iZotope Ozone 9 Review – The Evolution Of Mastering

Izotope’s flagship mastering software has gone through a couple of iterations since our Ozone 7 review. I took the current version, Ozone 9, through its paces to see how it’s evolved.

Izotope has, over the last several years, put a ton of R&D into the use of AI in their software. I’m aware there are musicians, producers and engineers on different sides of the fence when it comes to AI in music, but that’s definitely a discussion for another time.

What is clear, as time goes on, is that AI is here to stay, and will become more a part of the music production world. Izotope are very much at the forefront of the useful integration of AI in our musical software apps.

I was impressed with my first encounter with the AI in my iZotope Neutron review , where the software assisted in creating a rough start mix to work from. Now seeing it and hearing it in use in a mastering capacity was equally, almost terrifyingly impressive.

In essence, mastering is the very skilled use of EQ and compression to get the absolute best out of the mixed music; removing aural irritations to make it accomodating to the ear, and match with any other tracks (if it’s an EP /Record). Mastering turns a mixed track into a finished piece of music. Over the years the art of mastering has progressed to include a myriad of other tricks and techniques to continually head toward the musical perfection of a finished track. Ozone has a 17 year pedigree, and has steadily improved as a one stop mastering shop, with all the above mentioned elements included for a great mastered track.

Ozone has crammed 16 digital and analog emulated tools into one concise interface, to give you a hot chance of making the mix into a superb piece of music. You can chain the modules in any order you like, or open them as separate plugins. Both modern and vintage EQ’s and compressors, dynamic EQ, Exciter, Stereo imager, spectral shaper, Low end Focus, external plugin module, to name a few!

Ozone 9 – What’s New?

In this version of Ozone the AI has been upgraded. It works in similar ways to the AI in Neutron and Nectar; you instantiate the assistant, select a couple parameters, play the loudest part of the track, and boom, twenty seconds later the assistant gives you what it considers the best version of a mastering chain for the track. Now you can get the assistant in two flavours – modern or vintage. This might seem like a bit of a trifle, but really this was the most powerful thing about Ozone for me. Let me explain.

One of the most useful things for Ozone for me, as an untrained mastering engineer, is that it actually teaches me more about the skill of mastering, rather than doing it for me. Clicking between modern and vintage parameters for example, gives a very different sounding product. It opens up new ideas for me as to how to shape the finished mix to create a certain sound. I learned how that happens by observing where the AI placed modules in the chain, how it used them, and so on. I’ve definitely learned skills in my own mastering process that I can apply from here on due to seeing what the AI did.

Invariably, as with the other AI, and indeed many of the presets from Izotope, I found the suggestions made by the assistant to be over the top, and I needed to pull back or tweak the parameters heavily to get to a place I was pleased with. But, disclaimer, it always claims to just be a starting place, from where to tweak. So in that sense, it nailed it.

The machine learning algorithm has also expanded in the creation of two new modules; low end focus and master rebalance. These are also excellent when used in moderation. Low end focus I’ll chat about later. Master rebalance intelligently picks out the vocal, bass, or drum sounds from amongst the mix, and enables a rebalance of those elements within the master track, as if re-mixing slightly. Does the client suddenly want a radio version of the track with vocals up a bit? You can adjust the gain of the vocal here, and remarkably, it does it with little to no artifacts. Incredible.

Highlights for me

When I used Ozone 9 for a couple of mastering projects, the standout tools for me were these:

Tonal Balance Control 2

This has become one of my most treasured imaging and reference tools. You can visually see how the energy in four different freq bands compares to the average energy of over 10 different genres of music. If any ranges are just too much or too little, you’ll see immediately. And you can address the issues directly from the tonal balance window, as it links to any EQ you have open in the Ozone plugin. So if you see a dip in the 400Hz range, you can open up an EQ below it, and bump up a little, to see if that smooths it out. I absolutely loved this tool once I was getting near the end of the process, to see how my track stacked up against an average.

Low End Focus

Working with bass on a master takes monumental skill. EQ and Compression can quickly wreck the low end image, and give you a lot worse sound than the original. I’m not a highly skilled mastering engineer, so the Low End Focus module is almost worth the cost of admission by itself. It’s a spectral plugin, assessing the most important frequency elements of the low end, and gradually clearing out the less important ones, to give more clarity and punch down there. It’s easy to overuse, as with anything in mastering, but wow did it give some impressive results, making kicks and basses stand up in the mix a little more, or gluing them together better and getting a stronger center punch. I was really impressed with this plugin.


Module presets

Not only can you load up a master preset for a specific genre, instrument, or buss, but you can load up specific presets for each module. This I found super useful in learning the capabilities of each module, more so than RTFMing! Using the new modules like low end focus, with presets like center glue, consistent sub, center extraction – I could figure out how the few controls could be tweaked to get me certain sounds. I really enjoyed learning about the spectral shaper module here – it’s a really powerful tool that you can use on a specific instrument within the track. Evening out the snare hits, for example, is something that can be accomplished with this module.

Reference Tracks

Reference tracks are essential for mix and master. However good your ears are, your client might want something that’s slightly different tonally to your preferences. So having reference material from them is massively useful to ending up with a sound the client likes. I Previously used a different plugin for this, but the reference section in Ozone 9 is developed enough to be everything I need. Alongside being able to load several tracks, you can define sections of each track to be played/compared. To take the referencing to the nth degree, you can use the match EQ module directly with the reference files, ensuring tonal similarities with those of the references with this 8000 band matching EQ. Incredible!

Maximiser with dithering

The maximizer is a limiter with added options. The limiting is transparent, and you can select different flavours of limiting with different character. I liked the ability to emphasize transients before limiting occurs. Limiting can sometimes squash transients enough to take the punch out of, say, drums. Altering the transients here can alleviate that.

I particularly liked the ‘learn threshold’ function. This sets up the limiter to output a certain LUFS depending on the platform you’re looking at publishing on (-14LUFS is slowly becoming standard it seems)


Ozone continues to evolve with the addition of more useful tools. At this point they’re still keeping the bloating that can arise from adding more and more per upgrade, by keeping the GUI super clean, easy to glance and understand what’s going on, and by keeping useful but non-essential elements off the main window.

Of course, Ozone doesn’t have to be used just as a mastering plugin, and can be utilised in mix capacity too. But it truly shines as a mastering one-stop-shop. If you’re producing your own music and are looking for something that will kickstart your mastering skills, but remain a useful and powerful tool as you grow in experience and knowledge, then I would say Ozone 9 has no competition out there.

Ozone 9 comes in three different versions with varying amounts of utility. This review is based on the advanced edition.

Elements is a great place to start your mastering process, at $29. Standard is $249, and Advanced is $499. Upgrades from other editions is available on your account.

More info here 

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