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Covert Recorders Nagra JBR → DSP-1 →
As the device measures only 147 x 100 x 26 mm,
it could easily be hidden under a person's clothing,
making it the ideal companion for inconspicuous (covert) recordings.
The image on the right shows a typical Nagra SN/SNN recorder of which the
protective cover has been romoved.
The audio quality of the SN, that records onto narrow
3.81 mm wide tape, is unparalleled.
Furthermore, the quartz driven capstan drive motor is so stable,
that the recorder is suitable for use in motion pictures.
An optional pilot system keeps the audio in-sync with the film.
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The body of the recorder is milled out of a solid block of light metal alloy
and all components are created with a fine eye for detail.
Because of its stability, its superb audio quality and unrivalled mechanical
reliability, the Nagra SN became a desired gadget in the motion picture industry
as well as in the law enforcement and intelligence community, in particular for
covert recordings.
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First prototype in the early 1960s, but not taken into production until 1970.
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The image below shows a top view of the Nagra SN. The leftmost reel
is the so-called supply reel. The tape is fed from the supply reel,
over the tape guide and the tension arm, along the three audio heads:
first the (black) erase head, then the recording head and finally
the play-back head.
When no microphone or line input is connected, the Nagra SN acts
as a play-back device. Turning the recorder ON by pushing-in the
operation lever, will start play-back. If a suitable microphone or
line input is connected to the
rightmost green socket at the left side,
pressing the operation lever will cause the Nagra SN to start recording.
Any previous recording will be erased first.
The image above shows the Nagra SNN, which was the first model released
to the general public in 1970, after the initial prototype of the early 1960s.
It uses the full tape width for recording a mono signal at two
tape speeds – 9.5 and 4.75 cm/s – selectable with a screwdriver-operated
switch under the take-up reel.
It is the only model with an
ALC threshold adjustment knob.
Two years later, in 1972, the Nagra SNS was introduced. It was nearly
identical to the SNN, but recorded at half-speed (4.75 and 2.38 cm/s)
onto one half of the tape width. This reduced the audio quality, but
increased the overall recording time significantly. After several
reliability
improvements, Nagra introduced the SNG in 1973 — a mono half-track
version with a HiFi frequency response, followed in 1977 by the
SNST — a single-speed (2.38 cm/s) stereo version.
As the latter had a limited frequency response of 170-5000 Hz, Nagra
released the SNST-R in 1999. It ran at four times the speed of the
SNST (9.5 cm/s) and had a HiFi frequency response of 50-15,000 Hz.
It is believed that only a limited quantity of SNST-R units was ever manufactured.
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Loading a fresh tape onto the Nagra SN is pretty straightforward
and is similar to loading tape on a domestic tape recorder.
Place an empty reel on the axle at the right. It will be used as
the take-up reel. The reel should be locked by rotating the knob at
the centre about 90 degrees clockwise.
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The first prototype of the Nagra SN was developed in the early 1960s,
possibly after a request from US President John F. Kennedy, 1 who was very
keen on making covert recordings [8]. Due to the untimely death of
President Kennedy and the fact that miniature components were not widely
available at the time, the device was not further developed until ~1970.
When the SN/SNN was introduced in late 1970, it was clearly aimed at the motion
picture industry as well as the law enforcement and intelligence community,
hence the two recordings speeds: 9.5 and 4.75 cm/s.
It is often suggested that the letters 'SN' stand for Série Noir
(Black Series), but there appears to be no eveidence for that. It seems more
likely that it simply means Small Nagra, which is what it was called
internally at Nagra [7].
According Nagra, the SN/SNN was taken to the moon on one
of the Apollo missions in the early 1970s [1].
In 1972, the SN/SNN was followed by the Nagra SNS, which featured half-track
and slow-speed, making it more suitable for covert recording of long conversations.
Because of this, the SNS became a standard tool for many
law enforcement agencies and intelligence services worldwide.
Later models were suitable for HiFi, stereo and HiFi-stereo recording.
➤ Overview of models
For many years, the SN was Nagra's flagship for the law enforcement
community, but also for the motion picture industry (film) as it was
small enough to be hidden on the actor's body.
The Nagra SN was succeeded in 1984 by the
much smaller Nagra JBR,
but was kept in production until after 2000.
Over the years, more than 15,000 units were sold [5].
Furthermore, existing Nagra SN and
other models are still being
serviced by authorised Nagra service centers to this day (2019) [5].
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John F. Kennedy was the 35th President of the United States.
He was inaugurated on 20 January 1961 and was assasinated
22 November 1963.
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The success of the Nagra SN recorder did not go unnoticed.
Around 1987, the design was copied by the
Soviet Union (USSR) for use
by Cold War
intelligence services like the GRU,
the KGB and the Ministry of Internal Affairs
(MVD). The device was made by the Special Machinery Factory in Kiev (Ukraine)
and its exterior is a near-exact copy of the Nagra SN, except for
the audio level meter.
The image above shows an original Nagra SN (right) next to
Yachta —
the Soviet clone of the Nagra SNST (left).
On Yachta, the meter is replaced by an LED that indicates
a low battery level. The rest is virtually identical, as shown in the
image above.
Internally, the device is completely different however, as it was made
with special integrated circuits from Soviet
production.
➤ More about Yachta
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The Nagra SN was originally supplied in a black rectangular
storage cassette that measures approx. xx x xxx x xxx cm.
Inside the case
is a padded area for the recorder, the
microphone,
the remote control unit
and spare batteries.
The operator's manual
is usually stored behind a panel in the top lid of the case.
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A range of microphones was available for the Nagr SN,
such as the omni-directional lavalier version shown in the image on the right.
It has a metal clip at the rear that allows it to be fitted to the clothing.
It should be connected to the Mike/Line socket at the left
side of the recorder. Note that the recorder will automatically switch to
recording mode as soon as the microphone is connected.
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When the Nagra SN is hidden under the clothing, it will be difficult to
start or stop a recording. To overcome this, the wired remote control
unit shown in the image on the right was available.
The remote unit consists of a slide switch in a grey plastic enclosure,
fitted to a 1 metre long grey cable with a custom Nagra 5-pin plug at the end.
It should be connected to the 5-pin socket
(generally green) at the left side of the recorder.
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Althoug the Nagra SN was primarily intended for covertly recording
conversations, the unit was also capable of playing back a recorded session.
Normally, when playing back, the a pair of headphones had to be connected to
the 3 mm jack sockets at the rear left.
In order to play back the sound in, say, a room, Nagra developed the special
DSP-1 amplifier
in the late 1970s. It was battery-powered and was connected
to the phones socket of the Nagra SN.
➤ More information
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The interior of the Nagra SN can be accessed by loosing the
three large bolts
at the sides of the device and pulling away the rear shell
of the case. The interior of the recorder
will now be visible. It consists of seven small high-quality PCBs,
that all have their solder side facing upwards.
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The image on the right shows a bottom view of the Nagra SN after the
case shell has been removed. At the bottom right at the two 1.5V penlight
batteries that power the machine. At the top right is the
rear of the modulation meter.
The large circular metal unit to the left of the meter
is the slim-line motor that drives the unit.
Further details in the images below.
The block diagram, that is printed
inside the bottom case shell, should explain how the unit works.
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Year
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Model
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Description
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Speed 2
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Qty 3
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~1960
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SN
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Prototype
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?
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none
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1970
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SNN
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Mono full-track, ALC
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9.5 + 4.75 cm/s
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3972
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·
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SNN-2
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Thicker chassis (1.5 mm instead of 1 mm)
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·
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·
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·
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SNN-3
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Improved control and reliability
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·
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·
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1972
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SNS
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Mono half-track, half-speed
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4.75 + 2.38 cm/s
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6031
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·
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SNS-2
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Thicker chassis (1.5 mm instead of 1 mm)
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·
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·
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·
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SNS-3
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Improved control and reliability
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·
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·
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1973
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SNG
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Mono half-track HiFi 1
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4.75 + 2.38 cm/s
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42
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1977
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SNST
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Stereo 170-5000 Hz
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2.38 cm/s
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3844
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1999
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SNST-R
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Stereo HiFi 50-15000 kHz
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9.5 cm/s
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15
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Total
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15,000+
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Version with full frequency response.
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Specifications supplied by Günter Hütter [4].
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The numbers in the rightmost column show the production quantity by the year
2000 [3]. Please note that according to Nagra these numbers are inaccurate
and incomplete [5]. The total production quantity of the SN was more than
15,000 units.
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Model SN Year 1970 Type SNN Year 1970 Channels 1 (mono) Track width Full Tape speed 9.5 and 4.75 cm/s Input ≥200Ω, 3-80µA Response 60-15.000 Hz ±2dB - Automatic with adjustable theshold
Recording time 18µ tape: 26 min, 12.5µ tape: 38 min Power 2 x 1.5V AA-size battery Consumption 125 mA Dimensions 147 x 100 x 26 mm Weight 574 g
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Model SN Type SNS Year 1971 Channels 1 (mono) Track width Half Tape speed 4.75 and 2.38 cm/s Input ≥200Ω, 1.7-45µA Response 50-6.000 Hz ±3dB - Automatic
Recording time 18µ tape: 1h 40m per track, 12.5µ: 2h 30m per track Power 2 x 1.5V AA-size battery Consumption 125 mA Dimensions 147 x 100 x 26 mm Weight 574 g
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Model SN Type SNST Year 1977 Channels 2 (stereo) Tape speed 2.38 cm/s Response 170-5.000 Hz - Automatic
Recording time 3.5 hours (max.) Dimensions 147 x 100 x 26 mm
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Model SN Type SNST-R Year 1977 Channels 2 (stereo) Tape speed 9.5 cm/s Response 50-15.000 Hz - Automatic
Recording time 30 min. Dimensions 147 x 100 x 26 mm
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ALC
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Automatic Level Adjustment
When recording, this adjustment controls the compression level threshold.
It is located between the erase head and the tape tension arm, and has
a red knob. Note that ALC is only available on the SNN model. Other
models have a white plastic cap in this position.
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TTA
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Tape Tension Adjustment
This is a mechanical adjustment that controls the tension of the movable tape
guide (tape tension arm) at the front left corner. It is present on all
models.
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- Nagra SN, Operating Instructions. Mode d'emploi 1
User Manual (English/French). Code No 20.20.002.153.
Nagra Kudelski SA. Date unknown.
- Nagra SN leaflet
Nagra Kudelski SA. Date unknown. 4 pages.
- Nagra SN brochure
Nagra Kudelski SA. Date unknown. 8 pages.
- Preisliste für Miniatur-Tonbandgerät SN und Zubehör
Price list of Nagra SN recorder and accessories (German).
Austerlitz Electronic GmbH. 12 December 1970.
- Nagra SN, Set of Schematics 1
Nagra Kudelski SA. 12 May 1971.
- Nagra SN, Spare Parts 1
Nagra Kudelski SA. 1 October 1975.
- Nagra SN, Service Manual 1
Nagra Kudelski SA. October 1983.
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This manual is available from Nagra Audio [1][5].
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- Nagra - Audio Technology Switzerland, The Nagra SN
Nagra website. Retrieved March 2012.
- Nagra - Audio Technology Switzerland, The Nagra SNST-R (special version)
Nagra website. Retrieved March 2012.
- Nagra, Production overview and quantities
Internal Nagra document. Date unknown, est. 2000.
- Günter Hütter, Overview of models and specifications
Personaly correspondence, May 2018.
- Nagra Audio, Personal correspondence
January 2019.
- JBond (username), Nagra Stories Sound-men won't ever tell
JWSound Group forum, 29 January 2015.
- JBond (username), The Mystery of the Nagra 'Serie Noir'
JWSound Group forum, 5 August 2016, updated February 2018.
- Wikipedia, John F. Kennedy
Visited 1 May 2021.
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© Crypto Museum. Created: Sunday 25 March 2012. Last changed: Monday, 02 May 2022 - 16:07 CET.
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