Coxbox IV

The Michael Cox Electronics Coxbox IV is an anlalogue colouriser which is very similar in design to the Fairlight 108 colour synthesiser. The Coxbox has only three levels of keying (Black, grey and white)but the grey level is a kind of non-additive mix of the black and white levels resulting in a positive or negative linear key in the mid-luminance or grey areas of the picture. The Coxbox accepts composite video or luminance (Y) in and outputs RGB signals. When bought new, the user had a choice between two control panels (pictured above). The 123 control panel (right) has three groups of red-green-blue faders corresponding to black grey and white levels. The 122/1 control panel (left) provided an HSV (hue, saturation and video or luminance) interface. Some units also came with a 144/1 preset memory unit which was able to store settings on small plug in circuit boards which more or less duplicated the circuitry and controls of the 123 control panel (ie the faderswere represented by trimpots which could be adjusted on a small extender socket).

The Coxbox is far superior to the Fairlight 108. It produces rich textures, and can produce a greater diversity of interesting images while, at the same time, providing a much simpler interface. Unlike the 108, the Coxbox does not have any turnover (key threshold) controls on the control panel. These controls are accessible as trimpots on the front panel of the main unit, but I have found that, in most cases, it is not necessary to change these settings once they are set.

Block Diagram

Main electronics unit (middle), 144/1 preset store unit (bottom) and preset selector panel (top).

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