 Core features a copper plate that functions as the primary heat sink. This plate also acts as a busbar for powering the TO3 transistor, allowing connections to be directly mounted to the circuit board through the copper plate. This design eliminates the wiring typically associated with standard TO3 transistor configurations. Soulnote employs a unique mechanical approach in its products, including the A-3 Core, where the robust construction does not necessitate tight screw connections for certain components due to acoustic considerations. The amplifier block, along with its connections and both top and bottom covers, is secured loosely. Notably, the amplifier block incorporates a three-point structure with titanium sliders that allows lateral movement, accommodating thermal expansion and contraction.

Soulnote specifies an output power of 120 watts per channel at four ohms, with a frequency response ranging from 2 Hz to 200 kHz (+/- 3 dB, 1 watt, 8 ohms). The dimensions of the A-3 Core are 454 x 189 x 435 millimeters (W x H x D), and it has a weight of 29 kilograms. The manufacturer offers both black and silver finishes.