Accuphase C-280 (1983–1986)

Stereo preamplifier with dual-mono Class A design, built for analog and early digital audio playback.

Overview

The Accuphase C-280 is a high-end stereo preamplifier produced from March 1983 to 1986, positioned above the C-260 and below the C-290 in Accuphase’s lineup. It was engineered during the "Golden Era" of Japanese high-fidelity audio and designed to support both analog and emerging digital disc playback. The unit features a completely dual-mono structure with independent circuits and spatial layouts for each channel, emphasizing channel separation and signal purity. It includes a newly developed high-performance MC head amplifier with switchable gain and three-stage MC input impedance selection, making it particularly suited for low-output moving-coil cartridges.

Specifications

Frequency Response (Line/High Level)	20 - 20,000 Hz +0, -0.2 dB
Frequency Response (Phono/Disc)	20 Hz–20 kHz ± 0.2 dB
Total Harmonic Distortion	0.005%
S/N Ratio (Line/High Level)	110 dB (IHF-A)
S/N Ratio (Phono MM)	86 dB (IHF-A)
S/N Ratio (Phono MC)	74 dB (IHF-A)
Rated Output / Impedance (Unbalanced)	1.0 V / 50 ohms
Rated Output / Impedance (Balanced)	2.0 V / 600 ohm
Rated Output / Impedance (Tape Rec)	126 mV / 200 Ω
Maximum Output Voltage (Unbalanced/Balanced)	10.0 V
Maximum Output Voltage (Tape Rec)	19.0 V
Input Sensitivity (Phono MM)	2.5 mV
Input Sensitivity (Phono MC)	0.06 mV
Input Sensitivity (Line/High Level)	150 mV
Gain (Line → Tape Rec Output)	0 dB
Head Amp Gain	Switchable: +26 dB / +32 dB
Loudness Compensator	1: +3 dB (100 Hz), 2: +8 dB (100 Hz), +6 dB (20 kHz)
Subsonic Filter	15 Hz, 12 dB/oct
Attenuator	-20 dB, -30 dB, ∞
Semiconductors	Transistors: 225, FET: 16, IC: 33, Diodes: 167
Power Supply	100 VAC / 117 V / 220 V / 240 V, 50Hz/60Hz
Power Consumption	28 watts
External Dimensions	475 mm (W) × 151 mm (H) × 393 mm (D)
Weight	17.0 kg

Design

The C-280 uses a three-stage amplification circuit with all stages biased in push-pull Class A and enhanced by the cascode method. It features a fully dual-mono configuration, with dedicated power transformers for each channel and a dual-monaural power supply using two large transformers and four smoothing capacitors. Each transformer feeds six constant-voltage supplies to six independent modules. The power supply includes 264,000 µF of ELNA For Audio capacitors—22,000 µF per channel at 16 V. Signal routing uses nitrogen-sealed relays with gold-plated or silver-palladium contacts, wired in parallel for reliability. The volume control uses a precision metal film resistor ladder, and the unit includes 1 µm rhodium-plated terminals. The phono stage uses Silbird mica capacitors and high-purity silvered film capacitors, with a special flat amplifier for MC input.

Context

The C-280 was developed in response to the rise of digital audio and digital discs, bridging high-end analog and early digital playback. It is part of Accuphase’s "Classic Models Reference" and sits above the C-260 and below the C-290 in the preamplifier hierarchy. A later variant, the C-280 V, was produced from 1986 to 1990, and an extended version, the C-280L, also exists. Compared to the C-200L, the C-280 features a more robust power supply and higher original cost.

Market

Originally priced at ¥680,000, the C-280 was a premium offering and remains collectible, described as still costing "a lot" today. A listing five years ago noted a new price equivalent to $3,000. Known issues include rare failures in small radial lead capacitors resembling brown pillows, and hum problems potentially linked to transistor substitutions in low-level stages, with original components proving critical for stable operation.