Accuphase P-600 (1983)
A high-power stereo amplifier released in April 1983 with precision digital output meters and robust multi-impedance performance.
Overview
The Accuphase P-600 is a stereo power amplifier developed by Accuphase Laboratory, Inc. and released in April 1983. Designed as a high-performance solution for demanding audio systems, it delivers up to 700W per channel into 2Ω in stereo mode and can be bridged for monaural operation with output up to 1400W into 4Ω. It features digital power output meters with peak reading capability, stepped attenuators with ±0.1 dB precision, and extensive protection circuitry. The amplifier was positioned as Accuphase’s top-tier stereo class-A/B model during the early 1980s.
Specifications
| Production Year | April 1983 |
| Continuous Average Power (Stereo) | 700W/ch (2Ω), 500W/ch (4Ω), 300W/ch (8Ω), 150W/ch (16Ω) |
| Total Harmonic Distortion | 0.02% (1–2Ω), 0.01% (4–16Ω) |
| Frequency Response | 20 Hz – 20 kHz ±0.2 dB |
| Damping Factor (EIA 50Hz) | 300 (Stereo), 150 (Monaural) |
| Input Impedance | 20kΩ unbalanced, 600Ω balanced |
| Power Consumption | 1100W at rated output (8Ω) |
| Dimensions | 480 mm (W) × 232 mm (H) × 476 mm (D) |
| Weight | 38.5 kg |
| Original Price | ¥650,000 |
Design
The P-600 uses a class-A/B topology with a FET-input cascode bootstrap push-pull input stage and DC feedback via a servo amplifier to eliminate DC offset. The pre-drive stage is a Darlington cascode push-pull, while the output stage employs 14 wide-band 200W Pc transistors in a 7-parallel push-pull configuration per channel. MOS FETs drive the output stage, and the amplifier includes dual diode bridge rectification, a large toroidal transformer, and buss bars on filter capacitors. Digital power meters use a 12-bit A/D converter and a 4-bit microprocessor, displaying 0.001W to 999W with selectable impedance settings (2Ω, 4Ω, 8Ω, 16Ω) and 3-second or 30-minute hold. The stepped attenuator offers 1 dB steps from 0 to -20 dB, then -23, -26, -30, and -∞ with ±0.1 dB precision. A relay-controlled subsonic filter (10 Hz, -12dB/oct) is included.
Context
The P-600 was developed as Accuphase’s flagship stereo class-A/B power amplifier in the early 1980s, positioned above other stereo models in the lineup. While more expensive class-A amplifiers and the M-100 monoblocks existed, the P-600 was considered the leader among Accuphase’s stereo class-A/B offerings. It was marketed as an ideal amplifier for the new era of high-fidelity audio.
Market
Optional accessories included the Persimmon wood panel A-14 (¥16,000) and the heat dissipation fan O-81 (¥8,000). A known issue reported by owners is the digital output meter displaying the same number ("262") on both channels regardless of volume. Units intended for export often require voltage conversion from 100V to 240V.
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