The desk shown in the photos has been preserved, but seems to have had some changes made to it since it left the BBC. The image has been retouched to 'restore' the desk to the state that we remember.
We've not yet been able to find out exactly when these desks were introduced, but it was probably the late 1940s or early 1950s. BH studios equipped with them included all the third floor talks studios.
Mixing was at high level. The channel amplifiers had a maximum gain of 65dB and were followed by constant impedance faders. After being mixed the signal passed through the main fader and then the main amplifier, which also had a gain of 65dB.
The first fader on the left is the main, the second handled one of four outside sources, selected by the rotary switch above the fader. The remaining three channels were for two microphones and grams. In order to provide for tape outputs, one of the positions of the outside source rotary switch was used.
The small green buttons above the faders operated the cue lights.
To the right of the desk were four buttons which selected various desk conditions - Line-Up Tone, Transmission, Talkback and Loudspeaker Dim. Pressing the Line-Up button routed tone to the OS (second) fader. That fader was opened fully and the level of the tone was then adjusted using the main fader. When the studio was given a red light by a continuity or control room the desk was automatically switched into Transmission condition. This facility was retained on the Type A desk, though dropped from the Type B and subsequent designs. Talkback was available only in Rehearsal condition.
To the left of the PPM is the local red light switch. The rotary selector switch to the right was the monitor selector. This gave access to channel and outside source prefade feeds. An outboard unit housed the talkback mic and a ringmain selector.
By the end of 1965 there were three of these desks still in use in Broadcasting House. They were in studios B5 and 3D and in Recording Channel H56. There were a couple in Bush House (N42 and N43) and some in the regions.
This picture shows the desk in B5, photographed by Chris Chambers in May, 1978.