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1945 Theatre Catalog, 4th Edition, Page 348 (324)

1945 Theatre Catalog, 4th Edition
1945 Theatre Catalog
1945 Theatre Catalog, 4th Edition, Page 348
Page 348

1945 Theatre Catalog, 4th Edition, Page 348

are in line at all times during operation.

A hand brake which provides a means of bringing the motor, projector, and reproducer mechanism to a quick, smooth emergency stop.

Notice the improved and simplified sound changeover, volume control, vertical drive motor, fiexible coupling, straight line, drive, and hand wheel for easy threading.

The Westrex Master has been designed so that the future probable developments from Hollywood-such as automatic volume control and multi-track or stereophonic sound%an be added without extensive and expensive factory modifications.

The Westrex Master sound system can be used with any standard make of projector.

In the Westrex Master, the pro-amplifier is small enough to fit in the hand. The entire unit is placed in the reproducer next to the red-sensitive photoelectric cell.

This built-in feature is a long step forward from sound systems in which the pro-amplifiers are located some distance from the projectors. By discarding the old wall-style pre-amplifiers, special

wiring and expensive coaxial cable are eliminated.

With the pre-amplifier and photocell placed close together, line losses and noise pick-up are generally reduced. As further protection against unwanted sounds, both the photocell and the preamplifier are shock mounted and separated from the reproducer housing.

Basic to the Westrex Master pre-amplifierls smaller size are the miniature electronic tubes that are used. These wardeveloped tubes are not much larger than the end of ones little finger, but, in spite of this small size, they are powerful and highly efficient. Their practical Value has been established by extensive wartime use in radio receivers and transmitters for air craft, battleships, and submarines. These tubeseheart of the Westrex Master pre-amplifiereare not specialized and are obtainable through regular commercial channels.

The pre-amplifier and all other main parts of the Westrex Master are unit assemblies, so that any unit can be removed by loosening a few screws.

The Hydro dutter suppressor is Western Electric Export,s feature solution to one of the most vexing problems in


sound reproduction: mechanical flutter, an irregular movement of the film as it paszes the scanning beam.

When mechanical iiutter is excessive, it is easily and unfavorably noticed by the theatre audience. It makes the reproduction distorted and unnatural and robs the sound of vibrant, life-like quality.

Scientific electrical tests prove that the hydro Hutter suppressor does a better job of solving the flutter problem than previous methods. Latest standards for the industry-set by the Academy of Motion Picture Arts and Sciencesestate that flutter should not be more than 0.15 percent, and most pre-war reproducers had difficulty in meeting this standard. By using this hydro fiutter suppressor, new Westrex Master sound system has a flutter factor of only 0.07 percent, or less

than one-half of the standard set for the '

industry. Suppression of iiutter to this new low level adds a depth and realism to the sound that is impressive.

The hydro flutter suppressor is a simple mechanical device, with little to get out of order or to require maintenance. Located near the impedance drum, the suppressor operates on a hydaulic principle. A lever arm with ball-healing movement moves up and down in a special damping fluid within carefully controlled limits.

In normal operation, minute variations in sprocket speed may add extra slack or tension to the loop of film around the drum. Whenever this happens, the suppressor goes into action to hold the film tightly against the drum with a firm even pressure and the problem of mechanical fiutter disappears.

The Westrex Master power amplifier delivers 40 watts with harmonic distortion of less than 2 percent. There are no cumbersome racks or fancy cabinets, which add to the cost but contribute nothing to the amplification of sound.

The Westrex Master amplifier is the culmination of 30 years of experience by Western Electric in pioneering and perfecting amplifiers.

This amplifier operates on a negative feedback principle, developed by Western Electric and the Bell Telephone Laboratories. It delivers 40 watts of electrical energy for the smallest Westrex Master system, in contrast with 15 watts for the smallest pre-war Mirrophonic Master system which is now superceded. With special tubes, the Westrex Master power amplifier delivers 50 watts.

For theatres having up to 1,750 seats, the 40-watt system is recommended. The 50-watt system has enough power for a seating capacity up to 2,250. For theatres up to 3,700 seats, two amplifier units working together and giving 80 watts output are supplied. Two amplifiers, furnishing 100 watts are supplied for theatres up to 4,600 seats. For more than 4,600 seats, special extra amplification is necessary.

The chassis is fastened to a swinging sher so that the unit can swing out and lock on its side, thus exposing all Wires and connections to easy inspection and maintenance.

Component parts are safeguarded against excessive heat and humidity, thus enabling the equipment to withstand all climatic conditions.

Only a simple soldering job is news

1945 Theatre Catalog, 4th Edition, Page 348