Accuphase M-2000 (1997)

Name: Accuphase M-2000
Brand: Accuphase

Solid-state monoblock power amplifier sold in December 1997 with extreme power output and precision engineering.

Overview

The Accuphase M-2000 is a solid-state monoblock power amplifier made by Accuphase Laboratory, Inc., sold in December 1997 at ¥1,000,000 per unit. Designed to deliver constant voltage drive regardless of loudspeaker impedance fluctuations, it features a current feedback amplifier circuit that uses signal current rather than voltage in the feedback loop. Each unit weighs 50kg and measures 475mm wide, 252mm high, and 545mm deep, with a chassis built from massive aluminum diecast heat sinks, front and rear panels forming a rigid structure.

Specifications

Output Power (8 Ω)	250W
Output Power (4 Ω)	500W
Output Power (2 Ω)	1,000W
Output Power (1 Ω)	2,000W
THD	0.03% (4–16 Ω), 0.05% (2 Ω), 0.1% (1 Ω)
IM Distortion	0.003%
Frequency Response	20Hz–20kHz ±0.2dB (rated output)
Gain	28.0 dB
Damping Factor	400
Input Impedance	Balanced: 40k Ω, Unbalanced: 20k Ω
Power Consumption	950W (max, per Electrical Appliance and Material Control Law)
Weight	50 kg (110 lbs)
Dimensions	475mm W × 252mm H × 545mm D
Power Supply	100 VAC, 50/60Hz

Design

The M-2000 uses a current feedback amplifier circuit with 22 parallel push-pull transistors per monoblock, each rated for 130W collector dissipation and 15A collector current, totaling 5,700W combined collector dissipation. Output transistors are mounted directly to massive aluminum diecast heat sinks. The amplifier features modular construction, a 1.5 kVA "Super Ring" toroidal transformer in a damped enclosure, and two 40,000 μF filtering capacitors. All major signal path components—including PCB traces, ground bars, capacitor bus bars, input jacks, and speaker terminals—are gold-plated. The front panel includes a large analog power meter with peak hold and logarithmic compression. Balanced inputs use pin 3 as positive, and a phase inversion switch is provided. The amplifier is noninverting from its unbalanced input.

Context

The M-2000 was developed to realize constant voltage drive in response to wildly fluctuating loudspeaker impedance. Accuphase Laboratory, Inc. was founded by former Kenwood engineer Jiro Kasuga in late 1972, with Kenwood holding partial ownership of Kensonic (Accuphase) until the mid-1990s.