Overdub

Overdubbing lets one person record every part of a song. You record the first part, play it back, record the next part while hearing the first, and keep stacking until the song is full.

Where the new part goes depends on the tool:

• In a DAW, each overdub usually lands on its own track, so you can change its volume, move it or delete it later without touching the others.
• On a looper, you overdub while the loop keeps repeating, and the new part plays back from the next pass. Many looper pedals mix each overdub into the loop, often with an undo for the last layer. Looper apps often keep each layer separate, so you can mute or remove one later.

A punch-in is a related technique. Instead of adding a layer, you re-record a short section of an existing track: playback runs up to the mistake, recording switches on for a few bars (the punch-in), then switches off (the punch-out), and everything outside that window stays as it was.

Two things keep overdubs lined up. The first is a steady tempo: record to a click or a drum loop so every layer agrees on where the beat is. The second is latency, the delay between playing a note and hearing it. Bluetooth headphones can add enough delay that each new layer lands late, so wired headphones are the safer choice when layering. AirPods latency in music apps explains why and what to do about it. When you record a microphone, headphones also stop the playback from leaking into the new take.

In Gelato Synth and Gelato Chord, the loop recorder’s +1 button records an overdub: a new layer on top of the loop, up to eight, each with its own sound. The loop recorder is part of each app’s $4.99 unlock. 8 best looper apps for iPhone compares how other apps handle layers.