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Lacquer · Topic

Stem separation, sampling & privacy

Stems are a diagnostic tool and a sampling source. Both raise the same questions: how clean is the split, and where did the audio go to get split?

Stem separation is a diagnostic tool and, more and more, a sampling source. Both uses raise the same two questions: how clean is the split, and where did the audio have to go to get split? These essays compare Demucs and MDX-Net using the published benchmarks and a runnable listening window, explain why the copy you feed a separator sets the quality ceiling, and give a sampling workflow that chops around bleed instead of through it.

The privacy half is about unreleased music: the four terms-of-service clauses to read before uploading to a cloud splitter, what browser-local and offline processing actually protect (and the metadata that leaks anyway), and when local tools beat an upload queue. The thread through all of it: use stems to hear the problem, fix the mix itself, and keep unreleased files on your own machine when you can.

  1. Separated acetate ribbons above a turntable
    Stems · 21 August 2026 · 7 min

    Can stem separation fix a bad mix? Stems diagnose mixes, they don’t replace them

    Stem separation can’t fix a bad mix, but it shows what’s wrong. Mute or lower one stem at a time to find what eats your headroom, then fix it in the session.

  2. Two precision analyzers on black marble, one drawing a sharp cyan waveform and the other a magenta spectrogram grid, their beams crossing at the center
    Stems · 8 October 2026 · 11 min

    Demucs vs MDX-Net: what each separator gets wrong, and why

    Demucs vs MDX-Net from the published benchmarks and a runnable window test: who wins drums and bass, who wins vocals, and how to hear it.

  3. A cyan waveform lifting out of a dark video frame and splitting into five glowing stem lanes across black marble
    Stems · 8 October 2026 · 11 min

    Splitting stems from YouTube audio you own starts with the cleanest copy

    Want stems from a song you uploaded to YouTube? The copy you feed the separator sets the ceiling. Find the first-generation file, then split locally.

  4. An MPC-style sampler on black marble with a separated drum waveform sliced into glowing cyan chops and a faint magenta bass trace beneath
    Sampling · 8 October 2026 · 11 min

    Sampling from separated stems: chop around the bleed, not through it

    A producer’s workflow for sampling from AI-separated stems: audit the bleed, restore the attack, null-test, match key, clear what you don’t own.

  5. A sealed glass vault on black marble holding a glowing master tape, with a faint magenta upload beam stopped at the glass
    Local-first · 8 October 2026 · 10 min

    Before a cloud stem splitter gets your unreleased song, read four clauses

    Uploading an unreleased track to a cloud stem splitter is a rights decision. Four terms clauses to read, and how to prove a split stays local.

  6. A sealed black lacquer case on black marble holding a glowing master reel, cyan light inside, a magenta-lit unplugged network cable coiled beside it
    Privacy · 8 October 2026 · 10 min

    Keeping an unreleased master on your own machine, honestly

    What browser-local and offline audio processing protect for unreleased music, what they don't, the metadata that leaks anyway, and privacy claims to defend.

  7. Closed steel vault beside a quiet local workstation
    Practice · 20 August 2026 · 7 min

    Should you upload an unreleased master to the cloud?

    Upload an unreleased master only if you accept a vendor holding the file. Loudness, true peak, and clip checks can stay fully local with CoProducer.

  8. Vault and local workstation
    Local-first · 21 August 2026 · 7 min

    How to check LUFS without uploading your song

    You don’t need to upload a track to measure LUFS or true peak. A free meter plugin or one FFmpeg command does it in seconds, and your unreleased song stays put.

  9. A glowing cyan waveform on black marble split in two with magenta sparks at the cut, one end trailing into a smooth gold curve, a razor blade and a loop of tape beside it
    Editing · 21 October 2026 · 7 min

    Clicks at your edit points come from cutting mid-wave. Fade every cut

    Why audio edits click and pop: a cut or splice that lands mid-waveform makes an instant jump. A 5 ms fade or crossfade removes it. Includes a click-finder script.

More topics: Loudness & LUFS True peak, limiting & delivery Low end, 808s & mix dynamics 432 Hz, pitch & tempo All essays