Review: Behringer Neutron

There’s maybe no other manufacturer who has received as much bashing as Behringer has. Ranging from “they took our jobs” over “crappy and for kids” to “even if it’s good, it makes my heart cry”.

That last comment was targeted at Behringer’s DeepMind analogue polysynth, which takes not just a little bit of inspiration from Roland’s old Juno 106. And “crappy and for kids” could easily be coming from someone who just spent ten times the amount of the price of a Behringer Model D on a Moog Model D. But this review is about neither of those – it’s about their newest synth product, the Neutron.

Note that this review is presented in a rather disorganized fashion. I’m wildly jumping between topics.

In A Nutshell

The Neutron targets the super-hip market of semi-modular synths, which today is populated by traditional companies, niche makers, and now the mass-market oriented Behringer.

The box.

The Neutron is a desktop case not too dissimilar to Moog’s DFAM and Mother-32 in its shape. In the white package, you find next to the synth a quickstart manual, the (wallwart) PSU and a bag with six black patch cables and a ribbon cable. That ribbon cable also hints at the alternative installation option: this synth not only accepts connections conforming to Eurorack standard, it also can be mounted into an Eurorack case, taking up a whopping 80TE in the process.

The red faceplate is adorned by a total of 36 knobs in different sizes, several backlit pushbuttons, a few orange and blue LEDs and a MIDI in (DIN) connector. The right of the plate is held by a patchbay with an impressive 56 3.5mm connections, making it easily a “best in class” in that domain.

The back side shows a connector for the PSU (alas, no cable holder for this), USB (for MIDI over USB), a MIDI thru (DIN), and 6.5mm jacks for audio out/in and phones. Interestingly, the old DIP switches make a return for selecting the MIDI channel.

Feature-wise, there’s two oscillators, two ADSR envelopes, a BBD delay, an overdrive circuit, two attenuators, two slew rate limiters (one of them hardwired to portamento), a sample and hold circuit, and a LFO (which is the only digital component in this synth’s signal path safe for the MIDI/USB).

Unpatched (safe for a MIDI connection)

Digging Deeper: Audio Path


The two oscillators are reportedly based around one of the Curtis 3340 reissues. These chips had their place in many classic (and also modern) synths, among them the Memorymoog, the OB-8, the SH-101 and Jupiter-6, several Prophet versions, and from today’s lineup several Doepfer VCO modules (interestingly, their precision types).

These (triangle-based) ICs provide mostly everthing you’d want from a classic analogue VCO, including concurrent square/pulse, saw and triangle outputs, inputs for hard sync, soft sync and pwm, linear and exponential frequency control, and they are temperature-compensated (see some info on the original ones here).

Depending on a change in features of the reissue in use or not, Behringer decided to not give us linear FM (which is a pity, considering we have a synth which could otherwise be turned into a neat two-operator FM synth). Also, not all three waveforms are available at once, rather we get the choice to blend from sine over triangle and saw and pulse to something called “tone mod”, the two last ones offering to modulate shape. And that blending thing is a modulation target.

There’s 32’/16’/8′ settings and a “10-octave-mode” (meaning pitch is controlled over a wider range), there’s sync, a paraphonic mode, and finally a knob to blend between both oscillators (which, by the way, are identical safe for osc2 always being the sync target and osc1 the source if sync is engaged).


The so-called Moffat Filter is an original design of the guys at Midas who designed that synth (and hats off to said mixer design team for getting into synth design thing so quickly). It’s a two-pole multimode filter with two independent outs, with the settings being HP/BP, BP/LP and LP/HP respectively. The thing does start to sing when brought into resonance and is a…let’s call it “well-rounded” affair. It’s hardwired to env2 for modulation, but has another modulation port for frequency, and also one for resonance. Nothing spectacular, but a nice and flexible affair, also with the two outs.


Next is an overdrive circuit, which comes with drive, tone and level controls.  While the controls might remind you of your standard guitar overdrive stompbox, this circuit is different in so far that it works really well with bassy synth voices (something I also discovered with TC Electronic’s Dark Matter pedal. TC is also part of Behringer now).  It’s also worth mentioning that the tone control adds a nice sound-shaping option, not to dissimilar to Elysia’s Niveau filter, i.e. it will attenuate highs and boost lows or vice versa. Next is the delay, with knobs for time, feedback and mix. It goes up to a little more than 600ms (which is a nice range), and can be turned into feedback >1. There’s a downside here: if the mix knob is at what should be “completely dry”, you still can hear the delay slightly – which can be circumvented by turning time and repeat to zero. Will this lead to some comb filtering, thus negatively affecting the low-end? Unfortunately, this can’t be worked around by patching if you’re using the rear output (if not, you simply move your output patch cable from the “Output” to the “VCA” out jack).

Right now, I want to stop talking about features and talk about sound instead.

So…How Does It Sound?

When talking about low-cost gear (especially analogue gear), atrributes like “bland”, “lifeless” or “without body” are often mentioned.

This one is different.

It really came as a surprise that with most of the possible settings, this synth always has a really strong bottom end and sounds round and warm.

Yes, you can get it into acid-style screaming, but you need to specifically want to do it. Unless you specifically try otherwise (and know what you’re doing), this synth will always sound full, warm, and heavy.

So why is that? It’s obviously a combination of factors. The triangle-core VCOs help (and if you want to use that, the addition of a sine to its waveform arsenal does, too). Then there’s a filter that even if turned to pretty high resonance values does not thin out the bottom end, and the same holds true for the overdrive.

It’s not limited to bassy sounds, though. But rather than cutting like the trumpet section in a Buddy Rich recording, it makes itself known like the onslaught of french horns in a Richard Wagner opera when typically used in lead roles. Or, to compare it to 70s rock music, it’s more in the field between Pink Floyd and Genesis than in the area of ELP.

Digging Revisited: Other Stuff


Let’s start with the envelopes, of which there are two standard ADSR designs, normalled to VCA and filter (the latter with a depth knob in the filter section). Interestingly, the maximum time for A and D/R is vastly different: while I didn’t take scientific measurements, I found that while maximum attack is in the 3-4 seconds range, decay and release extends for around 20 seconds at maximum setting.
At the other end of the spectrum, those envelopes (which are analogue) are snappy as they should be, definitely able to generate nothing more than clicks (enjoy that with distortion and delay, or better still, with a filter just below resonance patched behind the VCA).

Next is the LFO, which is digital – something I chose to point out because all other signal generators and processors are analogue. The LFO has five waveforms to offer (sine, triangle, square and ascending/descending saw), and is specified from 0.01Hz to 10kHz, which is a lot of octaves (around 20). Unfortunately, the LFO will always sync its speed to incoming MIDI clock. There is no configuration option to work around this, so if you don’t want this to happen, either disable MIDI clock to be transmitted from your MIDI source, accept it, or don’t use MIDI at all (which is perfectly possible – semi-modular!). Due to the ability to divide MIDI clock  in 21 steps over eight octaves, you still get a lot of range and possibilities, though. A key sync button allows you to retrigger the LFO with each incoming MIDI note (not based on gate, sadly).


While our first looks (or listens) typically refer to the audio path components, auxiliaries are what makes the modular world go round.

The Neutron has a lot to offer in this domain, including:

  • two 2-in-1 summers,
  • two attenuators, one of them with a CV in (which makes it a second VCA!), and both of them with a knob (obviously),
  • a patchable slew rate limiter, and a second hardwired one called “Portamento” which gives us those glides between notes (only for MIDI notes, though),
  • a sample-and-hold circuit with knobs for rate and glide (this is a new one!), and a S&H clock input jack,
  • and finally a 1-to-2 passive multiple.

This is  a rather complete set of things. If there’s one thing I’m missing is something to simply create a DC voltage, something which some attenuverters (e.g. LPZW WK2) do by normalling the input to a DC voltage. However, the attenuator inputs are all normalled in some way to the LFO.

Leaving complaints aside for a moment, this complements the general synth structure well: by starting with a synth that is, in its unpatched configuration, a rather straightforward (if interesting) affair, you offer all of those auxiliaries to allow you to completely rewire it.

Velocity-sensitive synth? 2-operator FM? Completely possible…


It’s big. 56 jacks (24 inputs and 32 outputs) and as a result, offers a lot of options. Rather than going through all the connectors (which you can look up in the manual), I’d like to comment on some key findings:

  • with three inputs and two outputs, the LFO is one of the components with the highest connection count. I have not yet found it that useful, though…
  • I’d rather have a linear FM input for at least one oscillator (the 3340 does have that input).
  • Another thing that’s missed at least as much is the oscillator blend control. If I could patch that to LFO…
  • A highlight is the assignable output (more on that later). But a second one would be even better.

With all that said, a 56-point patchbay is a great addition to any synth. And my points of critizism are well within the usual range of an individual’s specific views.

Under The Hood

A synth with a MIDI input (or as in this case both MIDI and USB input) has, by definition, a digital brain, no matter how much analogue it might be otherwise. And a typical design choice is to let that brain do more than just MIDI to gate/CV – the Neutron is not different to other players like e.g. the Minibrute, the 0-Coast or MFB’s Nanozwerg Pro.

Rather than using USB and a specific software, this synth offers all configuration options via specific button presses – and MIDI channel is set with a DIP switch on the back (oldskool!).

Three of these settings have to do with waveform selection: independently for OSC1, OSC2 and LFO, you can select if you switch or blend through the different waveforms. There’s a poly chain mode and settings for envelope retrigger (which is important), The remaining two are settings (or rather options) I haven’t seen before: called “OSC tuning”, you can then show if your oscillators are in tune to a frequency standard (I assume it’s something based on 440Hz), which makes tuning easier than with about any analogue synth that requires tuning. This is a great idea.

Finally, you can assign the role of the “Assign” output to your choice among osc CV, note on velocity, mod wheel or aftertouch.

Each setting is controlled by a succession of a long press, twisting a knob, and long press again, with feedback provided via the various LEDs. While this is nothing that is easy to remember easily, I found it very well accessible given the circumstances of a device without a display.

The thing appears as a class-compliant MIDI interface, and MIDI input is the only thing the Neutron gets via USB. And btw, there’s a MIDI thru port – great in an area where most other synths don’t have that anymore.


From the general arrangement, the package resembles Moog’s current offerings in the semi-modular market: a slanted case with a 3HU surface plate, patchbay on the right, controls left of that, and all non-3.5mm-connections on the rear. And just like the Moogs (and Behringer’s own Model D), the thing can be Eurorack-mounted – and Behringer also supplies the ribbon cable for that.

One thing to consider is that, in comparison to the competition (and to monosynths in general), this one is quite big: at 80TE, it’s just below the size of a 19” Eurorack case.

There is a major point of criticism for me, and this is said width. Yes, the thing has a big patchbay, and I don’t consider a single connector there as wasted, but why the LFO shape knobs needs to be this big, why the envelope controls have a spacing of almost 3cm (that’s 1cm more than on a Doepfer envelope module) and similar choices are beyond me. This may very well be rooted in PCB layout considerations, or in parts shared with the Model D, but speaking just from the user perspective: it’s too big, and it would have been possible smaller.


I already mentioned something about the general sound – impressions I got when just using the synth with its normalled connections. This, however, is not why you get a semi-modular synth. You get it to put in patch cables.

But I just decided that patching ideas go into another post.

The Competition

If we name the sport “currently available keyboardless semi-modular monosynths with fully-analogue signal path”, then the competition looks like this:

  • Doepfer Dark Energy III (1osc, 1env) at €469,
  • Analogue Solutions Threadstone (1osc, 1env) at €499,
  • Make Noise 0-Coast (hard to count – “1osc, 1osc/env, 1 env”?) at €529,
  • Moog DFAM (2osc, 3 AD env) at €564,
  • Moog Mother-32 (1osc, 1env) at €575,
  • Arturia Minibrute 2S (2osc, 1 ADSR/1 AD env) at €598,
  • Pittsburgh Microvolt 3900 (again “1osc, 1osc/env, 1 env”?) at €649, and
  • Pittsburgh Lifeforms SV-1 (2osc, 1 env) at €664.

There’s actually more, but the other competitors cost more than twice as much as the Neutron.

So the next competitor is more than 30% more expensive, and (at least on paper) less powerful. Then again, most of the competitors are considerably smaller.


Behringer has made something and is able to sell it at a price below all competition, and that is no surprise.

What is a surprise, though, is that this product is a synth with a unique sound and unique character that is not just a cheap beginner’s synth, but an interesting addition to any collection of analogue synths.

There are points of criticism – the size, and the lack of linear FM inputs.

Apart from that, Behringer has created an interesting, flexible and affordable synth that serves both as a proper introduction to the modular world and a proper extension to a lot of setups.

I can’t really think of a reason not to get this – as long as you have the space in your setup.


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