The K3021's tremendous frequency range spans from 60 seconds per cycle to 15kHz. The frequency setting is done with coarse and fine tuning potentiometers and a switch alternates between VCO or LFO mode.
Voltage control of frequency is made possible via an 1V/octave input and a linear FM input with attenautor. A temperature compensated exponential converter with matched transistors provides for best tracking. A sync input is used for hard oscillator synchronisation.
In the K3021 a triangle is used as the core waveform from which the sine and the sawtooth are derived. Afterwards they are processed by a complex waveshaper generating single, dual and even triple pulse wave modulated waves, sounding sound way more complex and living than a conventional PWM.
The pulse width(s) are set manually with PWM Offset and via the PWM modulation input which can be attenuated. The wave forms are available at two different outputs:
- BLEND: This parameter blends from a selectable waveform (sine, triangle, sawtooth) to pulse which is done manually with Blend Offset and with a CV at the Blend In socket. The VCAs used for the blend function are high-quality with ultra-low distortion. The wave which has been selected with the Wave potentiometer is displayed with a LEDs.
- PULSE: At the Pulse Out only the output of the pulse shaper are emitted. The Pulse switch selects between a single, dual or triple PWM which is visualized with LEDs as well.
The 3021 Master VCO is based on the design of the 3021 Dual VCO but it was completely re-designed to replace discontinued or hard to find parts.
inputs: 1V/oct (CV IN), FM, PWM CV, Sync, Blend CV
waveform outputs: blend out, pulse out
3U Eurorack module, 18HP wide
current draw: 90mA at +12V and 50mA at -12V