Accuphase A-100 (1991)
A monaural power amplifier launched in 1991, built for high-current Class-A performance with extensive use of MOS FETs and premium materials.
Overview
The Accuphase A-100 is a monaural power amplifier made by Accuphase Laboratory, Inc., launched in November 1991. Designed without compromise for high-fidelity audio reproduction, it operates in pure Class A and uses a balanced bridge configuration across all stages. It was priced at 950,000 yen per unit at launch, reflecting its position as a high-end amplifier built with precision engineering and premium components.
Specifications
| Continuous average output (20Hz-20kHz) | 2 ohm: 400W, 4 ohm: 200W, 8 ohm: 100W, 16 ohm: 50W |
| Full harmonic distortion | 2 ohm: 0.02%, 4–16 ohm: 0.01% |
| IM skewness | 0.003% |
| Frequency response | 20Hz to 20000Hz, +/-0dB (at continuous average output, level control MAX); 0.5Hz to 150000Hz, +0 -3.0dB (at 1W output, level control MAX); 0.5Hz to 80000Hz, +0 -3.0dB (at 1W output, level control -6dB) |
| Gain | 28dB |
| Load impedance | 2 to 16 ohm |
| Damping Factor | 250 (8 ohm, 50Hz) |
| Input sensitivity (8 ohm) | 1.13V (full output), 0.12V (1W output) |
| Input impedance | Unbalanced: 20kohm, Balanced: 40kohm |
| S/N(A-correction) | 120dB (short input, full output) |
| Power Meter | Logarithmic compression peak level display, direct reading at 8 ohm |
| Semiconductors used | 16Tr, 44FET, 10IC, 44Di |
| Power | 100V, 117V, 220V, 240V, 50Hz/60Hz |
| Power consumption | 350W (no input), 480W (rated per Electrical Appliance Law), 350W (8 ohm rated output) |
| Exterior Dimensions | W475 x H240 (incl. legs) x D553mm (incl. handle) |
| Weight | 57.0kg |
Design
The A-100 is a pure Class-A monophonic power amplifier with a balanced bridge configuration throughout. The output stage uses 10 parallel N-channel and 10 parallel P-channel power MOS FETs per unit, bridged together—40 MOS FETs total across two units. The input stage features Accuphase’s original balanced pure complementary push-pull design with FET buffers in a custom 60mm x 35mm hybrid IC, shielded with thick aluminum. The signal path uses gold-plated copper, and power delivery relies on oxygen-free copper cylinders with gold plating. The chassis is constructed from 9mm-thick aluminum, and the power transformer is a high-efficiency toroidal type mounted in a die-cast aluminum case with damping filler. The heat sink, made of extruded aluminum, has a total surface area of 16.4 liters and weighs about 20kg, with a center handle for resonance control. Ultra-large solid brass speaker terminals, gold-plated and mounted in parallel for bi-wiring, ensure robust connections. The smoothing capacitor is housed in a 4mm-thick die-cast aluminum case with special fixing material, and high-purity wire shields the attenuator.
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Service Manuals, Schematics & Catalogs
- Manual — archive.org
- Catalog (1991) — archive.org
- Catalog (1992) — archive.org
- Catalog (1990) — archive.org
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