Strudel-AI-music/agentic_workflow/music_theory.md

Music Theory for Strudel Production

Practical music theory for generating professional-sounding Strudel code.

1. Notes & Octaves

Note Names (Strudel format)

C  C#/Db  D  D#/Eb  E  F  F#/Gb  G  G#/Ab  A  A#/Bb  B

Octave range: 0-8. Middle C = c4 (MIDI 60). Sub bass = c1-c2. Melody sweet spot = c4-c6.

MIDI Note Numbers

C1=24, C2=36, C3=48, C4=60, C5=72, C6=84

2. Scales

When to Use Which Scale

Scale	Mood/Feel	Best for
minor	Sad, dark, introspective	R&B, trap, lo-fi, ambient
major	Happy, bright, uplifting	Pop, dance, house
dorian	Minor but warm/jazzy	Neo-soul, funk, lo-fi hip-hop
mixolydian	Major but bluesy	Funk, rock, blues
minor:pentatonic	Universal minor	Any genre, safe choice
major:pentatonic	Universal major	Pop, EDM, any happy genre
phrygian	Dark, Spanish, exotic	Metal, flamenco, dark electronic
lydian	Dreamy, ethereal, floating	Ambient, film score, dream pop
blues	Gritty, raw	Blues, blues-rock, jazz
harmonicMinor	Dramatic, Middle Eastern	Dramatic builds, ethnic music
chromatic	Dissonant, all notes	Sound effects, transitions

Scale Formulas (semitones from root)

Scale	Steps
major	0 2 4 5 7 9 11
minor	0 2 3 5 7 8 10
dorian	0 2 3 5 7 9 10
mixolydian	0 2 4 5 7 9 10
phrygian	0 1 3 5 7 8 10
lydian	0 2 4 6 7 9 11
minor:pentatonic	0 3 5 7 10
major:pentatonic	0 2 4 7 9
blues	0 3 5 6 7 10

3. Chords

Building Chords in Strudel

Chords are multiple notes played at once using commas or brackets:

// Method 1: explicit notes
note("[c3,eb3,g3]")               // Cm chord

// Method 2: scale degrees
n("[0,2,4]").scale("C:minor")     // same Cm chord

// Method 3: voicing function
voicing("Cm7")                     // automatic voicing

Essential Chord Types

Name	Formula (semitones)	Strudel notes (from C)	Feel
Major	0,4,7	[c,e,g]	Happy, resolved
Minor	0,3,7	[c,eb,g]	Sad, introspective
Major 7	0,4,7,11	[c,e,g,b]	Dreamy, lush
Minor 7	0,3,7,10	[c,eb,g,bb]	Warm, jazzy
Dominant 7	0,4,7,10	[c,e,g,bb]	Tension, bluesy
Diminished	0,3,6	[c,eb,gb]	Tense, unstable
Suspended 2	0,2,7	[c,d,g]	Open, ambiguous
Suspended 4	0,5,7	[c,f,g]	Yearning
Add9	0,4,7,14	[c,e,g,d4]	Modern, bright
Minor 9	0,3,7,10,14	[c,eb,g,bb,d4]	Rich R&B

4. Chord Progressions

By Genre

Pop / Dance / Happy

Name	Numerals	In C Major	Strudel
Classic Pop	I-V-vi-IV	C-G-Am-F	note("<[c3,e3,g3] [g2,b2,d3] [a2,c3,e3] [f2,a2,c3]>")
Four Chord	I-IV-vi-V	C-F-Am-G	note("<[c3,e3,g3] [f2,a2,c3] [a2,c3,e3] [g2,b2,d3]>")

Sad / Dark / R&B / Trap

Name	Numerals	In C Minor	Strudel
Sad Minor	i-VI-III-VII	Cm-Ab-Eb-Bb	note("<[c3,eb3,g3] [ab2,c3,eb3] [eb3,g3,bb3] [bb2,d3,f3]>")
Dark Trap	i-iv-VI-V	Cm-Fm-Ab-G	note("<[c3,eb3,g3] [f2,ab2,c3] [ab2,c3,eb3] [g2,b2,d3]>")
Neo-Soul	i7-iv7-VII7-III7	Cm7-Fm7-Bb7-Eb7	note("<[c3,eb3,g3,bb3] [f2,ab2,c3,eb3] [bb2,d3,f3,ab3] [eb3,g3,bb3,db4]>")

Lo-fi / Chill

Name	Numerals	In D Dorian	Strudel
Dorian Chill	i7-IV7	Dm7-G7	note("<[d3,f3,a3,c4] [g2,b2,d3,f3]>")
Jazz ii-V-I	ii7-V7-Imaj7	Dm7-G7-Cmaj7	note("<[d3,f3,a3,c4] [g2,b2,d3,f3] [c3,e3,g3,b3]>")

House / Techno

Name	Numerals	In A Minor	Strudel
Minimal	i-VII	Am-G	note("<[a2,c3,e3] [g2,b2,d3]>")
Deep House	i7-iv7	Am7-Dm7	note("<[a2,c3,e3,g3] [d3,f3,a3,c4]>")

Dramatic / Cinematic

Name	In C Minor	Strudel
Epic	Cm-Ab-Bb-Cm	note("<[c3,eb3,g3] [ab2,c3,eb3] [bb2,d3,f3] [c3,eb3,g3]>")

5. Rhythm Theory

Time Signatures & Subdivision

Standard 4/4: 1 cycle = 1 bar = 4 beats.

• Whole notes: "c" — 1 per cycle
• Half notes: "c c" — 2 per cycle
• Quarter notes: "c c c c" — 4 per cycle
• Eighth notes: "c*8" or 8 items — 8 per cycle
• Sixteenth notes: "c*16" — 16 per cycle
• Triplets: "c*3" or "c*6" or "c*12"

Swing / Shuffle

Shuffle feel: elongate first of each pair with @:

note("[c@2 e] [g@2 b]")  // swing feel

Common Drum Patterns (16-step grid notation)

Each [ ] = one beat (4 sixteenths), x=hit, -=rest:

Four-on-the-floor (house/techno)

Kick:  [x---] [x---] [x---] [x---]
Snare: [----] [x---] [----] [x---]
HH:    [--x-] [--x-] [--x-] [--x-]

→ s("bd*4, [~ sd]*2, [~ hh]*4")

Boom-bap (hip-hop)

Kick:  [x---] [----] [--x-] [----]
Snare: [----] [x---] [----] [x---]
HH:    [x-x-] [x-x-] [x-x-] [x-x-]

→ s("bd ~ ~ ~ ~ ~ bd ~, ~ ~ ~ ~ sd ~ ~ ~, hh*8").slow(2) adjusted to taste

Trap

Kick:  [x------x] placed irregularly, sparse
Snare: on beat 3 (every 2 beats)
HH:    very fast rolls *16 to *32 with velocity variation

Breakbeat / DnB

Kick:  [x---] [----] [--x-] [----]
Snare: [----] [x---] [----] [x---]

→ Syncopated, off-grid kicks, fast tempo 170+

6. Arrangement Principles

Song Sections

Use <... > alternation and /N slowing for section changes:

// 4-bar chord progression cycling
note("<[c3,e3,g3] [a2,c3,e3] [f2,a2,c3] [g2,b2,d3]>")

// 8-bar pattern: 4 bars of A then 4 bars of B
note("<[pattern A]*4 [pattern B]*4>/8")

Building Tension

• Gradually open filter: .lpf(sine.range(300, 3000).slow(16))
• Add density: .every(4, x => x.ply(2))
• Raise pitch: .add("<0 0 0 12>")
• Increase delay feedback over time

Drop Technique

• Build section: filtered, rising, less drums
• Drop: full drums, open filter, bass hits hard

7. Frequency Ranges for Mixing

Range	Hz	Role	Strudel tip
Sub bass	20-80	Felt not heard	.lpf(80) on sub, sine waveform
Bass	80-300	Bass body	.lpf(300) for warmth
Low-mid	300-800	Warmth/mud	Be careful, can muddy mix
Mid	800-2000	Presence	Melody/vocal territory
High-mid	2000-6000	Clarity/bite	Lead synths, snares
High	6000-20000	Air/sparkle	Hi-hats, cymbals

Gain Staging Guidelines

Element	Gain range	Notes
Kick	1.0-1.2	Loudest element
Snare/Clap	0.6-0.8	Prominent but below kick
Hi-hats	0.15-0.35	Subtle, dynamic
Bass	0.4-0.6	Strong but not overpowering
Pads/Chords	0.1-0.25	Background wash
Lead melody	0.15-0.3	Present but not harsh
FX/Textures	0.05-0.15	Barely audible atmosphere