Following its excellent Argon monosynth and Xenon groove workstation, iceGear's Cassini is an analogue-style polysynth for iPhone that manages to pack a serious amount of programmability into its multiscreen interface.
Three oscillators and a sub-oscillator form the foundation of Cassini's sound. FM, oscillator sync and ring modulation can all be applied, and each oscillator's Shape control enables a degree of waveshaping, the exact effect of which is dependent on the currently selected waveform (PWM for the pulse wave, clipping for the sine, etc).
A good start, then, and the two filters (blendable between serial and parallel operation) keep things moving in the right direction. They offer a solid selection of modes: low-pass, band-pass and high-pass, the low-pass coming in 6, 12, 18 and 24dB/octave varieties.
Modulation-wise, a total of nine DAHDSR envelopes and six LFOs control various oscillator and filter parameters, including level, waveshape and pitch; and LFO frequency and shape can also be envelope-modulated.
The LFOs are particularly impressive, boasting a good array of waveshapes as well as a 16-step sequencer, an accent function and phase control. The envelopes are no slouches either, with Delay and Hold stages, plus velocity and keytrack modulation of the Attack and Decay/Release stages.
A quartet of assignable knobs on the Main page gives instant access to four parameters of your choice from across the entire synth.
Two extremely capable delays - one with delay time modulation, the other with a modulatable resonant filter - a powerful arpeggiator and a 3-band EQ put the icing on an already delicious cake. Beyond the synth itself, the de rigeur iOS music app functions are all present and correct: WAV recording and export via iTunes, plus AudioCopy and CoreMIDI support.
Like Argon before it, Cassini sounds great - gutsy, expressive and rich - and it's equally adept at basses, pads, leads and FX.