Manchester Playhouse stereo control desk

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!

 

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BBC Marconi AXBT microphone

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Marconi AXBT microphone

The BBC Marconi AXB pressure gradient microphone was introduced in 1934, reputedly as a means to avoid the cost of importing RCA44 microphones from the States.

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With its 2.5 inch ribbon and bass proximity boost, it became synonymous with the ‘voice of Aunty’ and an iconic symbol of the Corporation’s global reach.

bbc-axbt-chinese-sectionSubsequently improved with advances in magnetic materials, the T-painted AXBT (see top photo) with Ticonal magnet appeared in 1946 with an improved sensitivity for 6dB more output gain and better transient response.

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Whilst designed primarily for the speaking voice,  a fabulous microphone for ambient applications such as drum overhead with a tight angle of incidence and general room vibe in the modern music studio.

STC 4038 microphone

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4038 employing the old BBC handkerchief trick

Iconic BBC ribbon design, commercially manufactured under licence by Standard Telephone & Cables using spider technology.

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Developed from the PGS, the 4038 was the BBC’s successful attempt at designing a general purpose pressure gradient microphone, with excellent linear performance at a reasonable size and cost compared to the AXBT.

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The red line is Cole’s master reference microphone, kept in their anaechoic cupboard

Two versions were produced, a 30 Ohm version for outside broadcast and television studios, a 300 Ohm version for the sound studio.

Used just about everywhere in the BBC.

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STC standard T-bar for 4038s, with debatable comb filtering effect

Wonderful on just about everything!

BBC Type B equipment

eve-bbc-type-b-amplifierBBC Type B modular equipment was introduced in the mid 1950s, to replace the larger and more expensive post war Type A installations.

Based on a smaller and more readily available valve, the ECC81 (or 6060 with lower microphony) the Type B became a familiar sight in many BBC studios across the land, including of course the Radiophonic Workshop. It is surprising that so few appear to have survived!

RWS12

King of the roost was the AMC/5 microphone amplifier with fixed gain stages of 40 to 70dB. This had been developed from the earlier general purpose GPA/4 amplifier which was also used for microphone applications. Further down the gain chain was the C/9 line amplifier with 10dB in hand.

eve-bbc-type-b-installationAmplifiers were attached to specially designed frames, held in standard BBC issue 19″ racks.

Consoles were passive, constant impedance, utilising Painton stud faders and in some instances with quadrant faders, such as at the Radiophonic Workshop as seen here in the capable hands of Delia Derbyshire.

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The Kingswood Warren

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Kingswood Warren passive trolley mixer

The ‘Kingswood Warren’ system was originally custom built in the 1960s by R&D at Kingswood Warren for their loudspeaker testing facility.

Selected members of the audio fraternity were invited to listen to such famous BBC loudspeaker designs as the LS5/8 and LS3/5 monitors from behind a curtain, after drinks and canapes, as part of the design and commissioning process.bbc-listening-room-at-kingswood-warren

After the R&D establishment was relocated, the Kingswood Warren was re-purposed by EVE’s Radiophonic Studio as a unique mixing system, primarily for mastering use by Eve Mastering. Sadly the field telephone is missing, but everything else remains.

The Kingswood Warren
EVE Mastering

The Kingswood Warren is unique in being entirely modular. A vertical modular mixer!

Everything is patchable, with particular attention being paid to impedance matching between building blocks across the system to maintain level topology.  The entire system operates at 600 Ohm.

Whilst the original design did not require dedicated amplification being purely passive, the Kingswood Warren is now powered by 1950s ultra linear BBC Type B valve line bridging amplifiers, with the ability to switch via cross patching to BBC Type B microphone amplifiers, decade attenuators and external amplifiers if and where desired.

EVE BBC Type B amplifier
BBC Type B ampifiers

The mixing console is based on a passive constant impedance design, having the unusual feature of mechanically ganged faders, making it ideal for stereo work. This is achieved through an amazing precision engineered cog system using machined brass teeth.

Kingswood Warren photo by Hannes Bieger
Thanks to Hannes Bieger for this photo

Special thanks to Chris Chambers, Alistair Biggar and Phil Macbean without whom the Kingswood Warren would never have been possible.