Every sound you hear is a recipe — a blend of simple sine waves at different frequencies and amplitudes. The fundamental gives you the pitch. The harmonics give you the timbre — the thing that makes a guitar sound different from a flute playing the same note.
Each harmonic is a whole-number multiple of the fundamental frequency. Drag the sliders to mix your own timbre.
Try this: Start with the Pure Sine preset — just the fundamental. Then slowly add the 2nd and 3rd harmonics. Notice how the waveform shape changes, and if you're listening, how the character of the sound shifts without the pitch moving at all. That's timbre in action.
Fourier showed that any periodic signal — any repeating sound, any vibration, any wave — can be decomposed into a sum of simple sine waves. This means the sliders above aren’t just a toy. They’re the actual mechanism. When a luthier shaves wood from a guitar brace, they’re adjusting these ratios. When you turn the tone knob on your amp, you’re filtering harmonics. The math isn’t a model of the physics — it is the physics.