Интегральные усилители — Soulnote A-2

Soulnote of Japan builds the A-2 integrated amplifier in silver or black, and Soulnote regards it as the culmination of its fully balanced, non-feedback technology. Apart from normal stereo use it can be configured for several monaural operating modes, including a bridged BTL setup and a bi-amp arrangement, and a mode that turns it into a pure power amplifier is also provided. That flexibility lets one unit serve as a stereo integrated today and as half of a dual mono system later.

Key specs that matter

Rated output is 100 W x 2 into 8 ohm and 200 W x 2 into 4 ohm, and in BTL mono mode a single unit delivers 400 W into 8 ohm. Total harmonic distortion is 0.03 percent at 50 W into 8 ohm, with frequency response spanning 3 Hz to 240 kHz within 1.0 dB at 1 W. Signal to noise ratio is 110 dB IHF A. Three balanced and three unbalanced inputs are provided, all with 700 mV sensitivity, at 16 kohm impedance for XLR and 8 kohm for RCA. Consumption is 355 W in operation and 125 W at idle. The chassis measures 430 x 162 x 423 mm and weighs about 20 kg.

Engineering and use context

Soulnote says voltage feedback has been thoroughly eliminated from the output stage all the way back through the power supply circuit. Bias and constant current circuits rely on 2SK209 constant current parts and LEDs serving as constant voltage elements. Volume is set by a proprietary balanced attenuator that switches precision resistors with relays rather than a rotary potentiometer. Components are concentrated on a multilayer circuit board so that the input signal lines stay as short as possible. Power comes from a 600 VA bifilar toroidal transformer with fast recovery diodes and Elna capacitors. Each channel has four parallel pairs of 2SC2837 and 2SA1186 high-speed transistors in the output, fed by a four-stage Darlington driver, which Soulnote credits with ample capacity for driving loudspeakers. Six operating modes can be selected in total, covering stereo, BTL mono and bi-amp mono as integrated amplifier and the same three as power amplifier.

Pairing

A Soulnote S-3 disc player can be connected by XLR cables. A second A-2 turns the pair into a mono system, either bridged for more power per speaker or in bi-amp mode for loudspeakers with split terminals.

Alternatives

The Soulnote A-3 stands above it in the Soulnote line, rated at 120 W per channel and weighing about 31 kg.