Stem Separation
Stem separation splits a finished song back into its parts — drums, bass, vocals, guitar, and everything else — and drops them onto tracks in your project. It runs entirely on your device: no upload, no account, no per-song credits, and it works in airplane mode.
The reason it’s here isn’t archaeology. It’s so you can play the part yourself:
- Separate a song you want to learn or cover.
- Add the stems to tracks — they land perfectly aligned.
- Mute the guitar stem.
- Monitor your own guitar through homecrate amp.
- Hit record. You’re now the guitarist on that track.
The same trick works for any part. Mute the vocal and sing it. Mute the drums and play them in on the drum sequencer. Mute the bass and track your own.
🔒 Pro feature. Stem separation is available with Homecrate Pro. There is no per-song limit and no subscription — separate as many songs as you like.
[SCREENSHOT: Stem Separate tab with the stems and engine pills]
Opening Stem Separate
Tap ⋯ (more menu) → Open / Import, then switch to the Stem Separate tab.
Set your two options — how many stems, and which engine — then tap Pick a Song… and choose any audio file from Files, iCloud Drive, or your device.
Note: If you’ve turned off AI features in Settings, the Stem Separate tab is hidden entirely.
Choosing How Many Stems
| Option | You get | Best for |
|---|---|---|
| Guitar (6 stems) | Drums, bass, vocals, guitar, and other | Learning or replacing a guitar part — the only option with a dedicated guitar stem |
| Cleaner vocals (4) | Drums, bass, vocals, and other | Vocal work, acapellas, and karaoke-style backing tracks |
The 6-stem model buys the guitar stem at a small cost: vocals can carry slight artifacts. The 4-stem model has no guitar stem but gives the cleanest vocal isolation of the two.
Pick whichever matches what you’re going to mute. Your choice is remembered for next time.
Choosing an Engine
| Engine | What it is | When to use it |
|---|---|---|
| GPU · faster | Runs the model on the device’s graphics hardware | The default choice on modern iPhones and iPads — noticeably quicker |
| CPU · steady | Runs the model on the main processor | Works anywhere, on any supported device. The safe fallback |
Both engines run completely offline and produce the same set of stems — the difference is speed and how hard they push the device. If the GPU engine isn’t available in your build, its pill is dimmed and homecrate quietly uses the CPU engine instead.
Downloading a Model
Separation models are large, so none of them ship inside the app — that’s what keeps the download small enough to install over cellular. The first time you use a particular stems-and-engine combination, homecrate offers a one-time download:
[SCREENSHOT: Download model button showing the size for the selected combination]
| Stems | Engine | Download size |
|---|---|---|
| Guitar (6 stems) | GPU | ~110 MB |
| Guitar (6 stems) | CPU | ~136 MB |
| Cleaner vocals (4) | CPU | ~166 MB |
| Cleaner vocals (4) | GPU | ~168 MB |
- The download happens once, on Wi-Fi or cellular, and shows a progress bar you can cancel.
- Once installed, the model stays on your device and every future separation is fully offline.
- A Delete button appears next to any downloaded model, so you can reclaim the space whenever you want and re-download later.
- Each combination is separate. Downloading the 6-stem GPU model doesn’t give you the 4-stem CPU model.
Pick a Song… stays dimmed until the selected combination’s model is installed.
While It Runs
Separation is a real workout for the device. The progress screen walks through four phases:
| Phase | What’s happening |
|---|---|
| Reading Song | Decoding the audio file |
| Preparing Model | Getting the model ready for this device — the first run is slower |
| Separating Stems | The long one. Shows a percentage |
| Writing Stems | Saving the finished files |
[SCREENSHOT: Separation progress with the percentage and the on-device reminder]
Things worth knowing:
- Keep the app open. The job runs on this device and stops if you leave.
- If the device gets warm, you’ll see “Slowing down to keep the device cool…” — homecrate throttles rather than overheating. It’s still working.
- Cancel stops the job at any time, and the back gesture asks before throwing progress away.
- Songs up to 12 minutes are supported. Longer files stop with a “Songs up to 12 minutes are supported” message.
The Results Screen
When it finishes you get a Stems Ready list — one row per stem.
[SCREENSHOT: Stems Ready list with preview buttons and Add to Tracks]
| Action | What it does |
|---|---|
| Preview (per row) | Plays that stem so you can check it before committing |
| Add to Tracks | Places every stem onto a track in the project |
| Share All (.zip) | Bundles the stems into a single zip for the share sheet — AirDrop, Files, another DAW |
| Done | Closes without adding anything. The files stay on disk |
How stems land on tracks
Add to Tracks pins every stem at position 0, so all of them stay sample-aligned with each other and with the original song. Empty tracks are used first; if there aren’t enough, homecrate adds new ones up to your track limit.
If there still isn’t room, you’re offered the option to place as many as will fit — or told to clear some tracks and try again. See Adding & Removing Tracks for the track limits.
Separating Again
Stems are stored in the project’s own stems folder, and the files themselves are the record — there’s no separate list to manage.
- If the project already has separated stems, homecrate offers View Previous (reopen the results screen without re-running anything) or Separate New….
- Re-separating a song with the same name asks before replacing its existing stems.
- Separated stems are also safe from the per-track stem export — see Exporting Stems.
Tips
- Preview before you commit. A stem that sounds thin in isolation often sits fine once the other stems are back around it — and vice versa. The preview button is the fastest way to judge.
- Mute, don’t delete. Keeping the muted stem on its track gives you a reference to check your own take against. Unmute it, compare, mute it again.
- Separate before you set the tempo. Stems land at the song’s original speed. Match your project’s tempo to the song first and every grid line will line up.
- The 6-stem model is the play-along model. Unless you’re doing vocal work, start there — the guitar stem is the whole point.
- Bass and drums separate best. Vocals are close behind. Anything sharing a frequency range with something else (guitar under keys, for instance) is the hardest case for any separator, including this one.
- Plug it in and let it run. A long song on the CPU engine is a real workload. Charging and a cool surface both help.
- Isolated stems are great source material for the clip editor’s “To MIDI” button — a clean, single-note stem converts far more accurately than a full mix. See Working with Audio Clips.