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INTERNATIONAL PROJECTIONIST
Volume 34
APRIL 1959
Number 4
THE VIDEOTAPE* RECORDER
By GEORGE B. GOODALL Ampex Corporation
This is the first in a series of articles describing the Ampex Videotape equipment which is revolutionizing television programming. Recording pictures on magnetic tape is a complex process, and this initial discussion lays a foundation for the articles to follow.
!. BASIC PRINCIPLES OF MAGNETIC RECORDING
TN APRIL, 1956, Ampex Corporation unveiled probably the most sensational -■-magnetic recording equipment ever developed — the Videotape* Recorder. This machine makes it possible to record both sound and picture on tape, and has thus ushered us into the age of magnetic photography. It is the Videotape equipment which will be our main interest in this series of articles. However, even a very general outline of the principles involved in the video application would be worthless without at least a ably the first magnetic recorder to use superficial knowledge of conventional magnetic recording theory. Therefore, the first two discussions will concern normal audio recording on magnetic tape with particular emphasis on those characteristics which will be important in later discussions.
Let it be understood to start with that you are not going to be bored by the long, drawn out discussion of the history of magnetic recording which is the seemingly inevitable preface to any attempt to explain the basic theory of this process. But it seems pertinent to point out that the first patent on a magnetic recording device was issued some 60 years ago, and it was originally anticipated that its main use would be in the telephone and telegraph industries. So magnetic sound is not a recent innovation, conceived by some diabolical genius solely to complicate life in the theatre projection room.
It is also interesting to note that prob
* Trademark, Ampex Corporation.
INTERNATIONAL PROJECTIONIST • APRIL 1959
tape (steel tape, that is) instead of wire as the recording medium was developed for a motion picture application. About 1920 a British producer named Louis Blattner acquired patent rights to manufacture magnetic recording equipment for use in the en
tertainment field. His machine, the "Blattnerphone", supplied synchronous sound for some of the first talking pictures in England.
Why Magnetic Tape?
There are many advantages to recording on high quality magnetic tape using professional grade equipment. No other device can offer comparable fidelity of reproduction. Tape provides the convenience of immediate playback without processing, and the economy of being able to erase and re-record. It furnishes a large storage capacity in a minimum space. Technically one of its greatest attributes is the gradual overload char
MICROPHONE
Supply Reel'
REPRODUCE AMPLIFIER
Tolceup Reel
-TAPE TRANSPORT -Tape Guide
Erase
v ' r C HE US < RecordReproduce
These main components of a magnetic tape record/reproduce system are discussed herein.