This is a little confusing, but typical of the way many small British companies operated in the late 1950s. Both H.M.V. and EMI marketed the Stereoscope amplifier and preamplifier. EMI called the integrated amplifier the 'Stereoscope Twenty-Twenty' and the preamplifier the 'Stereoscope Control centre'. H.M.V. named them the 555 and 556 respectively. Both were identical and at various times built by The Gramophone Co. Ltd of Hayes, Middlesex and the Clarke & Smith Manufacturing Company.

The integrated stereo amplifier ( top two pictures, right) had an output of 10 watts per channel courtesy of two pairs of EL84 output tubes. The preamplifier (bottom, right) was basically the same as the integrated model but without an output stage.

Inputs were provided for microphone, pickup (magnetic and ceramic), tape and radio and controls were included volume, bass, treble, loudness and scratch and rumble filters. Preamplifier output was variable between 200mV to 6V (to match any power amplifier) and mixing of two channels could be achieved for recording purposes.

The main (and highly unique) feature of both these units was a small mini cathode ray tube mounted on the front panel with built-in calibration signal for setting balance, frequency response and monitoring output level. A bit of a gimmick really but very pretty to watch.

Prices when new were £66.3s for the integrated model and £40.19s for the control unit. These days expect to pay £250 (integrated) and £100 (control unit) for pristine working examples.

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