by FRANCIS PREVE
ONCE UPON A TIME (OKAY, IT WAS 1998), A SMALL
U&I Software created a revolutionary virtual instrument called MetaSynth.
Saying that MetaSynth was ahead of its time is a little like saying that Nikola
Tesla had some forward-thinking ideas. Any sound, however complex, can
be thought of as a stack of sine waves at different frequencies and volumes.
MetaSynth—which is still in production—could resynthesize any sound into a
editable Fourier transform of this stack, which gave sound designers the
manipulate audio at what felt like the Higgs boson level. The problem with it
these processes were neither truly realtime nor available as a playable plug-in
instrument. So when iZotope recently announced Iris—a realtime plug-in soft
delivers some of MetaSynth’s power, but with an even more approachable
additive resynthesis cultists rejoiced.
|Familiar synth staples like a ﬁlter, envelopes, and effects are on hand as well.
How It Works
The essential principles of Iris are immediately
intuitive. When an audio file is imported into
Iris’ sampler-like environment, its frequencies
are analyzed and displayed visually as a graphic
pattern, with the vertical axis representing pitch,
the horizontal axis representing time, and the
brightness of the multicolored pattern components representing the volume of
From there, you can process and affect the sound by painting on the graphic,
or exposing specific regions of the sound’s
For example, using the paintbrush tool, you
can highlight certain harmonic components of a
sample, making them audible. Paint at the bottom and you’ll hear the lower
at the top of the image and you’ll hear the high-
frequency components. Paint a wide swath from
the upper left corner to the lower right, and the
result is reminiscent of a lowpass or bandpass
filter envelope decaying over time. That’s just the
easy stuff. There’s also a “magic wand” tool that
selects contiguous areas of the image, based on
their brightness and proximity to each other.
Other tools include rectangular selectors for ex-
posing “blocks” of audio, and of course, an erase
tool for refining your audio selections.
In practice, Iris functions as a three-layer
sampler, with an extra “sub” layer that offers
preset selections for classic synth waveforms like
sine, saw, square, pulse, and a few noise options.
As with the samples, you can use the painting
tools to refine frequencies in truly unique ways,
delivering exotic animation that would be nearly
impossible to achieve via filters and LFOs alone.
While each of Iris’ audio layers function
similarly to a sampler, there’s no true multisampling, so what you get is the
source mapped across the entire keyboard
range. Granted, you can split the key ranges for
each of the three layers to get an approximation of multiple key zones. That
said, this isn’t
really a drawback, since Iris’ forte is abstract
soundscapes that you can’t achieve using other
Even so, Iris does have some nifty sampling
tricks up its sleeve, like a choice between straight
resampling and iZotope’s Radius RT time-stretching algorithm, which preserves
the timing of the
original sample while the keyboard changes the
pitch as you play. There’s also a fixed mode that
makes the sample play back at a specified pitch
regardless of what key you play.
As for traditional synthesis tools, Iris is loaded
with all of the essentials. Each layer has its own
ADSR envelope and a multi-wave LFO that can
be assigned to pitch, volume, or pan. Of course,
there’s also individual volume and panning to
fi ne-tune the mix of elements.
Globally, there’s a multimode filter, which is applied to all four
layers as a whole. iZotope didn’t
skimp here either, offering vintage filter modes
for each, including a nice TB-303 model and a few
saturated and screaming bandpass options.
Rounding out the whole package, Iris includes an array of four
simultaneous effects—distortion, chorus, delay and reverb—which can be
applied to the master outs or used as individual
sends on each layer. All effects are quality implementations, but the
distortion is especially flexible, with six different types ranging from a warm
tube emulation to nasty saturation.
A macro section lets you control multiple,
linked parameters from up to eight knobs a la
Ableton Live, and there’s also an X/Y pad. While
there’s a selection of presets that do clever tricks,
you can create your own assignments by right-
clicking on desired parameters. This is incredible for crazy morphing effects
Iris comes with a 4GB sample library to get
you up and running, and the majority of the
material really demonstrates the power of this
synth. There are also two a la carte libraries of
samples derived from glass and wood Foley-style recordings like marbles,
slams, and firewood—all transformed into
ethereal, sometimes eerie, sometimes majestic
soundscapes. A package including the glass and
wood libraries plus Iris itself adds $50 to the
With a synth this intuitive, the real fun comes
from rolling your own material, either by running
around with a microphone or dusting off a musty
old sample library and breathing new life into it.
Since, as mentioned, sound itself is based on multiple sine waves, you can drop
into an Iris layer, let the synth commence its
resampling magic—which includes detecting the
inherent key of the material—and then paint the
audio into something truly unique. Even a single
layer can leave your listeners wondering, “How
the heck was that sound created?”
When you start layering two or more samples
and maybe folding in a classic wave for support,
Iris truly comes to life. To demonstrate how in-
sanely powerful Iris can be, I created two audio
examples for this review. The first one is based
on a loop of me saying “Keyboard magazine” that
morphs into a powerful electro/dubstep bass line
and then a glistening soundscape. The growling
bass effect is derived by shaving off the high frequencies with an undulating
painting, which was
then processed further using Iris’ distortion.
The second example is derived from a short
Foley sample of a ship at sea that morphs into an
ethereal ambience that really must be heard to
be appreciated. I began by painting the lower frequencies first, then adding an
upper frequency sweep.
From there I added a paint-processed square wave,
then some filtering, then stereo delay and reverb. Each
step of the morphing process is clearly audible.
As with any 1.0 release, I encountered a few
unrepeatable glitches, including a moment where
the UI stopped responding and needed a reboot
(I’d been saving as I went along, so I recovered my
work quickly). For the most part, though, Iris was
quite stable and totally fluid.
Additionally, the MetaSynth lover in me was
yearning for two wish list features: the ability to
import image files into the resynthesis engine
(for recreating classic Aphex Twin-style effects)
and a broader array of image editing tools, but
give me a yard and I’ll beg for a mile—Iris is still
the most intuitive and unique synth for this type
of Fourier work, by far.
When it comes to soft synths, I’ve used them
all, and the only ones that make it into my daily
workflow are those that deliver results that I
simply can’t get from my analog and modular
gear. Ableton Operator and Collision, Native Instruments Komplete, and Korg’s Digital Legacy
collection are mainstays. What can I say? I like
synths with personality, which Iris has for days.
In fact, the first night I used Iris, I created the
foundation for an ethereal, melancholy progressive track. Iris is pure
inspiration from the moment you drop it into a track. If you’re a synthesist
who’s constantly prowling for revolutionary
methods of sound design and who makes a point
of avoiding me-too patches, then Iris will deliver
mind-melting results. For $249, this kind of innovation is clearly a Key Buy.
PROS Additive Fourier
resynthesis with a graphic
interface anyone can
understand. Collection of
unique and powerful ﬁlters.
Quality effects. Macro
options that make realtime
morphing easy to automate.
CONS Somewhat CPU-
intensive when using
Radius RT time-stretching
An amazing new treasure chest
of sonic possibilities that you
can manipulate with graphical,
$249 list | $199 street