Showmen's Trade Review (Jan-Mar 1947)

E-12 SHOWMEN'S TRADE REVIEW, February 1, 1947 Live Sound In The Theatre Outlining Some Of The Basic Factors Involved In The Use Of Sound Reinforcing Equipment The microphone at the lips of anyone who ventures to address the public nowadays has become practically a "must." It is needed for style even when it is not literally needed for obtaining stronger sound volume. In all theatres except the smallest, however, microphones serve both purposes. Sound reinforcing equipment — or public address equipment as it is more commonly called — is very often encountered by the men and women who make up a theatre audience. It is used for announcements in bus stations and railroad stations, it is used by politicians and others from sound trucks. Bowling alleys, ball grounds, fair parks, meeting rooms, schools, churches, are very often equipped nowadays with means for reinforcing sound from live source or phono pickup. In the theatre, public address presents a very special problem, not encountered in bowling alleys or bus stations. The sound quality in the theatre must be considerably higher than is needed in most other places. There are two reasons for this. First of all, in the theatre many of the patrons can hear the direct sound, the actual voice of the speaker or entertainer, in addition to the reinforced sound coming from the mechanical equipment. Any noticeable discrepancy in quality immediately stamps the theatre as using inferior apparatus for the entertainment of its patrons. People will remark on the difference, and incidentally go elsewhere if displeased. Secondly, the theatre audience has just been hearing, or soon will hear recorded sound, taken from the film. Those recordings on film are of higher quality generally than any phonograph record the average member of your audience is ever likely to hear. Theatre sound reproduction is better in quality than the majority of present home radios. In general, theatre sound is of higher quality than any reproduction your audience hears from any other mechanical device. Reinforcing equipment installed in the theatre should equal the quality of the regular sound reproducing apparatus. Otherwise, the audience cannot help notice the difference. In short, public address apparatus suited to theatre applications has little in common with the raspy, imperfect equipment that is still thought to be perfectly satisfactory for announcements in a bus station, or for helping the counterman call "scramble two" to the cook. The same showmanship that the large auditoria throughout the country use in the presentation of their diversified programs such as ice shows, symphony orchestras, national broadcasts, summer opera, rodeos and other similar applications, applies equally to the theatrical By Martin Bender Commercial Engineer Altec Service Corporation presentation of stage shows. It is obvious that in such applications only high quality, properly engineered installations will be tolerated. Such installations have been proven very definitely to be "Box Office." Installation In addition to requiring equipment of truly high quality, the theatre presents a further problem, not found in many other cases of sound reinforcement, in that both the selection of apparatus components, and the installation of them, must be "tailored" very exactly to the acoustical and structural problems of each individual theatre. The sound must not only be of good quality, but equally distributed among all seats. That is not always a simple requirement to meet. It is often more difficult to get correct distribution of reinforced sound than to get similar distribution of sound from the film — for the reason that when a microphone is present, sound from the speakers can react on the microphone, producing a condition of feed-back in which the sound system stops ALTEC-LANSING 12-position sound mixing panel. The six dials on the left, and the six on the right, each control sound from one microphone or other source — such as a record player. The three dials down the center of the panel are "masters." Volume from each single source is adjusted by its appropriate control dial; the adjusted volume from a group of such dials is further modified as desired by the "master" associated with that group. The dial at the top, center, is the overall "master" that controls the final output of sound volume from this panel, to the amplifier. functioning and gives out with nothing but a loud, continuous wail. Where this extreme condition is not encountered, there may often be a state of partial feedback with occasional fringes of wailing noise tagged on to the sound here and there. Correct location of the speakers in a reinforcing system, therefore, involves not — as in the case of sound from film — merely pointing them to get good sound volume in every seat, but also placing them so as to keep their sound away from the microphone or microphones as far as possible, not forgetting that the location of the speakers is important from the standpoint of creating perfect illusion. Installation problems further involve locating the microphones exactly where they are wanted for a showmanlike presentation of the entertainment or announcements they are to reproduce; matching the frequency characteristics of the equipment to the acoustic characteristics of the auditorium, and avoiding either echo or excessive reverberation. Installation of reinforcing equipment in theatres is therefore never a matter of buying casual equipment at random and hanging up a loudspeaker here and there. It is in every theatre a tailored proposition to be handled by a skilled and experienced sound technician. Where Altec Lansing equipment is used, the Engineering Department of Altec Service Corporation design, plan and supervise the installation of the system in order to insure maximum quality and efficiency. Persons whose experience consists of putting juke-box systems into noisy factories or other industrial locations find it difficult to cope with theatre problems, lacking as they do the experience and background needed for this type of work. Equipment Details The basic sound reinforcing system consists of a microphone, an amplifier, and a loudspeaker. That is the skeleton. Even a single microphone, used for announcements only, is often accompanied by a record player that puts background music into the amplifier at the same time, though at lower volume. For entertainment purposes, a number of microphones may be used. Therefore all announcing systems except the simplest commonly include a "mixer" which permits simultaneous use of several sources of sound, and "mixing" them properly before passing them on to the amplifier. A 12-position Altec-Lansing mixer is shown in the accompanying illustration. The six dials to the left, and the six dials to the right, each control the sound from one microphone or other sound source. The three dials down the center are "mas(Continued on Page E-24)