Guide 7 of 9 · Every Try it box opens the synth with its steps pinned on the rack

Melody & chance: chords, arps and generative patches

A sequencer plays the notes you give it. This guide is about two other ways of making melody: building harmony from a single key, and building patches that write their own music. That second idea, generative patching, is one of the things people love most about modular. You set up the rules, press go, and listen to something nobody has heard before.

Chords: one key, four notes

Pitch in a modular is just a voltage, where 1 is an octave and 1/12 is a semitone. So a chord is just maths: take the note you're playing and add a few fixed amounts. Add 4/12 for a major third, 7/12 for a fifth, and you have a major triad.

The Chord module does exactly that. One pitch goes in; four come out (ROOT, 3RD, 5TH, 7TH), each the root plus an interval. Patch them into three or four oscillators and one key plays a whole chord.

The Arpeggiator plays those chord notes one at a time instead, stepping on each clock pulse. UP, DOWN, UP/DN and RND set the order; Octaves spreads the pattern up the keyboard.

Polyphony: one voice per note

Here's a modular quirk: a cable carries one signal, so it can carry one pitch. To play several different notes at once, each note needs its own oscillator, its own envelope and its own VCA: its own voice.

Poly Keys hands each new key you press to a free voice, with a separate V/OCT and GATE pair for each. That's what "polyphonic" means: many voices.

Random notes that always sound right

Now for chance. A Sample & Hold grabs a value whenever its TRIG fires, and holds it until the next trigger. With nothing in its IN it samples noise, so it produces a new random voltage on every pulse.

Random voltages make random pitches, and most of those fall between the notes of any scale. Played straight into an oscillator, that sounds like a computer having a bad day. The fix is a Quantizer: it snaps any voltage to the nearest note of a scale you choose. Random numbers plus a scale makes melodies that never repeat but never sound wrong.

Try itAn endless melody

A clock, a Sample & Hold, a Quantizer and a voice with echoes, all unpatched. Wire the voice, then give it random notes:

Patch the voice in a line: the VCO's OUT into the VCA's IN, the VCA's OUT into the Delay's IN, the Delay's OUT into the Reverb's IN, and the Reverb's OUT into the Output's MONO.
Patch the Clock's 1/8 into the Sample & Hold's TRIG. Now it grabs a new random voltage every eighth note.
Patch the Sample & Hold's OUT into the Quantizer's IN, and the Quantizer's V/OCT into the VCO's V/OCT. Random voltages in, notes of a scale out.
Patch the Quantizer's TRIG into the ADSR's GATE, and the ADSR's OUT into the VCA's CV. An endless melody. The Quantizer's TRIG only fires when the note changes, so repeated notes merge into one.

Then play with it:

Change the Quantizer's Scale, Root and Range while it plays.
Add an LFO and patch it into the Sample & Hold's IN instead of letting it sample noise: now the melody rises and falls in waves.

⏻ Build lesson 21 in KablesThe modules are waiting, unpatched. These steps come with you.

A riff that slowly changes

Pure randomness never repeats, and that's its problem: real melodies do repeat, and repetition is what makes them catchy. The Turing Machine sits in between. It keeps a loop of random values and plays it round and round, so you get a riff. Its Lock knob decides how often the loop changes:

100%: the riff repeats forever.
85–95%: it slowly evolves, a note here and there.
50% or less: chaos.

Chaos: never repeating, never random

The Lorenz module solves three equations first found while modelling the weather. Its outputs never repeat and never settle, but they aren't random either: they wander, flipping unpredictably between two areas. On a filter or a slightly detuned oscillator, that sounds organic in a way an LFO can't.

Physics and life as sequencers

Two more ways to get structure without writing notes:

Bouncing Balls fires a gate every time a ball hits a wall. With a bit of energy lost on each bounce, the rhythm speeds up as the balls settle, just like a dropped ball on a table.

The Game of Life is a 1970 maths toy. Cells on a grid live or die by two rules (lonely or crowded cells die; empty cells with exactly three neighbours are born), and from those rules come patterns that grow, move and collapse. Kables plays the living cells as notes.

The art of generative patching

The best generative patches balance order and surprise. Too much order and it's a loop; too much surprise and it's noise. Some levers you now have:

Quantizers keep randomness in key.
Lock and Chance knobs decide how much changes.
A steady clock keeps it in time, even when the notes are random.
Delay and reverb glue random notes into something that sounds intended (effects guide).

What to remember

Pitch is a voltage, so a chord is the root plus a few fixed amounts.
Polyphony needs a voice (oscillator, envelope, VCA) per note.
Sample & Hold makes random voltages; a Quantizer snaps them to a scale.
A Turing Machine loops random notes into a riff, and Lock decides how fast it evolves.
Chaos, physics and cellular automata make patterns that are neither repeating nor random.