How wavetable synthesis works
Answer in brief
A wavetable oscillator reads one single-cycle frame over and over at the pitch of the note. A position control picks the frame, interpolation smooths the step between neighbors and warp modes bend how the frame is read. Moving the position over time is what makes the sound.
Single-cycle frames
A frame is one cycle of a wave stored as a short list of sample values. A common size, used by Serum and Vital, is 2048 samples. To play an A at 440 Hz the oscillator runs through that frame 440 times a second, and an octave higher it runs through twice as fast. The shape of the cycle sets the harmonics, so a smooth curve sounds pure and a jagged one sounds bright and buzzy.
The table
A wavetable is a row of frames kept side by side, anywhere from a few to a few hundred. Each table in the original PPG Wave held 64 waves. A good table is arranged so that neighbors sound alike, which makes a sweep through it sound like one sound changing rather than a string of different sounds.
Position and morphing
The position control chooses where in the row the oscillator reads. Leave it still and you have one fixed tone, no different from an ordinary oscillator. Move it with an envelope and each note changes shape as it plays, or move it with an LFO and the tone sweeps back and forth in time.
Many synths add other ways to reshape a table while you play. Some blend two separate tables, and the Korg modwave mkII offers 13 Morph Types that stretch, squeeze and reflect its waves in real time.
Interpolation between frames
When the position sits between two frames the synth has to decide what to play. Without interpolation it jumps from one frame to the next, which can sound stepped or grainy on a slow sweep. With interpolation it crossfades the two neighbors and the change sounds smooth. Xfer Serum 2 has a Smooth Interpolation mode that Xfer says allows near-infinite frame positions. Both behaviors have their uses, since the steps give a hard digital edge you may want.
Keeping high notes clean
A frame with sharp corners has harmonics that reach very high. Play it far enough up the keyboard and those harmonics pass half the sample rate and fold back down as harsh tones that do not belong to the note, which is called aliasing. Careful wavetable oscillators keep smoother versions of each frame for high notes. Vital’s page, for example, says its oscillators cut off sharply at Nyquist for almost no aliasing.
Warp modes
A warp changes how the oscillator reads a frame rather than changing the frame itself. The names differ from synth to synth, but the common ones behave in similar ways.
- Sync reads the frame faster than the note and restarts it every cycle, which gives a tearing, vocal sweep.
- Bend or phase distortion reads part of the cycle faster and the rest slower, which pushes the harmonics around.
- Pulse width squeezes the frame into part of the cycle and leaves silence in the rest, which thins the tone.
- Mirror and flip play the cycle forward then backward, or turn part of it upside down, which changes which harmonics are present.
- FM, AM and ring modulation use a second oscillator to bend the read speed or the level at audio rate.
- Spectral warps work on the harmonics directly, and Vital is built around this kind of warping.
Why moving the position is the sound
A filter sweep only changes how much of each harmonic gets through. A position sweep can bring in harmonics that were not there, slide a peak from low to high like a vowel changing, or swap a full tone for a hollow one. That is why wavetable patches are built around whatever moves the position. The same table can be a pad when it drifts slowly and a bass when an envelope snaps through it.
Sources for this page
- Studio 56: Studio 56’s official website, the publisher of this reference.
- Xfer Serum 2: Xfer Serum 2’s official page, the source of its description here.
- Vital: Vital’s official page, the source of its description here.
- Korg modwave mkII: Korg modwave mkII’s official page, the source of its description here.
- Wikipedia: Wavetable synthesis: Background on tables of single-cycle waves, scanning and interpolation between neighbors.
- Sound On Sound: PPG Wave 2.3 and Waveterm B (December 1996): Source for the 64 waves in each PPG wavetable.
The practical advice here is our own. A maker's description of its product is not a test of how it performs.
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Cite this page
Wavetable Synth. “How wavetable synthesis works.” Studio 56 Reference. Content reviewed November 8, 2026.
https://wavetablesynth.com/how-it-works/