I’m a great fan of the Korg MS-20, as it’s one of my favourite synths ever, so I decided to expand my modular with an MS-20 filter clone.
There are many emulators/clones in eurorack format for the Korg filter, but I focused on three modules:

• Doepfer X-treme filter
• Malekko (Wiard) Borg (Buchla-Korg)
• Analogue Solutions SY02

I like the Borg but it works only as a multimode filter that can out put only one signal, so it’s quite limited.
The Doepfer is interesting but I found the ASOL the more versatile and at the same time interesting  as carachter.
The first thing to say that  THIS IS NOT THE MS-20 FILTER!
In its way it can have common caracteristics and sounds very similar but it’s not the same.

The module has a vertical row of connections for CVand audio INs on the left and the knobs on the right.
There is a an INPUT LEVEL to adjust the gain for the incoming sounds, that useful to saturate or lead the filters to overdrive.
On the left there are 2 AUDIO IN .
Than there is the HIGHPASS Filter section with

• Cutoff
• Resonance
• HPF CV

The HPF CV has 2 CV in the first is attenuated by the knob while the second has no attenuation control.

The LOWPASS Filter section has the same controls:

• Cutoff
• Resonance
• LPF CV

As for the HPF even the LPF filter has 2 cv in and only the first is attenuated by the LPF CV.

There is aslso a VCA section with :

• Initial Level
• Volume
• Audio out (minijack)

The VCA has its 2 CV IN not attenuated.

This module is the FILTER/VCA section usedon the Analogue Solutions VOSTOK too, the construction is solid and the VCA it’s a really good add o this filter.
The filters have a really particular response , tryng to emulate the Korg MS-20 filters/VCA, and the input gain is the key to get smooth sounds  or enter in noise territory.
I’ve patched the synth in a very simple way to understand clearly the behaviour of this module.
I’ve patched only the first vco (from my MFB OSC02) directly into the first audio in of the sy02, used the MFB Dual ADSR to control the vca ancd the LPF.
With a low input level the sound is really mellow and “japanese”, smooth and deep.
As I turn the input level clockwise, the waveform gain in volume and in saturation until “distortion”.
Distorion is like a good overdriven sound , not a clear distortion.
As the filter , with a low input level flows into the filters they react quite smoothly and the resonance has a pleasant harmonic sound but reaches only little aggressive tones.
As the input level grows the filters start to saturate and overdrive the sound, and using ring mod with saw sources it creates a particular clipping , like if it would cut and drive the peaks of the saw waves.
A really interesting trick that every MS-20 user knows is using the HPF as a frequency booster.
In fact the resonance of the HPF can produce a really big amount of sub frequencies  usable to fatten up the sound.
If the HPF is controlled with the tracking of the keyboard  it can create very powerful SUB basses.

Behond the FILTERS  there’s a good (in my opinion) VCA that concurs to give a strong carachter to the module.
The VCA does not ave a superfast response or a extra dynamic behaviour, but it’s very warm and full, really musical!
For me it’s very important for a module to be “musical” because too often a modular synth can do amazing noises but cannot play a bass sound , and that’s quite absurd.
Doepfer modules  (like the A-132-3 DVCA I own) have a cleaner sound and more volume but are less musical (in my opinion but maybe you will like it), and I find this useful for percussive sounds or effects and less pleasant for melodic sounds.

Back to the SY02 , I’m really happy with this module, it has a certain retrò/MS-20 touch, but it also has a carachter of its own.
I really recommend it to everyone looking for a japanese touch in his modular sounds!