Harman Kardon PM635 (1992)
The Harman Kardon PM635 is an integrated amplifier released in 1992. It has a fully discrete output stage with 8 FETs and 8 transistors. The parts list shows eight MOSFETs - four 2SK1058s and four 2SJ162s - driving the output, plus a single IC (AVX: M5218P). It's a straightforward design, and it reflects Harman Kardon's engineering priorities of the early 1990s.
Documentation on the PM635 is modest but consistent. The official spec sheet from Harman Kardon's Japanese archive rates it at 100W+100W into 6Ω (1kHz, 0.7% THD). An owner review on AudioReview.com reports 75W per channel into 8Ω from 20Hz-20kHz with both channels driven, at an exceptionally low 0.03% THD. The two figures don't conflict. The loads are different, 6Ω vs. 8Ω, and so are the distortion tolerances. Both point to a genuinely capable amplifier. The phono stage is well-regarded, with a 2.5mV/47kΩ MM input sensitivity and RIAA deviation held to ±0.5dB across the full 20Hz-20kHz range. Line inputs (TUNER, AUX, CD, TAPE1, TAPE2) accept 150mV/47kΩ, and the tape outputs are rated at 150mV/2.2kΩ. Signal-to-noise is a strong 105dB on line inputs and 80dB on phono.
HiFI-Stereo (February 1987, p.103) covered the broader Harman Kardon amplifier lineup of the era. The PM635 follows that approach with its MOSFET output stage and 230W power consumption. It weighs 10.5 kg and measures 440 × 121 × 360 mm (W×H×D).
One owner who used the amp for three years described it as "very solid, very musical," with a pleasing soundstage and build quality comparable to a tank. That is the consistent thread in the limited user record. No original US price is documented, though a Japanese listing shows ¥38,000, which may or may not refer to this specific model. No current market prices or common maintenance issues are recorded.
Known Specifications
- Rated output: 100W+100W (6Ω, 1kHz, 0.7% THD) per manufacturer; ~75W/ch into 8Ω per owner reports
- Frequency response: 10Hz–40kHz +0/−3dB (line inputs)
- THD: 0.03% (PHONO→REC, 1V)
- S/N: 105dB (line), 80dB (phono, 5mV)
- RIAA deviation: ±0.5dB (20Hz–20kHz)
- Output stage: 8 MOSFETs (2SK1058, 2SJ162 ×4 each)
- Inputs: Phono (MM), Tuner, AUX, CD, Tape 1, Tape 2
- Outputs: 2× Tape
- Power consumption: 230W
- Dimensions: 440 × 121 × 360 mm
- Weight: 10.5 kg
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