Stack VCO

Audio Generators

1. Tuning Knob Sets the oscillator frequency when the Pitch input is at 0V. Double-click for middle C.
2. Fine Knob ±1 semitone adjustment around tuning frequency.
3. Hertz Knob ±5 Hz adjustment around tuning frequency.
4. Stack Knob Gradually adds more oscillators to the output.
5. Detune Knob Detunes the stacked oscillators relative to each other.
6. Pitch Input Calibrated for 1V/octave pitch signals.
7. VCO Output Output signal.

Overview ⚓︎

A Classic VCO sounds nice, but what do you do when it’s not thick enough? Add a second one and slightly detune it? Sure, but what if that’s still not thick enough? Add a third, a fourth, a fifth? How much rack space are you willing to sacrifice, and how many cables are you ready to connect to get that sound? Maybe there’s a better way. Maybe what you really need is a single Stack VCO.

Taking inspiration from the superb sawtooth oscillator of a classic Japanese virtual analog synth, we packed seven slightly detuned oscillators into a space- and CPU-efficient module. It produces lush and sparkling tones ideally suited for EDM and other high-energy genres.

Our design is not merely a boring reverse-engineered copy of the original: it features carefully selected detuning ratios, stacked triangle and square wave outputs alongside the traditional sawtooth, and full control over the number of oscillators in the stack.

In Depth ⚓︎

Tuning ⚓︎

Tuning is controlled by the main Tuning knob, the Fine and Hertz knobs, their respective modulation inputs, and the Pitch input. See Oscillator Tuning for more information.

Stack Depth ⚓︎

The Stack knob controls the number of oscillators in the stack.

• When fully counterclockwise, no oscillators are running, and the module produces silence.
• As the knob is turned clockwise, new oscillators are gradually added to the stack, from the least to the most detuned.
• When fully clockwise, there are seven oscillators running at full volume on each of the module outputs.

Because the Stack knob goes down to silence, this module can be used without a VCA or LPG. Simply set the knob to 0%, connect any envelope generator to a modulation input, and adjust the modulation amount to taste.

Detune Amount ⚓︎

The Detune knob adjusts the amount of detuning among the oscillators in the stack. It has no effect when only one oscillator is active (i.e. when the Stack knob is below 15%), and the effect is more pronounced when more oscillators are running.

Even at 0%, there is always a very slight detune amount present between the oscillators.