Decca Outside-Recording Techniques, by Peter van Biene

I joined Decca in January 1962, and after a year I asked to be transferred from the electrical workshop to recording outside away from Decca studios. My first job was at Walthamstow Town Hall where Decca were recording on behalf of RCA/Readers Digest with producer Charles (Chuck) Gerhardt and engineers Ken Wilkinson and Michael Mailes. The recording technique was a development of the Decca system devised by Roy Wallace in 1954. This consisted of the Decca Tree made from 2 pieces of Dexion in a form of a T-shape, with a 3-foot long crossbar and a central tail of about 18 inches. Wallace used KM56 microphones made by Neumann of Germany one at each end of the tree, left centre and right. They were mounted on a boom and were positioned over the conductor’s head at a height between 10 feet 6 inches and 11 feet 3 inches. There are several recordings still available which demonstrate Roy Wallace’s technique. Rimsky-Korsakov’s Antar was the first recording made using this new technique at the Victoria Hall in Geneva. Wallace tried new techniques continually, initially with the addition of 2 directional microphones on booms, one over the first violins and another over the cellos (to the right), and in addition a KM56 microphone over the woodwind supported on a boom from behind a rostrum with the microphone extended out over the front of the wind section. Additional variations were with the M49 microphone also by Neumann. There was a good reason for Decca using Neumann microphones exclusively, as they owned a part of Neumann’s holding company and thus obtained a good discount when buying direct from Germany.

This system of recording classical music was copied by other companies and is still used by engineers who although now independent once worked for Decca. Other engineers used different microphones – notably Ken Wilkinson who used the Neumann M50 – a fixed omnidirectional microphone.The previously mentioned KM56 and M49 microphones could be switched between omni, cardioid, and figure of eight. These recordings of Wilkinson’s had one disadvantage when the transfer was made to disc, as multiple omnidirectional microphones produced a large amount of out of phase base. On disc this manifested itself as an extensive vertical movement which could cause the pickup to jump. To overcome the problem Bob Goodman, a most experienced electronics engineer, devised a base phaser which cured the excessive vertical motion on disc.

Initially Decca outside-recordings were made with 2 different machines, the Ampex 350 series and the EMI TR90. These were the second phase of tape machines being developed in the late 1950s. Neither machine had sophisticated spool tension and there was a danger when editing of cross-cutting tape from the front of a reel to tape towards the end of a reel, as a pitch change could occur. 

During the later 1960s Decca started recording classical music both on stereo tape machines and also 4-track, for use as a backup and also for post-production work if it was felt the orchestral balance needed to be changed. I often remember making A-B tests between the stereo and 4 track machines. Surprisingly nobody could tell the difference. 

During this period Decca changed to using Studer tape machines, notably the C37 stereo and J37 4-track. These machines were all valve and had very sophisticated circuitry to ensure even-tension on tape spools. The capstans were synchronous and relied on steady AC frequency from the mains supply. 

Around 1970 Studer developed a portable stereo machine labelled A62 which still had a synchronous capstan and although Decca had six of these they quickly adopted the newer B62 which had capstans with an electronic feedback loop driven by an internal oscillator, which freed it from mains synchronicity. About this time newer multi-channel equipment arrived, designed and built by Roy Wallace, called STORM and although Wallace would never say we believed this stood for stereo or mono. The system had a maximum of 24 channels and inevitably the numbers of microphones used on orchestras grew and grew – I suppose the theory being that the number of microphones expand to the accommodation of the sound mixer being used.

Here I must add that these were the systems used for recording external to Decca studios, of which 90% were classical, used at venues such as Kingsway Hall, Walthamstow Town Hall, and Watford Town Hall in Britain, and at many venues overseas in Rome, Geneva, Stuttgart, Vienna etc.

When recording opera Decca had devised a system called a Sonic Stage: this involved the use of 5 directional microphones on the stage placed equidistant from left, half left, centre, half right, right and positioned exactly on a canvas drugget which has stencilled on it numbers from 1 – 11 (1 being far left, 11 far right) and squares in rows marked A B and C. In advance of a recording, the producer and assistant producer would work out positions on the
drugget for the singers, keeping the moves where possible as close to those which obtained in the opera house. Thus a singer could be instructed to sing on 1C when making an entrance from the left, to proceed to 3A whilst singing and end up in the centre of the stage, the effect of movement of course being fully covered by the stereo system. Choruses were usually grouped behind the active stage part described above and were covered by three directional microphones covering left centre and right. 

Peter van Biene, February 2011

© 2011 Peter Van Biene