An Overview of iZotope IRIS 2

iZotope's Iris 2 continues to reap the rewards of its spectral processing abilities and now also has a powerful new modulation system, enhanced effects and over 11 GB of content.  

There are an awful lot of virtual synths and samplers out there these days, and they all share many of the same features and options, each bringing its own specific twist to the art of sound creation. But every once in a while, a synth comes along that offers something truly different—iZotope's Iris 2 is a perfect example!

iZotope's Iris 2

Fig 1 iZotope's Iris 2.

Not long ago, iZotope incorporated their powerful Spectral Processing feature—from their audio repair software, RX—as the Spectral Filter in the original Iris synthesizer. Now, Iris 2 continues the evolution of that synth with a host of new features and enhancements, including a powerful new Modulation system, enhanced Effects, and new content that totals 11 GB in all. Of course, the centerpiece is still the Spectral Filter, which allows for an unprecedented degree of flexibility in audio tweakery and sound design. Iris 2 also incorporates iZotope's Radius RT pitch-shifting algorithm. Let's take a brief look at some of the key features.

All Mod Cons

The new Modulation system brings a very high degree of flexibility to programming sounds in Iris 2. Many synths & samplers offer a Modulation Matrix, often implemented as a set of text boxes that allows the assignment of various controllers—internal & external—to various parameters. But often, the total number of modulation routings is limited, and while this is probably fine for basic patches, it doesn't provide as much flexibility for more complex setups as, say, a classic modular synth would have. Iris 2's take on the Modulation Matrix concept offers up to three Modulators for almost every parameter—the three circles adjacent to each modulatable parameter. The assignments are made right there at the parameter itself, either by local menu or drag & drop (Fig 2). 

Fig 2 Modulation assignment in Iris 2.

Fig 2 Modulation assignment in Iris 2.

iZotope has incorporated a clever visual scheme to show & set the range (depth) of Modulation. Three color-coded rings surround each parameter, and these change as you tweak the Modulation depth from the mod assignment circle. Not only do you get a clear indication of the affected range, but as you play, the current position of the parameter is also indicated (Fig 2). This makes it a breeze to set the appropriate amount of modulation, especially when multiple Mod sources are applied to the same parameter. There are also user options for determining how multiple Mod sources will interact, when applied to the same parameter, something that's often pre-determined in many synths. 

Spectral Action

Of course, Iris 2's main event is the Spectral Filter. Using graphic tools—probably familiar from Photoshop and other image-editing software—the Spectral Filter lets you select (or remove) specific elements of a complex wave, for a degree of control that traditional Filters can only dream about. The Spectrogram display shows the individual harmonics and overtones of a wave—the horizontal white bars—over time. You can see how the spectral content  changes, as in Fig 3. Non-tonal elements of a sound—noise components—show up as fuzzier sections. 

Fig 3 The Spectrogram display—harmonic and non-harmonic content in a wave.

Fig 3 The Spectrogram display—harmonic and non-harmonic content in a wave.

With the various tools, you can isolate the individual sine wave components, both horizontally (for consistent timbral changes) or vertically (for rhythmic effects). You can even draw in complex selections with the lasso & brush tools. Fig 4A shows a selection that would be similar to combined lowpass & highpass filters opening up with a slow attack. Fig 4B illustrates much more complex, shifting tonal variations. There's virtually no limit to how you can modify complex waves (like the 11 GB collection provided, or your own samples)—even random drawing on a wave can provide interesting sounds and ideas.

Fig 4 A) A simple Spectral Filtering selection; B) a complex selection for shifting, rhythmic tonal variations.

Fig 4 A) A simple Spectral Filtering selection; B) a complex selection for shifting, rhythmic tonal variations.

A Brief Mastery of Time

Spectral Filter selections, like the internal envelopes (attack, decay) of a sound wave, will speed up or slow down as you transpose (play different notes across the keyboard). With unprocessed samples, this produces the familiar “chipmunk”effect; with Spectral-Filtered sounds, the timing of any Spectral Filtering shapes will also change from high to low notes. To provide more control over this, iZotope incorporated their Radius RT pitch-shifting algorithm, which preserves the timing of any time-based elements of a sound, when it's transposed. Although it's fairly CPU-intensive, Radius RT will let you play rhythmic loops at different pitches without the internal Tempo of the loops changing, and it will preserve the timing of any time-based Spectral-Filter selections you make, so high and low notes can play with, say, the same Spectral envelope attack time, from any note on the keyboard.

Iris 2—Sonic Fusion Explored

With the changes and enhancements, working in Iris 2 is now easier and more efficient than ever, once you've mastered the interface and feature set. To help with that, we've come up with a brand-new course to cover the brand new version of this deep and powerful instrument. iZotope Iris 2—Sonic Fusion Explored takes you through the synth from the ground up—there's even a brief primer on the architecture of subtractive synthesis, which forms the starting point for Iris 2's design. 

Fig 5 Iris 2's underlying subtractive synthesis layout.

Fig 5 Iris 2's underlying subtractive synthesis layout.  

The course first takes a look at Iris 2's take on the traditional elements of synthesis—including the 4 Sample Pools, that let you combine and map out a sound source of samples and oscillator waves, and the Global multi-mode Filter, which models a number of classic analog Filter circuits. The 5 Envelope Generators, and 5 LFOs—with their comprehensive collection of waveshapes—are explored, and basic patches are constructed, to introduce the workflow. 

The new Modulation system is covered in detail, as are the 4 effects—Distortion, Chorus, Delay, and Reverb—along with the keyboard mapping function, and more patches are created to show these aspects of the instrument in action. The Spectral Filter is, naturally, given a thorough run-through—with a little background on the nature of spectral processing, which the course provides, you'll be able to more efficiently target the sounds you want. Spectral Filtering for both instrument and sound design applications is covered, with examples.

Radius RT is explained and demoed, and to round things out, there's a comprehensive look at Iris 2's options for MIDI/keyboard control—its Global MIDI Assign function, as well as the Per-Patch assignment of keyboard controls, and the 8 Macro assignments, all of which make Iris 2 an exceptionally responsive instrument for live performance. The course wraps up with some practical considerations for sound library/sample management.

Fig 6 Macro and Global MIDI Assignments in Iris 2.

Fig 6 Macro and Global MIDI Assignments in Iris 2.

Iris 2, while it presents a traditional, accessible layout, is an instrument with some truly unique and powerful features on board, and Iris 2—Sonic Fusion Explored is designed to help anyone, from synth novice to mad scientist, tap into its creative potential. So give Iris 2, and this course, a look—you won't be sorry!

Here's a video tutorial on shaping sounds from the complete course:

Watch the whole course:

Joe is a musician, engineer, and producer in NYC. Over the years, as a small studio operator and freelance engineer, he's made recordings of all types from music & album production to v/o & post. He's also taught all aspects of recording and music technology at several NY audio schools, and has been writing articles for Recording magaz... Read More


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