One reincarnation of the Manchester Playhouse BBC studio facility, featuring an early stereo desk. Transportable stereo desks, based on C series transistorised amplifiers, were pioneered by John Longden in London and John Bower in Manchester who also experimented with early surround sound console designs.
This desk looks to be an earlier B series console, judging by the portable Type B racks, which may have been brought in as additions to a pre-existing Type B installation.
Also visible in the top photo are what look to be no less than 5 x AKG C24 valve microphone power supplies and associated stereo pattern boxes!
Part of the OBA/9, the MX/29 incorporated 4 passive constant impedance attenuators.
Utilised across the BBC during the Fifties, the one in the photo below was the original mixer for the Radio One Roadshow which launched in 1967.
The Manchester Playhouse, home to the Northern Dance Orchestra, utilised an array of BBC OB equipment, including no less than 5 x MX/29s as seen on the RHS of the picture below
The LSU/11 was a 1 watt, yes 1 watt loudspeaker, with an 8″ Wharfdale driver.
Designed as a compliment to the OBA/9 system, with portability in mind.
Additional items to the OBA/9 trolley were these communication units for lamp signalling between the operator and various microphone points.
The CMU/10 also provided for a P.P.M. meter which was powered off the OBA/9 rig.
Not currently in use, but looking forward to getting these lit up like a Christmas tree.
The OBA/8 system was introduced in 1938. Intended for portable use with war in Europe looming, it was more lightweight then predecessors and utilised a pentode valve for the first time in British amplifier design.
The whole system, designed for self operation, consisted of two OBA/8 amplifiers (one on standby), a passive MX/18 mixer, LSU/1 loudspeaker and comms.
Many units, particularly the MX/18 mixer, continued to find a use long after peace had been declared, in provincial studios and of course the Radiophonic Workshop.
Here is a picture of Daphne Oram with three such passive mixers, which utilised wire wound constant impedance attenuators (and an OBA/8 in the foreground).
The OBA/9 system evolved in the 1950s to replace OBA/8, with a smaller footprint and expanded facilities to meet the demands of outside broadcast engineers as the needs of broadcast expanded.
The whole system was designed to be ‘portable’ of a fashion; consisting of an MX/29 passive mixer, OBA/9 valved amplifiers with high gain and power supply, along with monitoring amplifier and distribution facilities. Ancillary items included a loudspeaker LSu/11 and communication units CMU/9 and CMU/10