German developer VirSyn first introduced Cube as a VST plug-in way back in 2003, so its revival as an iPad app is a pleasant surprise. While their earlier iPad app, Addictive Synth, relied on a combination of dual additive oscillators and a pair of extremely complex and flexible filters, Cube takes that concept and doubles down on its complexity by adding two more oscillator-filter pairs and an innovative approach to sonic morphing.
PROS: Deep additive synthesis engine allows four-way morphing between harmonic spectra. Direct editing of up to 512 partials for all four sources. 64-stage envelopes. Extensive arpeggiation options. Great performance, even on first-generation iPad.
CONS: Extensive synthesis tools may be daunting for new users.
Bottom Line: Mercedes S-class additive synthesis for your iPad.
$9.99 introductory | $19.99 full |virsyn.net
Cube offers vector control over four discrete additive oscillators, each with its own user-definable filter. The essential concept is fairly straightforward: Users can specify the harmonic spectra, with up to 512 partials each, for four tone generators. From there, they can apply a custom filter to each generator, as well as specify attack and decay states for the harmonic spectra, along with panning for each harmonic—and that’s just the starting point for a sound.
What’s more, VirSyn’s approach to these filters goes far beyond the usual four multi-mode options, allowing users to draw highly complex curves that have more in common with parametric EQ than the usual lowpass and highpass fare. In conjunction with the ability to precisely control the additive spectra, these filters are capable of truly otherworldly effects.
These tools alone would make for a stellar iOS synth, but VirSyn didn’t stop there. Instead, they added a slew of modulation features for animating the four tone generators via an X/Y axis. In addition to three envelopes, each with up to 64 stages (!), Cube’s spectral morphing axis can be further manipulated via a variety of CoreMIDI options including velocity, aftertouch, modulation wheel, breath controllers, and expression pedals. This adds up to some serious playability for an iPad synth.
In addition to these synthesis tools, Cube is fully stocked in the effects department. Each patch can be further processed via up to seven effects, including EQ, phaser, delay, overdrive, ensemble, chorus, and reverb. These processors go a long way toward adding richness and depth to the digital character of additive synthesis, and even on an original iPad, the CPU hit was negligible.
Rounding out the package is an extremely flexible arpeggiator that blurs the line between step sequencing and arpeggiation in clever and useful ways. As for talking to the rest of the iOS world, Cube is Audiobus-compatible and includes a recorder for exporting audio to the desktop, clipboard, or SoundCloud.
Cube’s approach to additive synthesis is extremely deep, especially for an iPad app, but that’s anything but a complaint. That said, making the most of a synth this complex requires significantly more dedication than does tackling another me-too virtual analog app. If you want your collection of iPad synths to have some serious sonic range, Cube delivers exactly that, in abundance.