Originally released as an iPad app sans the ‘Pro’, Infinite Pro (VST/AU) is the latest in an unfailingly impressive line-up of forward-thinking virtual instruments from Wolfgang Palm, the father of wavetable synthesis.
Its architecture centres on the morphing of multiple sound and noise sources, but its key selling point is the unmatched detail in which the partials within those sources can be individually altered over time. This, says Palm, makes Infinite Pro the first digital synth capable of emulating the nuances and harmonic variability of “natural” sounds.
Infinity and beyond
An Infinite Pro patch comprises up to five ‘sine resources’ and three ‘noise resources’, the first being resynthesised (ie, converted to series of sine waves) samples from a 300-plus-strong internal library, the second coming from a set of 50+ atonal sources. The sine resources range from synthesised inventions to real-world instrumental and environmental sounds, while the noise resources take in everything from acoustic and synthetic to percussive and vocal. And needless to say, external samples can be imported and resynthesised for use as both resource types, as can wavetables from PPG WaveMapper and WaveGenerator 2.
The five sine resources are selected and mixed in the Morpher - an X/Y pad that interpolates the gains of the morphing sine waves on the X axis and their frequencies on the Y axis. It’s a deep, potentially confusing system, but this isn’t the kind of synth you’re likely to approach with a particular sonic end point in mind anyway, so wild experimentation is the way to go. Essentially, the left and right resources define the morphable gain profile, the top and bottom resources govern the frequency profile, and the centre resource contributes to both. Drag the central puck around to morph manually or modulate it in the Modulation Matrix, and, if you like, record the results as a new user resource.
Sines over time
Clicking the Para button at the top of the Morpher page switches to Sine edit mode, wherein the progress over time of various “data points” on up to 200 individual harmonic ‘tracks’ making up the selected sine resource is edited using a bank of six knobs. These data points comprise frequency, amplitude, decay and LFO modulation (frequency, depth and start phase), and selecting tracks is done using a spinner flanked by next/previous buttons. Track selection and the effects of any edits made are clearly visualised in the zoomable and rotatable 3D harmonic display, and for broader changes, all or alternate tracks can be selected together. You can also randomise each of the six parameters over in the Random page.
Clicking the Structure button reveals another layer of control in the form of an editable 2D bar graph representing the amplitudes (and, for certain resources, frequencies) of every partial in the current track.
At first, being granted this level of access to the primordial structure of the sound is a bit daunting - most synth developers do everything they can to ‘cluster’ the editing of partials, after all - but sculpting your own harmonic tracks quickly becomes addictive, and invariably yields interesting results.
The Gain and/or Tune of each resource is adjustable, and movement of the playhead is controlled by any one of five envelopes. There’s an independently tuned sub oscillator, too, which can be set to double the entire main oscillator, or just the centre sine resource.
The Noiser works in essentially the same way as the Morpher, but with three vertically stacked resources. As well as its audible output (the mix balance of which is set using the S/N Mix knob), the Noiser can also modulate the sine waves of the main oscillator, with Low and High Cut filters targeting the effect.
Immediately after the Morpher and Noiser in the signal path, the Molder is a spectral filter that applies one of 45 preset ‘filter sweeps’ to each independently, timed according to the dedicated TVF (Time-Variable Filter) envelope. This isn’t analogue-style filtering (that comes later) but direct modulation of the sine waves themselves, imposing the spectral characteristics of the selected TVF on them. Interestingly, filter sequences from PPG Phonem can be imported into the Molder, for formant- flavoured processing.
With sine and noise resources handled in the Morpher, Noiser and Sine editors (see Sines over time), the Parameter page is where you adjust and process the oscillator as a whole, and apply modulation. Main and sub oscillator tuning, Glide time, bitcrushing and a 24dB resonant low- pass filter are on hand, while an incredibly small, poorly legended and maddeningly fiddly modulation matrix lets you assign four envelopes, four LFOs and several other sources to all the expected main parameters, including Morpher X and Y.
The envelope generators can work as regular ADSRs or be set to loop after the decay stage, while the LFOs offer saw, pulse, sine and S+H waveforms with width adjustment and positive or negative offset.
The modulation setup works fine, but we really think it needs to be given its own page, as the UI compromises made to fit into such a tight space make it a real pain to use.
At the end of the signal path, reverb, delay and overdrive effects polish things off nicely enough (but aren’t available as modulation targets); while the malleable virtual keyboard is quite fun to play around with, but obviously not as useful as it is in the iPad version.
Infinite Pro is every bit as complicated and cerebral as it looks, but once its architectural intricacies click into place and you get used to the unusual (in both good and bad ways) interface, that initial feeling of intimidation gives way to the realisation that this is an instrument that really can take you down sonic roads never before travelled.
As with every PPG instrument ever made, Infinite Pro is all about movement and modulation, and its overarching character is unmistakably ‘digital’. The ability to manipulate the individual partials within each sine resource (and the ease with which such technical trickery is executed), and the ever-gratifying Molder, set it apart, though, realising a new idiom of palpably organic and always-evolving sounds - pads, keys, percussion and FX, primarily - that no other synth could possibly create.
By no means immediately accessible, but incredibly rewarding and a constant source of happy accidents, Infinite Pro represents a shining milestone in softsynth design.