rhythm-and-groove

Rhythm and groove

Anatomy of a groove — one job per voice

Voice	Job	Typical placement
bd kick	foundation, defines the pulse	beats (1, 1+3, four-on-floor) or syncopated anchors
sd/cp	backbeat, the answer to the kick	beats 2 and 4 ("~ sd ~ sd" / "~ cp")
hh/oh	subdivision energy, forward motion	8ths/16ths; oh marks offbeats
rim/sh/perc/cb	syncopation, conversation between the others	the gaps the kick and snare leave

setcpm(120/4)
$: s("bd*4").gain(.95)                       // foundation
$: s("~ cp ~ cp").gain(.8)                   // backbeat
$: s("hh*8").gain("[.4 .7]*4")               // motion
$: s("rim(5,16,2)").gain(.4)                 // syncopated chatter

Build in that order; mute the percs and check the groove still stands.

Euclidean vocabulary — what (p,s) feels like

x(pulses, steps, rotation?) spreads hits as evenly as possible. First number = hits, second = slots.

Pattern	Shape	Feel
(3,8)	x..x..x.	tresillo — the universal syncopation (son, dembow, dancehall)
(5,8)	x.xx.xx.	cinquillo — busier, rolls forward
(2,5)	x.x..	lopsided, off-kilter
(3,16)	sparse	spacious perc accents
(5,16)		broken, hip-hop-ish kick scatter
(7,16)		rolling almost-straight 16ths with one hole
(9,16)		dense shaker that breathes
(7,12)		afro-leaning bell pattern territory

$: s("bd(3,8), ~ sd, hh(7,16)")        // tresillo kick under a backbeat
$: s("cb(7,12)").gain(.3)              // 12-slot bell against 4/4
$: s("bd(<3 5>,8)")                    // alternate density per cycle

Rotation shifts where the shape starts: "bd(3,8,2)".

Swing

.swingBy(amount, n) delays every 2nd of n subdivisions; swing(n) = swingBy(1/3, n) (triplet swing). n = the subdivision you're swinging (4 = 8th-notes pairs in a 4-beat cycle, 8 = 16ths).

Genre	Swing
House/garage	.swingBy(.08, 4) – .swingBy(.15, 4) (subtle push)
Lo-fi hip-hop	.swingBy(.2, 4) – .swingBy(1/3, 4) (heavy lope)
Jazz-ish ride	.swing(4) (full triplet)
Techno/DnB	usually straight; swing percs only, lightly

s("hh*8").swingBy(.12, 4)              // house hats
s("bd ~ sd ~, hh*8").swingBy(.25, 4)   // boom-bap drag

Swing the hats/percs; keep kick and snare anchored unless you want the whole kit to lurch.

Humanization: velocity patterns and ghost notes

Pattern the gain so no two hits are equal — accent the grid corners:

s("hh*8").gain("[.9 .5 .7 .4]*2")      // strong-weak-medium-weak
s("hh*16").gain("[.8 .4 .6 .3]*4").degradeBy(.05)

Ghost notes = very quiet snare hits between backbeats:

$: s("~ sd ~ sd").gain(.85)
$: s("sd*16").gain(.15).degradeBy(.6)  // random quiet chatter underneath
// or placed deliberately:
$: s("~ ~ ~ sd ~ ~ sd ~ ~ ~ ~ sd ~ ~ ~ ~").gain(.2)

Tiny extras: .pan(rand) on hats, .sometimesBy(.1, x => x.speed(1.2)), varying sample index .n("<0 1 2>").

Fills

lastOf(n, fn) fires on the last cycle of a phrase — the natural fill slot:

s("bd*4, ~ cp").lastOf(4, x => x.ply(2))                 // double-time bar
s("~ sd ~ sd").lastOf(8, x => x.fast(2).gain(.7))        // snare-roll turn
s("bd*4").lastOf(4, x => x.degradeBy(.5))                // dropout fill
s("hh*8").every(4, x => x.rev())                         // flipped first bar

Polyrhythm vs polymeter

• Polyrhythm: different pulse counts in the same cycle span — layers realign every cycle. stack or , does this: s("bd*3, cp*4") = 3-against-4.
• Polymeter: same step rate, different loop lengths — patterns drift and realign after several cycles. Use {} with %:

s("{bd ~ sd ~, cb cb ~}%4")    // 4-step kit vs 3-step bell, stepping at 4/cycle
s("{hh oh hh, rim ~ ~ rim ~}%8")

Rule of thumb: polyrhythm = tension inside each bar; polymeter = slow evolution across bars.

Layering rules — avoiding mud

1. One sub-heavy element at a time: kick or bass owns the low end at any instant — offset their rhythms, or duck/sidechain the bass.
2. Offset hats from the kick: offbeat hats ("[~ hh]*4") create the pump; hats on the kick just thicken it.
3. High-pass everything that isn't kick/bass: .hpf(300) on percs and .hpf(4000+) on hats cleans more than any EQ move.
4. Separate by register and pan: rim left, shaker right (.pan(.3) / .pan(.7)).
5. Leave holes — a groove is defined by its rests. If every 16th slot is filled, delete the weakest layer.

setcpm(126/4)
$: s("bd*4").gain(.95)
$: s("[~ oh]*4").gain(.5).cut(1)             // offbeat opens, choked
$: s("hh*16").gain("[.5 .3]*8").hpf(6000).pan(.6)
$: s("rim(3,8,1)").gain(.4).hpf(800).pan(.35)

Deeper reference: knowledge/mini-notation.md (euclids, polymeter), knowledge/functions-reference.md (swingBy, ply, lastOf).