Sequencers and arpeggiators

Here's an arpeggio: C, E and G over and over, one note every sixteenth, the way an arpeggiator plays a held C major chord. Every beat is accented so you can hear where the beat falls. Press play and listen to which note gets the accent.

The notes never change and the spacing never changes, yet the pattern feels like it's rolling over itself. The accent lands on C, then E, then G, then C again, and each bar starts on a different note. It takes three bars before C is back on the downbeat.

Now hold one more note. Before you press play on the version below: will adding B make the pattern feel busier, or calmer?

Calmer, and that surprises most people. With four notes, the cycle fits exactly into a beat, so C lands on every accent and the pattern locks into place. With three, the cycle and the beat disagree, and that disagreement is what makes the first version roll. The number of notes you hold changes the rhythm, even though every note is the same length.

Two ways to make a pattern repeat

A step sequencer stores explicit events: this note on step 1, nothing on step 2, that note on step 3. It's the machine behind "I Feel Love", where Giorgio Moroder had a modular Moog's sequencer play a relentless, pulsing bass line in 1977, and behind every 303 acid line since.

An arpeggiator stores a rule instead. You hold some notes, and it walks through them: up, down, up and down, in the order you pressed them, or at random. Change the chord under your fingers and the pattern follows.

They can produce identical notes. The difference is how you change them. A sequencer lets you put one surprise on step 11. An arpeggiator lets you reshape the whole pattern with one hand on the keys, which is why it's a performance tool as much as a composing one.

Where the cycles meet

Count it out. Sixteen steps in a bar, three notes in the cycle. Three doesn't divide sixteen, so each bar starts one step further along the cycle:

Bar	First note	Why
1	C	The cycle starts here
2	E	16 steps is five cycles plus one note
3	G	One more note further along
4	C	48 steps: three bars, sixteen full cycles

Musicians call this kind of disagreement a cross-rhythm: a group of three running against a grid of four. You hear it all over trance and synth-pop arpeggios, and it's the same push and pull that makes a lot of minimalist music shimmer. You get it for free just by holding three notes.

Restart or keep going?

Some arpeggiators start again from the bottom every time you press a new chord. Others keep walking. That choice decides whether you hear the three-bar roll at all. If the cycle restarts on every downbeat, C will always land on "one" and the rotation disappears.

Neither is better. Restarting makes a hook easy to recognise: the riff is the same every bar. Keeping the cycle running gives you motion over a steady accompaniment. Decide which one the song needs before blaming the chord.

Rate is a speed, and the beat is a feel

An arpeggiator needs to know how fast to go. In a DAW that's usually a note value: sixteenths, eighths, triplets. Maru's Arpeggiator sets Rate in notes per second instead, so you match it to your tempo yourself.

The conversion is quick. At 120 BPM there are two beats per second; four sixteenths per beat makes eight notes per second, so 8 Hz. At 90 BPM, sixteenths need 6 Hz. Change the song's tempo and you'll need to change the rate too.

Gate: plucked or connected

Gate is how long each note is held, as a share of the gap to the next one. Short gates make a plucky, staccato pattern with daylight between the notes. Long gates join them into a legato ripple.

The instrument has the last word, though. A pluck with a short decay sounds clipped whatever the gate. A pad with a long release smears every note into the next even at a short gate. If the pattern sounds wrong, check whether it's the gate or the sound.

The voicing becomes the melody

Hold C3, E3, G3 and the arpeggio is a tight little wiggle. Hold C3, G3, E4 and the same chord becomes a wide, rolling figure that sweeps over an octave. Same chord name, different riff.

Register decides the arpeggio's job, too. Down around C2 it's a bass line. Up around C5 it's sparkle above the band. A busy arpeggio in the middle of the keyboard fights with the vocal for the same space.

Same idea, different place: an arpeggiator plays your voicing one note at a time, so every voicing choice in Chords and voicing is also a melody choice here.

When more notes make less music

Hold every chord tone and extension you can reach and the result can sound impressive alone and then turn to fog under drums and a vocal. Long cycles are hard to follow; the listener never hears the pattern come round.

If an arpeggio is crowding the mix, take a note out before you reach for EQ. A smaller set often makes a stronger hook, because the ear can learn it.

Make it yours

Hold a chord on the Arpeggiator below and set Rate to 8 for sixteenths at 120 BPM. Try three notes, then four, and listen for the roll you heard at the top of the page. Then shape it: shorten Gate for a plucky pattern, add an octave with Octaves for a sweep.

When you find one that sits well over a simple bass note, save it as a preset with the tempo in the name ("Rolling 3 notes, 120"). Next time, you'll know the rolling feel comes from the note count, not from a magic setting.

Quick check

1. You hold a three-note chord and the arpeggio sounds restless; your co-writer wants it to feel steady. What's the smallest change? Add or remove one note so the count divides the bar (two or four), or set the arpeggiator to restart on every chord. Both put the same note back on the downbeat.
2. You set Rate to 8 for sixteenths, then the song moves to 100 BPM and the arpeggio drifts out of time. Why? 8 notes per second matches sixteenths only at 120 BPM. At 100 BPM sixteenths need about 6.7 per second.
3. You shorten the gate but the notes still blur together. What else could it be? The instrument's release. A pad with a long release keeps sounding after each note ends, so shorten its release or choose a plucky sound.

Next steps

• Go deeper: Algorithmic and live-coded patterns. Each pattern here is one fixed rule. What if you could write the rules yourself and change them while they play?
• Use it: Bass lines. Put a repeating pattern down low and give it a clear job.