Control Room of Broadcasting House, London

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.

00 C/R Mixer 00 S1 00 BM271 * 00 Big Ben
01 Despatch 1 -CH1 01 B1 01 BM549 * 01 SB Replacement 1 *
02 Despatch 1 -CH2 02 B2 02 BS154 * 02 SB Replacement 2 *
03 Despatch 1 -CH3 03   03 BS222 * 03 SB Replacement 3 *
04 Despatch 1 - CH4 04 RM4 04 BS275 * 04 SB Replacement 4 *
05 Despatch 1 - CH5 05 B5 05 DX689 * 05 SB Replacement 5 *
06   06 see note 06 LS683 * 06 SB Replacement 6 *
07 3CH Mixer 1 - A 07   07 Bay 65 Jack Inlet 1 07 1000 cps
08 3CH Mixer 1 - B 08   08 Bay 65 Jack Inlet 2 08 1000 cps 30 secs
09 3CH Mixer 1 - C 09   09 Bay 65 Jack Inlet 3 09 440 cps
10   10   10 Bay 65 Jack Inlet 4 10 440 cps 30 secs
11 Despatch 2 - CH1 11 1B 11 OB Chain 1 11 440 cps 10 secs
12 Despatch 2 - CH2 12   12 OB Chain 2 12 Test Oscillator
13 Despatch 2 - CH3 13   13 OB Chain 3 13 SB Test Room
14 Despatch 2 -CH4 14   14 OB Chain 4 14 Source Switch TV 1
15 Despatch 2 -CH5 15   15 OB Chain 5 15 Source Switch TV 2
16   16 CH 16 OB Chain 6 16  
17 3CH Mixer 2 - A 17 L1 17 OB Chain 7 17  
18 3CH Mixer 2 - B 18 L2 18 OB Chain 8 18 Home Distribution
19 3CH Mixer 2 - C 19 1A 19 OB Chain 9 19 Light Distribution
20   20 3A 20 OB Chain 10 20 Third Distribution
21 C&M1 - A 21 3B 21 OB Chain 11 21 Green
22 C&M1 - B 22 3C 22 OB Chain 12 22 TV Sound Dist
23 C&M2 - A 23 3D 23 OB Chain 13 23 Red
24 C&M2 - B 24 3E 24 OB Chain 14 24 Purple
25 C&M3 - A 25 3F 25 OB Chain 15 25 Chain 22
26 C&M3 - B 26 3G 26 OB Chain 16 26 TV Main *
27 C&M4 - A 27 4A 27 OB Chain 17 27 TV Reserve *
28 C&M4 - B 28 6A 28 OB Chain 18 28 Single Tx Home MW
29 C&M5 - A 29 6C 29 OB Chain 19 29 Single Tx Home VHF
30 C&M5 - B 30 8A 30 OB Chain 20 30 Single Tx Light MW
31 C&M6 - A 31 MV1 31 IMC1 31 Single Tx Light LW
32 C&M6 - B 32 MV2 32 IMC2 32 Single Tx Light VHF
33   33 MV3 33 IMC3 33 Single Tx Third MW
34   34 MV4 34 IMC4 34 Single Tx Third VHF
35   35 MV5 35 IMC5 35 Sw/C BM Opt-Out
36 London Airport 36 PP1 36 IMC6 36 Sw/C BS Opt-Out
37 St. Stephens * 37 PP2 37 Continuity 1 37 Sw/C ROW Opt-Out
38 Aeolian 1 38 PP3 38 Continuity 2 38  
39 Aeolian 2 39 PP4 39 Continuity 3 39 CBC Langham
40 Camden 40 PP5 40 Continuity 4 40 Emergency AMC
41 Farringdon 41   41 RT1 41 Spare GPA I/P 1
42 Jubilee 42   42 RT2 42 Spare GPA I/P 2
43 Paris Cinema 43   43 RT3 43 Spare GPA I/P 3
44 Piccadilly 1 44   44 TAT1 44 Spare GPA I/P 4
45 Piccadilly 2 45 H50 45 TAT2 45 Spare GPA I/P 5
46 Playhouse 46 H53 46   46 Tatsfield 1
47 GA Western 47 H56 47 Bush 1 47 Tatsfield 2
48 LH1 48 H58X 48 Bush 2 48 Tatsfield 3
49 Grafton 49 H58Y 49   49 GTS
* These sources also appeared in the separate Television Source Mult which used Y or Z codes to avoid confusion with the main mult.

A00 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.

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.

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.

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.

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.

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.

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 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.

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.

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 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.

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 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.

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.