This diagram shows how feedback could be used between the input and output of a tape machine, creating repeated sounds, which rose or fell in level over time, depending on the feedback setting.
A contemporary photp of a 'Crystal Palace'. The input jacks are to the left (all linked via a clever arrangement of 'normalling'), the output appearing on the jack to the top right. The four jacks in a horizontal line are wired together in case a parallel connection is required. The lever towards the bottom controls the speed of the motor.
A closer view of a 'Crystal Palace', showing the capacitance 'multiplexer drum' at the top, above the motor control levers and 'gearing'. The engineering, all by Dave Young, is to a very high standard.
Simple ring modulator, as used at the Workshop to create the Dalek voices, consisting of four germanium diodes and two 600 ohm audio transformers. A low frequency signal, usually below 30 Hz, was applied to Input 2.
Noiseless fader circuits, showing how the idea was developed by Dave Young into the Radiophonic 'Glowpot' mixing desk. He also developed a 'capacitance' fader, although this was never used in a mixer.
The 20 channel mixing desk that was installed in Room 12, also known as the 'Glowpot' desk.
Room 11. Detailed view of the 'Glowpot' desk, originally designed by Johnny Longden, with its modified 'quadrant' faders, some ganged together with metal clips. To the upper left are miniature PEUs, whilst foldback, echo and channel groups are selected on the right. The ADJUST ZERO controls accommodated any ageing of the lamps in the noiseless fader circuits.
Quadrant faders, as used in the 'Glowpot' desk. These don't have continuous resistive tracks. In fact they're switches, each contact being wired to separate resistors.
