Custom Hertz-per-Volt to Volt-per-Octave Interfaces

Quad Anti-Log Converter Box

One of our clients commissioned us to build an interface that would allow him to control vintage synths with linear (Hertz/Volt) control voltage scaling such as Yamaha CS 10s, Yamaha CS-15s, Korg MS-10s and Korg MS-20s with conventionally scaled 1V/Octave equipment. We designed a custom PCB that contains two channels of anti-log conversion based on the Korg MS-02 and two channels of V-trig (positive-going trigger) to S-trig (ground-shorting trigger) conversion, and used two of them to create a 4-channel anti-log box in a racecar-striped enclosure with handmade cherry end cheeks. The box has its own built-in power supply.  With it, our client is able to control 4 Hertz/Volt-scaled synth voices with the sequencers in his Eurorack system.

We have since adapted this same circuit to allow us to offer the service of adding built-in 1V/Octave control voltage inputs to any other Hertz/Volt synth, such as the Minikorg 700s as shown in the photo at right.

We can build a custom Hertz/Volt to Volt/Octave control voltage conversion box in any configuration you may wish!