Marantz SH-A20 (circa 1983)
The Marantz SH-A20 is a Japanese domestic market stereo pre-main (integrated) amplifier from around 1983, originally priced at ¥208,000. Documentation is thin. No professional reviews or production-run dates have surfaced. The specifications that do exist describe a serious, well-built amp from Marantz's early-1980s era.
The record shows a 130W + 130W (8 Ω) amplifier with a 0.02% THD rating (20 Hz - 20 kHz), frequency response of 5 Hz to 100 kHz ±1 dB, and an RIAA deviation of ±0.5 dB. It weighs 16.5 kg and measures 461 × 193 × 345 mm. The phono stage was clearly a point of pride. It used a full-scale MC head amplifier with carefully selected ultra-low-noise transistors rather than the conventional high-gain equalizer configuration, and the phono circuits ran push-pull at all stages. Input sensitivity is listed at 2.0 mV for MM, 0.11 mV for MC, and 150 mV for high-level sources. Signal-to-noise is 84 dB (MM), 78 dB (MC), and 94 dB (high level). A "doro selector" let the user tailor playback to the individuality of different MM cartridges.
The power amp section is a class AB DC design. It runs from a matched-pair dual FET input stage through 3-stage Darlington output transistors, which Marantz described as its Low-TIM approach to minimizing dynamic distortion. The power supply relies on a large toroidal transformer and what the period literature called a "super audio capacitor." Features include tape-to-tape dubbing, a microphone mixing circuit that could mix with any source, outputs for two pairs of speakers, defeatable tone controls, and a two-position loudness contour. The unit can also be used as a standalone power amplifier or preamplifier. It runs on 100V power, so it was clearly meant for the Japanese market only.
Current Russian classified listings (Avito, Youla) show it priced around 110,000-130,000 ₽, which suggests it is still a sought-after collector piece. Sellers describe the sound as exceeding expectations and note clean, quiet operation, but those are seller claims, not independent review. Japanese sources describe the design philosophy as putting sound "as close as possible to human sensitivity" ahead of technological showmanship.
Known Specifications
- Rated output: 130W + 130W (8 Ω, 20 Hz–20 kHz)
- THD: 0.02% or less (20 Hz–20 kHz, 8 Ω)
- Frequency response: 5 Hz–100 kHz ±1 dB
- RIAA deviation: 20 Hz–20 kHz ±0.5 dB
- Input sensitivity: Phono MM 2.0 mV / Phono MC 0.11 mV / High level 150 mV
- S/N ratio (IHF-A): Phono MM 84 dB / Phono MC 78 dB / High level 94 dB
- Dimensions: 461 × 193 × 345 mm; weight 16.5 kg
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