NOMZ Studios has recently updated its Windows application that takes the individual stems of a song and returns a finished master. StemMaster makes the mixing decisions first — levels, pans, per-track automation, riding the vocal through busy sections, ducking the bass under the kick — and only then masters the result to a true-peak-limited, LUFS-targeted finish. Because it works from the multitrack rather than a stereo bounce, it can act on one part at a time.
Thirty-four releases have shipped since the version most outlets covered. This is what a reader who saw the launch has missed.
The AI is optional, and one of its providers sends nothing anywhere
The engine that does the mixing and mastering is built in. It runs entirely on the user’s own machine, with no account, no connection and no upload, and it is the default.
A second, optional engine can be connected with the user’s own API key. Until this release the in-app Help said it worked with one provider. That had not been true for a long time: the list carries Anthropic, OpenAI, Google Gemini, xAI Grok, DeepSeek, z.ai and OpenRouter, plus two custom entries for any compatible endpoint. Anyone who read that line and concluded their existing key was no use here had been told wrong by the product.
One entry in that list had been documented nowhere at all: Ollama, which runs a model on the user’s own computer. No key, no account, no bill, and nothing leaves the machine — not even the measurements the hosted providers receive. The hosted providers receive measurements only, never audio.
Nothing about the engine changed. What the application says about itself did.
It shows its working, including where it stops vouching for it
Every decision is written in plain English in the Engine Notes panel — what was done, to which stem, and which measurement justified it. Since the launch that panel has learned to name the track rather than the type, to report the level each stem was placed at, and to say when a tonal correction hit its 2 dB limit instead of reporting the number it wanted.
1.1.27 added the part that matters most for anyone wary of AI copy: if the optional engine is in use, its own account of what it meant to do now sits under a heading naming the model and stating plainly that StemMaster does not check that paragraph, while everything above and below it is measured.
A sound you define, rather than six you pick from
Custom profiles arrived in 1.1.9 and became practical in 1.1.18: master a track, move the faders and width sliders until it sounds right, and save that as a profile with File > Custom Profiles > Save This Mix as a Profile. No JSON, no text editor.
Per-stem control grew alongside it. Every channel strip now carries a Primary/Secondary control that tells the engine which parts carry the song, and a width slider that narrows a stem and is audible while you listen rather than only on the next render.
Real sessions, not tidy ones
A kit recorded as separate kick, snare, overhead and room tracks is now balanced as one instrument, keeping the relative levels as recorded; the same applies to two mics on a bass rig or a doubled guitar. Large sessions were the other half of the work: a session is measured once rather than once per master, playback no longer breaks up on big projects, and a 3.9 GB multitrack that could previously run out of memory now masters in roughly a third of it.
Check the stem export yourself
StemMaster’s Full Mix stem export reconstructs the pre-master mix exactly. That is asserted in the automated test suite on every commit and the build fails if the residual rises above −60 dB, but taking that on trust is unsatisfying and the demo cannot settle it, because exports are disabled in the demo. So the files are published: a mix, its exported stems and the master, 24-bit FLAC straight out of the application, with instructions. Import the stems at unity, invert the mix, and the residual drops to −142 dB.
Availability
StemMaster 1.1.35 is available now for Windows 10 and 11 as a standalone application. It is available at a launch price of $69 USD as a one-time purchase until August 31st, 2026 (regular $99 USD). Free updates are included across the 1.x series. A macOS version is in testing, with no date announced.
A free demo is the full application with exports disabled and a periodic tag on mastered playback, which the download page says before the download rather than after it.
More information: NOMZ Studios
