Automatic Stem Separation

FreeMix can automatically split a track into its individual stems. Upload a full mix, turn on stem generation, and FreeMix separates it into four parts — drums, bass, vocals, and other (everything that isn’t one of the first three) — that you can play, download, remix, and sell like any other stems.

Separation runs on FreeMix’s own infrastructure. Your audio isn’t sent to a third-party service.

Separation quality

FreeMix separation is built on Demucs, a well-regarded open-source source-separation project.

There’s nothing to configure. You don’t pick a model — FreeMix runs the best separation your plan includes, automatically:

• Free — standard-quality separation.
• Pro and Studio — the highest-quality separation FreeMix offers. Cleaner results with fewer artifacts, most audible on dense mixes and on the “other” stem.

Every plan produces the same four stem types. The difference is quality, not what you get back.

What to expect from the quality

Stem separation is very good, but it isn’t perfect — no separation model is. A few honest expectations:

• Drums, bass, and vocals separate cleanly on most material.
• The “other” stem is a catch-all for everything that isn’t drums, bass, or vocals — synths, guitars, keys, pads, effects. Because it holds the most variety, it’s usually where any bleed or artifacts show up.
• Dense or heavily-processed mixes are harder to separate than sparse ones. Results vary with the source.

If you already have true isolated stems, uploading them directly will always beat separation — separation reconstructs stems from a finished mix, which is a fundamentally harder problem than exporting them from a project.

More stem types are coming

Today’s separation produces four stems. We’re working on models for more specialized types — synth, keys, guitar, and more. If you’d like to help make that happen, see Stems & AI training.

Separation limits by plan

Each plan includes a number of separations per month:

• Free — 3 separations per month.
• Pro — 25 separations per month.
• Studio — unlimited, within fair use.

Your allowance resets at the start of each calendar month. For the latest numbers, see the plans page in the app.

If you reach your monthly limit, you can still publish your track — the stems just won’t be generated automatically until your allowance resets or you upgrade. You can also upload stems directly at any time, on any plan, with no limit.

Consenting to help improve separation

When your upload includes generated stems, you’ll see an optional checkbox asking whether FreeMix can use those stems to help train its own separation models. It’s entirely optional and off by default. Full details are on the Stems & AI training page.