Nakamichi 681ZX stereo cassette deck with 3 heads, dual capstan, support for Type I / II / IV tapes, Dolby B + C, switchable MPX filter, pitch control, and advanced metering/controls typical of Nakamichi’s higher-tier decks.
Nakamichi 681ZX
Nakamichi 681ZX — serviced and bench-tested, ready for regular use.
Electronics checked end-to-end, transport serviced, functions verified, and final performance confirmed on the bench.
Story & Notes
A classic three-head Nakamichi built around serious cassette engineering: dual-capstan transport, Dolby B/C, switchable MPX filter, and pitch control—with the “ZX” generation focusing on high bandwidth and tight tape handling.
The 681ZX sits in the well-regarded 680-series lineage, with the later ZX generation keeping the strong HF performance and bringing back user-adjustable bias as part of the evolution of the line.
The 681ZX sits in the well-regarded 680-series lineage, with the later ZX generation keeping the strong HF performance and bringing back user-adjustable bias as part of the evolution of the line.
Work Performed
Electrical
Complete electrical service and reliability verification (aging points addressed as required)
Power supply checked and verified under load
Audio path serviced where technically justified
Functional verification: record/playback operation, monitoring, and Dolby function
Mechanical / Transport
Transport serviced and adjusted for correct tape handling
Tape path cleaned and serviced
Braking / torque / handling checks
Controls, switches, and connectors cleaned/serviced as required
Heads
Heads and tape path inspected and cleaned
Tape path geometry / azimuth checked
Complete electrical service and reliability verification (aging points addressed as required)
Power supply checked and verified under load
Audio path serviced where technically justified
Functional verification: record/playback operation, monitoring, and Dolby function
Mechanical / Transport
Transport serviced and adjusted for correct tape handling
Tape path cleaned and serviced
Braking / torque / handling checks
Controls, switches, and connectors cleaned/serviced as required
Heads
Heads and tape path inspected and cleaned
Tape path geometry / azimuth checked
Bench Test Summary
Tape speed: 4.8 cm/s
Heads: 3-head (separate record / play / erase)
Wow & flutter: ≤ 0.04% WRMS (weighted)
Frequency response (-20 dB): 20 Hz – 22 kHz ±3 dB (type IV)); 20 Hz – 20 kHz ±3 dB (type I / II)
S/N: ≥ 66 dB (Dolby B); ≥ 72 dB (Dolby C)
THD: ≤ 0.8% (type IV); ≤ 1.0% (type I / II)
Heads: 3-head (separate record / play / erase)
Wow & flutter: ≤ 0.04% WRMS (weighted)
Frequency response (-20 dB): 20 Hz – 22 kHz ±3 dB (type IV)); 20 Hz – 20 kHz ±3 dB (type I / II)
S/N: ≥ 66 dB (Dolby B); ≥ 72 dB (Dolby C)
THD: ≤ 0.8% (type IV); ≤ 1.0% (type I / II)
