Synth Education

Wavetable Warp Modes

Warp modes reshape the phase ramp before it reads the table, bending time itself to transform timbre without touching the waveform data.

Warping the Phase

In Part 76 we saw that a phasor sweeps linearly from 0 to 1, reading each sample of the stored waveform at a constant rate. But what if we bent that sweep? If the phasor races through the first half of the cycle and crawls through the second, it reads some parts of the table faster than others. The stored waveform is unchanged, but the output sounds different because the time mapping is different.

Pick a waveform shape below (the same ones from Part 76), then try each warp mode. The "Before & After" display shows the stored shape in gray and the warped output in blue. You can see exactly how the warp reshapes what you hear.

The Warp Modes

Bend

Compresses early phase and stretches late phase (an exponential curve applied to time). A sine wave becomes asymmetric: faster rise, slower fall. This adds harmonics that weren't in the original table, brightening the timbre.

Mirror

Folds the phase at a movable midpoint. The first half of the cycle plays the waveform forward; the second half plays it backward. This creates symmetry in the output even from asymmetric waveforms, and eliminates even harmonics at extreme settings.

PWM (Pulse Width)

A warp you already know from Part 10. Squeezes the first half of the cycle and stretches the second. With a sine table, this is exactly pulse width modulation. The duty cycle changes with the warp amount. Try it with a sawtooth to hear how PWM affects a different shape.

Hard Sync

A secondary oscillator runs faster than the primary and acts as a reset clock. Every time the sync oscillator completes its cycle, it forces the primary oscillator back to the start of its waveform. The primary never finishes its natural cycle; instead, you hear partial cycles crammed into the sync clock's period. This is the classic sync lead sound, that screaming, vocal-like tone. The warp amount controls how fast the sync clock runs: higher = more resets per cycle = brighter, more harmonically complex.

References

• Wikipedia: Oscillator Sync, hard and soft sync explained
• Massive X Warp Modes, NI's implementation of phase warping
• Serum Warp Modes, bend, mirror, FM, AM, and more