Removing AI-Separation Artifacts After Spleeter and Demucs

Yesterday a request arrived through the "What do you need?" form: "Remove separation artifacts". Today the feature is in production — here's what it is and how it works.

Where the artifacts come from

AI stem separation (Spleeter, Demucs, separators built into DAWs and online services) went mainstream: anyone can pull vocals out of a mix or make an instrumental. But the neural mask is imperfect, and the extracted tracks carry characteristic debris:

• "musical noise" — short isolated tonal bursts, like glass shards scattered across the spectrum;
• metallic burbling and watery tails;
• random fragments of other instruments.

A regular denoiser doesn't help here: it hunts stationary noise, while separation artifacts are the opposite — non-stationary and tonal.

How we remove them

Our approach leans on the nature of the artifacts: real musical events have neighbors — in time (a note lasts) and in frequency (harmonics, an instrument's width). Separation artifacts are loners: isolated peaks with no support around them.

The algorithm analyzes the time-frequency picture and compares every element against the median of its neighborhood (~170 ms × adjacent frequencies). Peaks that tower over their surroundings are gently pulled down to a reasonable level — by at most −12 dB, never to zero. Core material with normal structure is not touched at all.

Honest limits

• The function doesn't work miracles: heavily damaged material gets cleaner, not studio-grade.
• On normal tracks without artifacts it changes almost nothing — but there's no reason to enable it "just in case".
• It's a PRO module within a regular mastering (1 token), the "Remove AI-separation artifacts" checkbox in the settings. Via API — the separation_cleanup (0–1) parameter of POST /api/v2/master (docs).

Pairs beautifully with stem mastering: clean your extracted stems and assemble them into a coherent master in one pass.

Try it: magicmaster.pro/app?lang=en. Ideas — through the "What do you need?" form: this feature shipped a day after the request.