This is a six-oscillator synth based around dynamic wavetable synthesis. It draws upon additive technologies as well as VirSyn's familiar partial and spectral displays.
The app's functions are spread across a total of three pages: Wave, Control and Arp. Tapping to the Wave section reveals the partials of Waves I or II or the spectral curve of Filters I or II, depending on which you have selected. You can also draw individual partials (harmonics) in the display to create your own waveforms, which are then shuttled through the dual filters.
The filters are the coolest thing in this section. Rather than saddle you with a single resonance knob, you can draw in as many resonance peaks as you like.
Better still, you can morph between the filters either manually or using one of the available modulation sources. It's important to understand that each of the filters is tied to a specific wave. So, Filter I is always assigned to Wave I, and Filter II is always assigned to Wave II. This means that when you morph, you're morphing the whole lot.
The Control page provides a quartet of syncable LFOs, four envelope generators and control over the keyboard. An X/Y pad and the iPad's tilt axis are offered as mod sources, too. Modulation can be applied to filter cutoff, morphing, pitch and amplitude.
The arpeggiator is a full-blown analogue-style sequencer, complete with a 32-step grid for tapping in notes, octave values, accents and ties. We were pleasantly surprised by the results the random 'dice' provided here - virtually everything it churned up was musically useful.
Addictive Synth may be as habit-forming as the name suggests. Its sound quality is excellent and the interface is a joy to use.
It excels at digital tones, spectral pads and other atmospheric noises, but is equally useful for hard-hitting basses or in-your-face leads. In all, a good buy.