40 years ago, legendary synth designer Wolfgang Palm introduced the world to wavetable synthesis with his PPG Wave 2 synth. Unlike the static waveforms of an analogue oscillator, a wavetable oscillator loads a template – the wavetable itself – with descriptions of different waveforms. The oscillator reads and reproduces these, adjusting playback rate to control the pitch.
Technically a wavetable is no more than a series of digitally sampled waveforms laid end‑to‑end in a standard PCM WAV file. By using waveforms of an exact length, the oscillator can predict where each waveform starts/ends, and can select different waveforms from within the table. Throw in a bit of waveform‑blending and the oscillator can morph smoothly through all of the waveforms in a wavetable.
Initially, systems capable of creating wavetables were hugely expensive. But today your DAW has all you need, plus the ability to host synths to use as sound sources. That said, for editing and processing your waveform recordings, a standalone wave editor has its advantages, and so ideally your wavetable-building setup needs both DAW and wave editor.
Many wavetable synths can import custom wavetables, and you need one of these to play your creations. Some such synths also contain bespoke wavetable editing tools that take some legwork out of the otherwise manual process.
Read on as we get to grips with the fundamentals of this highly creative process…
Wavetable formats
First things first, let’s take a look at what’s going on behind the scenes…
The most important wavetable concept is the ‘frame’ or ‘window’. This is a span of audio that’s a specific number of samples in length, and which contains the template for a waveform; usually a single cycle. That waveform should be sized to fill the frame perfectly so that, when repeated, a constant static timbre is produced.
Different synths have different wavetable specifications, and these centre around the number of samples in a frame, the bit depth of those samples, and the maximum number of frames that a wavetable can contain. There is no standard for this, so you should always check a synth’s requirements before spending time creating wavetables for it.
The good news is that most modern wavetable synths have gravitated towards the same format: 2,048 samples per frame, any bit depth, and a maximum of 256 frames in a wavetable. These synths can also handle mono or stereo wavetable files, but there’s rarely much point in creating stereo wavetables, so use mono wherever possible.
Sample rate and wavetable frequency
From an oscillator’s perspective the sample rate of a wavetable WAV file is unimportant: 2,048 samples is 2,048 samples, irrespective of sample rate. However, because this is a fixed length, the frame size interacts with the sample rate you’re working at to determine the frequency of the waveforms contained within a wavetable.
