PolyKB III: Morphing French analog oscillators by XILS
4,0 / 5,0 | 
XILS-lab PolyKB III · Source: screen shot
XILS-lab PolyKB III sequencer · Source: screen shot
XILS-lab have a soft spot for unobtainable French synthesizers. The PolyKB III virtual instrument is their third attempt at capturing the essence of the 1983 RSF Polykobol II synthesizer. Although famously used by Jean Michel-Jarre, a production model was never fully developed. XILS-lab says that this is the synthesizer it should have been all along.
PolyKB III
The PolyKobol 2’s special feature was its morphing analogue oscillators. These can continuously move from triangle to saw, double saw to square and through to pulse. This continuous motion can make it a difficult thing to replicate in software, but XILS have captured hundreds of different waveforms to recreate the smooth transitions. And it works. Rather than the usual switching between waveforms you find on most synths you have this graduation between them. Once you engage an LFO to fiddle with the waveform knob, then you have lots of interesting tonal movement going on.
Having downloaded and played with the demo for a few minutes I’m finding it really quite interesting.
Features
Along with the oscillators, there are two multimode filters which they refer to as “creamy”. Then come the three ADSR envelopes with time multiplication and looping capabilities. There are 8 voices to play with and each one can be modulated and sequenced separately if you so wish.
Behind the strange blank panel, that seems to initially house a cassette tape, there’s all sorts of fun to be had. There’s a modulation matrix, both normalled and user configurable. There are two XY controls over space and voice where you can get little balls moving about. The sequencer can offer 128 notes of step sequencing. It looks a lot like a piano roll you’d find in a DAW, and you can enter notes with a mouse or play them in, in real or step time. The sequencer can also be employed as a step modulator. You can have effects controls here although you turn the effects on and off elsewhere on the GUI which is a little cumbersome. And they round it off with a simple arpeggiator.
GUI
The GUI is not as gorgeous as the 3D render image that’s knocking around but it does the job. All the knobs and controls respond well to single touch and are easy to grab on a touch-screen. Modulation isn’t reflected in the controls which is a shame – I really like to see knobs move when modulated as it’s an advantage of software, but that’s just me. The two dozen presets give a fair indication of what’s possible and they are all very pleasing. There are options to resize the GUI, which was a criticism of the earlier versions, but it doesn’t appear to work in the demo version.
The PolyKB III is an unusual synthesizer with a lot of depth for movement and modulation. The sounds can get very thick and fat and the possibilities do lean towards the endless. Download the demo and give it a try and I think you’ll find something unlike anything in your instrument library. Sadly all the videos on the website and YouTube are for the 2.5 version – so you’re going to have to try it for yourself.
The PolyKB III is available as a plug-in for €119 until the 21st January. It’s in AU, VST, RTAS and AAX for MacOS and Windows. More information available on the XILS-lab website.
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