Accuphase A-50V (1998–2004)

Name: Accuphase A-50V
Brand: Accuphase

Pure Class-A stereo power amplifier with dual-mono construction and 100W/ch into 4 ohms.

Overview

The Accuphase A-50V is a pure Class-A stereo power amplifier produced from December 1998 to 2004. Designed using the same technology as the flagship M-2000 monoblock, it represents the highest-end Class-A stereo amplifier Accuphase offered in the early 2000s. The unit features dual-mono construction, a switchable bridge mode for monaural operation, and balanced input terminals. It was succeeded by the A-75 and is part of the "V" series lineup that includes the A-20V, A-30V, A-50V, and A-100V.

Specifications

Power Output (stereo)	100W/ch into 4Ω, 50W/ch into 8Ω
Power Output (monaural, bridged)	400W into 4Ω, 200W into 8Ω
Total Harmonic Distortion	0.03% (4Ω–16Ω, stereo and monaural)
Frequency Response	20Hz–20kHz (+0, -0.2dB at rated power)
Damping Factor	100
Input Impedance	Balanced: 40kΩ, Unbalanced: 20kΩ
Gain	28.0 dB (stereo and monaural)
Signal-to-Noise Ratio	110 dB (A-weighted, input shorted)
Power Supply	100 VAC, 50/60Hz (switchable for other markets)
Power Consumption	550W (max, Electrical Appliance and Material Control Law)
Dimensions	475 mm W × 239 mm H × 545 mm D
Weight	45.1 kg
Power Transformer	1,000 VA, super-ring type toroidal
Filter Capacitors	Two 82,000 μF aluminum electrolytic
Digital Power Meter	True value display, 0.1W–400W (stereo), 1W–2000W (monaural)

Design

The A-50V uses a dual-mono, pure Class-A design with a current feedback (trans-impedance) amplifier circuit. Each channel employs 10 parallel push-pull pairs of power MOS FETs with negative thermal characteristics, driven by a cascode-connected MOS FET stage. The power supply uses a 1,000 VA super-ring toroidal transformer and two 82,000 μF filter capacitors. High-purity copper and gold plating are used throughout the signal path, including on the machined solid brass speaker terminals. Extra-large heat sinks serve each channel, and the digital power meter calculates output using an analog multiplier.

Context

The A-50V was positioned as the top-tier Class-A stereo power amplifier in Accuphase’s lineup during the early 2000s and served as the predecessor to the A-75, which retailed for $32,500 as of August 2023.

Market

A listed unit converted to 120V by an authorized US service center was priced at $4,316.09 four years ago, with excellent operational condition and minor cosmetic wear rated 8/10.

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