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!
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.
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.
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.
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.
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'