Pop lane exploring synthesized marimba. Bottom-up modal synthesis — no samples, no Kontakt libraries. Lives next to the dance / hippyhayzard / chillwave / hellsine / jungle lanes.

the synth #

synths/marimba.mjs — modal additive synthesis with mallet impulse + tube resonator. Same module shape as ../dance/synths/sinepower.mjs and ../hippyhayzard/synths/zitar.mjs.

mixEventMarimba(ev, out, { sampleRate, preset })   // node bed
renderMarimba(ev, { sampleRate, preset }) -> f32   // bare DSP
playMarimba(sound, ev, { preset })                 // AC sound.synth fallback

presets #

Core marimba (the lane's reason for being):

preset	partials	character
rosewood	1 : 4 : 9.2	classic concert marimba, warm, full tube
kelon	1 : 4 : 10	synthetic-bar, slightly brighter
bass	1 : 4	low extension, mostly tube, soft mallet
staccato	1 : 4 : 10 : 17	hard dry "tok," no resonator
roll	1 : 4 : 9.5	short ring for tremolo / sustained lines

Tuned-percussion family (same engine, different partial ratios — full mallet stack from one model):

preset	partials	character
xylophone	1 : 3 : 6	bright, short ring, hard mallet
vibraphone	1 : 4 : 10	metal bars, very long decay + motor
vibraphone_off	1 : 4 : 10	same but motor disengaged
glockenspiel	1 : 2.76 : 5.4	high steel, mode-2-dominated pitch
gamelan	1 : 2.4 : 4.7	bronze, inharmonic, long ring
woodblock	1 : 1.8 : 2.7 :…	barely pitched, mostly attack
kalimba	1 : 5.9 : 8.1	thumb-piano tine, near-pure mode 1

CLI demo #

node pop/marimba/synths/marimba.mjs                           # rosewood
node pop/marimba/synths/marimba.mjs --preset kelon
node pop/marimba/synths/marimba.mjs --preset bass --out ~/m.mp3

Renders a short showcase phrase across the marimba range to pop/marimba/out/marimba-<preset>.mp3. Listen with QuickTime, not Apple Music: open -a "QuickTime Player" pop/marimba/out/marimba-rosewood.mp3.

the song #

marimba.np — TBD. A short investigative piece that puts the four presets to work in their natural roles (rosewood lead, bass under, staccato accents, roll for a hold).

marimbaba++ — the disco remix #

marimbabapp.np — the lullaby grows up and goes to the club. Same F-major DNA as marimbaba, re-barred from a slow 56 BPM 3/4 nap into a driving 6/8 disco-shuffle (~115 BPM dotted-quarter). The triple feel survives the move — 6/8 is just a compound 3/4 — so the "twin-kle" and "ba-ba-ba bap" syllables still scan over a four-on-the-floor.

A ~6:07 club arc in 8 movements: intro → groove A → break → groove B (the full hook) → breakdown → build → drop → outro. The drums and the disco-octave bass are procedural DSP; the marimba presets carry the melody, chicken-scratch chord stabs, sparkle, and fills. The breakdown introduces "the float" — a calmer bridge melody not in marimbaba — and the final drop lifts the whole track +2 to G major at bar 264 for the classic disco key-change euphoria. A kick-triggered sidechain pumps the bass / pad / comp.

node bin/render-marimbabapp.mjs                  # → out/marimbabapp.mp3
node bin/render-marimbabapp.mjs --out ~/m.mp3
node bin/render-marimbabapp.mjs --bpm 122        # tempo variation

Section bounds land in out/marimbabapp.struct.json (same shape as marimbaba.struct.json). marimbaba itself — the lullaby + its storyline visualizer — is untouched.

the storyline visualizer #

marimbaba ships with a 9:16 Instagram-Story visualizer that tells one quiet story across the lullaby — jeffrey's late-night computer help call with Bill Gates. 10 colored-pencil + gouache panels, two per .np section, with a changing-emotion arc:

§	beat	emotion
0	hush1 — jeffrey approaches the house at night	anticipation
1	hush2 — the doorway hello	shy warmth
2	twinkle1 — crossing the room, Gates greets him	relief
3	twinkle2 — settles into a chair at the Model M	cozy
4	wow1 — points out the first step	uncertainty
5	wow2 — it clicks	wonder
6	baba1 — Gates tries it himself	anxious effort
7	baba2 — hands-on, together	teamwork
8	sleep1 — it worked	triumph
9	sleep2 — the drowsy close (the album cover)	calm

node bin/render-marimbaba.mjs --no-open   # → audio + out/marimbaba.struct.json
node bin/gen-sections.mjs                 # gpt-image-2 → cover + 10 panels (cached)
node bin/gen-sections.mjs --force         # regenerate all
node bin/gen-sections.mjs --only wow2     # one panel
node bin/preview-score.mjs                # → out/marimbaba-preview-score-portrait-insta-story.mp4

gen-sections.mjs inherits medium + identity verbatim from marimbaba.illy.txt; each beat variant re-stages the composition and carries its own emotion. render-marimbaba.mjs emits out/marimbaba.struct.json — 10 story sections + the marimba's note events per voice lane. preview-score.mjs builds the mp4 on the shared engine (pop/lib/preview-shared.mjs + cover-engine.mjs):

the string + sound elements — a verlet-physics playhead string down the centre; the note events ride past it as pitch-coloured blocks across 4 voice lanes, each note plucking the string;
3-layer backlight — warm glow from behind + a contrast vignette (so the figures read backlit, not lit-on-top) + a per-figure halo;
face zoom — the camera eases wide↔face twice per section, alternating jeffrey / gates;
6 transitions — iris / blinds / push / zoom-punch / pixel / diagonal-wipe, cycled across the 9 boundaries.

Figure bounding boxes for the face zoom + backlight live in marimbaba-forms.json — re-eyeball a box if its panel is regenerated.

sample sources #

Most of marimbaba is pure synthesis, but a few sourced samples sit in assets/. All are CC0 / public-domain (commercial-safe — see pop/SCORE.md). The canonical registry is pop/lib/menu.mjs → sample_sources; per-track provenance is also logged in out/.sfx-credits.txt.

sample	source	license
manhattan-siren.mp3	Freesound #223824 "Wail and Yelp.mp3" (WBJB1)	CC0

assets/whip-crack.* and assets/lamb-bleat.* are optional — drop a CC0 sample in and the renderer picks it up automatically.

research notes #

See STUDY.md for the physics / DSP background and the literature trail behind the preset numbers.