GP (General Purpose) Desks
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GP Desks described by Mike Chessher

As Brian Binding says on the previous page, the prototype in PP5 was not very well received, especially by Studio Managers involved with live programmes and if you compare it with the elegant and much photographed Type D desk in 3E you can see why. There was a wide divergence of views between SMs working on different types of programmes, which made Brian's job almost impossible. What he didn't know was that the mock-up had been presented to SMs as a desk for Schools Drama and not as a "blueprint for the future." The outcry led to the formation of a Technical Consultative Committee involving a group of SMs and the desks' designer. To be fair, as it also included the head of the department and the head of Radio Projects, it was more than "consultative", but much bargaining lay ahead.

Studio B5 in 1984

Studio B5's desk in 1984
Here then is B5, a small talks studio with its Mk 1 GP. The faders from the left are main, clipped together stereo group, 2 stereo echo returns, 4 outside source channels and beyond the script space, 6 local channels. Whilst there may have been some argument about script space, one thing SMs had always agreed on was that outside sources should be on the right! Incidentally, all the channel faders are closed. The keys above the faders are for cue lights.

The 4 modules at the far left are outside source cue send modules. The red button diverts the output to the jackfield for use with a cue line rather than a control line. The modules in the upstand are for channel gain and EQ and the channel routing modules are below with group/ind routing, 2 aux bus bars, echo and a (red) pan pot above locking PFL/AFL buttons.

To the left of the main PPMs are repeat "limiting db" meters for the com/limiters which are themselves located out of eye line away to the right. Below are tone send buttons, local red light, transmission/rehearsal and buzz back buttons and (green) power supply indicators. The prominently placed blue and white buttons to the left of the main monitoring panel are for telephone ring and answer. Tape remote starts are just above the script space. Talkback keys are Master, Studio, Aux, Slate and 4 Outside Sources.

It might not be perfect but it's strange to think that, before a bit of rebuilding work, there was a Marconi desk here.

The SM members of the Technical Consultative Committee enthusiastically set to work on the layout of a new desk to be known as the GP Mark 3. The new desk would have script space in front of the faders, a lower profile and redesigned EQ, monitoring and OS cue modules. Unfortunately there was not much effort available to turn these ideas into drawings to take to a manufacturer and time was running out for the many Type B desks around BH and especially so for S1 which was still Type A. So work on the new desk was delayed and a compromise desk was devised using the existing carcase and modules apart from a much improved OS cue module. This became the GP Mark 4.

Studio 3C
In the Mk 4 desk, extra script space in front of the faders was achieved by removing the cue light keys - foot operated cue lights were much preferred, anyway. The centre modules with monitoring, etc, were moved to the side of the desk. This meant placing the PPMs in a pod on the top of the desk.

Studio 3C closeup

3C, above, was the first GP Mk 4 to appear and was well received but clearly illustrates one of the problems with GP. While SMs tended to think of it as a "pick and mix" system, it was very difficult and expensive to keep altering the drawings, so it had to be a standard size carcase with standard wiring. It was just as difficult to remove facilities as add new ones. 3C didn't need 24 channels, so some of the modules were kept as maintainance spares. They were later added as the desk looked odd without them. Note that the PPM pod has been kept as low as possible by cutting away the surounding woodwork.

B15 in 1984
It is easier to pick out some of the details in these pictures of B15. There are 14 local and 10 outside source channels which can be routed to a choice of 3 groups or IND. The outside source cue modules have buttons to send cue, clean feed and talkback to cue and control lines in any combination with a choice of 4 cue feeds derived from the 4 (green) ringmain selectors below the modules. Next come the telephone ring and answer keys with the prefade/talkback keys below them.

B15, as the main phone-in studio, normally used the last 6 outside source channels for telephone balance units and the indicator lights above the faders are non standard.

B15 in 1984

The left hand wing of the desk starts with main controls for the aux bus bars, group amplfiers and echo controls. Then comes the monitoring panel with tape remote starts and talkback keys below. The cluster of talkback keys includes 3 auxilaries. AUX 1 has been retained as a totally independent talkback, whilst AUX 2 and 3 are intended for use by presenters and are mastered by studio talkback.

Closeup of 5A's desk in 1984
The auxilary (prefade) LS is above the monitoring panel. The row of tone send buttons has grown because "Tone to clean feed" is included and there are 10 of them on this desk. (A facility rarely used in radio and dropped from the later Mk 3 desk.)

To the right is a closer look at a Mark 4 monitoring panel, this one actually is from 5A.

The two rows of white buttons at the top are mono and stereo monitoring selectors, the mono one includes Prefade and Aux outputs, whilst the stereo one has main and group outputs and is used for monitoring off-tape record feeds. (It was normal practice when recording programmes to monitor, or at least spot check, the delayed feed coming from the record machine playback head.)

The main monitoring controls are on the right with volume and balance controls either side of a programme ring main switch, followed by studio and auxilary controls.

Broadcasting House began to fill up with GP Mk 4 desks and they proved their worth in studios as different as 3C (by now used for WATO/PM transmission because building work had started in the 3B area) and S2, a large studio often used for Schools music programmes.

It became clear that the brand new lower profile Mark 3 desk would now be limited to four "mixer" studios requiring a TO position to handle outside sources. After much anguish it was decided to stick with a proven design and make the Mark 3 as a mixer version of the Mark 4. Apart from the cost implications, one of the most telling reasons for sticking with the same design was that, at that time, most SMs worked across a wide range of studios. The number of controls had greatly increased, compared to Type B and at the same time radio had speeded up, so to be able to grab the same control in the same place in different studios was a great advantage.

Studio 3B in 1983

3B was one of two Mark 3A desks with 24 channels - 10 local, 2 dedicated phone channels and 10 outside sources. The other Mk 3A later went into 4A. There were two Mark 3 desks with 32 channels (20 outside sources) in B9 and 4C. Apart from the ability to transfer the SMs outside talkback working to a headset, there were few changes from the Mark 4.

The Technical Operators position is on the left with outside source selection and cue modules. For everyday use when this position was not staffed, 4 of the cue modules are duplicated to the right of the faders. Here too are cue modules for the dedicated telephone channels and a switch-down panel to select telephone balance units. Note that the "Tone to Clean Feed" buttons have now gone.

The studio was in the location of the original H30 and on the opposite side of the cubicle in the space occupied by the original 3B studio was 3K. This was designed as a back up/preparation studio to 3B and had a 12 channel GP desk with access to all 3B's outside sources without reference to control room. Originally it was designed for one SM operation with tape machines either side of the desk. This required a different method of working from anywhere else and was not a success. 3K was quickly changed to the conventional arrangement.

M15A machines
Alas, we have no pictures of 3K but here is a picture of the tape machines in use at the time. It shows the Telefunken M15As and a couple of cart machines.

The large box on the wall is a Tape Control Panel. This is an elaborate way of routing all repro sources to a number of bus bars or individually in mono or stereo. Another panel out of shot carries record input selectors.

Studio 3B in 1983 - OS modules
Each individual GP channel module had 6 high quality outputs - Main, Separate, Aux 1, Aux 2, Echo and Prefade.