By-ways of Engineering 

9 June 2017 tbs.pm/11992

THE CONTROL ROOM

There can be no more vivid description of what goes on in the Control Room on the top floor of Broadcasting House than the extract from the pages of the Engineers’ Log-book given below. (The extract, by the way, relates to a transmission from the Empire Station at Daventry.)

But, if vivid, the description is incomplete. Control-Room engineers are responsible not only for controlling three separate programmes — National, Regional, and Empire — on their journey from the microphone to the transmitting aerial, but for the testing and maintenance of the Control-Room apparatus, of that in the studios and listening rooms, and of the twenty-three studio microphone circuits. And a considerable part of their day’s work is concerned with rehearsals — so much, in fact, that rehearsals are differentiated from transmissions and dealt with at control desks exclusive to them. Consequently, and in order to avoid any danger of interference with transmissions, the Control Room has been divided functionally (but not physically) into two. As a whole, the room is shaped like an “L,” the long “arm” being allotted to transmissions, and the short “arm” to rehearsals.

Up on the eighth floor, the word “wireless” must be accounted a laughable misnomer. There is wire everywhere — about 142 miles of it (or enough to stretch from London to Ostend) — connecting the Control Room with studios, echo-rooms, dramatic-control panels, listening rooms, and house listening points, and also connecting the Control-Room apparatus to the battery room. But, at first sight, you won’t see an inch of it. The floor of the Control Room is false, and the cable-runs — the floor-boards over which, of course, are removable — are beneath it.

Engineers at work in the Transmission Control Room: the apparatus racks are on the right

If, however, you go behind the two wall-like racks of apparatus, you will see wire enough to make you regard with awe the men who put it there and the men who can sort it out. These wires connect up the “A,” “B,” “C,” and “D” amplifiers, the fuse bays, the lines-termination, relay, test, and experimental bays, the check receivers, loudspeaker and house-’phone jack-fields … but it will be better for our peace of mind if we let a programme guide us through it all.

The source of the programme may be in a BBC studio or at some point outside Broadcasting House. Wherever it is, unless it is a Regional centre’s local programme — i.e., produced in a Regional studio and broadcast only from the Region’s own transmitter — it must come to the London Control Room.

On reaching the Control Room, a programme from a studio leads us to an “A” amplifier; then to a control desk, where the turning of knobs “fades up” or “fades down” the programme; from the control desk to a “B” amplifier; on to yet another amplifier, a “C,” and at the “C” the programme must leave us, because from there it travels along the cables connecting the Control Room to the several transmitters from which it is radiated. At the same time it goes through special amplifiers to the various headphone and loudspeaker points within the building. The lines-termination bays are the points of departure and the “arrival platforms” for programmes coming into the building.

A programme originating at a point outside the building — the Tower of London, or in a Manchester studio, say — would lead us along a similar route through the Control Room, except that, on arrival, it would go to a “D” amplifier, instead of to an “A,” and thence to the control desk and the “B” amplifier.

A programme rehearsal would go, through the appropriate amplifiers, to a rehearsal-control desk, whence it would be fed back to loudspeakers on circuits within the building — e.g., in listening-rooms, dramatic-control rooms, producers’ and directors’ offices.

Every broadcast programme is subjected to a double listening check. Each control desk is manned by two engineers: one listening to the programme as it passes through the Control Room, and the other to the same programme as picked up by a check receiver, thus simulating the conditions of the ordinary listener. The first engineer is responsible for fading up the various programme items at the appropriate times, and for giving the necessary light cues to the studios concerned. In regulating volume, he keeps a constant watch on a meter in front of him. The second man, while checking the programme as received back by radio, writes up the “log.”

All the amplifier switching and the operation of the relays that bring into the broadcast the six “pips” of the Greenwich Time Signal and the familiar voices of Big Ben and Bow Bells (the interval signal), are in the hands of the men on duty at the control desk. The two rows of apparatus racks are some feet behind them, but there is no need for the engineers to leave their chairs: rows of switches on the desk are variously connected to the units in the apparatus racks so that each unit may be operated by remote control.

Occasionally — but the occasions are amazingly few — a bell will ring in the Control Room. It will mean that one of the 1,500 fuses has blown, thus putting out of action the unit that it protects. To identify one small fuse in one of half a dozen frames each containing 250 fuses would be an almost insuperable task were it not for the fact that, when a fuse blows, it not only automatically sets the bell ringing, but lights pilot lamps distinguishing the fuse-bay and fuse-row concerned, and releases a spring that acts as an indicator. Then replacement is only a matter of seconds. But even so, every item of apparatus is duplicated, and so spares can be brought into use immediately trouble occurs.

Yet another of the Control Room’s jobs is the operation of the system of studio signal lights. Outside each studio there are yellow, blue, and red light ; inside are red, blue, green and white lights. The official responsible for studio bookings controls the yellow light, which, when switched on, indicates that the studio concerned has been allocated. The inside green lights are cue-lights, operated from the dramatic-control panel. But the red and blue lights — and, indirectly, the white — are switched on and off by the Control Room engineers: the red, indicating an actual broadcast, from the transmission desk; the blue, indicating that a rehearsal with microphone is in progress, from the rehearsal desks. The white light comes on when the Control Room telephones to a studio, and it remains on until the call is answered.

High-tension batteries of 300 volts with a capacity of 75 ampere-hours; low-tension batteries of 6 volts with a total capacity of nearly 5,000 ampere-hours, to meet the demand of some 660 thermionic valves; three separate supplies of grid bias; and a 24-volt supply of 1,000 ampere-hour capacity for operating signal lamps and the 3,000 odd relays, meet the Control Room’s demands for power. Each of these battery supplies has a stand-by of equal capacity.

The Control Room’s organisation, its atmosphere of calm efficiency, its awesome, shiny-grey boxes of mystery, are eloquent of modern marvels, progress—all that is up-to-date ; but headphones, which many listeners discarded years ago, are still in daily and constant use.

AT NIGHTINGALE SQUARE

The headquarters of the Research Department of the BBC’s Engineering Division are several miles outside the radius of the limelight that shines on Broadcasting House — a fact that is consistent with the Division’s habit of hiding its indispensable light under the bushel of obscurity. BBC engineers consider that what matters to the listener is the result, not the means by which it is achieved. So, to find the home of the Research Department, one must go to Nightingale Square, in Balham, South London.

The building occupied by the Department is a “retreat” in more than one sense. Before it passed into the hands of the BBC’s research people it was owned by a Belgian religious order (for which it was built in 1858), and was used as a convent for aged nuns. Conversion to secular use — and the BBC, necessarily, has had to make many structural alterations — has by no means disguised the original function: if the clue provided by the arched windows be insufficient, the evidence that a chapel was once there is conclusive. When the Corporation took possession the chapel, of course, was in situ. Obviously, until it had been fittingly withdrawn from the service of the Church, it could not be at the disposal of the BBC, and so a solemn ceremony of deconsecration was conducted on the premises by Roman Catholic dignitaries. To-day, the experimental studios and sound-measurement rooms occupy a large part of the space, but the original roof and portions of the original walls — decorated with designs in green and gold and bearing fragments of Latin texts — may still be seen.

Seventy-six members of the BBC’s staff go to work at Nightingale Square each day. Though only twenty-seven of that number may rightly call themselves “research” engineers, the work they do calls for the services of seven technical assistants and a clerical staff of twenty, in addition to keeping eleven men busily employed in a model workshop. The premises they occupy require a maintenance-staff of eleven, of whom two are occupied in caring for the pleasant grounds that, as yet, surround the main building.

The Department itself is divided into four main sections: Acoustics, Low Frequency, Radio, and Valves. In “Acoustics” they grapple with problems of studio and microphone design; the “Low Frequency” staff undertake experiments with such things as amplifiers, loudspeakers, and transformers, and also investigate methods of recording; the “Radio” section is concerned with transmission, reception, field-strength measurements, and anything that has to do with the actual propagation of wireless signals. In the Valve Section, of course, they deal with nothing but valves — every one of the thousands used by the BBC.

All four Sections can provide material to interest a visitor — even the “non-technical” visitor. “Acoustics” took me into a room draped with layer upon layer of cotton-wool. Behind the layers were thick blankets, and there were more blankets under foot. “I could fire a revolver in here,” said my guide, “and all that you’d hear would be the ‘click’ of the hammer.”

Then he led the way to another room, glaringly white because of the glazed tiles that covered its walls, floor, and ceiling, and full of echoes. They call it the “reverberation chamber.” In yet another room were small, wool-filled frames, which could be stacked at will against the walls to provide another method of studio “damping.” The sight of a wall half concealed by built-up frames brought irresistible thoughts of the engineers “playing bricks.”

The largest valve used by the BBC — an output valve of the long-wave transmitter at Droitwich. Comparison with an ordinary receiving valve (seen on the top of the trolley) gives a vivid idea of the valve’s size

Three of these rooms — there are five of them and they are used, of course, for sound-measurement — must be the ultimate in isolation from the outside world. They constitute rooms within rooms, for each has independent walls of concrete, a foot thick and air-spaced from the original walls. Each has its own ceiling and a floor that is separated from the true floors of the structure by rafters of cork. All five are equipped with doors reminiscent of the conventional strongroom.

Photographic equipment and a dark-room are other features of the Acoustics Section. With their aid, sound is transformed into terms of vision, and the engineers can see positive prints of the progress of their experiments.

The laboratories of the Low Frequency and Radio Sections must represent a wireless engineer’s paradise. Racks of apparatus, shining mysteries of grey cellulose and chromium, line the walls; isolated instruments stand on benches in the middle of the room. Much of the equipment, as might be expected, can be seen in few other British laboratories. My guide indicated a knob-studded box on one of the benches.

“That’s our latest acquisition,” he said. “There are only two in the entire country.”

Although the Radio Section engineers spend a great deal of their time at the laboratory bench, their work must have given them an unrivalled knowledge of the British Isles. For theirs is the task of assessing the radio value of potential sites for transmitting stations. Attached to the Section are four vans and a mobile transmitter with which the engineers tour the neighbourhood of a proposed site, the transmitter operating from the site itself, while the vans take measurements of “field-strength” at points in the surrounding district. Another aspect of the Section’s work concerns ordinary broadcast reception: shelves in the laboratory where this work is done are stacked with receiving sets of every type.

To visit the Valve Section is to realise how vitally important is the part played by a valve in the broadcasting machine. In the records that the Section keeps are details of the characteristics and life of every valve purchased by the BBC. These records contain some astonishing facts. They show, for example, that the valves used in the transmission of programmes from Daventry alone number 178; that replacements of transmitting and receiving valves amount in one year to nearly 1,600; that some of the transmitting valves may have a life of up to 25,000 hours — denoting about six years’ continuous service. Which is as well: large valves capable of so long a life may cost £750 apiece. [£47,000 today, allowing for inflation -Ed]

The effects of the work that goes on so quietly at Nightingale Square are world-wide. They are not only reflected in all the BBC’s programmes — they are to be found in the story of the development of broadcasting. But though ponderous reflection is an inevitable conclusion to a tour of the BBC’s Research Department, relief may be found in introductions to three other features of the Department’s life. One is Jack, a member of the staff who is the son of an airedale and an alsatian and whose “wages” are claimed each week through the petty-cash sheet; another is the staff “gym” on the top floor of the building; the third is the garden that borders the drive to the main entrance. Nightingale Square is literally a place with “roses round the door.”

“S.B.” FROM ALL STATIONS

Once upon a time every listener in Great Britain knew the meaning of “S.B. from all stations.” It was as familiar a phrase in the language of broadcasting as “electrical recording” is now: the BBC, in its printed and microphone announcements, used it daily to describe any programme that was to be simultaneously broadcast from all the British transmitters. Then gradually it fell into disuse and was finally dropped. Today, probably, few listeners have ever even heard of it; fewer still could explain the meaning of the abbreviation “S.B.”

Map showing how the BBC’s network of permanent lines, which link the studios to the transmitters and to each other, covers the British Isles

Yet, inside the BBC, simultaneous broadcasting is a term that daily usage keeps very much alive — and it will live at least as long as the BBC has its Lines Department. For what was once regarded as a remarkable thing has become a routine matter, and the linking by telephone line of studios and transmitters is an established part of most broadcasting services. In Britain, it is the BBC Lines Department that, working in co-operation with the British Post Office (from which the telephone lines are rented) is responsible for the care and maintenance of the national network in which between sixty and seventy permanent circuits, representing 5,000 miles of line, link transmitting stations and studio centres to Broadcasting House in London and to each other.

Ensuring that the quality of the lines is up to the required standard involves daily tests over the network’s entire length, the establishment of “repeater” stations at various points in the chain, the permanent or temporary use of specially-designed apparatus. Each day, engineers in charge at the transmitting and studio centres supply the Lines Department with detailed reports on the previous day’s working of the lines, and any faults are made the subject of immediate enquiry and rectification. It is a proof of the extent of this part of the Department’s work that the routine work arising out of the “routing” of the programmes — that is, the selection of the lines along which the programmes shall travel each day — keeps two girls busily employed.

In the early days of British broadcasting, the S.B. system used open-wire telephone lines — the programmes travelling along the familiar pole-suspended wires. But the very nature of such a method meant a high risk of interruption from bad weather, road accidents, and similar causes. As a result, considerable progress has been made with the design, laying down, and treatment of underground cables containing circuits especially designed for broadcasting purposes, and most of the British programmes are now so carried from point to point.

Several circuits are used for the connexion of BBC stations. That intended for the carrying of the programme is known as a “music line” ; another is used for verbal communication between the engineers, and there is a stand-by in the event of a break-down in the “music” circuit.

Although a telephone line designed for the efficient transmission of the spoken word may provide a satisfactory speech circuit, the “music” line makes far greater demands on engineering resource. The line must be capable, of course, of carrying a far wider band of frequencies; it is of paramount importance that all frequencies within the band should be evenly transmitted; there must be no interference of any description. The listener might well consider that these demands have been satisfied, but engineers always see room for improvement. Experiment and research in the interests of “better lines” is a staple job of the Lines Department.

The apparatus at Broadcasting House used for testing the 5,000 miles of line that constitutes the network

But the welfare of the British network is by no means the only concern of the Department’s twenty-six engineers. They have to collect, as well as distribute. In the course of the year the engineers handle about 3,000 temporary circuits — lines rented from the Post Office for the purpose of bringing to the nearest studio a broadcast from an outside source. Every such programme — and there are dozens each week, as listeners must know — means for the Lines Department the requisitioning, booking, installation, routing, and testing of two or more circuits. It often happens that the decision to broadcast an event to Empire listeners as well as to Home means that the broadcast in question has to be treated as two — in other words, if the material to be heard by oversea listeners differs from that to be heard at Home (as when separate running commentaries on an event are found necessary), two separate pairs of circuits have to be installed.

The scope of the “collection” side of the Lines Department’s work is far from being limited by Britain’s coast-line. Broadcasts from Europe are frequent, and may have to be “collected” by lines from places as far distant as Budapest, Rome, or Helsinki. On such occasions, the Department collaborates, of course, with the oversea authorities concerned.

The lines engineer’s job is very much a behind-the-scenes activity. (Incidentally, they like it that way — BBC engineers shun the limelight with impressive unanimity.) It is only when something goes wrong that one is reminded of their existence — and the rarity with which things go wrong in a job that necessarily has a large and unshrinkable margin of error is a tribute to the way in which the job is done.

In the language of the lines engineer, “a technical hitch” may mean anything from “cross-talk” to the complete breakdown of a circuit. “Cross-talk” is the engineers’ description of unwanted speech caused by induction from a neighbouring line, and is liable to bring strange effects into a broadcast. Once, years ago, listeners to a symphony concert were astonished to hear their loudspeakers tell them, in the middle of a slow movement, to “put a sock in it!”

And then there is the lines engineer’s bete noire: the discovery, at the last moment, that circuits proved by advance tests to be perfect have developed serious faults. Not so long ago, an Empire programme was affected in this way. Two hours before the broadcast the engineer making the final tests found that the circuits had become hopelessly noisy. Right up to the advertised time of the broadcast a Post Office breakdown gang frantically climbed up and down poles in a desperate effort to eliminate the fault. They succeeded — eighteen minutes after the broadcast was due to begin and three minutes after listeners to Daventry had heard an announcement cancelling the programme.

The Lines Department regard that occasion as one of their failures. They willingly searched records and memories for more incidents like that. But I had to leave before they found any.

A SERVICE ROAD OF BROADCASTING

When the sentimentally-minded at Broadcasting House yearn for another peep at the transmitter of the first London station, or at the first dramatic-control panel ever used by the BBC, their thoughts turn to Avenue House….

When the equipment of a studio is under consideration, or a transmitter needs an emergency replacement, or transport of officials, apparatus, and musical instruments, is required, the requisitions go to Avenue House….

The BBC buys a valve-holder: it must be tested at Avenue House; an amplifier must be modified or an apparatus-bay wired: they are sent to Avenue House.

Avenue House, in BBC usage, means the Equipment Department. The name has lived, though the private residence and grounds in Clapham, South London, that it once described have long since become the place where the BBC keeps its Designs Section, central stores, experimental workshop, test room, transport fleet — and an unofficial “museum,” in which apparatus associated with the history and development of British broadcasting is being preserved.

Avenue House, the home of the BBC’s Equipment Department

But responsibility for the museum is a minor part of the Equipment Department’s job. Its principal duty is the provision of all technical equipment on the “speech-input” side of the BBC’s work — which means that the Department supplies (and, where necessary, designs) all the control positions, amplifiers, mixers, gramophones, valves, microphones, and similar apparatus required at BBC centres in London and the Provinces. In all, 168 men and a dog contribute to the work. The all-male staff includes engineers, draughtsmen, clerical assistants, mechanics, store-hands, and drivers; Biff, the dog, is the official assistant to the night-watchman, and has an uncanny faculty for identifying strangers.

Pleasant lawns and flower-beds — even a small orchard — once surrounded the Victorian house that not so many years ago was “home” to the Governor of Brixton Prison, which is just across the road. Today, most of the orchard has vanished under the brick-built building that houses the test rooms, the museum, the Designs Section, and the drawing office, and where flowers and grass used to be there are now the stores, a spacious garage, and the workshops. But there is still a lawn on which the staff may enliven the lunch hour with football and cricket; there are beds of flowers under office windows; and a tree-shaded drive leads from the main road to a tiny lodge – now known as “the Mess” — and the main yard.

A Test Room at Avenue House, showing the standard test bays

Though, as far as possible, commercial firms supply the BBC with its technical equipment, certain specialised work — and especially experimental work — can be carried out to the best advantage by the Corporation’s own staff. Up-to-date facilities, therefore, are available in the experimental workshop for modifying or renovating apparatus, for constructing experimental amplifiers and the like, and even for applying the cellulose finish to a completed unit.

However, most of the equipment is bought outside, though a manufacturer has to be able to meet exacting requirements before he gets the BBC’s order. The importance of ensuring that every piece of equipment — a grid-leak no less than a dramatic-control panel — conforms to a high standard needs no emphasis. So an important part of the Equipment Department is the Testing Section, through which every component must go before it is passed for service.

In the Designs Section of the Department one meets the men who draw up the plans for any speech-input equipment that may be wanted, either for installation at new premises or for modernising existing plant. Allied with them is the Drawing Office, which produces all the drawings of BBC equipment (with the exception of transmitting and power plant), and provides the engineers with their indispensable blue prints. The BBC engineers’ desire for blue prints must be insatiable — 37,000 are turned out every year.

It is fortunate that the garage at Avenue House is never called upon to accommodate all the BBC’s vehicles at once. It is a large garage, but it would have to be very much larger to give room to them all at the same time. There are seventy-eight of them. There are private cars, shooting brakes, ’buses, small vans, pantechnicons, for the transport of gear and personnel; there are a transmitter-lorry and field strength-measuring vans, which are sent out to test sites for prospective transmitting stations; there are the mobile units used for outside broadcasts, for on-the-spot recording, and for televising outside events; there is the “O.B.” control van, which goes on the road for occasions such as the broadcast of the Armistice ceremony at Whitehall. Among them all, the vehicles cover close on a million miles every year.

One of the trickiest jobs of the transport people is moving from point to point the instruments of the various BBC orchestras, for which work the pantechnicons are used. They are on the road every day, and are as liable to be seen on Continental highways as in the streets of London. Some years ago, for instance, when the BBC Symphony Orchestra gave a concert in Belgium, two of the vehicles carried the instruments of the Orchestra’s 119 players to Brussels and back within seventy-two hours — and not so much as a violin – string suffered from the journey.

One other section of the Equipment Department is a clue to a little-known but vital feature of the BBC’s work: the official reception and checking of the broadcast programmes, for which purpose receiving sets are established at many points throughout a wide area. It is the Receiver Section at Avenue House that supplies and maintains those sets.

In one way, it is an injustice to regard Avenue House as a “by-way” of the BBC: the Equipment Department may lie off the beaten track of the ordinary listener, but it is an indispensable service road in the world of British broadcasting.

About the author

Wilfred Goatman began working at the British Broadcasting Company’s station 5WA in Swansea, where his was the first voice heard on air. He later worked in the Public Relations Department at Broadcasting House in London. These articles were originally written as features for BBC Empire Broadcasting magazine under the pen-name “J. C. MacLennan”, and all nine were collected into the book By-ways of the BBC, published in late 1938 by P.S. King & Son.