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1954-55 Theatre Catalog, 12th Edition, Page 288 (252)

1954-55 Theatre Catalog, 12th Edition
1954-55 Theatre Catalog
1954-55 Theatre Catalog, 12th Edition, Page 288
Page 288

1954-55 Theatre Catalog, 12th Edition, Page 288

move to the center of the stage, the volume of the 35-cycle carrier is raised and the 30-cycle (left) and 40-cycle (right) carrier signals are reduced. Of course, any combination of levels can be obtained to give the impression the sound is coming from any intermediate location on the screen. It also is possible to raise all carriers to full output at the same time.

In practice, the recording is made in the conventional manner and volume variation is accomplished by including the three low-level, low-frequency carrier signals on the same track with the speech and music. When played through a standard, single-channel optical sound system, these carrier tones are inaudible. Because of this, the Perspecta release print will play as single sound in any theatre in the world. However, the same Perspecta release print will produce the finest stereophonic sound in a theatre equipped with the Fair-child Perspecta Integrator and multiple speakers and amplifiers.

Installation Considerations

To install the integrator, it is necessary only to connect the output of the projectors to the input of the integrator at a point past the changeover position. Only one integrator is used in a projection booth. A selection of input impedances is available so that low-impedance (500 ohm) and high-impedance sound head outputs are accommodated by a preamplifier with a wide range of gain. The output impedance of the three channels is 600 ohms for connection to the input of the three theatre power amplifiers. A three-gang, GOO-ohm, 20-step volume control is then inserted at the output of the integrator to control the auditorium sound level.

No changes whatsoever are made to the projectors. The film carries normalsized sprocket holes, thus requiring no special splicing machine. This film is not subject to the hazards of magnetic-type recording, as it is not affected by heavy AC fields nor subject to easy abrasion. Hum troubles are at a minimum because the system operates with lower gain than the magnetic-type recording.

Another feature noticeable to the listener is the quietness of the no-signal sections of the picture being presented. In Perspecta sound recording there is only one track to contend with so far as














THIS DIAGRAM illustrates what a theatre operator must do to install Perspecta stereophonic sound it the theatre is already equipped for a magnetic track system. The only equipment needed is one

integrator unit and a transfer

signal-to-noise ratio is concerned, whereas in multitrack systems all channels are open, whether carrying sound or not. With the Perspecta Integrator in operation each channel is closed except during the actual transmission of sound.

From Proiectionist's Standpoint

Perspecta sound presents no novel procedures to learn. The same film is used as in the past; the same method of threading, and the same old splicer familiar to all projectionists, The motoroperated, enclosed rewinder may be used as usual, and the film can be located without harm near motors or rectifiers.

With the integrator, it is possible to run not only stereophonic prints but also conventional optical non-stereophonic prints without even throwing a switch.

THIS is Perspecta stereophonic film. The three low-frequency tones which govern the sound have been recorded on same track with other sounds.

switch. The black symbols seen

represent existing eqiupment.

This ease of operation is accomplished by an automatic switching arrangement built into the integrator. When a singleoptical-track film is being run, this switch moves to the timono-sound" position and the sound comes out through center horns only. When a Perspectasound-track film is being run, the switch moves automatically to the "Perspecta sound" position and the sound enters each horn as originally planned by the sound recording studio.

Maintenance of the unit is quite elee mentary, As the equipment has been thoroughly designed following conventional practices. The unit has good accessibility for maintenance purposes.

Compatibility with existing equipment and method is an outstanding advantage of Perspecta Stereophonic Sound system. Comparative simplicity of the integrator and the entire system keeps installation and maintenance costs low.


Integrator .1 THEATRE CATALOG 1954-55
1954-55 Theatre Catalog, 12th Edition, Page 288