I’ve been working with Ozone for what feels like an eternity – it has been my go-to mastering suite for well over a decade. Hardly any other plugin family has accompanied me so consistently through my career as a sound designer. I already took a deep dive into Ozone 11 (you can still find that Ozone 11 review here) , and even back then, I was impressed with how much it streamlined my workflow. Over the years, I’ve also stayed in close contact with professional mastering engineers, exchanging thoughts and learning from their daily experience.

This review, therefore, also reflects input from people who master music full‑time, to ensure a balanced and accurate perspective. But Ozone 12 takes things to a completely new level. It’s not just small refinements; it genuinely changes how I work with a master.

Mastering is not about making a track simply louder – it’s about making it translate to the outside world. Ozone 12’s new tools are built exactly for that, ensuring that a mix keeps its vibe even on small phone speakers or cheap earbuds.

What’s new in iZotope Ozone 12?

Master Assistant: Custom Flow

One of the most important upgrades in Ozone 12 is the completely reworked Master Assistant. It now offers two modes: Automaster and Custom Flow. Automaster works like the familiar “one-click” solution from Ozone 11, but Custom Flow is where the real progress happens.

In Ozone 11 the Assistant was often too heavy-handed: limited user input, a tendency to over-compress, widen too aggressively, and brighten the mix to the point where I had to undo half of what it did. With Ozone 12, this problem is finally addressed.

Custom Flow allows me to decide beforehand which modules should be active, define a target loudness in LUFS, pick from expanded genre references, set the overall processing intensity (from subtle to transformative), enable True Peak limiting, and even extend the analysis time up to 60 seconds. This gives you a much better handle on the process right from the start. There are many dynamic musical styles, and Ozone can now analyze both verses and choruses. This was simply not possible in the previous version. So the new analysis time is a huge improvement.

One of the biggest strengths of Custom Flow is that it lets you choose between subtle and transformative processing – a flexibility that reflects how mastering engineers deal with very different client expectations.

The difference is obvious: instead of a dense, over-processed proposal like Ozone 11 often produced, you now get an intuitive, balanced starting point that already feels closer to the artistic vision. Professional mastering engineers I’ve spoken with share the same impression – the results are more natural, less destructive, and require far fewer corrections.

So Custom Flow turns the Assistant into a genuine collaborator rather than a correction you have to fight. It saves time, avoids over-compression, and makes Ozone 12 much more intuitive compared to its predecessor.

IRC 5: louder without the pumping

The new IRC 5 mode in Ozone 12’s Maximizer is the most significant upgrade since iZotope introduced modern limiter algorithms. In Ozone 11 the limiter often felt heavy-handed: transients got shaved, the stereo field widened unnaturally, and once you pushed loudness harder, the whole mix started to breathe in a distracting way.

IRC 5 changes that completely. It behaves more like a multiband limiter, targeting only the parts of the spectrum that actually need control. That means the kick keeps its punch, the snare retains its snap, and the low end doesn’t collapse just because the top end is busy. At the same LUFS, the amount of audible pumping is drastically reduced, so you can reach competitive loudness with much less compromise.

For club-oriented techno, dub or any style that demands both volume and clarity, this is a breakthrough. IRC 5 finally lets you push into that extra dB or two of loudness without crossing the line into distortion or flatness – something Ozone 11 could rarely achieve.

Stem EQ: real stem work on a stereo file

Stem EQ is genuinely revolutionary. It separates a stereo master into vocals, drums, bass, and “other” using modern machine-learning stem separation, then offers independent EQ for each category. That alone sets a new standard – being able to boost a buried vocal by a couple of dB, tame a harsh hi-hat, or clean up low-mid muddiness without returning to the mix session is something that simply wasn’t possible before.

What’s particularly impressive is how clean it sounds. While soloing may reveal some artifacts, within the full mix, the result is astonishingly transparent. Of course, fixing issues at the mix stage is still ideal, but when mastering engineers only have stereo files, providing proper stem masters is more expensive for clients and is not always done. With Stem EQ, Ozone 12 offers a powerful, cost-effective workaround that streamlines the workflow in ways that were previously unreachable.

Ozone has clearly reset expectations here: Stem EQ is not just useful, it’s a game-changer for real-world mastering scenarios. It feels like EQing in another dimension – similar to what Eventide’s SplitEQ did for transient vs. tonal shaping, but now applied to stems inside a stereo file. This feature simply blew me away.

Bass Control: translating the low end

The Bass Control module in Ozone 12 is a genuine step forward because it takes the guesswork out of the most difficult part of mastering: the low end. Instead of juggling EQ curves and compressors until the subs “feel right,” you now get clear visual feedback with Balance and Punch meters that show exactly where your bass energy sits compared to proven reference targets.

Beyond that, Bass Control lets you directly sculpt how the low end behaves over time. Punch shapes the transient attack of kicks and bass, Sustain Power adjusts the body and decay, while Peak Control keeps stray spikes under control – either transparently in clean mode or with a touch of grit in dirty mode. There’s also an option to add subtle harmonics, making the bass audible even on small speakers where true sub frequencies disappear.

In practice, it means you can dial in just a few dB of change and immediately hear how the kick and bass translate better across headphones, cars, and club systems. For electronic music, it ensures that weight and impact survive on big systems, but the module is just as useful in rock, pop, or acoustic tracks where uncontrolled low end can quickly swamp the mix.

It’s faster, more consistent, and more reliable than trying to manage the low end with traditional tools alone – and for many engineers, it sets a new benchmark in how low frequencies can be mastered.

Bass Control already feels like a lifesaver for problematic low end, though I sometimes wish it allowed negative sustain adjustments – since many mixes suffer from overly long bass decays. Even without that, it sets a new benchmark for mastering low frequencies.

Unlimiter: restoring dynamics

I often hear from mastering engineers that they receive mixes already pushed far too hard – over-compressed, clipped, sometimes almost lifeless. And in those situations, Ozone 12’s new Unlimiter comes at exactly the right time. It can bring back a sense of dynamics and transient punch, essentially reviving material that might otherwise feel “flat.” It won’t erase distortion baked into the file, but it can make a squashed premaster workable again. For many engineers, this feature can be the difference between a frustrating job and a successful master.

That said, Unlimiter is not a magic fix – in practice, it feels more like a subtle transient restorer than a dramatic repair tool. It helps, but don’t expect miracles. Nevertheless, it must be said that there is currently nothing comparable.

Why Ozone 12 beats the competition

Alternatives like Softube Flow can certainly deliver good-sounding results, but they require much more effort and experience to get there. The reason is simple: Flow relies on presets created by professional mastering engineers. While these presets can be valuable starting points, they are not AI-driven and therefore not tailored to each individual track. As a result, they often need heavy adjustment to fit a given mix.

Ozone 12, on the other hand, analyzes the source material directly and generates a processing chain that adapts to the specific song. And the new Custom Flow, in particular, lets you influence your own individual ideas for the final master right from the start. This makes the initial result more relevant and usable straight away, without the trial and error of bending a generic preset into place.

A seasoned mastering engineer with years of experience can certainly achieve professional results with Softube Flow. But Ozone 12 is not just a shortcut for less experienced producers – it’s also a trusted tool in professional studios worldwide. That combination of AI analysis, flexibility, and usability gives it a clear edge. And with unique features like Stem EQ and Bass Control, Ozone offers possibilities that simply don’t exist in Softube Flow.

Editions and Pricing

• Elements – Entry-level with core tools and Assistant.
• Standard – Adds IRC 5 and Bass Control.
• Advanced – Full arsenal including Stem EQ and Unlimiter, plus component plugins.

At the time of writing, Advanced retails for €549, Standard for €239, and Elements for €59.

Final Verdict

All things considered, Ozone 12 proves itself as a mastering suite that works for beginners, advanced producers, and professionals alike. The AI-driven Master Assistant is more reliable than ever, and with the new Custom Flow you finally get real influence over the process: deciding which modules are used, how intense the processing should be, and how closely the result matches your intent. This makes every master feel more personal and less like a generic preset.

What excites me most are the new modules. The IRC-5 mode in the Maximizer lets me reach competitive loudness without the pumping and artifacts that were common in Ozone 11 – a massive improvement. And the Stem EQ is simply unique: being able to refine vocals, drums, or bass inside a stereo file changes what’s possible in real-world mastering. Combined with the flexibility of Bass Control and the safety net of Unlimiter, Ozone 12 covers situations no other suite handles this smoothly.

Even subtle EQ moves can feel like lifting a blanket off your mix – one of those small but crucial touches that makes a track sit naturally alongside commercial releases.

Looking back, my projects have consistently grown in quality with each Ozone release, but version 12 delivers the biggest leap so far. Beyond technical improvements, it has sparked new creativity and made shaping music faster and more intuitive.

For me, Ozone 12 is not just another update – it is the most complete and musical mastering software available right now. And it clearly deserves the Sounds of Revolution Award.

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Cheers,
Oliver Schmitt aka Sounds of Revolution (SOR)