AP mast (2K)


by Arthur Dungate


Stereo sound experiments

  *Stereo tests
The programme was Record Review.
BBC Engineering 1922-1972 by Edward Pawley, Ch 6.1 p433 --

The first determined moves towards stereo were made towards the end of 1957, when the BBC decided that the increasing availability of stereophonic gramophone records and the public interest that was being aroused justified serious consideration of stereophonic broadcasting.

Late in that year an experimental transmission took place at night, the left- and right-hand channels being transmitted by two of the VHF transmitters at Wrotham. The programme came from a tape supplied by EMI, with items recorded in this country and in America. The BBC was in the forefront of systematic research into the audio-frequency problems. Many subjective tests were carried out over a period of two and a half years — a laborious task, which established the tolerances applicable to phase-shift between channels and other parameters.

This work was done in collaboration with the operational and programme staff; orchestras and artists had to be engaged to perform specially for the tests. It was an expensive exercise but it yielded valuable results, which have contributed to international discussions on the audio-frequency standards for stereo that are still continuing, notably in the CMTT (Commission Mixte des Télégraphes et Téléphones).

Putting this accumulated knowledge into practice the BBC began to make experimental stereo transmissions, which on 18 October 1958 developed into regular fortnightly transmissions, on Saturday mornings.

The Third Programme transmitters (VHF and MF), which were free at that time, were used for the left-hand channel and the television sound transmitters for the right-hand. An hour’s programme* was broadcast, consisting in part of discs issued by the recording companies but also including material produced by the BBC. Listeners had to use two receivers, a VHF or an MF receiver and a television receiver, placed suitably in the room.

At locations well within the service range of the transmitters the stereo effect was very good. These experimental transmissions continued for some years and generated a great deal of correspondence from all parts of the country, although it was made clear that the system could not be used for a regular programme service because it was incompatible.

[from: BBC Engineering 1922-1972, Edward Pawley, Ch 6.1 p433]