Stem separation
Understand stem-separation quality
Separation helps you reshape a finished mix, but it does not restore the original studio session. Judge each part both on its own and in your new arrangement.
Why one part contains another
In a finished recording, the instruments are already mixed. A voice and a synthesiser can share similar frequencies, while reverb ties sounds together. The model estimates which material belongs to each group, and those estimates are not always exact.
A trace of drums in another part is often called bleed. Watery sounds, rustling or changed transients may also be separation artefacts. They do not necessarily mean the file is damaged or the download failed.
Check the result step by step
- Mute the original track so it does not play at the same time as the stems.
- Listen to all four parts together at a moderate level.
- Solo the part you need in a busy section. Do not judge the whole result from a quiet introduction.
- Compare it with the original at a similar perceived loudness. A louder version can easily seem better simply because of its level.
- Check the stem inside the intended mix. A small artefact may be unobtrusive with other instruments, or become more obvious after processing.
Make practical adjustments
Start with level and gentle EQ. A trace of bass in the vocal stem may be less distracting after reducing unwanted low frequencies. Heavy filtering can also remove useful vocal detail, so listen carefully. Reverb may soften a dry part, but it cannot restore missing information.
To remove vocals, listen to the other three groups together. To keep only drums, check whether leftover musical sounds interfere with your new track. Sometimes a short, clean excerpt is more useful than an entire separated recording.
Choose a good source
Use the highest-quality version available to you. Saving an MP3 as WAV does not recover lost detail: it changes the format, not the recording's quality history. Heavily distorted, overloaded or repeatedly compressed material can be harder to separate cleanly.
Four exported WAV files are not four independent studio recordings. Their duration and timing allow them to play together, but the combined sound may differ from the original mix.
Know when to use another approach
If you need precise notes and freely replaceable instruments, start with MIDI and Maestro. If you need a completely clean vocal, use an original vocal recording when available. Keep the original until the work is finished and respect the rights attached to the source material.