Stem mastering is a variant of mastering that starts from several track groups instead of a single stereo file. Rather than delivering the song already summed into one WAV, you deliver a few stems — for example vocals, drums, bass and instruments — and the engineer processes them with a degree of control that traditional stereo mastering doesn't allow.
It's a niche service: most projects with a good mix don't need it. But when that extra bit of control over the final balance is required, it makes the difference. At Stitos we offer it 100% online, like the rest of our services.
How it differs from normal mastering
Stereo mastering works on the final result of the mix: a single file. The engineer adjusts the whole, but can't isolate elements. If the vocals ended up a touch low, there's no way to raise them without affecting everything else.
Stem mastering partly removes that limitation. By receiving separate groups, the engineer can:
- Adjust the balance between families. Slightly raise the vocals, control the weight of the lows or give air to the instruments without touching the rest.
- Process groups independently. Apply specific EQ or compression to the drums or the vocal bus before summing everything in the master.
- Correct small mix imbalances. Without going back to the original session, which is useful when the mix isn't yours or you no longer have access to it.
It's not a second mix: the goal is still to master. But the extra layer of control solves situations that would be impossible with a closed stereo.
When it's worth it
Stem mastering makes sense in specific cases:
- You want to leave room to fine-tune the balance at the master stage, without reopening the mix.
- The mix was done by someone else and you can't go back to the session to tweak something.
- There are a few elements (the vocal, the lows) that need independent treatment from the rest.
- You're after maximum control on an important release and the difference justifies the extra work.
If your mix is already solid and balanced, stereo mastering is probably all you need. And if what you have is the individual tracks unmixed, what you're really after is professional mixing, not stem mastering.
How to prepare and send the stems
The key to stem mastering is exporting the groups well. If the stems don't sum correctly, the result won't match your mix. The basic guidelines:
- Group by families, not track by track. Between 4 and 8 groups is ideal: lead vocal, backing vocals, drums, bass, harmonic instruments, effects.
- Export all from the same start point (same time-zero) so they line up to the millisecond.
- 24-bit WAV at the same sample rate, with the mix processing already applied on each group.
- Leave headroom on the sum. When you play all the stems together, the whole should sound exactly like your final mix, with room to master.
We have a full guide on how to send stems for mastering with the detailed checklist and the most common mistakes to avoid.
Does your project call for stem mastering?
Tell us how your mix is and what you're after. We'll tell you whether stem mastering adds anything in your case or whether stereo mastering is enough, and send you a quote with no commitment.
Get a quoteFrequently asked questions
What's the difference between stem mastering and normal mastering?
Stereo mastering works on a single final file. Stem mastering starts from several track groups (for example vocals, drums, bass and instruments) that are processed separately before being summed. That allows adjustments impossible with a single stereo, like raising the vocals or controlling the lows without affecting the rest.
How many stems should I send?
Usually between 4 and 8 groups: lead vocal, backing vocals, drums, bass, harmonic instruments and effects. There's no need to separate track by track; the goal is to group by families to have control without turning it into a full mix. We'll guide you based on your project.
How do I export the stems?
All from the same start point, as 24-bit WAV at the same sample rate, with the same mix processing applied on each group and leaving headroom on the sum. When played together they should sound exactly like your final mix.
Do I need stem mastering or is normal mastering enough?
For most projects with a solid mix, stereo mastering is enough. Stem mastering makes sense when you want extra room to adjust the balance, when the mix isn't yours and you can't go back to it, or on projects where a few elements need independent treatment.