Projection engineering (Jan-Dec 1931)

Page 26 PROJECTION ENGINEERING Installation of w sou nd" in Great Britain By Bernard Brown When "sound" was introduced precipitately in theatres in the British Isles many difficulties were experienced. The present article tells how these were overcome. FIGURES have been published showing the progress of installation in Great Britain, but little has been said so far of the difficulties encountered. It is sometimes thought that owing to the smallness of many of the cinema halls installation was a relatively simple matter, but unfortunately this argument was by no means universally true, and so a few notes on the subject may prove of interest to American projectionists. The rush for wiring started, of course, with the presentation of "The Singing Fool," although "The Jazz Singer" was the first feature film to be screened in London. Most of the early installation work was done by the Western Electric Company and RCAPhotophone, Inc., although British Talking Pictures and British Acoustics also were active. By far the greatest proportion of cinemas were wired by the Western Electric Co., which still holds the majority. The first difficulty to be tackled by the companies was the lack of trained men. There were plenty of radio engineers available, but talking pictures were naturally foreign to them and furthermore they were not acquainted with cinema projection and theatre conditions generally. In face of this difficulty the Western Electric Co. opened installation schools in London and gave their engineers a two weeks' intensive course on the principles of talking picture apparatus and installation. To cater for the operating side of the business a number of projectionists were employed to erect the universal bases and run the show for a week after the opening date. The newly fledged British sound engineers were in the first place controlled by what was known as the "Flying Squad" from America, which did not leave the coun try until installation had been placed upon a sound basis. Early days of installation were hectic, indeed. No one really understood the new apparatus and supplies were always badly in arrears. Unfortunately, too, the question of power supply greatly complicated matters and straightforward transformer jobs were the exception rather than the rule. As is fairly well known, in Great Britain there are literally scores of different types of power supplies to be found within a mile or so of each other. The standard imported equipment required 110 volts a-c. at between 50 and 60 cycles. For some reason or other no d-c. equipment was introduced into the country. Probably this was just as well as otherwise great confusion would almost certainly have resulted. Some of the earliest theatres to be installed obtained their converted supply by means of rotary converters, but these machines were not found entirely satisfactory and were soon abandoned, their place being taken by the regulation motor-generators. In all cases where rotary conversion plant was employed dual sets were installed so as to insure freedom from breakdown. Besides machines for supplying the alternating current, battery chargers also were required. Of course, if the supply to the theatre was of the correct frequency a type of valve charger was sufficient. In other instances, however, a small 30-volt motor-generator had to be fitted. Undoubtedly the greatest trouble was caused by power supplies of a-c. where the frequency was outside the limits previously mentioned. In these cases twin sets of converters had to be fitted which, together with the battery charger, gave a total of ten machines, which were a weighty proposition and occupied much space, not always to be found easily. It was usually possible even in the smallest cinema to clear a room providing adequate space for the installation of conversion gear. Unfortunately, however, this did not necessarily solve the problem. In the first place, it was almost certain that the available floor space would be some considerable distance from the operating room, thereby complicating the wire runs. Again, if the conversion room-tobe was not on the ground floor the local building authorities had something to say on the question of floor loading. This usually meant ripping up the floor and fitting in girders and concrete. In the ordinary course of events this would be an unpleasant task, but it was rendered even more so when the whole job had to be completed within five or six days. Another annoying feature of rooms chosen for conversion plant was that few of them provided sufficient wall space for reasonable placement of the starting and control gear, which in those days was fitted in the conversion room itself and not in the operating room as insisted upon at a later date. Ten machines with their accompanying starters,meters, and shunts require very careful laying out if the completed job is to look presentable and not be a mass of twisted conduits. The battery room was another source of trouble, although more illusory than real. It was required that the battery room be situated within forty conduit feet of the operating room. It usually took a great deal of searching to find the necessary space, and even when this was obtained the battery charger had to be located at a much greater distance. In such cases it was usually arranged for the shunt control of the charger together with the automatic make and break, to be fitted in the battery room, while the starter, etc., were fitted near to the charger itself. Much trouble over this might have been avoided had engineers troubled to work out the possible voltage drop which was really infinitesimal. In many cases the exhibitor was compelled to build small cubicles in the auditorium itself. It was quite common to see one of these at each side of the circle. In one would be housed the batteries, and in the other the non-synchronous turntables, and during opening week some trouble would be experienced in keeping away curious patrons. Most of the later-built British cinemas had the screen within a foot or so of the back wall of the auditorium, thus leaving no room for the large exponential horns. There were only two ways out of the difficulty : either to bring the proscenium arch forward or recess the back wall. The latter was generally the method chosen, but even this was not