iZotope Iris 2 reviewed

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When I first reviewed Iris in 2012, it was love at first sight. Iris offered a fresh approach to synthesis that allowed users to “paint” directly into a sample’s spectral data, delivering wholly unique results unlike any hardware or software synth I knew of. Now, Iris 2 retains all of the original’s graphical editing functions, while expanding subtractive synthesis functions and vastly improving the modulation options. What’s more, Iris 2’s user interface is much more intuitive than its predecessor, with every function available from a single window. Let’s find out more.

Each sound in Iris 2 can consist of up to four samples (each with its own spectral editor) that can be layered, mixed, and/or split across the keyboard. The combined output of these sample engines feeds a resonant filter that offers 17 different modes. Four effects, consisting of distortion, chorus, delay and reverb, can be applied to the samples--either after the filter or via individual sends for each of the samples. Modulation includes five envelopes, five LFOs, eight macros, and a few MIDI performance control options. Combined with an 11GB library of samples ranging from Foley effects to samples of vintage gear, the whole package is amazingly versatile, despite its unusual underpinnings.

Sample Engines

Each of Iris 2’s sample layers is identical. While Iris 1 had three layers and an analog-style oscillator, Iris 2 now has four sample-based engines and no oscillator (which is offset by a huge collection of sampled analog oscillators, to be clear). Every sample includes its own visual frequency editor, which is based on iZotope’s RX spectrogram technology. When a sample is first imported, its waveform data is analyzed and displayed in FFT format. From there, graphic design tools like paintbrushes, rectangular and lasso selection tools, and a “magic wand” that intelligently selects harmonics and related frequency groups, allow users to manipulate complex spectral data directly with immediately audible results. For example, painting in the upper area of the spectral display exposes the high frequencies, while applying those tools to the lower region exposes the bass content of a sample. The horizontal axis correlates with the sample’s timeline, so if you paint a bunch of evenly spaced dots from left to right, you’ll get rhythmic results.

The coolest aspect of this approach is its immediacy and intuitiveness. If you take a sample of ocean waves, wind, or other natural ambiences, then paint freehand over it, the result will be an ethereal, evolving soundscape that would be nearly impossible to create using traditional synthesis tools. On the other hand, if you carve out a narrow block through the middle of the sample from start to finish, you’ll get a bandpass effect.

Each of the samples also includes the usual looping functions (forward, back and forth, and the like) as well as being able to operate on one of three modes. Fixed mode plays back the sample with the same pitch, while resample mode functions much like a traditional sampler with the expected keyboard tracking. “Radius RT” mode takes things in a more modern direction, keeping the timing of the original sample while allowing keys to change the pitch. Granted, this mode is much more CPU-intensive, but for certain kinds of rhythmic patches, the results are truly impressive.

The mixing tools for the four sample engines are what make Iris 2 so sonically compelling (see image at left). Each sample includes tuning, gain, and pan controls, as well the option of applying any of Iris’ four pre-filter send effects. You can also restrict the range of each of the samples to specific areas of the keyboard. Since there are only four samples to work with, Iris 2 can’t really perform traditional multisampling functions, so it’s better to think of this feature as a four-way split-and-layered keyboard. Even so, it allows for some really creative sound design effects, like enhancing the bass of a patch by adding a sine wave to the lowest octaves and gently mixing it in—or blending the highest frequencies of an air jet to the top octaves.

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Synthesis Tools

While the sample engines include only minor changes to the original Iris feature set, the subtractive synthesis tools have been completely revamped in major ways. For starters, there are now 17 filter modes (compared to ten in version 1). These include two formant types and a selection of lowpass, highpass, and bandpass responses that are modeled after “New York” and “Tokyo” filters. These new modes really add a lot more flexibility and keep Iris competitive in this area.

What’s more, the modulation tools have been completely redesigned. In the original version, each sample had its own dedicated amp envelope and LFO with pan, volume and pitch options (along with a filter envelope and additional global LFO). In Iris 2, the envelopes and LFOs are now freely assignable to almost every synthesis parameter, as well as every effect parameter. And since every parameter can accept up to three simultaneous inputs, this results in much deeper and complex sound design possibilities.

In addition, the LFOs and envelopes have been updated. For example, the LFOs now include 26 waveform options. Some of these new waveforms are downright bizarre, like “pyramid” and “pinch.” Making the new waves even more useful is Iris 2’s ability to warp and twist the waveforms in real-time, with modulation inputs, to boot. For example, you can use LFO 2 to modulate the shape of LFO 1, then modulate its depth with velocity and send the result to a formant filter’s cutoff, or the both of the stereo delay times in different amounts, or all three destinations. Because, why not?

Best of all, all of the modulation resources can be applied via drag-and-drop methods, much like NI Massive or Xfer Records Serum. And if you don’t like the results or want to modify the results further, you can switch to right-clicking for a slightly different approach.

The only snag is that given all the new modulation features, iZotope had to sacrifice direct backward compatibility with version 1. This is unusual as soft synths go, and likely to be frustrating for power users with large collections of original material. Not all is lost, though. If you have mission-critical needs for the Iris 1, both versions can peacefully co-exist on your drive. At the NAMM Show there was talk of iZotope releasing a converter app in the near future, but as of this writing, it hasn’t arrived.


Every one of Iris 2’s new features is a meaningful improvement over the original. While I’ve heard some longtime users grumble that they wish there was more focus on iZotope’s spectral tools, you can’t have everything. Frankly, I’m most impressed by the fact that iZotope is committed to developing one of the most exotic yet enjoyable soft synths on the market. If you’re already a fan of Iris (and the compatibility issues aren’t a deal-breaker), then the upgrade is well worth it. And if you haven’t yet experienced the power of Iris, now is the time to give its demo version a much closer look. There’s really nothing else out there like it.


Innovative sample editing tools allow users to draw spectral data directly onto each sample. Broad array of new filter modes. New interface is keeps all synthesis and modulation tools in a single window. Large 11GB library of useful sample data.


Not 100% compatible with Iris 1 patches, which require a separate conversion app. Radius RT playback mode is CPU-hungry. Multisampling is limited to four key ranges.

Bottom Line

A one-of-a-kind soft synth that excels at exotic sound design.
$299 list | $249 street | $99 upgrade from Iris 1 | izotope.com