Sources and source codes in 1961. Notes by Barry Taylor.

The previous page describes the working of the uniselectors used in the source selection system. Here are the codes that had to be entered using the buttons seen on the right. This early code allocation (11th April 1961) was issued prior to the uniselector Control Room becoming fully operational. See below for an explanation of the sources. If you click on the source names the page should scroll to the appropriate entry. Click on the upward pointing arrows to return to the top of the source list.

* These sources also appeared in the separate Television Source Mult which used Y or Z codes to avoid confusion with the main mult.

A00	Related pages Mixer 1A | Photos of S2 & 3 | Photo of B1 C/R Mixer - The Control Room Mixer, always referred to as Mixer 1A rather than simply 1A because 1A was already in use as the name of a studio in Egton House. Used for multi-outside source productions, this studio was the direct descendant of Dramatic Control Panels, S2, S3 and B1.
A01-A05	Despatch 1 - CH1-5 - Despatch Cubicle 1. The Despatch Position was designed to centre all news items in one area under the control of a 'Master Operator' assisted by a relief operator. Normally 4 simultaneous circuits could be handled. In practice 4 simultaneous circuits were quite rare. The Despatch Position only handled overseas circuits, namely those from Europe via IMC, from North America via TAT and anywhere else on radio circuits via RT. Having liaised with the GPO operator, the Despatch Position operator briefly confirmed two-way contact with the reporter/correspondent and then switched the Traffic Manager 'into the circuit'. The first priority for the Traffic Manager was to record (on machines remotely started by her in H30, Alexandra Palace and Bush House) the reports the correspondent was filing. After this was done messages were passed (international telephone dialling was yet to come). If necessary and on request to the Traffic Manager, News Editors in Bush House and Alexandra Palace (where TV News was based) could speak to the correspondent. This facility was enabled by the Despatch Position operator who may have been monitoring the circuit or if not the Traffic Manager had a direct phone line to him/her to request the facility. Provision was also made for live inserts into news bulletins (a very rare event in the early 1960s) with conference facilities planned for 3G, 3F (both in Egton House where the newsroom was located) and Mixer 1A. The latter was changed to 3B when that new mixer studio was completed and the newsroom moved from Egton House to the 3rd floor of BHX. The conference network that made the facilities described work was in fact a very large clean feed network such that everyone could hear everyone else but not themselves to avoid howl-rounds if loudspeakers were in use. This was achieved with a matrix of 50dB attenuators. The conference feed to Bush House (for example) then consisted of everyone except Bush House paralleled together and fed through an amplifier with a gain of about 50dB. A total of 21 amplifiers was needed and as space was limited these were transistor amplifiers, the only ones in the whole of the 1960s control room. These were 3 stage amplifiers using germanium transistors and basically designed as mic amps. The first versions of this amp used a GET6 followed by an OC71 and OC72, later versions used a GET106 followed by two GET104s.
A07-A09	3 CH Mixer 1 - A, B and C - A three-channel mixer with 3 separate outputs located in the same cubicle as Despatch Cubicle 1. Treated as a spare to the mixer in Despatch Cubicle 2.
A11 - A15	Despatch 2 - CH1-5 - Despatch Cubicle 2. Identical to Despatch Cubicle 1 and only used if there was a fault or routine maintenance in Cubicle 1. See above.
A17 - A19	3 CH Mixer 2 - A, B & C - A three-channel mixer in Despatch Cubicle 2 identical to that in Cubicle 1. Occasionally used to mix 2 or 3 London OB contributions to regional Home Service sports programmes. Later the area became the cubicle of Continuity G.
A21 - A32	C&M 1-6 - A & B - Control and Monitor Positions. The direct descendants of the control positions in the 1932 control room and the 'Bays' in the Wartime control room. Normally used as 6 positions each with two independent outputs, each pair could, by operation of a single switch, be converted to a 2-channel mixer with a main gain control and 4 independent outputs.
A36	London Airport - The unattended BBC studio at the Airport, usually abbreviated to LAP. (The airport is better known today as London-Heathrow, LHR).
A37	St. Stephens - The unattended (i.e. no engineer or studio manager) BBC studio from where Parliamentary correspondents filed their reports.
A38 - A46	Aeolian Studios 1 & 2; Camden; Farringdon; Jubilee; Paris Cinema; Piccadilly 1 &2; Playhouse - The Outside Studios now long since closed. 'The Goon Show' was recorded in the Camden Theatre and sometimes in The Paris, a converted cinema. The Paris was also the venue for 'Beyond Our Ken' and 'Round the Horne'. (The Paris was always so called in the Control Room to avoid any confusion with the BBC studio in the French capital, which was always referred to as Paris France).
A47	GA Western - A small studio in Western House.
A48	LH 1 - A medium sized drama studio in The Langham. Other studios in what was once, and is now again, The Langham Hotel were used for staff training.
A49	The Grafton - Another outside studio.
B00	S1 - BH sub-basement, the studio known earlier as BB.
B01	B1 - BH basement. B1 was the major events mixer soon to be superseded by Mixer 1A.
B02	B2 - BH basement. A small studio.
B04	RM4 - Recording Mixer 4 sharing the same studio as B2. Originally intended for mixing record programmes without speech; it was booked as 'B2 +RM4' when the studio was required. After the B2 desk was removed it simply became B4.
B05	B5 - BH basement studio.
B06-B16	Destined to be the codes for the new BH extension studios B6 - B16 which were still under construction at the time of this listing. CH, the Concert Hall, on B16 was later moved to another code. B11 was allocated to 1B which was a lip mic in the Sports Room in Cavendish Mansions.
B17	L1 - Lower Ground BH immediately under Reception. The so-called VIP studio, decorated with glassware displayed in cabinets.
B18	L2 - Lower Ground Cavendish Mansions. The Radio Newsreel studio.
B19	1A - Studio on the first floor of Egton House always called 1A Egton to avoid confusion with Mixer 1A. Later renamed as Egton 1.
B20 - B30	3A, 3B, 3C, 3D, 3E, 3F, 3G, 4A, 6A, 6C & 8A - BH studios except news studios 3F and 3G which were in Egton House. (The newsroom was in Egton House at this time). These two were later renamed Egton 2 and Egton 3. 8A, a drama studio, was often referred to as 'Studio 8' rather than 8A.
B31-35	MV1 - 5 - Music studios in Maida Vale.
B36 - B40	PP1 - 5 - Schools and small talks studios in 1 and 1A Portland Place.
B45-47	H50; H53 & H56 - Recording channels on the fifth floor of BH extension. These had studios with a Type B Mk II desk in H50 and H53 and a Marconi in H56.
B48-B49	H58X & H58Y - Outputs from 2 pairs of playback tape machines in the Central Recording Room H58. (H58 replaced H18, which was on the eighth floor of BH, located in the area previously occupied by the 1932 Control Room). Note that at this time only engineering staff were permitted to operate tape machines. In the photo the machines which appeared in the source mult as H58X and Y were at the far end of the room.
C00-C06	BM271, BM549, BS154, BS222, BS275, DX689, LS683 - Incoming lines known as SB (Simultaneous Broadcast) lines which, more correctly, should have been called Regional Contribution lines. BM, BS, DX and LS are GPO abbreviations for Birmingham, Bristol, Daventry and Leeds. The numbers are abbreviated GPO line designations. For example BS275 was PW12275, the PW standing for Private Wire. (Lines wholly within the GPO London Region were coded PW/LR.)
C07-C10	Bay 65 Jack Inlets 1 - 6 - Pluggable inputs to the source mult located on Bay 65 (adjacent to OB and TV positions).
C11-C30	OB Chains 1 - 20 - Outside Broadcast Chains of pre-wired and/or normalled equipment i.e. Rep. coil, passive equaliser, attenuator and D amplifier.
C31-C36	IMC1 - 6 - IMC stands for International Maintenance Centre, a section of the GPO that dealt with circuits to Europe. On these codes were local ends from IMC for music, cue and control lines following the convention of music line=1, control line=51, cue line=101. These were not of course the actual GPO line numbers but were a very convenient shorthand for liaising with and booking lines on and off with IMC.
C37-C40	Related page The 1960s continuities are described here... Continuities 1 - 4 - Outputs from the Continuity Suites for use when the suite was used as a studio (a very rare occurrence).
C41 - C43	RT1-3 - Lines from the GPO Radio Terminal at Brent. Outside of Europe and North America all news material arrived by radio telephone circuits. (Music and Cue lines.)
C44 - C45	TAT1 - 2 - Lines from the GPO Trans-Atlantic Terminal for circuits to USA and Canada. (Music and Cue lines.)
C47 - C48	Bush 1 - 2 - Two circuits from Bush House.
D00	Big Ben - Output from a BBC microphone and amplifier at Westminster. Announcers have been known to cue 'the chimes of Big Ben'. Wrong, of course, as Big Ben is the large bell which produces the strokes and its four companions are responsible for the chimes.
D01 - D06	SB Replacement 1 - 6 - The outputs of chains of equipment similar to OB chains and intended for the replacement of SB lines under fault conditions or if the GPO needed to do work which would make an SB line LTI (liable to interruption). In practice the replacement circuit was overplugged so that it appeared on the code of the line it was replacing.
D07	1000 cps - 1000 cycles per second tone. The use of Hertz for frequency was yet to come.
D08	1000 cps 30 secs - A pulse of 1000 cps tone every 30 seconds on the minute and half minute with a long decay time. Known as 'bing tone'.
D09	440 cps - 440 cycles per second tone.
D10	440 cps 30 secs - 440 cps bing tone similar to D08.
D11	440 cps 10 secs - 440 cps 10 second bing tone which did not occur at exactly 00,10,20,30,40 and 50 seconds past each minute but varied by ±2 seconds over the minute. The 50 sec. bing actually occurred at 52 seconds.
D12	Test Oscillator - Output of a test oscillator for frequency response test on lines. Done manually originally but replaced circa 1965 by a sweep oscillator and automatic pen chart recorders in the regional centres.
D13	SB Test Room - Output from Lines department test room.
D14-D15	Source Switch TV 1 & 2 - Two sources from the TV sound position (not BBC1 and BBC2 - there was still only one network at this time).
D16-D17	Related page The continuity interchange process is described here... Home, Light, Third, Green and TV Sound Distributions - Home, Light and Third were feeds from the output of the continuity interchange unit. Green was GOS - the General Overseas Service - more or less what today is called World Service, and came from Bush House.
D23-D25	Red, Purple and Chain 22 - Programme feeds from Bush House. Chain 22 was fed to the Droitwich transmitter following Light Programme closedown after the midnight shipping forecast.
D26 - D27	TV Main and Reserve - Two feeds of what was then the one and only BBC Television channel.
D28 - D34	Related page The single transmitter system is described here... Single TX, Home, Light and Third - See link in box for details.
D35 - D37	Sw/C BM/BS/ROW Opt-Out - Opt-out TV sound feeds from TV Switching Centre (based in BH). (ROW=Rowridge, the south of England transmitter on the Isle of Wight.)
D39	CBC Langham - Output from a small office/studio in The Langham used by CBC (Canadian Broadcasting Corporation) before they moved to their own premises in Gt. Titchfield Street in the late sixties.
D40	Emergency AMC - There was an 'Emergency' Mic socket in Type A studios that went direct to Control Room. In the event of a failure of a studio's equipment its mic would be plugged to this microphone amplifier.
D41 - D45	Spare GPA I/P 1 - 5 - Spare amplifier outputs.
D46 - D48	Tatsfield 1 - 3 - Three lines from the BBC receiving and monitoring station at Tatsfield.
D49	GTS - Greenwich Time Signal which to make line failure detectable was generated as continuous tone with 6 gaps before every hour and 15, 30, 45 minutes after the hour. It was sourced from the Royal Observatory, Herstmonceux, Sussex. The 'pips' were generated in BH by gating a tone source with the incoming signal.