Writing the VCO calibration algorithm

The Voltage Controlled Oscillator (VCO) is a device whose output frequency depends on a control voltage (the so-called “CV” on vintage synths frontpanes!). This device (associated with others like a Voltage Controlled Filter — VCF — and a Voltage Controlled Amplifier — VCA) can be used to create rich musical signals. This device however — as many analog devices — does experience temperature and humidity drifts and as such, requires precise calibrating if we want to play musically accurate notes!

What is Themis

Analog electronics has gained renewed interest in the last decade in the stimulating field of music synthetisers due to the onset of renowned brands like Arturia or Dave Smith Instruments. The initial impetus was to enrich the sound created by the instrument and make it more “human” by inserting analog chips at specific location in the signal path. These chips are non-linear by essence, and sensitive to temperature and humidity in a way that is too complex to model in a microprocessor.