Multifunction Dual Phototransistor VCA

EARTH is a dual VCA built around a common part used in an unusual way. The opto-isolators at the core of the VCAs are most often used in modern switch-mode power supplies and use a phototransistor as their output instead of the photoresistor used in vactrols. When used in a VCA, they have a sweet, slightly rounded over tone, are very quiet when closed and respond to CV much more quickly than vactrols. They also produce a smooth asymmetrical distortion that can be controlled by adding a dc offset to the audio signal. The VCA has an exponential response and a DC coupled signal path that allows for use with control signals.

The link and invert buttons add the level and CV inputs from the top 'earth' VCA and pass them down to the lower 'satellite' VCA. This makes multiple functions possible including stereo VCA, VC crossfade, VC pan, pseudo sidechain compression and VC mix. The top VCA's input and output are normalled and mixed respectively into the bottom VCA's input and output making it easy to use the pair in various ways without external mixers or mults.

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  • 16 mA +12V
  • 35 mA -12V
  • 0 mA 5V
  • 25 mm deep

This Module is a prototype or in a concept phase.

submitted Oct 5th 2016, 02:17 by coppertraces | last Change Oct 7th, 16:28 by coppertraces
Specs are approved by the manufacturer