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Xils Lab recently unveiled the PolyKB III synthesizer. This synth is based on the original legendary and highly coveted French Poly Kobol 2 hardware synthesizer. The PolyKB III is a polyphonic synthesizer featuring 3 morphing analog modeled oscillators,

8th February 2017

XILS-Lab PolyKB III by Synth Guru


Product: PolyKB III
Developer: Xils Lab
Formats: VST, Audio Units, AAX, OSX 10.7+ (32 & 64-bit) and Win XP, 7+ (32 & 64-bit), NKS
RTAS (Pro Tools 7.0+), AAX (32 & 64-bit)
Disk Space Required: 30GB
Price: $170, €159.00
DRM: iLok account (Free, dongle not required)
Demo: Available

The Scope:

Xils Lab recently unveiled the PolyKB III synthesizer. This synth is based on the original legendary and highly coveted French Poly Kobol 2 hardware synthesizer. The PolyKB III is a polyphonic synthesizer featuring 3 morphing analog modeled oscillators, 2 multi-mode filters, 3 envelopes, 2 LFO’s, poly-sequencer, arpeggiator, vintage effects, and much more. The French RSF Poly Kobol 2 was manufactured in very limited numbers during the late 1970’s, approximately 200 were made. The chances of getting a hold of one are practically nil, but you can get a near perfect analog sound reproduction with the PolyKB III.

The Interface

The user interface is a very accurate and a highly detailed visual representation of the original RSF Poly Kobol 2 synthesizer. It offers a wide range of features that enable the creation for a rich authentic analog sound. The “creamy” multimode filters are self-resonating and sport the Xils LAB high end 0df technology. Coupled with the analog modeled envelopes (which come with powerful time multiplication and looping abilities), and complex LFO’s, to deliver warm harmonics and overtones. I had the opportunity to listen to demos of the original synth and I’m astounded by the matching sound similarities of the PolyKB III.

On the left upper section of the synth, there’s a rectangular cover depicting a cassette recorder. The original Poly Kobol 2 also had this feature which is something I wasn't aware of. This was truly a novel idea for that time period. It even has a spinning animation of a cassette reel inside the cover. As one moves the left sided slider, it reveals a series of hidden compartments as listed below.

Step Modulator Sequencer

This is a 4x128 step sequencer which can be used as a behemoth Modulation only Step Sequencer. It can write up to four separate step sequences, in which each line can be up to 128 steps long! Utilizing the User Matrix, each of the four sequenced lines can be used to control up to four different synthesis parameters. The parameters may include filters, oscillators, envelope segments, or LFO output levels.

Polyphonic Sequencer

The Polysequencer consists of 8 parts and has the ability to record up to 8 parts in real time or in step mode. Sequences can be transposed via the root note with the tuned mode. Phrases can also be triggered while you play live. Furthermore, your custom sequences can also be saved for later use and can be used as a source modulation within the mod matrix resulting in astounding sequences. MIDI automation is also available.

Voice XY Pad Modulator

The Voice XY Pad Mod is represented by red spheres that can be moved with the mouse to any position within the screen or set to a pre-selected position by using the menu. Some of the options in the menu include Center, Around, and Raw to name a few. Each sphere represents a voice and each new note played that is affected by this mod will sound different from the previous and next note being played. Each sphere can modulate two separate parameters and each with a dedicated X or Y amount knob. There are three main amount categories consisting of Oscillators, Filters, and Envelopes. Each category has a sub-menu, here you can assign the Wave, Filter, or Frequency for any of the OSC’s 1-3, Filters 1-2, level, and Envelope 1-3. The result is a staggering amount of unique sounds that can be shaped to your taste.

Space XY Pad

The Space XY Pad enables the user to create exclusive Dynamic Stereo Modulation scenes that truly must be heard to be believed. Each note can have a distinct place within 3D stereo space. Put on a set of headphones and it’s like being in a room full of swirling and dancing fireflies! This is definitely one of my favorite features.


The Arp has three playing modes, Free, Changed by Note, Changed by Cycle. There’s a Chord Sequence option that can be selected by semi-tone and space separated. Additionally, there are Swing, Gate controls. There are also controls for keyboard Drift, After-Touch, Velocity, and Bender. Lastly, there’s a Voice Unison option for up to six voices.

Wired Modulator Matrix

This versatile matrix allows for over 35 hardwired modulations. There’s a mono and poly mode, destinations also include various sources like, LFO’s, VCO’s, Wave, VCF, Envelopes, OSC’s, AM & FM and much more.

User Modulator Matrix

Here you’ll find 4 custom macro modulator matrixes, each of which can control up to four parameters for a total of up to 16 freely assigned modulations. This is truly monumental in size and a sound designer’s dream come true! The amounts can be assigned both in the positive or negative direction.


PolyKB III comes with a series of on-board effects including Delay, Phaser, Chorus, and EQ.

* Please see below to view screenshots of the user interface.

The Scores

Sound Quality: Remarkable sound quality. The beauty of this synth are the Per Voice modulation engines and the morphing analog modeled oscillators, with three of them at your command, the possibilities are limitless as you travel deeper into vintage territory. This synth just sounds amazing and is a sound designer’s dream, it’s jam packed with options to achieve spectacular custom tailored sounds. Oh, and did I mention the sweet spot? Simply HUGE! The sounds are beautiful and clean, from the creamy multimode filters to the analog modelled envelopes. I think you will like it a lot. The sounds of the PolyKB III are hypnotizing and capture the essence of time travel across the sea of lush evolving pads, soundscapes, sequences, and arps.

Ease of use: The modulation matrix is both intuitive and easy to follow. Within minutes you’ll have original customized sounds that can readily be used in virtually any track. With the resizable UI, you won’t have any trouble reading the labels or navigating through the mod matrix.

Features: The user interface is outstanding and it’s a beautiful rendition of the original RSF PolyKobol 2, including the wood body and side panels. With the ability to resize the interface, one can clearly see all the knobs and buttons with ease. I'm a big stickler for resizable UI's and this one is perfect! The modulation matrix is easy to follow, enabling the user to focus on the creation of music instead of getting bogged down during the patch creation process. Speaking of patches, PolyKB III comes with a wide assortment of pads, leads, basses, bells, arps, sequences, woodwinds, and strings just to name a few.

Bang for buck: Outstanding value that won’t break your budget. This is a high-quality product that could easily become your desert island soft synth.

Overall: Bottom line, the PolyKB III is a gorgeous sounding synth that’s within reach for all those that aspire to play the beautiful sounds of the original HW RSF Poly Kobol 2. If you love vintage synths, you’ll definitely want the PolyKB III to become a part of your synth collection. Highly recommended for sound designers, synth enthusiasts, and for beginners looking to learn synthesis.

Attached Thumbnails
XILS-Lab PolyKB III-polykbiii.jpg   XILS-Lab PolyKB III-screen-shot-2016-12-30-19.02.12.jpg   XILS-Lab PolyKB III-screen-shot-2016-12-30-19.03.38.jpg   XILS-Lab PolyKB III-keyb-arp.jpg   XILS-Lab PolyKB III-cassette-recorder.jpg  

XILS-Lab PolyKB III-effect.jpg   XILS-Lab PolyKB III-sequencer.jpg   XILS-Lab PolyKB III-space-xy.jpg   XILS-Lab PolyKB III-user-mod.jpg   XILS-Lab PolyKB III-wired-mod.jpg  

XILS-Lab PolyKB III-voice-xy.jpg   XILS-Lab PolyKB III-sequencer.jpg  

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