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Part 80

Melodic Sequencer & Drum Machine

A synthesizer without a sequencer is like a typewriter without paper. You can make sounds, but you can't compose with them. This lesson adds two fundamental tools: a melodic step sequencer for pitches and a multi-row drum machine for rhythm.

Step Sequencing

A step sequencer divides time into equal steps (typically 16). Each step holds an instruction: play this note, or stay silent. The sequencer advances through steps at a fixed rate (set by BPM), firing notes at precise times. It's a musical grid, the same idea as a piano roll in a DAW, but constrained to discrete steps.

Melody Mode

In melody mode, each step stores a pitch. The grid reads left to right through time, and up/down through pitch. Click a cell to place a note; click again to remove it. Scale quantization limits the available pitches to notes in a chosen scale, so everything sounds musical, even random clicks. The sequencer drives a simple subtractive voice: oscillator → filter → VCA, the same chain you've built since Part 1.

Drum Mode

In drum mode, each row is a different percussion voice (kick, snare, hi-hat, clap) and each step is on or off. This is the same trigger sequencer from Part 33, but now with multiple rows. The four voices use the synthesis techniques from Parts 31–41: sine + pitch sweep for kick, noise + body tones for snare, filtered noise burst for hi-hat, and bandpass noise for clap.

Try it: start in Melody mode with the "Arpeggio" preset, then switch to Drums and try "Four on the Floor." Use the BPM slider to find your groove.

Tempo
Presets
Scale

Click cells to place notes. One note per step.

Osc
Filter
Envelope
Presets

Four voices: kick, snare, hi-hat, clap. Toggle steps to build a beat.

Two Sides of the Same Coin

Melody and drum sequencers are really the same mechanism. Both divide time into steps and fire events on a grid. The difference is what each step controls: pitch in melody mode, trigger in drum mode. In hardware, step sequencers output control voltages (for pitch) and gate/trigger signals (for rhythm). The sequencer doesn't care what it's driving. The same 16-step loop could control a filter cutoff, a reverb mix, or anything else with an input.

References