Review of the XILS-lab ‘miniSyn’X’ Synthex synth emulation

May 2, 2015


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XILS-lab is a French company specialising in software recreations of some of the most famous classic analogue synths and Vocoders including the EMS VCS3, and the RSF PolyKobol.

The miniSyn’X software emulation of the Elka Synthex brings one of the most iconic (and rare) 1980′s era analogue synthesizers to within reach of a much wider audience.

Original Elka Synthex

Original Elka Synthex

If we say that Jean-Michel Jarre owns three original hardware Synthexes and still uses them in the studio and on tour and that Stevie Wonder bought the very last unit to come off the production line in 1985, then you get an idea of its standing in the superstar music community.

The software emulation comes in the form of a multi-format plug-in (AAX, AU, RTAS, VST) that can be used with all popular DAW’s across both Mac and Windows platforms and is both 32 and 64 bit compatible.

Installation of the plug-in was straightforward.  After downloading and running the exe, you have to choose an installation folder and also point to the correct plug-in folder for your DAW.  The first time you load an instance of the miniSyn’X you’ll be asked to enter the license number which comes with the purchase.  No dongle to worry about which is nice.

Although the miniSyn’X does not support operation as a stand-alone application, XILS-lab do reference free VST hosts for Windows and Mac should you want to play it outside of a DAW application.


The on-screen control layout of the miniSyn’X follows the original Synthex hardware control panel fairly closely which means a spacious and easy to use layout available in two screen sizes either 1024 or a whopping 2048 pixels wide.  Bearing in mind that there are now a lot of dual screen users, this makes a lot of sense.

The heart of this synthesizer are dual layer DCO based sound generators with two oscillators per layer, each with Pulse Width Modulation. Each layer has its own Multimode Filter, two ADSR envelope generators (one controlling the amplifier output level and one controlling the filter) and a dedicated LFO with a good choice of waveform types and routing options. Add in a noise generator, glide/portamento, an emulated BBD based analogue chorus and a global, joystick controlled, LFO, and you have a very powerful polyphonic synth. How they ever managed to package all of this in its original analogue form is beyond comprehension and it’s nice to see that the software emulation sticks so closely to the original.

To get a better idea of how this comprehensive specification works, I’ll go through the steps to create one of my favorite presets included with the plugin, the appropriately named ‘PA Vangelis B LtZ’



The heart of the original Synthex machine, and the miniSyn’X emulation, is a dual layer eight-voice synthesizer.  The original Synthex came with eight digitally controlled monophonic synthesizer circuits which were incredibly stable for their day, allowing them to be combined for polyphonic use in three modes, Double, Split and Single.

Double allows both layers to be played simultaneously. Split allocates one to each half of the keyboard and Single brings either one of the two layers into play.

The software emulation provides a control panel for each layer so you only see what you need to control for each layer. This contributes much to the uncluttered layout.

So let’s make a start to create the patch.

We going to use both layers in Double mode so both will play simultaneously across the whole keyboard.  I’ll switch the control panel to Upper layer first and solo it so the Lower layer is muted.

We’ll set up the two Oscillators as shown below.


You’ll see that you can set the Octave in feet and there is a rotary transpose control (+- 12 semitones).  Each of two oscillators (per layer) offers a choice of saw, triangle, square and pulse with its own dedicated PWM and Ring modulator mode. With Pulse Width Cross-Modulation switched on, the width (or duty cycle) of one oscillator can be controlled by the waveform of the other oscillator. With the ability to add multiple waveforms per oscillator, you get a very powerful foundation for sound synthesis.

I’ve set Osc 2 Sync ‘off’ so that the two oscillators are free running with respect to each other. With O2 Sync switched ‘on’ oscillator 2 is forced to start a new cycle whenever oscillator 1 does. This means that oscillator 2 can only play harmonics of oscillator 1 which can be useful when Oscillator 2 is modulated with an LFO, an envelope, or used through the glide. We’ll use this sync facility in the Lower layer sound.

So have a listen to what we’ve created so far …


Envelope Generators

miniSyn-X-3Okay … that kind of starts and stops with a bump!  so let’s turn to the Envelope Generators.

Each layer has its own dual Attack-Decay-Sustain-Release envelope generator, one dedicated to the filter and the other used to control the level of the final oscillator amplifier output.

We’ll set the Amplifier ADSR as follows:

Attack : 46ms

Decay : 1200ms

Sustain : 58%

Release (note off) : 1000ms

Adding those ADSR settings modifies the sound as follows;


So that’s starting to sound a little better but now we need to some frequency filtering.



CEM3320The original Elka Synthex had probably the most sophisticated filter circuit built around the classic CEM3320 filter chip ever to have been used commercially.  It used analogue switches to reconfigure the filter blocks and provided four filter responses.  The emulation has added one more response to give a total of five as follows;

LP12 : low pass filter with 12db/octave slope (new)

LP24: low pass filter with 24db/octave slope


BP6: band pass filter with 6db/octave slope

BP12: band pass filter with 12db/octave slope

HP12: high pass filter with 12db/octave slope

The filter section has controls to set the filter cut-off frequency, resonance (including a self oscillating mode), degree of keyboard follow Cut Off modulation and Overdrive (with pre/post filter selection).

And as the filter has its own set of ADSR envelope controls, we’ve got some quite useful dynamic filtering available to refine the basic synth sounds.

On this layer we’re going to use a Low Pass filter with a 24db/octave slope and a turnover frequency of 2,600Hz.

Combined with the filter ADSR settings shown earlier, we have transformed the sound quite significantly …




miniSyn-X-5Staying with sound sources, each of the two layers has access to its own Low Frequency Oscillator, which can be used as a modulation source.

There is a choice of LFO waveforms from Sine, Triangle, Saw, Ramp, Square, and Random, and again you can use multiple types simultaneously to construct some novel LFO waveforms.

You get the expected Frequency and Depth (of modulation) controls plus delay, fade and sync controls, the latter allows you to sync the LFO rate to the DAW session tempo.

Setting the LFO controls as shown opposite gets us to …




This effect can be switched to either glide or portamento and can act on either of the two oscillators pitch or the filter frequency. You can set the speed that the effect takes and the amount, in semitones, from which the glide starts towards the target frequency.


For this layer, we’re going to use the portamento effect set as shown above, which gets us to …


Okay, that’s the Upper Layer finished.

Now we set up the Lower layer with its own settings as shown below.


Again I switched solo on so you can hear this layer on its own …


A very different sound with oscillator 2 set to trigger in sync with oscillator 1, and you’ll hear that the amplifier ADSR has a much shorter release time (140ms) compared to the Upper layer.


Global Parameters

As this is polyphonic synthesiser, you get to set how many voices are enabled for each of the two layers, between 1 and 8. This can be useful not only to set the synth for mono synth lines, e.g. for bass parts but also to deal with any notes stealing problems with patches when you can try increasing the polyphony for that voices layer, all subject to having enough CPU power to cope.


A balance knob is available in either Split of Dual modes to control the relative levels of the two layers, and a further knob allows a number of stereo effects to be achieved, both between the layers and on a note by note basis.

Now we play both layers together with Stereo and Balance settings shown above to get to the final preset sound …


And a slightly longer snippet to give you an idea of why this was my favourite preset from those provided with the plugin.



What else is in the box?

In addition to the LFO per layer, there is an additional global LFO which is allocated to a joystick.  This allows the user to add a whole bunch of additional mod wheel type effects including vibrato and Wah.

And to round off the choice of sound sources, there is a white/pink noise generator with rotary control to adjust the amount of noise added to the main oscillators.

Just like the hardware original, the miniSyn’X has its own polyphonic sequencer allowing you to record and play up to 4 voices triggered by 4 different sequences. The sequencer clock can derive its rate from the DAW’s project tempo if required.

The original Elka Synthex was unusual in providing a built in chorus affect using two dual bucket brigade delay lines allowing the Synthex to operate as quality string synthesizer, probably the only synth of its day to provide this facility.  The miniSyn’X recreates exactly the same chorus effects as the original with the same three presets.


Loading and saving patches, and presets

Okay,  you have a very powerful synth machine at your figure tips, so how does it work out in use? The original Synthex provided 40 presets and a further 40 user memory slots to store your own sound creations.

The miniSyn’X has none of the limitations of the original and provides 128 Factory presets to give you a foundation to build from.  Thankfully you can’t accidentally delete these so it’s a simple of matter of selecting one, adjusting to taste for a particular session, then saving with a different preset name within the library.  Additional presets are available from XILS-lab if you don’t want to spend too much time making your own.

A simple A-B facility allows you to compare two versions of a patch quickly.

Voice banks are sensibly grouped and can be displayed by instrument type, genre and even by author so its fairly easy to browse through the library. You can also set up your own projects within the library to that all voices used within a project can be stored together.


Summing Up

It’s really nice to work with a synth emulation not based on sound samples.  The miniSyn’X comes with a great range of presets which are easy to adapt so you can create and store your own favourites with the reassurance that the factory presets can be revisited from time to time.  There are even random and AI assisted layer loading should you want some inspiration for new sounds.  MIDI automation and control mapping is provided for more than 100 parameters so it’s easy enough to bring some of the virtual knobs into your keyboard/controller.

XILS-lab have clearly put a lot of time and effort into recreating the classic Elka Synthex in the form of the miniSyn’X plugin.  It’s very competitively priced and would make a great addition to your synth locker.

Highly recommended.

Robert Campbell
May 2015

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