StemMaster is a standalone Windows application from NOMZ Studios that mixes and masters full multitrack stems in a single pass, rather than treating mixing and mastering as separate stages. Where conventional mastering software processes a finished stereo mix or a handful of submix stems, StemMaster works from the complete multitrack: it makes mixing decisions first (levels, pans, per-track automation, riding the vocal through busy sections, ducking bass under the kick) and only then masters the result to a true-peak-limited, LUFS-targeted finish. Every decision is logged in an Engine Notes panel showing which track was adjusted, by how much, and why, and any manual fader or pan change triggers a fast re-render that holds the loudness target, with A/B comparisons kept loudness-matched throughout.
The target user is anyone who receives multitrack stems and needs a finished master without building a mix session first: producers, mix engineers wanting an automated starting point, or artists without a full mixing workflow. It sits between one-click mastering tools, which only touch a finished stereo file, and full DAW mixing, which requires manual setup.
StemMaster runs entirely locally, with no account, upload queue, telemetry, or internet connection required. An optional bring-your-own-key LLM engine (Anthropic, OpenAI, and compatible providers) is available; when enabled it sends only compact measurement summaries, never audio. It is not a plugin and requires no DAW or plugin host.
Features
- Loads full multitrack stems and performs mixing (levels, pans, per-track automation) before mastering.
- Automated vocal riding through busy sections and dynamic bass/kick ducking.
- True-peak-limited, LUFS-targeted mastering output.
- Engine Notes panel documents every automated decision and its measured evidence.
- Manual fader/pan adjustments trigger a re-render that holds the loudness target.
- Loudness-matched A/B comparison between versions.
- Optional bring-your-own-key LLM engine (Anthropic, OpenAI, and compatible providers); sends measurement summaries only, never audio.
- Runs fully offline with no account or telemetry.
Pricing and Availability
Available now for $69 as a one-time purchase, with free updates for all 1.x versions and activation on up to three machines. A free demo (full application, exports disabled, periodic audio tag on mastered playback) is available at nomzstudios.com. Requires 64-bit Windows 10 or 11.
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