Back to Top ▲

Electric Actions, Past And Present

By Mr. James I. Taylor

Click for larger image

Fig 1

Fig 2

Fig 3

Fig 3a

Fig 4

Fig 5

Fig 6

Fig 7

Fig 8

Fig 9

Fig 10

Fig 11

Fig 12

Fig 13

Fig 14

Fig 15

Fig 16

Fig 17

Fig 18

Fig 19

Fig 20

Fig 21

Fig 22
The invention or the discovery of the elect-magnet must be attributed to , who was born in 1783 at Whittingham, in Lancashire. Sturgeon was by trade a shoemaker and served for eighteen years as a private soldier in the Royal Artillery. He was entirely self-taught, an enthusiastic experimenter with electricity, and he described his first electro-magnet in a communication to the Society of Arts in 1825. This magnet consisted of a bent bar of soft iron coated with varnish, on which was wound eighteen separated turns of bare copper wire. The weight of the core of this magnet was approximately seven ounces, but when current derived from a single cell was passed through it a weight of 9 lbs. could be supported. The gauge of the wire is not specified, neither are we told of the current consumed but the principle was established.
The publication of Sturgeon's experiments stimulated other investigations, and in 1831 we find in the U.S.A. disclosing an improvement. Instead of insulating the core he covered the wire with silk, and increased the number of turns, thus greatly improving the efficiency of the magnet.
the Kendal organ builder and a friend of Sturgeon was one of the first to see the possibilities of the magnet as applied to organ action and commenced to experiment, but there is no record of him achieving practical results. , organist and composer, took out a patent in 1852 for the application of magnets to open the pallets of slider soundboards, in Germany had the same idea, and indeed built several organs on the system, but they were not satisfactory. The first real step towards a reliable action seems to have been made by in his patent of 1864, which was an ingenious and simple combination of magnetic and pneumatic mechanism, comprising a chamber valve and internal motor (Fig. 1).
In collaboration with (of pneumatic lever fame) a further patent was filed in 1868, in which the magnet operated charge valves and an external motor. (Fig. 2).
About this time of London became interested in electric action. He was greatly impressed by an electric organ in the Church of St. Agustin, Paris, and as a result acquired rights to use the Barker-Peschard action. The first electric organ in England was built by Bryceson for the Theatre Royal, Drury Lane. This was a one-manual and pedal instrument, and was, it is believed, eventually moved to The Polytechnic, Regent Street.
Among other Bryceson electric organs were those at Rugby School Chapel (where it is said the batteries required weekly recharging at a cost of 30S. each time); St. Augustine's Church, Highbury; St. George's, Tufnell Park; Christ Church, Old Kent Road; and St. Peter's, Parkstone, Bournemouth.
After this spell of activity a period of several years elapsed before any further progress was recorded, but research was proceeding and in 1886 Father Willis installed the organ at Canterbury Cathedral, by far the most important instrument to be equipped with electric control up to that time. It was in service for more than sixty years - a performance which speaks well of its sound design and workmanship. By the courtesy of our President I am able to show an illustration of one of the original magnets for your inspection (Fig. 3).
The key contacts were of the mercury type, as shown in Fig 3a.
Various other workers were studying the problem about this time, among them being Conti (whose system was used in some organs by Bishop & Son) and These early actions, however, though worthy of admiration as pioneer efforts, were not all capable of reliable performance.
There were great difficulties in the matters of current supply, which usually had to be obtained from primary batteries of one kind or another, or from the rather primitive accumulators which were far from perfect in those days when they were more of a curiosity than a tested commercial article.
Another and almost constant worry was the unreliability of the key contact devices which were necessary to handle the relatively large amount of current consumed by the magnets in these early designs. This raised difficulties from sparking on the release of the key which caused failure at the point of contact, and when efforts were made to ensure a rubbing contact which would be self-cleaning the key touch became unpleasant. In an effort to overcome this, some of the early builders used the mercury cup device which was fairly successful when only a single contact was needed but which presented difficulty when required in multiple for couplers. Other types, one of which is shown here (Fig. ç) were used by various builders, but these again were not entirely suitable for multiple use.
This, then, was the general state of affairs until the advent of about 1886. Hope-Jones was not an organ-builder. He was a telephone engineer of considerable ability, a clever inventor, an organ enthusiast, an impressive personality, and a great showman. I only saw him once, when as a small boy I blew the organ for him at All Souls' Church, Nottingham, when he came about 1900 to survey for a new organ. But I shall always remember his distinguished appearance and his tactful but authoritative handling of the Church officials. it is said that Hope-Jones designed his first action without knowing anything of previous experiments. This, however, scarcely seems credible, for his first work at St. John's, Birkenhead (in which he had the assistance of a great craftsman in the late E. Franklin Lloyd) showed a remarkable appreciation of the imperfections of earlier designs and a real effort to overcome their failings (Fig. 4). In the first place, the magnets were smaller than any previously designed, of higher resistance and therefore smaller current consumption. He used the magnet armature in the dual capacity of armature and valve (an idea originated, I believe, by Schmoele & Mols) and his entire design was calculated to make the best use of current sources then existing. The whole of his coupler mechanism was electric, the stop action only used current whilst actually moving the slides, and the swell shutter action whilst moving the shutters. And finally, the organ was controlled from a compact all-electric stopkey console with round wire key contacts (as shown in Fig. 6) and which was movable.
No wonder that this instrument caused a sensation in the organ world. The response of the action was enthusiastically commended by many famous organists of the time, who gave valuable testimony to its efficiency, and The Hope-Jones Organ Company was launched on a career during which were built some important cathedral, church and concert organs some of which are still serviceable.
Unfortunately, for reasons now well understood, the Hope-Jones action proved unreliable in use, despite its promising beginning. The constant urge to economise current proved fatal to the consistent performance of the magnets: the travel of the armatures was reduced until in some cases it was but one hundredth of an inch, and the low voltages employed were incapable of surmounting the slightest obstacle in the form of dust or tarnish. Further, the travel of the armature disc depended on a wooden cap and a thickness of bedding leather on to which the cap was fitted, both of which could be affected by atmospheric conditions, thus causing failure.
And finally, the armatures were supported by wind pressure only, so that when the organ was not in use they fell into the "on" position and sometimes refused to lift when the wind came on owing to residual magnetism or slight stickiness in the paper with which they were usually covered. But though his action had many defects the principle which Hope-Jones, more than anyone else, established what has been the basis of most of the successful actions since his time.
The disc armature valve is still widely used with thoroughly satisfactory results, and the Hope-Jones round wire contacts and coupler switches were used for many years by some of the foremost firms in the industry. Concurrently with the work of Hope-Jones and others in this country great progress was being made in Canada by the famous firm of who as early as 1893 introduced key contacts of substantially the type in general use today, coupler switches of an improved type, and a top-resistance touch of ingenious and effective design. Hope-Jones electric actions were used in a number of organs by Messrs.
Norman & Beard More Information
Click Icon
and Messrs. of Hereford, but the majority of English builders preferred and recommended pneumatic actions as a normal system.
And so we come to the early years of the present century, and to matters of which I can speak from personal and practical experience. Mr.
John Compton More information
Click Icon
had for many years been attracted by the possibilities of the Extension method of Organ building. But the problems involved were obviously very difficult to solve in terms of pneumatic action, however well and compactly designed. He therefore turned his attention to electric mechanisms, and the first extension organs built with these methods in 1909 proved so successful and reliable that he determined to build only electric organs in future, a decision which at the time caused much surprise to those who still viewed electric transmission with suspicion. Indeed many here will remember discussion which for many months flourished in the
Musical OpinionThe magazine is still in print
Click Icon
on the respective merits of pneumatic and electric actions.
After the 1914-1918 war it became apparent that American organ builders, who had been able to operate almost unhindered during hostilities had made considerable progress in electric control, and that in one form or another it was rapidly superseding pneumatic transmission. Between the wars also, there arose a demand for cinema organs which posed some quite new problems. Not only had the mechanism of these instruments to be responsive and reliable, but durability of a quite unusual degree was required to withstand the continuous use of the organs each day. The lessons learned in producing these instruments and observing their performance will be mentioned later, but there is no doubt that their general good behaviour assisted the change of opinion which became general among British organ builders and brought about the adoption of electric transmission as the standard system for organs of all sizes.
This short review of the history of electric action brings us to a consideration of some of the original components which preceded those at present in use. First, the Chest Magnet 0f which there have been so many types, and which forms the initial movement in the majority of organ mechanisms.
In the early days detail of construction and, indeed, general design was severely limited by the manufacturing methods then available. Thus we find that the Schmoele & Mols tubular magnet was supported in a wooden block, and access to the hinged armature valve was difficult. The first pattern of Hope-Jones' magnet had a zinc disc as its magnet support, a wooden cap, and a free disc armature valve with an adjustable valve seat (F1g. 7).
The cap was held in position by a pair of wire hooks and was relatively easy to detach for armature cleaning. These two are typical of their time, and little advance was made for a considerable period. When, however, the die-casting process became a practical method of producing components to precise dimensions, further progress became possible. Hope-Jones was, I believe, among the first to use the process as applied to chest magnet assemblies shortly after his arrival in America, and in 1908 Mr. John Compton designed and used a die-cast block and cap, with a star shaped valve seat. This shape of exhaust aperture was designed to give the maximum amount of edge within the diameter of the armature disc so as to permit a free exhaust with small disc travel. These castings were originally made from a zinc alloy which was inclined to warp. It was also somewhat brittle, causing occasional fracture of the locating pins of the cap. In a subsequent design the metal composition altered to a tin-base alloy, and the design generally improved from a die-casting point of view (Fig. 8).
It will be observed that in both these patterns a disc armature and fixed travel was used. They were quite successful, but as it is sometimes convenient to use magnets in a side position, the next pattern incorporated a hinged armature and an adjustable valve seat (Fig. 9).
This was an improvement and this pattern was used for some years until
Bakelite The first plastic made from synthetic components.
Wikipedia page
Click Icon
moulding became a thoroughly practical and economical method. Since then mouldings have been largely used for magnet components and many other action purposes. The example shown in Fig. 10 has been made in large numbers but with small modification for the past twenty years with excellent results and is typical of simple moulded construction. Other types are shown in Figs. ii, 12 and 13. Chest magnets as a whole vary considerably in resistance and current consumption, some being wound for as little as 70 ohms and others as much as 150 ohms. Special purpose stop action magnets of from 250 to 400 ohms have occasionally been used, but high resistance is not normally considered necessary now that reliable generators or rectifiers are available for action current supply. The post-war shortage has brought forward a number of fresh patterns which will no doubt fulfil their purpose, as they are mostly based on well-tried designs.
Reliability at the magnet having been achieved, the key contact and coupler system became the next matter for attention. I have already mentioned some pioneer types-the mercury cup, various kinds of round wire and strip contacts. Many of these served fairly well in their day as they were mostly used in churches where the duty was not heavy and wear a not too serious problem. I think it is true to say, however, that the advent of the cinema unit organ hastened the development of the durable and trouble-free contacts of the present day. These instruments were played for several hours daily, and key contacts of the types in general use proved unequal to the conditions. The result of many intensive tests under working load here and in America has been the almost universal adoption of hard silver as a contact material though phosphor bronze is satisfactory for duties where a definite rub can he arranged to keep the surfaces clean. The problem has been finally solved by mounting the contacts in either wood or Bakelite blocks, so that up to nine per key can be operated from a single block or larger numbers by duplicating the contact assemblies. This type of block is shown in Fig. 14 which depicts a key with the contact underneath. This type of contact block was apparently a Casavant invention and was first used by them at Montreal Cathedral in 1893, in conjunction with a toggle spring which gives a top-resistance touch. The method of applying these assemblies varies according to the taste of the designer. In America they are generally located under the key (Fig. 14). In this country they are employed both under and over the keys with equal success (Fig. 15).
Coupler switches were the next headache for our early designers. The original Hope-Jones pattern left much to be desired, for although generally well-made it was unreliable unless given frequent attention. The Casavant coupler was a more robust affair, and in the last quarter of a century many other dependable types have been evolved. Of these some are pneumatically operated as, for instance, the Skinner, early Willis, Rutt, and the Walker design in which the couplers are held off by the wind and brought on by springs, thus providing an automatic cleaning action each time the wind is switched on. Direct electric couplers, however, have the advantage of compactness, and a number of trade designs are now in general use. A standard type is shown in the diagram at Fig. 16. This is convenient where extension is employed, as the wiring for the various pitches is easily arranged and the minimum of cabling is needed.
In cases where more contacts are required than can be conveniently operated by the key, relays are necessary. Broadly they embody two distinct principles. The first and more usual pattern consists of either pneumatic or electric movements for making contacts which are used in conjunction with coupler switches. The second type combines the contact and coupler mechanism in one assembly. A good example of the former was the Wurlitzer electro -pneumatic design. Direct electric units, however, seem to be gaining favour and are becoming much used for piston action and other multiple contact purposes. Combined contact and stop action relays have been in use for the last forty years, and Fig. 17 shows a design which was standardised in 1929 which again is particularly adapted for extension work owing to the economy in wiring it makes possible.
Three forms of stop control are in common use, namely, stop-knobs, stop-, keys and tilting tablets and luminous stopheads. All these types presented a problem to the pioneers with regard to the piston action. Stop-knobs are the least easy to deal with, as they require more power over a longer travel than either of the other systems. They are therefore quite often operated electro pneumatically, but there are several methods of direct operation by solenoids which give excellent results, as, for instance, the twin solenoid systems used by Messrs. Willis and Messrs. Walker, and the efficient double-acting solenoid designed by Mr. Norman Hall and others.
Stopkey design seems to have settled down around the double lever magnet principle which is simple and compact. It will be noted that when in the off" position no current passes through the "off" coil when a piston is operated, thus reducing consumption and minimising noise (Fig. 18).
Luminous stop-heads require a reversible movement, one type of which is shown in Fig. 19. This, as you will observe, is developed from a standard stop-key component. In this case a supplementary magnet (which is energised when the stophead is depressed) applies current to either the "on" or "off" coil, according to the position of the rocking lever, thus reversing its position.
Adjustable combination actions have interested manly designers. Simple switch hoards serve most purposes, and much ingenuity has been displayed in their make-up. But it is in many cases desirable that instant adjustment should be provided at the console. In some American designs of the electro-mechanical rocker type adjustment is achieved by holding the piston to be set and arranging the combination required by hand whilst the piston is held.
In others a separate setting piston is provided for each thumb piston. It would seem, however, that the single setter system is most favoured from the player's point of view. This type requires some means of directing the current from the piston or its relay to the "on" or "off" stop movement according to the position of the stop itself, and this is often arranged by providing a double-acting magnet or solenoid for each stop on each piston. Another method, which cuts down the number of such devices is shown here. It will he seen that each stop has a horizontal bar which is, in fact, a silver and Bakelite sandwich. The front silver strip is connected to the "off" movement and the back to the "on". Each strip is operated by a lever magnet which is energised only when the stop is on and the setter piston is in use. Each piston has a vertical strip of Bakelite perforated with triangular apertures as shown, so that when the strip is in the "off" position the contacts can move freely without becoming displaced from the silver bars. When it is desired to fix a combination, the stops required are chosen, the setter piston is operated and the horizontal bar corresponding to any stop which happens to be on moves across. When a thumb piston on which the combination is required is operated the vertical strip is pulled down and the contact slides to the apex of the triangle, bringing it into line with the "on" position, into which the contact is deposited on the release of the piston. On releasing the setter piston the horizontal bars resume the "off" position and remain there until the setter piston is operated again. This method has recently been used in the organ at City Hall, Hull, where some 48 double-touch thumb and toe pistons are adjustable on both first and second touch, and four general pistons control 159 stop movements. A talk of this nature would not be complete without some reference to direct electric chest action as standardised by the Wicks Organ Co. of America. In this action the pipe valve is operated directly by a lever magnet of simple design thus dispensing with pneumatics (Fig. 20).
The idea has also been developed in this country and very efficient units are available which work well on pressures up to 6ins, or so.
Another ingenious design is the invention of Mr. Clifford Hawtin. In this type the initial pluck of the valve is overcome by placing the valve out of centre with the magnet, so that the armature descends first at the end farthest from the valve, which opens slightly giving the effect of a split pallet. Fig. 21.
There is also the Austin rolling armature magnetic valve, which has, I am told, been extensively used in America (Fig. 22).
In general, electric action has now, reached such a state of efficiency that it is difficult to indicate further avenues for research. It is always risky to prophesy, but there would seem to be distinct possibilities of controlling powerful units with large current consumption by means of thyratron valves. This has already been explored by the Kilgen concern in America, with, I understand, interesting results. Selsyn three-phase controls would appear to be worth investigation for swell shutter control, and plastic and nylon covering for cable wire is now proving a rival to the cotton, enamel and rubber insulation to which we are accustomed.
In closing this paper, I should like to thank those members of the Society who have kindly co-operated in providing some of the samples of mechanisms old and new which I have been privileged to use. Before the war I had a very complete collection, but this was unfortunately destroyed with the Compton Works in the fire of 1940 and replacement is difficult. May I thank you also for your patience. A talk of this duration must of necessity be somewhat sketchy, but if I have interested you the preparation of this paper will have been well worthwhile.
Extract:- Journal of the Incorporated Society of Organ Builders. Volume 1
Minutes of September 1949