Projection engineering (Jan 1932-Mar 1933)

Projection Engineering JANUARY, 1932 The public-address and radio program system in the Waldorf-Astoria Hote By Robert C. Sturgeon FOR nearly half a century the name Waldorf-Astoria has been synonymous with the highest ideals of hotel excellence. With the construction of this new hotel at Park Avenue and Forty-Ninth Street, New York City, the same traditions have been carried out. Among the many and varied appointments provided by the Waldorf-Astoria for the convenience, comfort and entertainment of their guests is the most elaborate and complete system for the electrical distribution of entertainment ever brought together under one roof. The radio control room or nerve center of this intricate system, located on the sixth floor of the hotel, is a large, well lighted room that becomes a showplace where guests see how they are supplied with good radio reception. The radio room contains not only all the equipment for radio pickup, publicaddress amplifiers, etc., but houses an Fig. 1. Distributing panels. up-to-date sound motion picture booth equipped like a modern theatre. The radio system provides in general facilities for : 1. The distribution of six programs to the 1940 guest rooms. These six programs may be radio entertainment from broadcast stations or music originating in the hotel, such as dinner programs for the dining rooms. The loudspeakers in the bedrooms have a selector switch and volume control mounted in the speaker housing itself, thus allowing the guest to select and control any one of the six programs. 2. The reproduction of programs in the public rooms throughout the hotel. This may be an organ recital originating in the grand ballroom or an address by President Hoover coming from Washington by direct wire. There are 24 public rooms throughout the hotel equipped with loudspeakers sufficiently large to handle the volume required. 3. A centralized antenna system which enables permanent guests in the 140 residential suites to connect their individual radios to a common antenna. 4. The re-enforcement of speech and music in the public rooms. For example, a dinner is held in the grand ballroom where many notables are speaking. A public-address system amplifies the voices of these speakers so that everyone hears each word perfectly without the knowledge that the voices are actually being amplified. After dinner the assembled guests retire to the reception rooms and the grand ballroom is made ready for dancing. The orchestra tunes up and presently the dance begins. A vocalist steps up to the microphone and begins to sing. The Page 7 Fig. 2. Remote control panel. dancers hear his solo much more clearly and naturally than if he had used a megaphone. 5. The showing of sound motion pictures. As well as two permanent machines for use in the ballroom, there are two portable machines in the smaller public rooms. 6. The picking up of programs intended for broadcasting which are monitored, amplified, and sent out by line to remote points such as broadcast transmitters or key stations. Before going into details let us summarize the huge amount of equipment installed in the Waldorf-Astoria. Let us first look at the apparatus installed in the control room. There are 39 audio amplifiers in all ; everything from small speech amplifiers delivering a few milliwatts to several large power amplifiers each capable of delivering 12 watts of undistored output. These 39 audio amplifiers require 190 vacuum tubes of various types such as vapour arc-rectifiers for changing a-c. to d-c. which is used for plate supply, as well as large and small tubes used in the various circuits of the audio amplifiers. Associated with these amplifiers are mixers, gain controls, volume indicators and a host of other necessary control devices. Throughout the hotel are 72 condenser microphone outlets each supplied with filament and plate current from the control room. Special circuits