Review Behringer Neutron Synthesizer

A year and a half since Behringer first plunged into the analogue synthesis swimming pool with the Deepmind 12, it is back with a (UK-designed) dual oscillator monophonic/paraphonic semi-modular synth, that can likewise be installed in a Eurorack case for combination with an existing modular setup.

A year and a half is a long time for a company, like Behringer, with such a big variety. In that time, there’s been much speculation occurring from some of the craftily spun ‘leaks’ that revealed its intention to revisit an entire host of timeless synths and drum devices, and reimagine them for the 21st century. The very first fruits of this were the Design D, based upon the legendary Minimoog.

Of course, Behringer is no stranger to controversy when its comes to look and performance (and its apparent resemblance to other completing items). Nevertheless, like the Deepmind, the synth on evaluation here is initial in both feel and look. The Neutron’s front panel is of an unique red style, and appears to have been influenced (for better or even worse) by synthesiser aesthetic appeals of the 1990s. It includes vintage Moog-style knobs with a 56-point mini-jack patchbay to the right.

The rear panel hosts 1/4″ jack sockets for line level audio in and out, and an associated headphone output. A USB socket is consisted of for two-way MIDI communications, though parameter values can neither be sent or received. The MIDI THRU on the rear can, nevertheless, be pressed into service for producing multi-unit polyphony via the Polychain feature. There is also a MIDI input on the front panel, important if you want to install it in a modular Eurorack system.

The Neutron features two comparable oscillators based around the V3340 VCO chip. This is an entertainment of the famous CEM3340 found in a host of traditional synths (see boxout). Both oscillators have a similar set of controls. The Variety button changes in between three different octaves. The Tune control supply +/- 1 octave of modification, however when all the Variety buttons are lit, changes to a +/- 10 octave (with both low and high extremities inaudible to anything except a sub-bass loving mouse). This mode is best when using the Neutron as a standalone sound-effects generator. The oscillators can generate five various wave shapes, but there is more versatility here than is initially obvious.

As you ‘d expect, Sine, Triangle, Sawtooth and Square (with independent Width control) are all present. Nevertheless, an extra ‘Tone Mod’ setting enables you to call in some additional, harmonically intriguing, sonics. Here the Width control appears to change some type of wave-shaping circuit. This isn’t quite the complete photo, as the Forming control likewise enables you to move smoothly between nearby wave shapes. This can even come under external control via the patchbay. Combined with oscillator Sync, a White Sound generator, and the capability to freely mix in between the two sound sources, there is quite a bit of flexibility on offer. Usefully, you can likewise add an external audio source to the oscillator mix by plugging in to the rear panel audio input.


When combined, all these components are routed through the filter section. This has three main filter modes all based around a 12dB/octave design. Fed by an easy square wave, we evaluated the filter in low-pass mode, and it formed the noise in a largely rewarding way. Although a little less abrupt than the majority of 24dB/octave styles, it supplies quite a bit of bite. Turning the resonance up pushed the filter into self-oscillation which, with keyboard tracking engaged, generated a tone that was in tune throughout the keyboard. There is a secondary filter output on the patch bay which permits the production of a notch filter alongside the switchable band, low and high-pass types.

As the Neutron is a semi-modular style, there is a normalised routing for the various modulation sources. In this case the LFO is routed to control filter cutoff, and a Mod Depth control in this area determines its general strength. At fast LFO (audio) rates this produces some additional fascinating tones. The patchable nature of the synth enters into its own when modulating the LFO rate and depth to manage the strength and tonality of these newly developed side-band frequencies. Envelope 2, an uncomplicated ADSR, is likewise routed to manage filter cutoff (via the Envelope Depth control). For fast to medium sweeps this works well, though it would have been nice to have longer optimum attack, decay and release times.

One issue that was especially frustrating was the method which even percentages of resonance pressed the filter into saturation area. It’s terrific to be able to access the dirtier side of things, however this shouldn’t be to the detriment of more standard tones. Even with the overdrive section called down completely, the level from the oscillator area was hot enough to destroy the tonality of some sounds. In fact, it needed routing the signal via among the attenuators in the patchbay to bring it within a reasonable variety. A dedicated level control for each oscillator would have been useful here.


In the later half of the 1970s, synthesisers began employing incorporated circuits (ICs/chips) as a replacement for circuits utilizing a larger number of discrete elements. As well as providing cost savings, these chips allowed for better stability and enhanced calibration and control. Nevertheless, while some only rate a synth using fully discrete circuitry, these early ICs have ended up being revered in their own right.

One great example of this is the CEM3340. Initially produced by Curtis Electromusic, they are back in production today. To make complex things even more, there are a variety of modern clones that take advantage of the fact that the initial Doug Curtis design runs out copyright. Music Group, Behringer’s parent business, has been making ICs through its Coolaudio subsidiary for more than 15 years, with a client base that includes Dave Smith Instruments and Elektron. On its website you’ll discover the V3340 (oscillator) and 3320 (filter) to name a few (including pail brigade delay ICs). These synth chips were also utilized in the Oberheim OB-Xa, a clone/ homage of which Behringer has promoted as one of its future items.

As discussed briefly above, the Neutron has a (bi-polar) LFO, and like the primary oscillators, has numerous wave shapes that can be combined effortlessly from one to another. With a greatest frequency of 10kHz it is capable of audio rate modulations that produce the abovementioned side-band frequencies. Secret Sync re-triggers the LFO cycle with each brand-new note, and turns it into a pseudo envelope generator if needed.

Our only dissatisfaction is that there aren’t 2 independent LFO generators on Neutron. Perhaps we’re just being greedy, however we make sure area might have been made by employing a smaller LFO Forming control. Having gone through the VCF, the signal enters the overdrive section which adds variable quantities of distortion. The manual states that the tone control forms the noise of the overdrive, but this tilt-style EQ/filter likewise impacts the signal with overdrive at its minimum setting, which makes it useful for general tone-tweaking responsibilities.

After this area’s level control, the audio earnings into a VCA controlled by Envelope 1 (another four-stage affair), and then into an analogue delay area. This employs a ‘new’ old-style chip using a series of capacitor components in so-called Pail Brigade configuration (with 8192 stages). Delay lines such as this are exemplified by a somewhat noisy, lo-fi noise – and this one is no exception, with character trumping fidelity at lower delay times and with the feedback (Repeats) pressed to the max. This is a terrific addition to the synth, putting dubby squelches, Italian retro scary sound results, and modulation treatments such as chorus and flanging within simple grasp.

However, there was one substantial issue on the review unit. Even with the mix control twisted firmly to its minimum, the delay output might be heard bleeding into the dry signal path. Hopefully this will not be an issue on full production units. That takes care of a lot of elements in the audio signal course, though there are a couple of additionals in regards to control parameters. It’s nice to have a devoted Sample & Hold area (for creating random stepped modulations), and 2 Slew Rate Limiters. These slow down the rate of change of any inbound control signals, and the Neutron has 2 onboard.

One is dedicated to portamento sliding of legato notes, and the other can be applied to any signal through the patchbay. 2 signal attenuators are another great addition. By default, the LFO is routed through Attenuator 2 and after that on to the pulse width of each oscillator. However, the attenuators would gain from greater resolution at the lower end of their travel variety (like when fine tuning vibrato).

The final, and extremely substantial, piece of the Neutron equation is the patchbay. This isn’t some general nod to modularisation, however an extremely useful addition to a capable synth. In fact, it goes rather a method beyond most of its competitors in regards to the sheer number of patch points. This makes it an ideal tool to get the hang of the ways in which user patching can be harnessed in the pursuit of initial and appealing sounds. The Neutron has its defects, and there are some frustrating style concerns.

Nevertheless, it does sound good, and in regards to bang-for-your-buck, it’s quite a steal. While it does an excellent task at producing more sensible noises, it likewise excels at the odd and fantastic. At first, we checked it by itself, and had a lot of enjoyable without a keyboard or MIDI cable television in sight. Behringer may just have a winner on its hands.

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