WTVCO

WTVCO Screenshot

An 8-bit wavetable voltage-controlled oscillator. The CV inputs are assignable. Digital inputs 1 & 2 shift the pitch range down and up by octave steps.

The visualizer shows the selected waveform. A, B, and C are the source waveforms and ~ is the output wave. Use the encoder to choose new source waves, or navigate to the parameter adjustment and mapping pages by pressing with ~ selected.

As the core feature of the applet, CV modulation of the Blend parameter will change the shape of the output waveform. When Blend CV = 0V, the output will resemble waveform A, at +2.5V it will resemble waveform B, and at +5V, waveform C. Any CV in between will produce a proportional interpolation of the corresponding pair of source waves. Voltages beyond +5 and below 0 will result in “inverted-interpolation-overflow-wavefolding,” which is rad. Try it!

I/O:

  1/3 2/4
TRIG Oct-Shift Down Oct-Shift Up
CV INs Assignable (Pitch) Assignable (Blend)
OUTs Interpolated Waveform 1 Interpolated Waveform 2 (Reversable)

Parameters:

  • Pitch - controls output frequency.
    • Encoder adjusts base pitch in semitone increments. Pitch for both outputs are shown on Params menu.
    • CV input modulates pitch offset using V/Oct standard (CV1 controls Output1, CV2 controls Output2). CV1 is set to Pitch offset by default.
    • Full frequency range is from 8000ish to 0.0101 Hz. Responds well to audio-rate FM.
    • Works great as a funky LFO (can wobble with a period as slow 99 seconds, before CV offset).
    • Toward the high end of the frequency range there are some interesting artifacts and aliasing effects.
  • Blend - morphs output waveform proportionally between a pair of selected source waveforms (A/B or B/C).
    • Blend can be adjusted by encoder, or CV input modulation. CV2 is set to Blend by default.
    • The Output Visualizer displays blended wave shape. A, B, and C visualizers show the respective source waves.

  • Osc2 Reverse - waveform of output 2 is reversable on the Params menu.

  • Volume - regular ordinary volume attenuation, [0-100%].
    • Controls volume of both outputs.
  • SqDuty - controls the width of the pulse wave.
    • 127 = 50% (square).
  • SR.Div - sample rate division.
    • Tells the phase accumulator how many controller cycles to wait before updating.
    • Decreases the pitch in “sub-harmonic” intervals.
    • Also produces some very nice downsample distortion at higher values.
    • Sequence this parameter for interesting results!

Outputs:

  • Output 1 - Osc1 Interpolated Waveform: Does everything a normal VCO does, and looks cool doing it.
  • Output 2 - Osc2 Interpolated Waveform: A second voice with the same shape as Output 1’s waveform,
    • Independent Pitch control, assignable to CV2 input.
    • Output can be toggled between Forward and Reverse mode, quite useful when used as an LFO.

Aux Button Functions:

  • Noise Freeze - while the Noise wave is displayed in the waveform selection menu, toggles between “realtime” and “frozen” noise buffer.
  • Random-Step Re-Roll - while the RandStp wave is displayed in the waveform selection menu, instantly re-randomizes the step heights.
    • The steps are randomized each time the waveform is re-selected, but this shortcut prevents extra encoder movements.

Credits:

Authored by beau.seidon, with lots of good advice from qiemem and djphazer.

Inspired by Professor Bruce Land of Cornell University, and particularly Lab 3 (Audio Synthesis) from his “AVR microcontroller lectures 2012” YouTube series.