Nakamichi OMS-40 (circa 1986)
The Nakamichi OMS-40 was the company's first serious standalone CD player, priced at ¥138,000 around 1986. What documentation survives is mostly from a single Japanese spec source. It describes a player built with unusual attention to the analog stage, which fits Nakamichi's tape-deck habit of caring about details other makers glossed over.
The design brief, as recorded, was about resolving low-level signals that tend to get buried in noise. Nakamichi fitted a deglitching system between the D/A converter and the analog circuits. It skips the usual sample-and-hold approach and uses a transistor with switching speed an order of magnitude faster than conventional parts. The D/A conversion is handled by L/R-independent dual 16-bit converters with a precision ladder IC, fed by a 16-bit digital filter with roughly twice the order of the one in the lower OMS-30. That hints at where the OMS-40 sat in the lineup. The analog output stage is fully discrete, with a bipolar transistor differential input, and a 5th-order Chebyshev active filter set at a 30 kHz cutoff keeps group delay flat out to 20 kHz.
The power supply got the same attention. It is multi-regulated, with a dedicated master regulator for the analog section and separate L/R local regulators for each buffer and line amplifier, all configured without feedback loops. An isolated ground system and a copper shield plate on the board keep digital noise away from the analog circuitry. The transport uses a 3-beam laser pickup and a damper-floated mechanism. The chucking method is pure Nakamichi: a spindle tapered with aluminum shavings centers the disc, and a magnet chuck arm holds it.
Known specs are solid. Frequency response is 5 Hz to 20 kHz ±0.5 dB, signal-to-noise ratio is 100 dB or better (IHF A-weighted), dynamic range is 93 dB or more, channel separation is 94 dB or more, and THD is 0.004% at 1 kHz. Line output is 2.5V into 220 Ω. The unit measures 430 × 100 × 322 mm and weighs about 7.1 kg. It came with an infrared remote (the RM-4CD), a headphone output with level control, program memory for up to 15 tracks, repeat play, and a direct-play function that loads and starts the disc when you press play with the drawer open.
No production years beyond the circa-1986 price point have surfaced, and no period magazine reviews of this specific model have turned up in the archive. A service manual is available from several sources.
- Type: CD player
- Price: ¥138,000 (circa 1986)
- D/A conversion: L/R-independent dual 16-bit, ladder IC
- Digital filter: 16-bit, twice the order of the OMS-30's
- Analog filter: 5th-order Chebyshev, 30 kHz cutoff
- Frequency response: 5 Hz – 20 kHz ±0.5 dB
- S/N ratio: 100 dB or more (IHF A-WTD)
- Dynamic range: 93 dB or more
- THD: 0.004% (1 kHz)
- Dimensions: 430 × 100 × 322 mm
- Weight: approx. 7.1 kg
- Remote: RM-4CD, infrared
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