Предусилители — Accuphase C-3900

The C-3900 is the top precision stereo preamplifier from Accuphase, the Japanese electronics maker based in Yokohama. Development began to mark the company's 50th anniversary and took five years, and the C-3900 was introduced in 2020 as the culmination of Accuphase's AAVA volume-control work. It was later succeeded by the C-3900S, which lowered noise by a further 15%.

Key specs that matter

The C-3900 provides four balanced XLR and six single-ended RCA line inputs, with two balanced and three single-ended outputs. Volume is controlled by Dual Balanced AAVA, and the input stage is a high-gain discrete current-feedback amplifier with ANCC noise-cancelling circuitry. Left and right channels have separate toroidal power transformers, separate filter capacitors and separate amplifier units. A headphone amplifier is built in. The chassis measures 477 x 156 x 412mm and weighs 24.6kg, with a natural-grain wood cabinet.

Engineering and use context

Most preamplifiers set volume with a resistive attenuator, reducing the signal level before or after amplification, which changes impedances and adds noise. Accuphase's AAVA (Accuphase Analog Vari-gain Amplifier) removes the resistive attenuator from the signal path. The signal is converted from voltage to current by a set of V-I converters with different gains, and the volume position switches combinations of these converters, changing the amplifier's gain directly. Impedance and frequency response therefore stay constant at every volume setting, and noise stays low at the levels most often used in practice. Balanced AAVA uses two AAVA circuits in a balanced connection, and the C-3900's Dual Balanced AAVA drives two such balanced units in parallel, lowering noise by about 30% compared with previous Accuphase preamplifiers. The volume knob does not turn a potentiometer - it drives an in-house position sensor built into a precisely machined, extruded aluminium block, giving accurate angle detection. Circuit boards use glass-cloth fluorocarbon resin for low dielectric loss, and the dual-mono layout keeps the channels electrically independent to minimise crosstalk.

Pairing

With four balanced and six single-ended inputs, the C-3900 acts as the control centre for complex systems with several sources, including phono stages and DACs. Its balanced outputs suit long runs to Accuphase power amplifiers such as the A-300 or M-series monoblocks, and the second pair of outputs can drive a subwoofer or second amplifier for bi-amping.

Alternatives

Accuphase's own C-2900 applies Balanced AAVA to a less expensive preamplifier sitting below the C-3900.