Triphase Oscillator

$385A sawtooth oscillator with three independent phases and a bipolar mixer.

Explore the sonic space of phase cancellation! Phase cancellation shapes the characteristics of all acoustic instruments. It forms the basis of chorus and phaser effects. It gives vibrancy to detuned oscillators. The moving sound of pulse width modulation or the roaring sound of animated supersaws are a small part of a much larger sonic space that the Triphase Oscillator is built to discover.

The Triphase Oscillator produces three different sawtooth waves at the exact same pitch but with independent phase control. These are blended in a bipolar CP3-type mixer, giving a rich waveform at the output. By blending in a wave with a positive polarity, you reinforce in-phase harmonics; by blending a wave with a negative polarity, you reduce in-phase harmonics. The phase differences between the waves distribute the harmonics from in-phase to out-of-phase. The result is a comb-filter effect, like the effect produced by an acoustic reflection, with notches and peaks spaced evenly throughout the frequency range. Conventional pulse width modulation can be obtained by blending two sawtooth waves with equal but opposite polarity. Supersaw-like behavior can be obtained by using phase CV with the same polarity for all three waves. But many other interesting spaces can be reached. For example, by setting the phases correctly you can cancel out the first harmonic and get a saw an octave higher, or cancel both the first and the second harmonic, giving you a saw an octave and a fifth above the fundamental frequency. Modulation then brings back these canceled harmonics.

The Triphase Oscillator is completely analog, built around a sawtooth core that is functionally stable and accurate but sonically alive. It has linear FM on all three waves, and an excellent hard sync that can create shredding harmonic sweeps. The CP3 type mixer gives good distortion at higher levels, allowing you to blend three 5-volt-peak waves without worrying about headroom. All CV functions at audio rate. With an LFO driving the phases, it can easily replace the classic analog three oscillator setup, and in this configuration it’s one of the fattest things you have ever heard. But the Triphase oscillator is much more than a thickener, and can just as easily produce thin reedy sounds or subtly shifting harmonic drones.

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