This article originally appeared in the June 1966 issue of American Cinematographer, and is posted here with the magazine's permission. The below photo, courtesy of the Swedish Film Institute’s Image Archive, did not appear in the original article, but has been added here for illustrative purposes.

The Academy Award-winning

”This equipment provides the motion picture industry
with a well-engineered, high quality, compact,
versatile recording system for location recording.”

Nagra III & SELA mixer

To the fashionable crowd that packed the Santa Monica Civic Auditorium on the evening of April 18 to witness the 38th Annual Academy Awards Presentation, and to the millions of viewers watching the colorcast of the affair throughout the nation, the big news centered on the ”Oscars” awarded for Best Actor, Best Actress, Best Picture, etc.

But to filmmakers everywhere, especially those who are frequently required to record sync-sound under difficult location conditions, the significant award was the Class II plaque presented to Swiss electronics engineer Stefan Kudelski for the design and development of the Nagra portable 1/4-inch tape recording system for motion picture sound recording.

Concerning the Nagra, the Academy's official statement read:
”This equipment provides the motion picture industry with a well engineered, high quality, compact, versatile recording system for location recording. An outstanding feature of the recorder is the constant speed characteristic resulting from its unique control circuitry.”

None of this is news to the thousands of users of the Nagra in the Hollywood studios. United States radio and television networks and in filming situations throughout the world.

However, few of these technicians, as well as those among the glittering assemblage that witnessed the presentation of the plaque could have had any inkling of the remarkable saga of a man and his work that led up to that moment.

Stefan Kudelski was born in Warsaw, Poland, on the 27th of February, 1929. His family had an engineering background, and included, in particular, several technical college professors.

His father studied as an architect, but his principle field of work was in the chemical industry. His mother is an anthropologist.

In 1939, the Kudelski family fled in front of the Germans, and regrouped itself in Hungary. From there, they passed on to France, where Stefan Kudelski continued his education. After the German invasion of France, the Kudelski family lived in the Vichy Zone. Stefan Kudelski's father, being an officer on active service, organized a resistance network, which fell in 1943, but the Kudelski family managed to escape to Switzerland. Both his father and his mother were honored for their activities during this period with the French Croix de Guerre.

Established in Geneva, Young Kudelski continued his studies at the Ecole Florimont. He became interested in electronics before he had finished his secondary schooling there. He built up a small laboratory at home and worked on the problems of generating extra high tensions by means of high frequency oscillators, with a view to electrostatic dust extraction from the air. After that, he made an instrument for measuring the accuracy of watches, based on a counter with a crystal controlled gate. These experiments were in the nature of an apprenticeship and, although he took out several patents, no commercial exploitation was made.

In 1948 he started studying at the Ecole Polytechnique in Lausanne, in the Physical Engineering faculty. As the electronics section of the faculty was not sufficiently developed at this time, he continued to work in his own laboratory, as well as doing his general studies at college.

About this time, the first magnetic recorders were put on the market. During the war, the Germans made a few tape recorders, but they were generally unknown to all but a few, but the principle was established in the 19th century. Stefan Kudelski immediately realized the potential of using the memory incorporated in a magnetic tape for the automatic control of machine tools, but the science of magnetic recording was still in its infancy and he decided that it would be better to familiarize himself with all the aspects of tape recording before specializing in sophisticated systems.

To this end, he made several tape recorders, and he saw that there would be a ready market amongst radio stations for a small portable tape recorder working off self-contained batteries, and such a recorder was a practical proposition. In this idea, he foresaw that it could not only be an exercise, but a means to earn a little cash to pay for his studies, and to form a foundation for his future work. The Kudelski family, of course, lost their entire fortune during the War.

And so the first commercial tape recorder was made in 1950. Its dimensions were 5"x7"x12" and weighed 11 lbs. It was called the Nagra. The motive power for the tape transport was a spring motor of the type used for portable phonographs of the era. The amplifiers used battery powered tubes fed from A and B dry batteries. By modern standards, the quality of sound obtained from the recorder was poor, but the radio stations of the day found it acceptable. The worst fault was the flutter in tape speed caused by the centrifugal motor governor. In 1953, the model was improved by incorporating mechanical filters to smooth out these variations in tape speed. This was the birth of the Nagra II, which aroused the interest of the movie industry. One of the first full length feature films to use the Nagra during shooting was ”Black Orpheus”.

Stefan Kudelski examined several systems for synchronizing the camera with the tape recorder. One such system worked from a signal generated by the tape recorder which then slaved a rotary converter feeding a synchronous motor on the camera. This method had disadvantages, being wasteful of power. At that time, power transistors were not sufficiently developed to allow the elimination of the rotary converter. The method finally adopted, as have others, is the reverse of this method. The camera generates a signal which is recorded on the same tape as the sound, thereby reducing the power consumption enormously.

From 1956, he researched into the possibility of a self-contained tape recorder without a centrifugal speed governor, this latter causing endless trouble with the clockwork drive. This resulted in the Nagra III, which was launched in 1958. The success of this model was enormous, and enabled the Kudelski organization to develop from a specialized laboratory to a true industrial establishment.

At the present moment, he is developing smaller and lighter versions of the Nagra, and he is trying to achieve the highest possible operational reliability, using techniques previously employed only for military equipment. This accent on reliability is aimed to eliminate as much as possible of the servicing of professional tape recorders.

Stefan Kudelski is married to a Doctor of Medicine, and they have three children, a boy of 6 and two girls of 4 and 1.

He takes a keen interest in jazz and classical music, photography, and does some 16 mm cinematography. He likes to spend odd moments skiing but, above all, he likes water sports, including skin diving.

For transport he uses a twin engine Cessna, being an Instrument Rated Pilot. He bought this aircraft in the U.S. and flew it across the Atlantic with the help of another pilot, via Newfoundland, Azores and Portugal.

Such is the stranger-than-fiction story behind the remarkable Nagra recorder and the remarkable man who conceived it — the same man who walked modestly to the platform on the evening of April 18, 1966 to receive his tangible symbol of the highest recognition the motion picture industry can bestow.

In addition to receiving an Oscar Plaque from the Academy of Motion Picture Arts and Sciences, Stefan Kudelski, while in Hollywood, was entertained at a luncheon of sound directors and sound engineers of the motion picture and television industries.

During this luncheon, Kudelski explained, in some detail, the evolution that is now taking place in his manufacture of recording equipment, His long-range objective is to provide a recorder which will run for five years without service or trouble.

This program is underway in the recorders that are now being delivered. It includes an increasing use of silicon transistors, tantalum condensers, and the elimination of all belts. The recorders now being delivered to include a larger percentage of silicon transistors. The current model NTBH and NTPH have the same tape deck and controls as in the past. These instruments will be followed by the Nagra 3D Non-Sync and 3L Sync Recorders. These titles will be used for the recorders which include all of the advanced features.

During his discussion, Mr. Kudelski pointed out that the steps that he is taking do not obsolete the current equipment's and, that from general performance standpoint, the customer will never know the difference.

On a still longer range basis. Mr. Kudelski described the new IS Recorder, which is even now in the start of manufacture. The IS Recorder will incorporate all of the long life and reliability factors which are being incorporated in the Nagra 3D and Nagra 3L, plus a new motor and a simplified control system. The new motor is driven by a closed loop servo system, somewhat similar to the earlier recorders. However, its new mechanical construction, greater power, and lower starting inertia, should provide a better tape transport than any other equipment that has ever been manufactured. The new IS will also have a modernized version of automatic gain control. Instruments of this type will also include all the features that are necessary for complete automation. Models will include 1/4" stereo or multitrack 1/2" tape handling.

During the discussion Mr. Kudelski indicated that there is going to be a continuing evolution and continuing improvements in his recording equipment. This will, in time, include a two pound recorder.

In closing, Mr. Kudelski pointed out that people who have need for new automobiles do not wait for next year's model. As the improvements do not justify the delay, he expects to see a similar trend in recording equipment, which should not block the immediate sales of equipment's now being offered.


The Nagra is normally equipped for mixing with a single microphone plus either a line or bridging input.
By the addition of a BS preamplifier the line input can be converted to a second microphone input for two microphone mixing.
4 microphones and a line input are available through the use of the BM auxiliary mixer and normal input.

Using 15" Speed, only available on Nagra, frequency response flat to within 1 dB from 30 cycles to 18,000 cycles.

High-powered Class B amplifier provides 2 watts of power for undistorted reproduction.

The DH self-contained auxiliary speaker-amplifier provides remote quality monitoring either during recording or reproduction.

The auxiliary ATN power unit can be used as a synchronizing transformer when the camera is being driven by a 60 or 50 cycle power supply.
The ATN power unit can also be used to provide external power to the Nagra, operating independently of the internal batteries.

The Nagra is the only recorder using a closed-loop servo drive. This provides the lowest flutter and wow of any known portable recorder.

3 Speeds are available with no mechanical linkage, as the speed is controlled electronically by accurately tuned resonant circuits.

The recorder is equipped with stroboscopic discs for speed comparison with 60 or 50 cycle power source.

The SV auxiliary speed variator can be used to change the speed of the recorder (at 7 1/2"/sec) for purposes of music-pitch change during recording or to correct for improper camera speed during synchronous transfer from 1/4" tape to sprocket-driven magnetic film.

Provides complete portability of recorder with no cable connections. Camera can be driven separately from a time control or a power line.

With high-frequency bias, this system provided the first trouble-free method of synchronization.

The auxiliary Synchronizer is used for synchronous transfer from tape to sprocket-driven film. This is the least expensive reliable system of synchronous transfer.
The Synchronizer is also used for synchronous playback of pre-scored music for lip synchronization during camera action.
The Synchronizer can also be used as a source of a synchronizing signal when the camera is being driven by a 60 or 50 cycle power supply.

When the SLP or SLO is used for synchronous transfer of 1/4" tape from the Nagra to sprocket-driven magnetic film, a bloop can be introduced on the transfer sound at the point of camera start.

The forward and reverse control and the tape tension rollers are arranged for easy fast forward and fast backward monitoring, fast stop, and normal reproduction for easy editing.

The exclusive straight-line threading feature not only provides a simple but also a foolproof method of threading.

The self-contained lineup oscillator is used to provide a level index on the tape, thus all transfer prints and reprints from the Nagra will be at the correct level.

Included in the Nagra is a bloop oscillator which can be made to function automatically with the flashing of a hand-held bloop lamp in front of the camera or the flashing of a bloop lamp installed in the camera.

1200' 7 inch reels can be used on the Nagra when operated with the lid open.

Click here to download a Narga III Instruction Manual

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