Nagra SN-series

There are four versions of the Nagra 'SN':

Nagra SNN - full track recording at 3 3/4 and 1 7/8 i.p.s. - high quality recording in Mono

Nagra SNS - half track recording at 1 7/8 and 15/16 i.p.s. - surveillance quality recording in
             Mono

Nagra SNST - Stereo recording at 1 7/8 and 15/16 i.p.s. - surveillance quality recording in
             Stereo

Nagra SNSTR (recent) - Stereo recording at 3 3/4 and 1 7/8 i.p.s. -  high quality recording in
             Stereo

Performance Specifications

Frequency response spans 50-60 Hz to 15 kHz (±2 dB), wow/flutter at 0.05-0.1% RMS, and S/N over 62 dB, with low distortion (1% at 400 Hz) and 70 dB erase. Equalization supports 50 µs/3180 µs playback standards.​

Electronics and Controls

Features include mic/line inputs for dynamic/omni mics, headphone monitoring with confidence playback, and a dual-scale meter for levels/battery. ALC compresses dynamically; outputs via 3.5 mm jacks (600 Ω headphones).​

Build and Applications

Solid metal chassis ensures durability for concealed use in sync-sound filming or data logging, with overdrive rewind for speed. Prized for Swiss precision, though parts like belts age; ideal for portable, high-fidelity analog capture.​

The Nagra SNN is a compact, portable monaural reel-to-reel tape recorder from the SN series, introduced in the 1970s for field recording, journalism, filmmaking, and scientific applications, using narrow 3.81 mm (1/8-inch) tape on small open reels. It emphasizes extreme portability with solid-state electronics, automatic level control, and Swiss precision mechanics in a milled metal body weighing under 600 grams. The SNN is a marvel of Swiss miniaturization: a fully professional reel-to-reel recorder that fits in a jacket pocket, yet meets the broadcast standards of its day. The SNN variant focuses on full-track mono recording at higher speeds compared to slower siblings like the SNS.

The SN family uses specialized 1/8-inch tape on 3- to 5-inch reels, yielding 26-40 minutes per side depending on speed and model. Heads are permalloy full-track (mono) or half-track/stereo configurations with manual rewind crank.

Tape & Transport System

• Tape format:
  ¼-inch (6.35 mm) open-reel magnetic tape

• Reel size:
  Special miniature reels (significantly smaller than standard 5-inch reels)

• Recording format:
  Mono, full-track

• Tape speeds:
  Typically around 1⅞ ips (4.75 cm/s) or lower (exact speeds varied by version)

• Transport design:
  Ultra-quiet, low-vibration motor
  Precision capstan optimized for silence rather than maximum speed accuracy

• Wow & flutter:
  Secondary priority compared to noise suppression and duration

The SNN transport is notable for being nearly inaudible at close range, a critical requirement for covert use.

Audio Electronics

• Circuit topology:
  Fully discrete, transistor-based

• Frequency response:
  Optimized for speech intelligibility, not music
  Approximately 300 Hz – 5 kHz (varies with speed)

• Signal-to-noise ratio:
  Modest by hi-fi standards, but excellent for long-duration surveillance recording

• Bias & EQ:
  Tuned specifically for low-speed operation

• Compression / limiting:
  Often included to maximize intelligibility across wide level variations

Inputs & Outputs

• Primary input:
  High-sensitivity microphone input

• Microphones:
  Designed to work with specialized covert microphones

• Controls:
  Extremely limited user interface
  Emphasis on simplicity and concealment

• Outputs:
  Minimal monitoring capability (often none during recording)

The SNN was not intended for real-time monitoring in the way professional recorders are.

Power System

• Power source:
  Internal batteries (specialized compact battery packs)

• Operating time:
  Exceptionally long continuous recording duration

• Power management:
  Designed for stable operation over long unattended sessions

Physical Design & Construction

• Form factor:
  Extremely compact, flat profile

• Chassis:
  Precision-machined metal housing

• Noise suppression:
  Extensive mechanical isolation
  Motor decoupling and damping

• Heat management:
  Passive, silent operation

The SNN is often described as one of the quietest analog tape machines ever built.

Synchronization

• Sync capability:
  None

• Time reference:
  Not designed for post-production synchronization

• Primary objective:
  Capture intelligible speech covertly, not editorial accuracy

Security & Secrecy Features

• Non-standard reels and parts

• Restricted documentation

• Serialized production

• Distribution controlled directly by Kudelski

Historical Significance

• Represents the extreme end of analog miniaturization

• Demonstrates Nagra’s ability to engineer purpose-built machines beyond broadcast and film

• Influenced later covert recording technologies

• Rarely seen outside museums or private collections