Lo-fi Music Generator

What this is. A generator of lo-fi hip-hop — the slow, warm, slightly worn instrumental music people put on to study, write or work to. Press play and it composes as it goes: a jazzy chord progression on a piano or an electric piano, a soft bassline under it, a lazy swung drum loop, a sparse melody over the top, and the crackle of a record that has been played too many times. Under it you can add rain, wind, waves, a fire, distant thunder and birdsong. It never runs out and never loops back to the start, because every bar is written the moment before you hear it. Leave it running in a background tab; that is what it is for.

Where the music comes from. Nothing here is a recording, a sample or a MIDI file. The chords come from 8 four-bar progressions of the kind lo-fi borrows from jazz — the ii–V–I, the I–vi–ii–V turnaround, a minor drift — played as seventh, ninth and thirteenth chords, which is where the genre's soft, unresolved colour comes from. Each chord is voiced the way a pianist would: the root left to the bass, the remaining notes packed close together in the middle of the keyboard, and the chord rolled from the bottom up rather than struck as a block. The melody is built from the key's pentatonic scale and the chord's own notes, landing on a chord tone on the strong beats and wandering a step or two at a time in between.

The groove. Lo-fi drums are a hip-hop beat played slowly and slightly late: kick on the one, snare on two and four, hi-hats in between. Here there are 4 patterns, and each bar varies its pattern a little — a ghost snare here, a dropped hat there — so a loop that is identical on paper never quite repeats. The sixteenth notes are swung, so every second one lands a fraction late, and the swing itself drifts a little from bar to bar and drum to drum, with the hi-hats dragged furthest. The snare sits about 17 milliseconds behind the beat — the average measured for a laid-back drummer — and every hit is nudged a few milliseconds, more often late than early, because listeners hear an early hit as a mistake and a late one as feel.

Tuned against real recordings. Every instrument and background sound here was measured against freely licensed recordings of the real thing — two pianos, Rhodes performances, lo-fi drum hits, worn records, fires, wind, waves, thunder and birds — and adjusted until it measured the same: where the overtones of a piano note sit and how fast each one fades, how long a snare takes to die away, how bright a hi-hat is, how much of a fire is sudden pops. None of those recordings is played or downloaded; they were a ruler, used once. The piano is built from up to eight tones per note, tuned slightly sharp of each other the way a stiff piano string tunes its own overtones, which is most of what separates a piano from an organ. Prefer the classic lo-fi sound? Switch the keys to the electric piano.

Why it sounds old. Everything musical goes through three effects that imitate a worn tape or record. A slow wobble bends the pitch by a few cents, the way a tape that is not quite running at constant speed does. A low-pass filter takes the top off, as an old recording loses its treble. And a gentle saturation rounds off the peaks. Each time the kick drum lands, the chords and bass dip by a few decibels and swell back — the "pumping" that lo-fi producers get from a sidechained compressor. The crackle and the ambience are added after all that, at whatever level you set, so they sit around the music rather than inside it.

Ambience, with or without the music. Rain, wind, waves and a fire are continuous beds; thunder and birdsong arrive now and then, each strike and phrase shaped differently, so there is no loop to notice. They start switched off — turn up any of them in the Ambience part of the mix. Turn the music layers down and the tool becomes a nature-sound generator on its own; turn it all up for a rainy-window study session.

How a track is put together. Each track has its own key, two progressions (an A and a B), a drum pattern, a bass style, a comping rhythm, an amount of swing and a name — one of 400 — all drawn from one number, the track's seed. It opens with 4 bars of piano alone before the bass and drums come in, then cycles through 8-bar sections in an A-A-B-A shape: a groove, the same groove with a melody, a breakdown on the B progression where the drums drop out for half the section, and the melody again. A small fill on the drums leads into every new section. Under the chord name, the two rows are the A and B progressions spelled in the track's key: the row being played is the brighter one, and the chord you are hearing is highlighted, so you can see the breakdown switch to B and follow the changes as they go round. The melody is one short idea — a call, an answer, the call again, then a bar of rest — and about a quarter of tracks have no melody at all, as a good deal of lo-fi does not.

A playlist, not one endless loop. Four chords for ten minutes wears thin, so after two or three minutes the track winds down — the melody goes, then the drums, and the piano plays out softly — and the next one starts on its own piano intro, in a new key, with new chords and a new groove. Turn off Move on to a new track to stay on the one you like, or press Next track to skip ahead. The chords are voiced the way a pianist moves between them: each note of a chord goes to the nearest note of the next, holding the notes the two share.

Sharing a track. Because the whole playlist follows from one seed, the same link always plays the same music, bar for bar, on any device. The address bar holds the seed, the tempo and which track of the playlist you are on; send that link and whoever opens it hears the track you are hearing, and the ones after it. The mix and volume stay on your device, because they are about your speakers rather than the music.

Downloading a track. The Download WAV button renders the track again, faster than real time and without playing it, through the same instruments, effects and mix you are listening to — ambience included — and saves it as an uncompressed WAV file at CD quality. Every bar is the same function of the seed that the player uses, so the file is the track you hear, note for note; only the random grain of the rain and crackle differs. It is WAV rather than MP3 because an MP3 encoder would be a large download for every visitor, and any audio app can turn a WAV into an MP3.

Tempo. Lo-fi lives between about 70 and 90 beats per minute. The slider goes from 60 to 100 and starts at 75. A change takes effect at the next bar line rather than mid-bar, so the beat never stumbles.

Privacy and offline use. Every sound is synthesised by your browser with the Web Audio API, so there is nothing to download or stream and the tool keeps working with the network switched off once the site has loaded. There are no accounts, no ads and no analytics or tracking of any kind. Your track, tempo and mix are saved in this browser only.