Harmonics - ectoplasma

A harmonic oscillator stacks frequency multiples of one fundamental. Push upper partials to add brightness and edge.

Every musical note you have ever heard is a stack of frequencies, not one. When a guitar string vibrates at 220 Hz, it also vibrates at 440, 660, 880, 1100 Hz and beyond - all at the same time. These are its harmonics: integer multiples of the fundamental frequency. The first harmonic is the note itself. The second is double that frequency. The third is triple. The pattern continues upward in a neat, predictable ladder called the harmonic series.

This is why a piano and a clarinet playing the same note sound completely different. They produce the same fundamental pitch, but each instrument has its own recipe of harmonic strengths. That recipe is called timbre. The machine below lets you write your own recipe from scratch.

What Harmonics Look Like

Each card below shows a different combination of harmonics summed together. Watch how the wave shape grows more complex as overtones are added.

What Each Slider Does

H1 is the fundamental - the root pitch your ear locks onto. It is the note itself. Every other harmonic is measured relative to this one.

H2 vibrates at double the frequency. It adds warmth and body without changing which note you hear. Think of it as reinforcing the fundamental from one octave above.

H3 (triple the frequency) introduces a slightly hollow, reedy quality. Clarinets are dominated by odd harmonics, which is partly why they have that distinctive woody tone.

H4 through H8 add increasingly fine detail and brightness. Pull H1 down and push the upper harmonics up - the timbre becomes strange and bell-like. Bells are one of the few acoustic objects where higher partials can be louder than the fundamental.

Harmonic Patterns in Nature

Certain patterns recur everywhere in nature and in synthesis.

A square wave contains only odd-numbered harmonics (H1, H3, H5, H7). Set the even sliders to zero and listen to the hollow, woody result.

A sawtooth wave contains all harmonics in a steadily falling slope. These are not arbitrary shapes. They emerge directly from the physics of vibrating strings, air columns, and electrical circuits.

Try it: Set H1 to 100%, all others to 0%. You get a pure sine wave. Now bring H2 to 50%, H3 to 33%, H4 to 25% - that descending 1/n pattern builds a sawtooth wave from scratch. You are literally constructing a waveform from its component frequencies.

The Timbre Controls

Brightness tilts the entire harmonic balance without touching individual sliders. Positive values boost upper partials. Negative values muffle the tone - like hearing something through a wall.

Spread gently detunes the upper harmonics against each other. It thickens the sound the way a chorus of slightly out-of-tune voices sounds richer than a single voice.

Try it: Click the preset buttons (1-6) and watch the sliders animate. Preset 1 is almost a pure sine. Preset 6 is glassy and bright. Watch the oscilloscope - the shape you see is literally the sum of all those harmonics added together.

Why Instruments Sound Different

Real acoustic instruments have harmonics that shift constantly. A bowed cello string produces different harmonic levels depending on bow pressure and speed. A trumpet's upper partials surge forward as the player blows harder.

Static harmonics sound synthetic by comparison. That is exactly why synthesisers sound the way they do - and why that can be a useful quality rather than a limitation.

Distance as a filter: The lowpass filter at the bottom of the machine cuts upper harmonics. In the real world, distance does the same thing naturally. Thunder close by cracks and snaps. Distant thunder only rumbles. The high frequencies got absorbed by the air.