When the BBC Overseas Service moved into Bush House at the start of the
Second World War, there was a shortage of studio mixing desks because
of the sudden expansion. As a stop-gap measure a number of 1938 vintage
outside broadcast mixers - the OBA8 - were installed.
The BBC at that time made its equipment last... these desks were still
in use thirty years
later - I've made programmes on the wretched things, and I took the
photo above in January 1969. The desk is much as it was when it was
installed: the outrigger panel on the extreme left was added in the
1960s to accomodate the tape machines which were then being
installed in studios. The small microphone over the mixer was added
around that time for the Studio Manager to make the short announcement
which preceded most transmissions (previously there had been a ribbon
microphone slung over the gramophones). The microphone in the studio is
an ST&C 4038 ribbon - when the desk was first installed it
probably have been the much larger AXBT ribbon microphone.
the main amplifier (valves, of course) was very good and much quieter
than many later desk designs, the mixing was done at low level: that
is, the microphone outputs were fed straight into the mixing controls
without amplification, and the outputs of these controls mixed without
the use of buffer amplifiers. The result was that not only were the
controls very prone to noise when you moved them, but fading up one
channel lowered the level of anything else faded up at the time.
make working them more difficult, there was no transmission talkback,
to allow the Studio Manager to talk to the studio while recorded
inserts were being played. This led to considerable skills in mime as
instructions were passed back and forth. Try asking someone 'which tape
do you want next?' without being able to talk to them.
around 1969 these desks were finally removed and replaced with Bush
House's first transistorised desks, which brought their own set of
interesting problems - that's another story.