Review: MFB Nanozwerg Pro

Being able to assemble everything to your liking is one of the key advantages of modular synths. If your newly assembled wavetable synth gets a ladder filter, a lowpass gate, a six-pole opto-FET design or something else is entirely up to you.

With that comes the necessity to do just that. To assemble a simple synth voice, you’ll need between four and seven modules, each of which will set you back roughly between 60 and 200 bucks.

To deal with this, there’s voice modules. A voice module is everything you need for a synth voice, plus some patch points – so essentially a semi-modular synth without a case. For typical subtractive-style voice modules, prices range from ca. €250 to slightly above €1000. On the low end of the spectrum, there’s the MFB Nanozwerg Pro. Which I decided to get.

The time I decided to get it was when I went into this Eurorack stuff for real. Meaning early in June of 2018. Which is a long time ago. Which also means that it has been discontinued since. Pity.

Key Features

The Nanozwerg Pro is the eurorack module version of MFB’s Nanozwerg desktop synth, the smallest member of the discontinued “Zwerg” (dwarf) series of analogue monosynths.

“Analogue” also applies to the Nanozwerg Pro, however it only applies to the signal path – meaning the modulation sources are digitally generated.

In a 24TE eurorack case, you get an oscillator plus sub and noise source, a 2-pole multimode filter, two ADSD/ADSR envelopes and one LFO. Connectivity-wise, there’s a total of 14 patch points (in two rows on the right: eight ins and six outs), plus a jack with supplied adapter for MIDI connectivity, and on the back (next to the standard backplane connection) a connection to MFB’s proprietary MBus instrument interface – something like a faster MIDI.


The synth follows the usual oscillator -> filter – VCA setup known since the olden Minimoog days.


The main oscillator offers choices of triangle, descending saw, square or pulse waveforms switchable with a pusbutton and indicated by a red LED. Using the same UI, you switch between register from 32′ to 4′. Another pushbutton switches the (square) sub oscillator between 1/2, 1/3 and 1/4 (meaning octave, two octaves and a very welcome duodecime down from the main oscillator) or switches to a noise source. Three knobs in this section are responsible for tuning (+/-6 semitones), mix (from 0 to full-on main osc to blend between osc/sub to sub back to 0) and for oscillator mod (which can be either routed to pitch or PWM for the pulse wave and is normalled to LFO).

There’s an additional small knob (which is small, and also doesn’t give proper visual feedback) for glide. I see this lack of visual feedback as acceptable (different to the pan knobs on MFB’s Drum-99 where this is really stupid and you can’t just by visual inspection set something to center – but I digress).

For patch points, we get pitch CV, oscillator mod and oscillator sync (yes, that’s possible!) as ins, and the mixer out.


We get a two-pole multimode filter, offering LP/BP/HP and notch. Controls include the usual cutoff/resonance pair, envelope mod (called “contour”), VCF mod (normalled to LFO), and a small knob for key tracking.

The patch points are filter in and out and VCF mod.

Incidentally, this filter was also included in the filter comparion post/video.


Two identical ADS(R)/ADSD envelopes, each with three knobs and a button working on both together.

With the button, you can switch between an ADSR mode with a fixed, very short release and the classic ADSD mode.

The envelopes are normalled to filter cutoff and VCA, plus each envelope gets an output. Both are triggered by the gate in.


Something I’d consider an above-standard affair here: shape goes continuously from falling saw over triangle to rising saw over square to something called S&H (which is a random source into a S&H running at the LFO rate). Rate gets another knob and goes from rather slow well into the audio range.

There’s also a “one shot” button with LED, which allows you to set this one as a simple third envelope (e.g. to patch it to pitch for some bassdrum sounds).

We also get patch points for this: inputs for rate and shape, and an output.


The most important one is obviously the 2×7 patchbay, grouped in 8 inputs and 6 outputs. For inputs, we get CV and gate (obviously), LFO rate and wave, VCO mod and sync, and filter input and frequency modulation.

For outputs, there’s boths envelopes, the LFO, mixer, filter and the main out.

Then there’s MIDI via the typical 3.5mm connector (an adapter to DIN is supplied). The MIDI implementation is nothing short of spectacular, as all parameters can be controlled by CC messages. Unfortunately, the module also seems to have a bug which sometimes leaves notes hanging that were played via MIDI. What causes it is unknown to me, but unfortunately, there’s no easy workaround – rather than switching off the power supply (which typically means switching off the whole case). You can get lucky though and arrive at a drone-like voice that you didn’t plan for, which only happens at the end of a performance. Otherwise, great feature set or not, this is a rather disappointing property.

In Use

The first thing I noticed was that the output signal is rather weak (in the sense of “low level”) in comparison to about any other oscillator or filter I have in my setup, which you need to consider when setting levels in your mixer, and that is a big disadvantage.

The second finding was that although MFB have crammed a lot of functionality into a mere 24TE, the thing is really good to use with regard to real-time control of parameters. The knobs aren’t too close or too small, and putting the patchbay onto the side of the module (one of two competing design philosophies) helps as well.

Regarding the actual sound, the first things I arrived at were rather chiptune/acid-lead-style. That is not to say that you can’t do beefy bass lines, ambient leads or even percussion sounds with it, but the basic character simply doesn’t lead us in any of those directions. However, that shouldn’t obscure the fact that this module is in fact very flexible, and the clever design of the feature set helps to make this a really versatile synth voice. It seems to me that maybe the filter is lacking the most with regard to the individual components of this synth voice – while it does its job, it does so in a pretty bland way – but then again, let’s not forget that it’s even a multimode filter, and the entire module costs as much as some of those fancy filters cost alone.

With all that flexibility, it’s really a jack of all trades synth – but while it clearly fails to be a master of all (or most) of those trades, it is definitely a master of at least the chiptune lead/arp one.

I’d like to share a video of a track which reportedly was done with this synth as the only voice:

In one of my earlier videos, the synth lead part was done with this MFB Nanozwerg Pro (through a Doepfer A-188-1 BBD):

The Competition

This is somewhat sill now that I’ve waited so long with this review, as this module is no longer available. Ah well…

Almost all of the competition which offers a proper synth voice in one module tends to be much more expensive and/or considerably less powerful.

From the not-yet-but-very-soon-available stuff, there’s Doepfer’s new A-111-6 voice, which I already discussed in this post. Considerably cheaper and smaller at €180 and 10TE, it’s also less powerful and flexible. A more powerful module in the same general price range would be Behringer’s Neutron – but at 80TE, it’s not something to fit the “additional voice that I can fit anywhere) category. There’s Eowave’s Domino and Acidlab’s M303, both of which are smaller, but more expensive (at around 300 bucks) and much less flexible.

In the end, it comes down to either the Nanozwerg or the Doepfer, and that decision is in the end down to cost/space versus feature set.


A Swiss army knife. Where you have a stunning lot of features, most of which don’t even come close to the stand-alone competition. But some are actually great (like the small blade, or the metal saw). Plus, it’s small. And a lot of people have one.

The MFB Nanozwerg Pro is exactly like that. It may not be your first and immediate choice for that impressive bassline, or a really metallic snare drum or whatever, but it can always help out if you need another highpass or bandpass, another LFO, another envelope, and let’s not forget another decent VCO. Or another full-blown voice – and for chiptune sounds, it will be your go-to solution.

There’s the issue with the truly disappointing documentation, the MIDI note hangs, and the one with the weak output signal, and those are three definitive subtractions.

Still, both with regard to bang-for-buck and bang-for-size, I recommend this as your Eurorack’s Swiss army knife.

From June 2018 to August 2019, it has stayed in my big rig.

2 thoughts on “Review: MFB Nanozwerg Pro

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