Precision miniature tape recorder
The Nagra SN was a high-precision
minature audio tape recorder
built by Nagra-Kudelski
in Cheseaux-sur-Lausanne (Switzerland) from 1970 onwards.
It was based on a prototype from the early 1960s
and was built to the highest possible Swiss standards.
During the Cold War, the Nagra SN was popular at either side
of the Iron Curtain:
both the CIA
and the Stasi loved it.
As the device measures only 14.5 x 10 x 2.6 cm,
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 recorder of which the
protective lid 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 the film-making
business. A special pilot system keeps the audio in-sync with the film.
The body of the recorder is milled out of a solid block of light metal alloy
and all components are created with the finest eye for detail.
Because of its extreme stability, its superb audio quality and unrivalled mechanical
reliability, the Nagra SN became the preferred recording machine for many
law enforcement agencies around the world and for the intelligence community at large.
It was used numerous times in the motion picture business,
both on-screen and as a production tool.
The letters 'SN' stand for Série Noir (Black Series) as the recorder
was originally ordered by US President John F. Kennedy for use by the American
secret services .
According to the Nagra website, the SN was even taken to the moon on one
of the Apollo missions in the early 1970s .
In 1972, the SN was followed by the Nagra SNS, which featured half-track
and slow-speed, making it more suitable for covert recording of a conversation.
Because of the extended recording time, it became a standard
tool for many law enforcement agencies and intelligence services.
Due to the limited size of the device, there was no mechanism to rewind
the tape automatically as with later recorders. Instead, the operator had
to fold-out a small crank that is located at the top center,
and wind the tape back manually. The image on the right shows how
it was done.
First, the recorder has to be placed in REWIND mode, by
pulling-out the operation lever
at the bottom left and pushing it up a little,
so that it is locked in place. This uncouples the mechanism.
Next, unlock the rewind crank by pushing-in the
horizontal grey knob at the top and
erect the small pin at the center of the crank.
You may now rewind the tape by
moving the crank clockwise.
For many years, the Nagra SN was the most propular professional body
wearable audio recorder in the law enforcement scene, but also in the
motion picture industry (film) were it was used for recording the actor's
voice when shooting a movie. In total,
nearly 14,000 units were built by the early 1980s.
Eventually the Nagra SN was succeeded in 1984 by the even more sophisticated
and smaller Nagra JBR: a body wearable recorder without controls and
with a separate playback unit.
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 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,
pressing the operation lever will cause the Nagra SN to start recording.
Any previous recording will be erased first.
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.
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
in the late 1970s. It was battery-powered and was connected
to the phones socket of the Nagra SN.
➤ More information
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.
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.
- 1960: Nagra SN - Serie Noir (prototype)
- 1970: Nagra SNN - Mono full-track recording (9.5 and 4.75 cm/s) (3972)
- 1972: Nagra SNS - Mono half-track recording (4.75 and 2.38 cm/s) (6031)
- 1973: Nagra SNG - Version of the SNS with full frequency response (42)
- 1977: Nagra SNST - Stereo version (3844)
- 1999: Nagra SNST-R - HiFi version of the SNST (15)
The numbers in red indicate the production quantity by the year
Any links shown in red are currently unavailable.
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© Crypto Museum. Created: Sunday 25 March 2012. Last changed: Monday, 04 September 2017 - 08:12 CET.