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Subtractive vs Additive

Build one note with subtraction and addition.

Two opposite strategies

There are two fundamentally different ways to build a sound. They start from opposite ends and meet in the middle.

Additive: building up from silence

Additive synthesis begins with silence and stacks individual sine waves (harmonics) on top of each other, one partial at a time, until the combined result sounds the way you want.

Think of it like painting: you start with a blank canvas and add colours one brushstroke at a time. Each sine wave is one brushstroke. This is the principle behind pipe organs and Hammond tonewheel organs, where each drawbar controls the volume of a single harmonic.

Subtractive: carving away from a bright wave

Subtractive synthesis starts with a harmonically rich waveform - a sawtooth or square wave packed with overtones - and carves away frequencies with a filter. This is the method used by Moog, Roland, and Korg synthesisers. Most hardware synths you will encounter are subtractive.

Think of it like sculpture: you start with a block of marble (all the harmonics) and chisel away until the shape you want emerges.

Try the machine

The machine below lets you hear both approaches applied to the same note simultaneously. Use the Subtractive slider to set the filter cutoff, the Additive slider to control how much of the stacked-sine signal you hear, and the Harmonics control to tilt energy between low and high partials.

Machine 20

Volume -inf

Subtractive 400 Hz

Additive 45%

Harmonics 25%

Motion 50%

The trade-off

Subtractive is fast and intuitive.

Pick a rich waveform, sweep a filter - the sound changes in a way that feels immediately musical.
The downside: you are limited by the harmonics already present in your starting waveform. You can only remove what is already there.

Additive gives you total precision.

Every single partial can be set to any amplitude - in theory you can recreate any sound that exists.
The cost: complexity. A realistic bell or vocal timbre might need dozens of individually tuned sine waves, each with its own envelope.

The controls explained

The Harmonics slider controls a "tilt" across the eight additive bands. When tilt is negative, energy concentrates in the lower partials, giving a darker, rounder tone. When tilt is positive, higher partials gain energy and the sound becomes brighter and thinner.

The Motion control adds slow, cyclic variation to the harmonic amplitudes. At zero, the additive tone is static. As you increase motion, the partials drift in and out of prominence, creating a shimmering, evolving texture.

Most real-world synthesisers combine both approaches. A "subtractive" synth might let you blend oscillator waveforms (an additive idea) before filtering. A wavetable synth scans through pre-built additive spectra and then passes the result through a subtractive filter chain.

Things to try

Set Additive to 0% and sweep the Subtractive cutoff from high to low. You will hear the sawtooth wave lose its brightness as the filter removes upper harmonics.

Then set Subtractive fully open and bring Additive up. The eight sine-wave partials blend in, and you can shape their balance with the Harmonics tilt. Listen for the difference in texture: the subtractive path sounds smooth and continuous, while the additive path has a more precise, organ-like quality.

The eight bands shown in the visualiser correspond to harmonics 1 through 8 of the base frequency (261.63 Hz). Harmonic 1 is the fundamental. Harmonic 2 is the octave above. Harmonic 3 is an octave and a fifth. This pattern - the harmonic series - is the foundation of all pitched sound.

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