Projection engineering (Jan 1932-Mar 1933)

MAY, 1932 Page 19 producing these 120 line-per-inch discs. Through the elimination of resonant frequencies from the entire electrical system from microphone to wax cutter, and through the use of properly designed studios, or sound stages, it is comparatively a simple matter to hold a very high level of sound on disc, without cross-overs or break-downs, in the recorded groove. This is the first step in the practical elimination of surface noise. Of course, the entire electrical system must be free from any extraneous noises, due to faulty design, or construction. In this connection it might be well to mention here that a great improvement has recently been made in recording with the introduction of a new type of magnetic microphone. This type of microphone is remarkably free from noise even when a high gain is used. Other points which assist in overcoming the surface noise are : 1. A recording wax which cuts smoothly at room temperature and which will not absorb chemicals from the plating solution. 2. Proper preparation of the wax for electro plating. 3. A perfected system of plating to build up in succession a "master," "matrix" and "stamper," which involves the depositing of microscopically grainless copper to build up shells having perfect surfaces. 4. The record material, itself, must be of such a composition that it will not create undue surface noise in the playing of the record. All of these processes have reached a high state of development through many years of experiment by the various phonograph record companies, dating back long before the advent of the electrical amplification system, when the voice to be recorded was shouted into a horn, the actual air vibrations being at once impressed on a diaphragm, which was mechanically connected to the cutting stylus. We may now outline the actual procedure followed in adding sound to a picture which has already been photographed. Also, added to the picture which we shall discuss is a talking sequence introducing the picture. It might be well to mention here that in view of the fact that once a recording is started it must be continued without interruption clear through to the end, it sometimes becomes necessary to resort to dubbing for re-recording. This permits short sequences to be recorded and when the finished records of these are obtained can be played back through the recording equipment and then rerecorded, all on one disc. By this method the different shots can be edited and arranged almost as easily as though the sound had been recorded on film. Corner of control room showing mixing panel and dubbing machines. Window looks out on sound stage. Microphone is used for talking to sound stage during rehearsals. Take, for example, a one-reel subject showing a type of tractor being used in farm operation. Here we have a number of shots of the tractor performing definite tasks in the course of its work, which requires a running description talk to give the necessary educational value to the picture. For an effective presentation the picture opens with appropriate music during the titles, followed by the speaker making an introductory talk, then the shots of the tractor at work, with the descriptive talk, and ending with a few bars of music. A camera, and a projector, both synchronized, or interlocked with the wax recording machine are in a soundproof projection room. The silent film is loaded and ready to project on to a small screen in the studio. At a convenient point in front of the screen are the microphones, one for the musicians and one for the speaker. It is best that the speaker be seated comfortably as he must watch the picture and time his talk to correspond. The monitor, or mixer, is located in a sound-proof booth at a point where the monitor man can watch the speaker, the orchestra, and the screen. He hears the sound exactly as it will be heard in the finished talking picture. In another room are located the wax recording machines and associated amplifier equipment. Telephones connect the recording room, projection room, and monitor booth. After rehearsals and timing, when everything is ready to be recorded, a signal is flashed in the studio that everything is "ready." Following the "ready" signal are the "quiet" and "begin" signals, which are operated by the wax machine operator. These electric signals must be located where they are visible to the cameraman, the projector operator, the monitor man, and those in the studio. At the "begin" signal both the wax machines and camera start turning. After a five-second interval allowed for the motors to get up to speed, the musical director starts the orchestra. At a predetermined point, just before the speaker starts his talk, the music is faded down and remains very soft, or it is faded clear out until the speaker has finished, when the musical accompaniment is again brought up to a climax at the end of the reel. Most directors prefer to have the first wax master played back so that errors can be corrected and the recording made over. At times several playbacks are necessary before every detail has been made perfect. Two waxes are always cut simultaneously so that in case of breakage or damage to one there is still one to process without having to remake the recording. After recording, waxes are carefully examined with a microscope for flaws, and an experienced operator can tell at once whether or not the recording is good or bad, just how loud it is and whether the tone quality is all that it should be. When the recording is declared satisfactory by the monitor man, the musical director and the wax operator it is safe to assume that the finished record will be 100 per cent perfect. A DR. PETER A. SNELL RECEIVES S. M. P. E. FELLOWSHIP DR. PETER A. SNELL of the University of Rochester has been awarded the Society of Motion Picture Engineers' Fellowship according to an announcement made by the Society. The fellowship was made possible through a donation of $1,500 by the late George Eastman to the S. M. P. E. for establishment and administration of the fellowship. Dr. Snell prepared for college at the Hill School, Pottstown, Pa., graduated from Princeton University in 1928 and served as assistant in biochemistry at Princeton University during 1929 and 1930. He received his degree of Master of Arts in 1930 from Princeton University and since then has continued the medical curriculum at the University of Rochester School of Medicine. In 1932 he received his degree of Doctor of Philosophy from Princeton University. He is the author of several scientific papers, two of which were written in collaboration with Dr. E. Newton Harvey. Dr. Snell will, within a short time, begin active work along lines which it is believed will be constructively useful to the motion picture field. In particular, investigation will be made into some phases of production and measurement of the physiological processes involved in visual fatigue. "I am much impressed with the qualifications of Dr. Peter Snell and feel that his selection for the Society of Motion Picture Engineers' Fellowship will result in valuable contribution to the science of motion picture engineering," stated Dr. Alfred N. Goldsmith, president of the S. M. P. E.