International projectionist (Jan-Dec 1947)

'QUALITY7 REPRODUCTION (Continued from page 6) at least only the lower partials, will be well represented. This is particularly interesting as it is exactly the result that is obtained from a good piano. If we assume the correctness of this thesis, it should be possible to trace similar tendencies in the trend of development of other orchestral instruments, although as musical development is an art and not a science, it is to be expected that the time scale will be measured in hundreds rather than in tens of years. Nevertheless, the results can be just as positive as those obtained by any scientific process. Tracing the development of any orchestral instrument is a rather difficult proposition, as instruments may, and do, become obsolete for reasons other than tone quality. Restricted range, difficulty of fingering or blowing, size or even mere fashion may end the popularity of an instrument. The advantage (or otherwise) of reducing the upper end of the frequency scale can be checked by the reader in a very simple manner when listening to an actual orchestral performance, preferably when listening to the performance of a brass band in the open air. The acoustic output of instruments like the trombone and trumpet is largely concentrated along the axis of the horn, the concentration becoming more marked at high frequencies. Thus the frequency characteristic is "flat" on the axis, while the high-frequency output falls relative to the 500-cycle components as the listener moves off the axis, i.e., "top cut," can be put in without electrical equipment being involved. If this experiment be tried indoors, the listener should be fairly close to the instrument in order to minimize the effect of reflections. The theme will not be pressed further, but instead an attempt to draw some conclusions will be made. Public Preference Inquiry It appears that in a high-quality reproducer system with total distortions 10-15 db. below the level at which separate tests indicate distortion as "just noticeable," public preference for a restricted frequency range exists. This optimum range is approximately 3 db. down at 70 cycles and 6,500 cycles, but is somewhat dependent on program material. A similar preference appears to exist when electrical reproduction is not involved, except that an even more restricted range appears to be preferred, though absolute data on this point is not as complete as is desirable. It does appear that the presence of distortion is not the only reason for the general desire to "top cut." In providing a tone control the engineer is making it possible for the great mass of the general public to express an opinion on a subject that has previously been the prerogative of musical circles. It is suggested that this opinion serves to confirm the general trend of the tone quality of orchestral instruments, though further investigation is required. Insofar as the public tend to go further than musical instrument designers have gone in removing the upper par tials, it would appear that some organized investigation of public preference is necessary as a guide to the designers of musical instruments and others interested in sound reproducing equipment. Assuming the correctness of the present thesis it may be well asked: "What is the communication engineer going to do about it?" It is suggested that the present practice of transmitting with a flat or slightly rising characteristic and providing each listener with a tone control is the correct procedure. This gives a measure of pre-emphasis and de-emphasis, which, while not going as Throw Away Your Headache Powders! MM Unexpected repair and replacement bills give any manager a headache. With an RCA Sound Service and Parts Replacement Contract the cost of all parts and tubes for sound and projection equipment can be budgeted on a monthly basis. For the price of just a few admissions per day your sound equipment receives regularly scheduled check-ups and prompt emergency service. Checl; the famous "Seven Benefits" below. Your RCA Theatre Supply Dealer will gladly explain their advantages. Or write RCA Service Co., Inc., Dept. 43-B, Camden, N. J., for full details. Scheduled checkups Emergency service Regular maintenance Valuable technical data Insures peak performance Complete parts replacement Emergency sound systems "CA SERVICE COMPANY. IMC. RAD tO CORPORATION of AMERICA CAMDEN M.J. INTERNATIONAL PROJECTIONIST February 1947 27