Oscillators and Waveforms

A waveform is a harmonic recipe that sets the base colour and where filtering begins.

Related

TimbreEqualizerProphet-5Modern

The question

The first knob on many synths is the waveform. Sine, triangle, square and saw can all be a starting point, so what differs, and why does a change recolour everything?

How it works

Any periodic wave splits into a fundamental and integer harmonics. A sine has only the fundamental. A triangle carries odd harmonics falling as the square of the number, so it reads soft. A square also carries odd harmonics, falling more slowly, which gives the hollow, woody tone. A saw carries every harmonic and is the brightest and roughest. Pulse width redistributes the harmonics, and a narrow pulse sounds thinner and sharper. Real oscillators must manage aliasing, especially high up.

Settings and what you hear

Waveform sets brightness and whether even harmonics exist. Octave sets register; fine tune and detune make oscillators beat and thicken the width. Narrowing pulse width first thins, then sharpens. Saws suit leads and basses, squares hollow leads, triangles soft pads.

What to listen for

Hear a square and a saw on the same note, then add a low-pass to each. The square lacks even harmonics, so it keeps a hollow core after filtering; the saw has continuous harmonics and sweeps smoothly. Detune two saws and notice the beating widen the sound and dirty it at the same time.

Common misconceptions

That waveform affects only tone and not how a filter behaves; that a saw is always louder, when brightness and level are different things; that phase is irrelevant, when it changes transients in stacked layers.

Sources

• Gordon Reid, Sound On Sound Synth Secrets — waveform spectra checked, not quoted
• Udo Zölzer, DAFX — Digital Audio Effects, oscillators and aliasing chapter — background checked, not quoted

Used for fact-checking only; all prose is original.