Интегральные усилители — Soulnote A-3

Made in Japan in silver and black versions, the Soulnote A-3 integrated amplifier brings the circuitry of the P-3 preamplifier and the M-3 power amplifier together in one chassis, which Soulnote says was done without compromise. Its central idea is a full split between left and right channel grounds, reached through simplified non-feedback circuits, careful board artwork, minimised high-current loops and the removal of inductive parts. Relay control signals pass through photocouplers so that the two channels stay isolated.

Key specs that matter

The rear carries three XLR inputs plus three RCA inputs, with 480 mV input sensitivity and a maximum gain of 33 dB. Maximum output is 120 W x 2 into 4 ohm. Total harmonic distortion is 0.27 percent at 1 W into 8 ohm, and the frequency response reaches from 2 Hz to 200 kHz within 3 dB under the same conditions. Signal to noise ratio is 110 dB. Besides the single set of speaker terminals, the rear offers REC OUT and a volume bypass output, each in balanced and unbalanced form. Power consumption is 180 W, falling to 86 W at idle. Including spikes the case is 454 x 189 x 456 mm, and it weighs approximately 31 kg.

Engineering and use context

A single push-pull SEPP pair of TO3 bipolar transistors forms the output, preceded by a four-stage Darlington arrangement that uses powerful TO3P devices as driver and pre-driver. A copper heatsink doubles as the bus bar of the power supply, removing wiring inductance and tying the power and amplifier boards together mechanically. Voltage gain comes from the Type-R circuit, a single-stage design of high gain referenced to ground that uses naked foil resistors only. Input selection switches the ground as well, and the volume control switches resistors with RSR relays and more naked foil parts. The supply is a fast non-feedback design with 470 uF film capacitors and SiC diodes. The ground anchor sits in a side chassis isolated by ceramics, and an unfixed structure with a titanium three-point sliding system lets the chassis move horizontally. A volume bypass function sets a fixed gain of 22 dB, and several units can be linked through a 3.5 mm stereo mini plug. Supplied items include a remote control, spikes, a spike isolation board, spacers and a power cable.

Pairing

The REC IN and REC OUT terminals connect a recording device, and the Soulnote S-3 disc player connects through balanced cables.

Alternatives

The Soulnote A-2 is a lighter integrated model of the brand rated at 100 W per channel.