Предусилители — Accuphase C-2900

The C-2900 is a stereo preamplifier from Accuphase Laboratory of Japan and, by the maker's count, the fifth generation of its precision preamps built around the AAVA volume system. That lineage began with the C-2800 in 2002 and continued through the C-2810 in 2006, the C-2820 in 2011 and the C-2850 in 2016. Accuphase states that the new model carries over technology from the C-3900, which it names as its flagship preamp.

Key specs that matter

The front panel offers switchable overall gain of 12, 18 or 24 dB, balance control handled through the AAVA circuit, mono or stereo operation, and an attenuator that drops the level by 20 dB at once. There is a loudness compensator, a subsonic filter against ultra-low frequency noise from warped records, per-input phase adjustment and a display for input and volume level that can be turned off. Two balanced outputs sit on the rear together with recorder connections for line level in and out and EXT PRE inputs for linking an external preamplifier. A discretely built headphone amplifier draws high output current from its own dedicated supply.

Engineering and use context

AAVA stands for Accuphase Analog Vari-gain Amplifier, a volume principle that takes every variable resistor out of the signal path. In the C-2900 two AAVA modules run in a fully balanced arrangement from input to output, and the company quotes noise about 21 percent lower than in the C-2850. The knob is only a position sensor, and its motor and gear set float on custom silicone rubber mounts with specially made grease for quiet movement. Signal switching uses logic-controlled relays. Circuit boards are made of glass cloth fluorocarbon resin with gold-plated copper foil and sit in rigid aluminium frames, with separate amplifier units for left and right. The internal layout is inherited from the C-2850 and is symmetrical around a large toroidal transformer with heat-radiation fins, and four custom 10,000 uF capacitors, 40,000 uF in total, filter the supply. The case has a mirror-finish wooden cabinet and cast iron insulator feet, and a remote commander is supplied.

Pairing

Vinyl replay needs the optional AD-2900 phono board. It switches between MM and MC, offers MM gain of 34 or 40 dB and MC gain of 64 or 70 dB, and gives five MC load values of 10, 30, 100, 200 and 300 ohm, the 200 ohm step being new. MM input impedance is fixed at 47 kohm. Its head amp uses bipolar transistors for MC and junction FETs for MM, followed by a differential RIAA stage, and Accuphase quotes 29 percent lower MC noise than the AD-2850.

Alternatives

The Accuphase C-3900 is the stereo preamplifier from which the C-2900 inherits its balanced AAVA technology.