Synthesis
Every sound you have ever heard is air molecules moving. Synthesis is lying to air. Convincing it to move the same way as a piano. Or a voice. Or something that has never existed.
Interactive
Waveform Lab
Four primitive waveforms. Everything in synthesis starts here. Click one. Listen. The shape on screen is the shape of the air.
Theory
The Harmonic Series
Play any note. Physics generates an infinite tower of higher frequencies above it. Integer multiples. The harmonic series. Timbre is which harmonics are present, and how loud each one is.
A sine wave has only the fundamental. A square wave has the fundamental plus all odd harmonics. A sawtooth has all harmonics. That is why they sound different. Same pitch. Different harmonic content.
Methods
Six Ways to Make Sound
Each method is a different philosophy. Additive builds. Subtractive carves. FM transforms. Granular shatters. The right method is the one that makes the sound in your head.
Additive
build up from sine waves.
Start with silence. Add a sine. Add another at double frequency, half amplitude. Keep adding. Every sound in the world is this. Just sines, all the way down.
Expensive. N harmonics = N oscillators. Organs do this.
Subtractive
carve away from noise.
Start with a harsh waveform. Sawtooth, square. Run it through a filter. Cut the highs. Shape the lows. The sound is what remains after the filter. Most analog synths work this way.
Cheap. One oscillator, one filter, one envelope. Classic.
FM
modulate frequency with frequency.
One oscillator changes the frequency of another. Fast enough and you get sidebands. New harmonics appear from math, not physics. The DX7. Electric piano. Bell sounds. Metallic and complex from two sine waves.
Efficient. Mathematically unpredictable. Requires ear training to program.
Granular
shred samples into dust.
Take any sound. Slice it into tiny grains, 10–500ms each. Play the grains in any order, any pitch, any density. Scatter them across time. The original sound dissolves. Something new emerges from the texture.
Heavy. Thousands of grains per second. Clouds of sound. Glitchy time-stretch.
Wavetable
scan through frozen waveforms.
Record one cycle of any waveform. Play it at any pitch. Store hundreds. Morph between them over time. The Waldorf, the Serum, the PPG. Waveforms as data you can navigate.
Medium. Interpolation between wavetables = motion. Modern standard.
Physical Modeling
simulate the instrument.
Mathematics that pretends to be a string, a pipe, a drum membrane. Karplus-Strong for strings. Waveguides for wind. The model responds to physical parameters. Harder to program but it breathes.
Variable. Strings are cheap. Full orchestras are not.
Shape
ADSR
A waveform plays forever unless you stop it. An envelope tells it how to live and die. Attack, Decay, Sustain, Release. Four parameters. Every sound has them, even if you never touched a synth.
How fast to reach full volume. Slow = pad. Fast = pluck.
How fast to fall from peak to sustain level.
Volume while the key is held. Not time — a level.
How long to fade after the key is released.