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BBC Stereo transmissions - 1920's style.

Capt. H J Round, Wireless World, June, 1958.
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Hi-Fi and Stereophony

There seems to be a revival of interest in stereophonic sound and this brings back the memory of our first experiments in the subject in the 1920s.

Working in conjunction with the late Capt. A G D West of the BBC we fitted up one transmission from the Opera House, Covent Garden, for stereophonic work in 1925. The two radiators were 2LO and Daventry. How many heard the result, aside from ourselves, I have no record, but to our own receiving arrangements it was fairly satisfactory.

Two microphones spaced a foot or so apart were fixed on the edge of the stage by the footlights at the Opera House and their output ran via two amplifying systems to the two transmitters.

It had previously been noted in earlier non-radiating tests with spaced microphones that, when receiving with two telephone earpieces, movement to the right or left was clearly defined but that in the main the sounds came from the back or the top of ones head.

I believe it was Mr W I Picken who remarked to me on hearing someone walking across the microphone room that it sounded as though someone was walking over his grave.

When using two loudspeakers the effect vanished as the sounds were, of course, being put artificially in front of one.

However, a new effect was noted during the opera transmission. The microphones were, as I stated, placed by the footlights and they were between the stage and the orchestra. With a soprano singing on the stage and the orchestra accompanying her I noted at once that with telephone reception she seemed to be in front of me, but the orchestra sounded behind. Male voices, however, joined the orchestra, so that the effect was in some way due to frequency. West and I had many discussions as to the reasons for these curious effects. Many obstacles of course are in the way-of hi-fi and stereophonic sound for normal house use, particularly from radio transmissions. Rooms are not large enough and many wives and neighbours object to the volume of sound necessary for correct effects.

The question of sound strength and correct quality was pretty thoroughly thrashed out many years ago - after Harvey Fletcher had published his monumental work on Speech and Hearing (Macmillan, 1929), and correcting devices for all strengths were worked out. But then, as now, quality and naturalness were the worry of only a very small percentage of the population. Nearly everybody in those days, and very probably now, was content with the sound of his own loudspeaker.

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