(Note: this is a high-level overview of my notes on sound synthesis, to be used as a reference. Some knowledge of music is assumed)

Sine wave = fundamental frequency

Harmonic: wave w/ a frequency that is a positive integer multiple of the fundamental frequency

Chords can be represented as a set of sine waves added together (Fourier series)
- E.g., a square wave is approximated the fundamental and a series of harmonics added/subtracted

Pulse-width modulation (PWM): controls harmonic spacing

Synthesis Types

(non-exhaustive)

• Subtractive: most heavily used, starting with rich waves (saw, triangle, etc) and filtered down
• Additive: starts with simple waves (sine) and adds harmonics (e.g., organs)
• Wavetable: movement across a 3D shape (heavily used now, e.g. Serum)
• FM: modulates the frequency of one oscillator (carrier) with another (modulator)
• Sample-based: filtering a prerecorded sample

Basic Parameters

• Oscillator (wave type)
• Volume/amplitude
• Filter (frequency blocking)
  - High pass = block low
  - Low pass = block high
  - Band-pass = allows a certain range
• Envelopes
  - Attack: how fast from 0 to full volume
  - Delay: how fast from full to sustain volume
  - Sustain: controls decay endpoint
  - Release: how fast it fades out
• LFO (low frequency oscillator): always runs, only really uses waveforms as a controller
  - Modulates one or more of the oscillators over time (basic FM synthesis technique, interestingly)

Basic Wave Types and Characteristics

• Sine: smooth
• Sawtooth: grating
• Triangle: halfway b/w sine and saw
• Square: saw + triangle, or a hard-clipped sine

Wave Placement

• Lead: square or saw
• Pad: square or saw
• Bass: triangle, square, or saw
• Sub-bass: sine or triangle

Effects

• Compressor: everything
• Distortion: bass (grit + warmth)
• Bitcrush: 8bit or lofi
• Chorus: 80s
• Delay: dream
• Reverb: ditto (turn decay up for ambient)
• Tremolo: soundscaping

FM Specifics

Timbre of modulated waveform is determined by:
- Ratio b/w frequency of carrier and modulator
- Volume of the modulator (how strongly the modulator impacts the carrier)

Principles:

• Match carrier frequency to the fundamental of the played note (ratio of 1:1)
• More harmonics = brighter sound
• C:M ratio of 1:1 = even & odd harmonics
• 1:2 = only odd harmonics
• Integer ratios produce harmonics in the natural harmonic series of the fundamental (i.e., harmonious/tonal)
• Non-integer ratios create the metallic/atonal sounds that FM synths are known for
• Less is more: you only need 1 or 2 modulators over the carrier to make any sound you want

Patches

808s:
Attack: 0-10ms
Delay: 400-600ms
Sustain: 0
Release: ~15ms
Wave: sine
Add distortion and filter to taste

Growl:
Saw + saw w/ 7-9 voices, detuned
Lowpass filter
Short release, nothing else matters
Sidechain (with lfo controlling volume)

Add reverb to taste

Subs:
Sine, 1 voice
Attack: ~5ms
Release: ~70-90ms

Rhodes:
Attack: 10ms
Delay: 2sec
Sustain: -10dB (variable)
Release: 50-100ms
Wave: Sine
Filter: lowpass
Add voices to taste
Detune all the way
Link LFO and noise to fine tune of Oscillator 1

Add eq, reverb, and chorus to taste

Pluck:
Attack: Short
Delay: ~1sec
Sustain: Short
Release: Short
Wave: any
Oscillators:
1: low
2: high (voices 5-9)
Volume envelope automates filter cutoff
Add delay and reverb to taste

Synthwave:
Pitch up osc 2
Add noise
Filter keytracking on
Turn down filter cutoff
Turn up resonance
Filter (ms)
Attack: ~25
Delay: ~50
Sustain: ~35
Release: ~65
Volume (ms)
Attack: ~10
Delay: ~40
Sustain: ~60
Release: ~60

Sine LFO, route to osc1, osc2, and filter
Rate and depth ~12

Add reverb and chorus to taste

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