Catch a song idea before it goes, with SUS4 Sketchpad

For SUS4 Sketchpad for iPhone, iPad and Mac5 min readUpdated 29 September 2026

Ideas turn up at the wrong moment: in the car, halfway through another song, at 2 a.m. A voice memo catches the sound, but a week later you have forty files called "New Recording" and no idea which key the chorus was in.

SUS4 Sketchpad keeps everything for one idea in one place: the title, key and tempo, the lyric, the chords and a voice note. Here is how to get an idea down fast, and how to come back to it later and actually finish it.

The short version

New sketch. Tap New sketch and give it a working title you will recognise later.
Set key, BPM and time. Tap the Key, BPM and Time chips. New sketches start at C major, 100 BPM, 4/4.
Record a voice note first. Under Voice notes, tap the mic and sing or play the idea before you try to write anything down.
Add the chords. Tap Add chord and build the progression from the root and quality pickers.
Type the words you have. Put whatever lyric you have under Lyrics. Half a line is fine. Tag the sketch so you can find it again.

Record first, write second

The fastest way to lose an idea is to start by typing. Open a new sketch, tap the mic under Voice notes and sing or play it straight away, even if it is only a hum. Everything else can wait. The recording holds the feel, the rhythm of the words and the tempo that you will struggle to rebuild from notes alone.

Then tap the chips under the title. Key offers all 12 major and 12 minor keys. BPM has a slider from 40 to 220 and quick picks from 60 to 180. Time lets you set beats per bar (2, 3, 4, 5, 6, 7, 9 or 12) and the beat unit. It takes ten seconds and saves you working it out again later.

SUS4 Sketchpad on iPhone editing a sketch called Harbour Lights: A minor, 92 BPM, 4/4, tags indie, ballad, live set, a verse and chorus lyric, and the chords Am, F, C, G, Am, F. — A sketch in progress (App Store screenshot): key, tempo and time up top, then the lyric and the chords.

Chords and words

Tap Add chord to build the progression. Pick a root (C to B) and a quality: major, m, 7, maj7, m7, sus2, sus4, add9, dim or aug. Chords appear as chips in order, and you can remove any of them with one tap. Keep the progression to the section you have. A verse on its own is a perfectly good sketch.

Type what you have under Lyrics, even if it is only a title line and a hook. Mark sections with [Verse] and [Chorus] so the shape of the song is clear when you come back. Notes & tags at the bottom is the place for the rest: "try it slower", "sounds like the bridge of the other one", and tags such as ballad or live set so you can find it again.

Humming a melody (Pro)

Capture melody, on the notebook screen, listens while you hum or play and works out the key, tempo and notes for you. With Pro, the melody is saved to the sketch as MIDI. You can edit the notes in a piano roll and export a .mid file to finish the idea in your DAW. Pro also adds AI chord suggestions and an AI assist for the lyric, which offers lines you can Append, Replace or Dismiss.

SUS4 Sketchpad capture screen on iPhone: "Hum or play — we’ll figure out the key, tempo + notes", a 00:00 timer and a large microphone button. — The melody capture screen (App Store screenshot).

Coming back to it

A sketch is only useful if you return to it. Once a week, open the notebook and play back three old voice notes. Most won’t survive, and that’s fine. The one that still makes you want to pick up a guitar is the one to take further: fill in a second section, record a better voice note, and when it is ready, take it into a writing session or a studio day.