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Review: iZotope Ozone 9

Major Update Adds Even More Powerful Tools to Mastering Suite

The Master Rebalance module is one of the highlights of Ozone 9 Advanced.

Ozone has always offered powerful processing and a user-friendly interface, allowing it to appeal to both experienced engineers and mastering newbies. With the release of Ozone 9, iZotope keeps that pattern going. It adds three new powerful, yet easy-to-use modules that accomplish complex mastering tasks simply, and features a new and improved Master Assistant, which analyzes your audio and suggests settings.

Ozone comes in Advanced, Standard and Elements versions. When discussing new features in this review, I’ll indicate which are included in the various versions. I did my testing in Ozone Advanced 9.0.2.

As with previous versions, you can run Ozone either as a standalone application or as a plug-in, which iZotope refers to as the Mothership. What’s more, in Ozone 9 Advanced, the assorted modules from the program are available as individual component plug-ins in your DAW, which can be handy for both mastering and mixing.

You can load up to 16 audio files in the standalone version. In addition to applying your processing chain to each one, you can trim the beginning and end of the audio file and add fades. There’s no way to zoom in on the beginning or end to get a close-up look at what you’re trimming, however. Though not imperative, a zoom control would be helpful. Playback is limited to one audio file at a time, so you can’t listen for spacing between songs from Ozone’s GUI.

The Master Assistant (Advanced, Standard, Elements) was added in Ozone 8, and it has been improved in Ozone 9. The basic idea is that it analyzes your music and then, employing its artificial intelligence, figures out a setting for you to use as a starting point.

In Ozone 8, when you clicked on the Master Assistant, it took you to a page entitled, “What are you going for?” which allowed you to choose between Streaming, CD and Reference for calculating your target output level. Reference was based on a reference track that you could upload and Ozone 8 would analyze.

In Ozone 9, your choices have been expanded pretty significantly. Now there are three categories of user options presented on the “What are you going for?” page, and your choices will determine the behavior of the Master Assistant.

First, you can choose Modern or Vintage in the Modules category. Because Ozone has both modern and vintage versions of most of its processors, you can choose which ones the Mastering Assistant will use.

Next, you have two choices to make in the Loudness and EQ section: Manual or Reference. The former lets you choose between three output target levels: Low (–14 LUFS), Medium (–12 LUFS) and High (–11 LUFS). Reference will use the level of a song or other audio file you upload as guidance.

The third category is Destination, where you can pick Streaming or CD, and Ozone will automatically set the correct amount of headroom. Once you’ve made your selections, hit the Next button, then hit Play so that Ozone can do its analysis.

As the music plays, you see an onscreen checklist of actions starting with Analyzing Audio and Analyzing Dynamic Range, Setting Maximizer threshold and more. All told, the list has seven items that check off in real-time as the Assistant finishes with them. The whole process takes maybe 10 seconds, and you’ll hear the effects of the processing as it gets near the end of the list.

The new Master Assistant offers more user-selectable options.

Then you can choose to accept it, or you can change the previous settings and re-run the Assistant. There’s no point in re-running it if you don’t change the settings because the results will be virtually the same every time, given the same song and same settings.

The Master Assistant was quite a useful feature in Ozone 8; in Ozone 9 its expanded user options make the results more customized. The module choices and settings that it comes up with are always usable and often get you most of the way there. Most likely, you’ll still want to do some tweaking to match the specific attributes of your project.

If all you want is a finished-sounding result for sending out a demo, you’ll probably be fine just using the modules and settings provided by the Assistant. Often, if I’m in that situation, I’ll put the Ozone 9 plug-in on my master bus, and I’ll end up with a polished result with correct levels right away.

One of the completely new modules in Ozone 9 is called Master Rebalance (Advanced only). It can take a mixed master and adjust either the vocal, drums or bass levels up or down. It can only change one level at a time.

The GUI for the Master Rebalance module is simplicity itself. First, you click on a Focus instrument, either Drums, Bass or Vocals. Then move the Gain slider (±8 dB) to get it to the level that you want to hear the results in real-time. You also get a frequency display that shows the focus in blue in the foreground and the remaining signal in gray in the background. It’s useful as a visual confirmation of what you’re doing, but you really just need your ears.

Master Rebalance is designed for those situations where you have a project to master and there’s an imbalance on a song, but it’s not feasible to have the mix recalled and adjusted by the mix engineer. In the past, when mastering engineers faced such a situation, it frequently required some serious processing gymnastics and often entailed a compromise because the fix could cause problems with other aspects of the mixed audio.

iZotope has a similar feature in RX7 called Music Rebalance, which allows you to simultaneously adjust four different source types (Bass, Percussion, Vocals and “Other,” which is the remaining signal after the first three sources). Although the RX version has more range and parameter control—it also has Sensitivity sliders for each source type—I found the version in Ozone 9 to be easier to use, mainly because in RX you have to use Preview mode to hear the results, and you get a reduced-quality preview some of the time.

With Ozone’s Master Rebalance, it’s almost as if you’re still mixing. You move a fader, and the level of the source type you selected goes up and down in real-time, seamlessly. I tested it out both on my Mac Pro and on my much slower MacBook Pro, and performance and smooth playback of the feature was the same.

I’ve now tried it out on quite a few different recordings, and I’m really impressed. It is particularly useful on vocals or drums, but the bass setting works pretty well, too. I didn’t hear any degradation of the signal, even when employing extreme boosts or cuts. The algorithms are quite amazing.

I did notice that when I significantly boosted the vocal level, it also pushed up a lead guitar solo that was panned to the center. But overall, Master Rebalance could be a timesaver for experienced mastering engineers and a miracle worker for those who don’t have the experience to address imbalances in a stereo file.


Another addition is the Low End Focus module (Advanced only). It’s designed to make the bottom end of a song more or less punchy and to reduce muddiness. It exclusively processes a user-adjustable low-end frequency range, with a default range of 20 to 250 Hz.

The new Tonal Balance Control 2 includes many more genre choices.

You get two sliders, one labeled Contrast and the other Gain. Contrast can be set to negative or positive values. The former smooths out low-end transients and the latter adds punch. Gain is a makeup gain to compensate for frequencies that are reduced by negative Contrast settings.

You can also choose between two operating modes: Punchy or Smooth. As you might expect, Punchy is designed to be more aggressive and Smooth more subtle.

A Listen button solos the frequency area being processed, which can help you choose the range and adjust the parameters. One of the many notable aspects of Ozone is that, in most of its modules, you have the option to solo just the frequency area or effect parameter you’re working on.

To get a sense of the capabilities of Low End Focus, I recommend that you start by stepping through the included presets, which have names like Clean and Punchy, Center Focus, More Kick, and so forth. They’ll show you right away what the module is capable of.

I would imagine that many experienced mastering engineers will prefer to make their own adjustments to the low frequencies using EQ and dynamics processing, but for everyone else, Low End Focus is an excellent addition for enhancing what’s going on at the bottom end of the audio.

Previous versions of Ozone included a Match EQ function that you could access from inside the Equalizer module, but in version 9, iZotope has added a dedicated Match EQ module (Advanced and Standard). It’s designed to let you quickly capture a frequency spectrum from a reference track of your choice, and then impose that onto your audio, to a greater or lesser degree.

It’s simple to use; you just import a reference file and learn its target spectrum, which only takes a few seconds after you press the Capture button. Then you capture the spectrum for your song, and Ozone automatically replaces some or all of it with the reference. You can use the Amount and Smoothing sliders to increase or decrease the percentage of the reference frequency that gets imposed on your audio.

It’s easier to apply than it was in previous versions and works well for what it is, but it’s not a panacea. Imposing the frequency profile from an amazing-sounding song doesn’t mean your song will then sound just like it. To me, it’s an effect that sometimes can be useful, and I’m certainly happy that iZotope has improved its friendliness by separating it into its own module.

Another useful addition in Ozone 9 is the inclusion of Tonal Balance Control 2 (Advanced only), a new version of the plug-in whose first version was released along with Ozone 8. You can open it in the Ozone module chain using the Plug-In module, which lets you insert outside plug-ins.

It’s designed to let you compare the frequency balance of your audio to that of a reference track or one of the preset categories iZotope has included. There’s no processing involved. It’s just a way to check if the energy of your song in the Low, Low-Mid, High-Mid and High-Frequency categories is within a normal range for a particular musical style. It’s also beneficial at the end of the master bus when you’re mixing.

The first version only had three preset categories—Bass Heavy, Modern and Orchestral—which were useful but lacking in specificity. In Tonal Balance 2, you can choose from 12 genre-related categories, which is a significant improvement. If you can’t find an exact genre match for your song, you can find something close.

Users of Ozone Standard who upgrade to version 9 will be pleased to discover that iZotope has added three modules that were previously only in Ozone Advanced. These include Vintage EQ, Vintage Limiter and Vintage Tape. All three are quality effects that offer more “analog”-sounding processing than their modern counterparts in the Ozone module collection.

With those three Vintage plug-ins added, iZotope upped the maximum number of processors in the Ozone 9 Standard module chain to 12, so you have the capability to insert one of each module type.

Another notable addition for all three Ozone versions is a resizable GUI. Just drag the right corner to make it larger. You can even fill up the whole screen with it if you want. According to iZotope, Ozone 9 offers faster performance than before. I can’t say I noticed that, but Ozone has always operated very smoothly. Also new in all the versions is support for Native Instruments NKS, allowing it to run inside an environment that supports that format.

The latest incarnation of Ozone offers plenty of impressive new features, none more so than Master Rebalance, which makes you scratch your head in wonder and say, “How did they do this?” I also was quite impressed with the revisions of the Master Assistant and Tonal Balance Control.

All three Ozone versions, but particularly Advanced and Standard, have been improved significantly and are well worth an upgrade or an outright purchase. If you can spring for it, go with the Advanced version, as it offers the most comprehensive processing options.


COMPANY: iZotope
PRODUCT: Ozone 9 (Advanced, Standard and Elements)
PRICE: Advanced $399; Standard $199; Elements $99
PROS: Processor collection more comprehensive than ever; Music Rebalance offers impressive and time-saving results; Master Assistant now significantly more customizable; Low End Focus module helpful for shaping bass-frequency content; Match EQ available in its own, easier-to-use module; Ozone GUI can now be significantly resized; Tonal Balance 2 offers many more genre choices; vintage modules included with Standard version; standalone or plug-in operation provides flexibility; most modules offer soloing options for frequency bands or parameter types
CONS: No way to create between-song spacing for CDs; no zoom controls for trim and fade operations