International photographer (Jan-Dec 1939)

• • PROJECTION SyMpOSIUM, pART VII. oiplete lowdown on scrupulous technical care exercised in developing test reels for theatre use in Academy Revolt Council's campaign for standardizing theatre sound equipment characteristics, by ARC committee chairman. By JOHN HILLIARD MGM Studio Sound Department STEREST to technicians and particularly to ;tionists is the work of the Academy Re1 Council in standardizing theatre sound ment characteristics. The state of this ct is brought up to date in a report by Hilliard, chairman of the committee in e, which was presented as one of the s at the SMPE spring convention in Hollyin April. During the past two years Internal Photographer has kept projectionist airs and other interested technicians and xeUives informed on this work. This month • reak in on our projection series by outai'ing engineers of the sound equipment laifacturing companies, to present the first si Irnent of the full text of the Hilliard reft It will be concluded next month. — Ed. 0 ( n\ members of the SMPE familiar in gena with the theatre standardization work of i -Council, from direct contacts with the Mc.il and Committee and from previous renr and publications detailing our activities, i is paper will cover only very briefly phases ii program which are already well known. ii oncentrate more upon activities upon which le! has been little or no previous publication. "reat deal of our effort during past year i ii in devoted to preparation of various types I st films and tools for use in the field, so ief outline of difficulties encountered and ii cms which had to be solved before we i able to even approach our ultimate aims lo these lines will undoubtedly be of interest. ' nil this Committee was set up early in 1937, niiirst step was to recommend Standard Eleci( Characteristics for common types of theatre | during equipment, in order that the studios 0 I be able to record for best possible reproU'lon on these standard systems. !|mdard Electrical Characteristics were arrived 1 . visiting various representative theatres in H oral district, and conducting a great numei if listening tests at various settings of the le rical characteristics in each theatre. Imie|ately at the start of this work need was :(|;nized for a test reel containing representavj sound recordings from all studios. Such el was made up and through its use the olnittee was able to correlate listening tests >ij ucted in the various theatres. is test reel was so useful to the Committee 1! il was later decided to make prints availEl to those in the field who might have need ii such a reel — that is, equipment manufacp 5, servicing organizations, theatre circuits. U During the past year or so a great many i s ol the reel, known as the Research Counil, Theatre Sound Test Reel, have been disi lid throughout the United States, and prints ' been sent to Canada. Holland. Belgium, ; Germany, Sweden, France, England, AusI i. Switzerland. Czechoslovakia, Brazil and ".ii Africa. pwever, for purpose of checking theatre re1 ucing equipment in the field, the reel was ojdered to be somewhat too long, so the Comije has recently made up a new Theatre 4 d Test Reel. Because of its shorter length I 'proximately 1000 feet, this reel should be of " derably more value for every day theatre ce use. ntaining representative examples of record'i rom current product from each of the eight New Bulletin Available Technicians, and particularly projectionists interested in the work of the Academy Research Council in striving to improve the standards of theatre sound reproduction, will be interested in a new Technical Bulletin just issued by the Council, which presents in handy form the full details and costs of the various test reels now available for adjusting and maintaining theatre sound reproducing equipment to quality standards. Work of the Council in developing these reels is thoroughly ilescribed in the accompanying article. If you haven't a 'ready received your copy of the Bulletin communicate with Gordon S. Mitchell, manager of the Council, at 1217 Taft Building, Hollywood, or if you prefer. International Photographer will be glad to forward your correspondence. studios participating in the Research Council cooperative technical program, this Test Reel furnishes a quick and immediate check of the overall sound quality of an auditorium as set to the Standard Electrical Characteristic and with the type of product played regularly in the theatre. The reel contains both sound and picture, with dialogue and music recording so chosen that assembled reel contains a representative example of sound as currently recorded by each studio. One of these recordings is a Hi-Range print which serves as a check on amplifier capacity in relation to volume of auditorium which is under consideration. Reel also contains an excerpt of piano and ol her musical instrument recording, included for purpose of furnishing more critical flutter test. For setting theatre sound reproducing equipment to Standard Electrical Characteristic, Theatre Sound Test Reel furnishes a tool by which an optimum setting for presence and intelligibility, combined with natural balance between high and low frequencies, may be obtained for all current product. Use of this reel demonstrates inadvisability oi having too much low-frequency electrical response which brings out noise reduction bumps, footsteps and parisitic low-frequency noises present on set. We might point out that judgment is required in use of Theatre Sound Test Reel as product must be evaluated in terms of material at hand, that is. crowd noises and people talking in a loud voice or excited manner should not be expected to have same quality and chest tones which are present in conversational dialogue in a quiet intimate scene. The Council and Committee have always felt that electrical and acoustical curves furnish valuable means of setting equipment, but that the final criteria should be listening test of equipment. For this reason all of our standards to date have been set up on the basis of listening tests correlated with engineering data. One of the purposes of the Standard Electrical Characteristic is to provide basis for an eventual standard recording characteristic. We believe that new Theatre Sound Test Reel demonstrates fact that recording characteristics of various studios are very much closer together than they were a year or two ago. Material contained in the reel is not a sample of the best recording available, but is typical of average. Committee also realizes that it is necessary to keep samples of recording from various studios in the reel up-to-date and for this reason a procedure has been set up whereby individual studios will, from time to time, submit new samples for inclusion in the Theatre Sound Test Reel of approximately same length as sample already included in the reel. All users of Theatre Sound Test Reels will be notified of these substitute samples as they are available, and will be given the opportunity of purchasing individual new samples to be spliced into their print. By rotating and spacing this "substitution of samples" procedure, prints of the reel will be kept up-to-date at minimum of cost to users, and new samples will replace deteriorated prints. This will furnish an inexpensive means of replacing reel as well as keeping it representative of up-to-date recording. In Committees work in setting up Standard Electrical Characteristics, need for a good Standard Multi-Frequency Reel was very evident as this type of reel provides only tool to evaluate listening tests in terms of Electrical Characteristics. Previously, two general types of Frequency Reels had been in use. One of these was a toerecorded negative in which the printing process had been eliminated to obtain steadiness of level in each frequency, a good frequency response, and freedom from printer trouble. This method proved quite satisfactory from a technical standpoint, but negative was costly to make and its life in field was short in comparison to life of a print. The other was prints of either variable density or variable area recording. Prints of Frequency Reels were subject to several sources of variation, some of which follow: (1) Weave trouble in recording and reproducing. <2i Bad flutter content in both high and low frequencies. <3l Variation in printer slippage which cause non-uniform high frequency response. i4) Non-uniformity of emulsion during drying process and manufacture, causing periodical changes in density and gamma which in turn create a variation in output of as much as 1 db. In considering this matter. Committee found (in opinion of users of this type reel) that some of available reels contained too few frequencies, while others contained too many frequencies — in one case, the frequency reels not having a iernational Photographer for June, 1939