Arpeggiator
A function in synthesizers and sequencers that plays a held chord back as a sequence of notes.
What it means
An arpeggiator is a function in electronic instruments that automatically breaks up a chord held down at the same time into a short, repeating sequence of notes, instead of letting it sound as a full chord. The name comes from arpeggio, the broken chord played note by note, as it originally arose on the harp.
The player presses several keys at once, the arpeggiator stores that chord, and plays its notes back automatically in sequence for as long as the keys are held, or until a new chord is grabbed.
Musical use
Arpeggiators first appeared in the 1970s in home organs as part of automatic accompaniment functions, for instance in analog Yamaha Electone models offering several selectable arpeggio patterns. Since then they have become standard equipment on many synthesizers, sequencers, and music software.
Typical settings control the tempo of the repetition, the order of the notes, such as up, down, or alternating, and the range over which the pattern can spread through octave transposition. In electronic dance music, synthwave, and film scoring, a steadily running arpeggiator often shapes the rhythmic character of an entire piece.
An arpeggiator should be distinguished from a classical arpeggio: the latter is shaped and varied deliberately by a performer, while the arpeggiator produces a fixed, automatically generated pattern. It differs from a sequencer in that it works directly from held keys and needs no separately programd note sequence.
Many devices also let the arpeggiator's tempo be locked to a piece's overall tempo, so the note sequence fits rhythmically exactly with the rest of the arrangement. Some software instruments extend fixed patterns with random or freely programmable note orders, turning the arpeggiator into a small composition tool of its own.
Performance practice
Try out different patterns and speeds before committing to an arrangement, since even small changes in tempo or octave range strongly alter a piece's character. Use the arpeggiator deliberately as a rhythmic element, not just a sound effect, and combine it with filter movement to keep the repetition alive.