The recording of video signals on magnetic tape is today such an integral part of television that it is hard to imagine a broadcasting system with out it. Uses include prerecorded programs, reruns, instant replays, news and network time delay, all of high quality. Before magnetic tape methods, recordings depended upon photographing of television images, which had serious cumulative degradations of the picture signal as it was processed and transmitted due to signal-to-noise ratio. The techniques also were too slow. With magnetic tape, the video remains in electrical form from camera to receiver.

RCA, the leader in research in 1950, investigated ultra-sensitive film to improve picture quality. Color television was David Sarnoff's main goal, and the recorder was to record color, not monochrome as a first step, a very difficult task. When this failed to solve the problem, Harry F. Olson tried a magnetic method using a Longitudinal Recorder with the tape pulled past a fixed record and playback head. The speeds required led to timing instability (wow and flutter), and non-linearity with the video signal being recorded directly on tape. Peter Goldmark of CBS tried photographic recording with the film exposed by scanning it with an electron beam. Both RCA and CBS were unsuccessful.

Enter Ampex, a small company founded by a Russian immigrant, Alexander M. Poniatoff. Charles P. Ginsburg, with a team of six engineers who were open-minded, were willing to review the literature of others in the field, and were not inhibited on what "didn't work before." Included in the team were Ray M. Dolby, who later developed the Dolby noise-reduction system, Charles E. Anderson who urged the use of FM, Shelby Henderson who was a skilled model maker, Alex Maxey, who developed the variable-position tape guide, and Fred Pfrost, who designed the recorder / playback heads.They concentrated on a practical device, and were content to first record monochrome video. They also had good luck, including the recent development of mylar tape with its proper degree of elasticity.

The problems of high head-to-tape speed and timing stability were solved by mounting the recording heads on a rim of a rapidly rotating headwheel (see Fig. 1), and pulling the film past the headwheel so that the head is moved past the tape. Timing stability was thereby achieved. The problem of recording linearity was solved by the use of vestigial sideband FM instead of AM. A variable-position adjustable tape guide (Fig. 2) held the tape in contact with the headwheel and overcoming the "venetian blind" effect.

Four Record/playback heads are mounted on the V-shaped rim of a two-inch headwheel. The two-inch tape is partially wrapped around the rim and is pulled past it at a speed of 15 ips as the wheel rotates at 14,400 rpm. The recorded tracks are transverse to the tape.

The vacuum block tape guide holds the tape in contact with the headwheel. By pushing it upward, the stretch of the tape can be controlled, thus matching the dimensions of the tape and wheel and eliminating the venetian blind effect. It was fortunate that the Mylar tape base, which had just been developed, had the proper degree of elasticity.
 
 
 
 

On April 14, 1956, the Ampex recorder was demonstrated to CBS and ABC, but not NBC (or rival RCA), and was an immediate success. Ampex went on to dominate the field until 1960, when RCA developed a transistor video recorder, then went on under A.H. Lind to invent the color recorder.