New Gear Review: Behringer Pro-1 Synthesizer
Can the Behringer Pro-1 uphold the reputation of the classic Sequential Circuits Pro-One it was inspired by?
Behringer is making synths now. Yes, that’s right. As unexpected as it may seem, and as complicated as it’s become, the German-based manufacturer has spent the last few years making its presence known in the world of synthesis.
A few of their releases have been their own original designs, but most of the Behringer synth lineup currently is made up of unofficial clones of previous instruments that already have public adoration. The first of this series was the Behringer Model D, which took Moog’s famous circuit and put it into a Eurorack-friendly enclosure with a few new tweaks. Most head-turning was the price—$299 USD, brand new. Tongues started waving, preorders started lining up, and despite the wait, Behringer’s Model D has lived up to the hype. It’s nearly—if not totally—impossible to tell the difference from the real thing, and this version of the famous synth can fit into a backpack, not to mention the fact that its price is within reach for a much wider audience.
There have been a fair number of divisive voices questioning the ethics behind Behringer’s practices. Behringer has responded in kind that everything they are doing is perfectly legal and within the trademark rights. However, they haven’t totally stuck to this strategy. Behringer has gotten praise for their own original designs as well. Two examples are the Deepmind12, an analog poly-synth that starts with a Juno-like framework and piles on effects and deeper modulation; and the Neutron, which is a similar format to the Model D but uses two 3340-based oscillators and a much larger array of patch points for greater timbral possibilities.
Unlike those two synths, the Behringer Pro-1, quite obviously, will look familiar. As you can no doubt decipher based on its name, looks, and overall appearance, it is largely a reproduction of the Sequential Circuits Pro-One analog mono-synth, which came out in 1981 and became a favorite of many young programmers and bands alike. Behringer’s version of the famous instrument is said to be an exact replica of the internal analog circuitry—they even managed to recreate the original typeface used on the front panel. Interestingly, Behringer’s team did add a few new tweaks that significantly expand what the Pro-1 can do. So, let’s dive in.
Features
The signal path of the Pro-1 as mentioned, follows the exact design of Dave Smith’s original, so if you are familiar with that machine, there won’t be many surprises here—though there will be a few!
There are two oscillators, the first of which offers sawtooth and square waves, with a variable pulse width of the square wave. There are four octaves to choose from, as well as a Fine Tune knob, which sweeps slightly less than an octave in either direction. The pulse width modulates from 50% to almost a full 100%, at which point it is nearly inaudible. The second oscillator also has sawtooth and square waves, but adds a triangle wave into the mix as well, which adds a nice warm, subby flavor to the Pro-1’s sound.
Each waveform can be turned on or off individually for each oscillator, so a lot of timbral complexity is already possible before the signal even gets to the filter. Each oscillator has its own Level knob in the mixer section, and there’s also a separate white noise generator. When an audio signal is plugged into the external audio jack on the front panel, that knob becomes a volume for that source. (More on the other jacks on the front panel later.) Oscillator one can be synced to oscillator two for those classic tearing/ripping sounds that you’d associate with many classic 80’s synth riffs.
Curtis Audio, the company founded by Doug Curtis that produced the original CEM3340 that was in the Pro-One, started reproducing the chips not long ago, but Behringer uses their own clone of the 3340 VCO chip. The chip is made by CoolAudio, which is, you guessed it, owned by Behringer. There are now quite a few Eurorack modules that use other 3340 chips as well, so that famous Curtis chip sound of the CEM3340 isn’t as hard to come by as you’d think. These are the voice chips made famous in the original Pro-One, the Roland SH-101, SCI Prophet 5, Oberheim OB-Xa, Jupiter 6, and other synths, but they’ve now also been featured in Behringer’s Neutron and Crave tabletop synths. Suffice to say, the 3340 sounds very good in the Pro-1, and every analog adjective you can think of—juicy, vibey, warm, alive, etc.—applies here.
The Pro-1 also features a very growly and flexible 4-pole low-pass filter. Confusingly, Behringer’s site incorrectly lists the synth as having a choice of low- or high-pass filters—this isn’t true, unlike their Model D recreation. The Pro-1’s filter can self-resonate and act as a sine wave oscillator when key tracking is set by ear, though this takes a bit of trial and error as proper tracking isn’t exactly when the knob is set to 10.
Just like the original, the Pro-1’s filter character is fairly different from the classic Roland flavor. While these adjectives can be interpreted totally subjectively, I’d describe the Pro-1’s filter as being more “zappy”, and the SH-101’s filter as being more ”rubbery”. I realize we’re dangerously close to dancing about architecture here but it is worth noting.
Moving along in the Pro-1 signal path, you will find full ADSR envelopes for both the filter and the amplitude envelope, a Master Volume knob, as well as an Overall Tuning knob. Unlike the Model D, the Pro-1’s headphone output doesn’t have a separate volume control.
The original Pro-One was famous for its “complex” modulation matrix, where three sources could be routed to five destinations either directly or through the mod wheel. This is recreated exactly in the Pro-1, and using it is where some of those more idiosyncratic sounds will come from.
One improvement over the original is that Behringer have made the Pro-1 duophonic. Each oscillator can be triggered to play a separate pitch by flipping up the somewhat confusingly-labeled “Poly” switch on the front panel, though both oscillators share the same envelope and filter settings. Setting the glide to Automatic, as opposed to Normal mode, allows for legato sounds when several notes are held down at once.
Further improvements over the original include the fact that the Pro-1 is now MIDI-fied, both with full size MIDI input and thru jacks, and a USB connection which effectively functions as a MIDI interface. As mentioned, the Pro-1 also features Eurorack compatible patch points on the top of the front panel. It’s also possible to remove it from the case and use it in your Eurorack case, with power coming from your power source.
In Use
Just like the original, the Pro-1 features a 40-note sequencer with the ability to store two sequences, even after shut-off. Programming in notes is a bit archaic but it works fine. The arpeggiator is identical as well, with just two choices (up and up/down), and no ability to change octave range.
If you’re familiar with the original Pro-One, you’ll be quite quickly surprised at how familiar the Pro-1 will seem. Though you’ll also realize something else very quickly—this is a front-panel synth and what you see is what you get! Nothing in the form of presets here. However, this does mean that you learn to program it rather quickly.
A view of the Pro-1’s streamlined rear panel.
Despite the fact that it must be programmed manually, it’s possible to summon a very wide range of sounds from the Pro-1. The original Pro-One was always known for its deep bass, despite the fact that increasing the filter’s resonance does cut some low end. This behavior is replicated on the Pro-1, though it never seemed to be a huge problem. One thing to note is that the lowest MIDI note that you can trigger on the Pro-1 is C1. This is another ”quirk” inherited from the original design.
Regardless, all manner of bass, lead, and noise effects are possible. Even pad-like sounds are possible by tuning the oscillators to your choice of interval and setting the filter to self-resonate, effectively adding a third oscillator and making three-note chords possible. If you’re looking for pulse width modulation, the Pro-1 excels in several varieties. Using the modulation matrix to route either the LFO or the filter envelope to affect the pulse width adds a lovely thick movement to the sound. It’s easy to overdo it given that the pulse width goes all the way to 100%, which can be useful when trying to apply a tremolo-like effect.
The fact that there are patch points also greatly increases what’s possible, even though the built-in modulation matrix is still intuitive and powerful, especially compared to the relatively meager modulation sources the Model D offers. Assign a few modulation sources to the modulation wheel, and a simple timbre can be twisted into something with claws quite quickly.
To Be Critical
Behringer has probably been sending out boatloads of these, but that’s really no excuse for the fact that mine came very badly calibrated out of the box. Oscillator two didn’t track properly across even an octave, and the oscillators were set to two totally different pitches with both Pitch knobs set to noon. Opening up the unit and tweaking two internal calibration knobs fixed both of these problems, but it did take a bit of fine-tuning to get right.
It’s also easy to compare the Pro-1 to the Model D given that they are both classic mono-synths. Even though it’s a simpler circuit design overall, the Model D does have three full oscillators and a noise source, as well as a built-in way to overdrive the filter input. The Pro-1 would really benefit from being able to add just a bit of grit before it got to the filter, though I’m sure something is possible with the proper patching using an external VCA.
It also would have been nice if the Cutoff knob had been a bit enlarged like it is on the Model D—that makes finding it on a dark stage much easier. And while we are suggesting changes to the original design, one area that could greatly benefit is increasing the possibilities of the arpeggiator. It’s very simple here.
Summing it Up
Behringer is doing something most other manufacturers haven’t dared to do—taking old classic designs, making subtle tweaks, and putting these new instruments into small, desktop enclosures with low price tags to match. And unsurprisingly, its working! The Pro-1 sounds and behaves exactly like you’d expect an original vintage Sequential Circuits Pro-One to. This also means it comes with all of the same idiosyncrasies as the original—not including those clacky keys that often failed!
Overall, this is an instrument that I literally was dreaming of a few short years ago upon having to sell my beloved Pro-One that came in a bespoke purple case and supposedly previously belonged to a member of The Cars. If you had told me that I would soon be able to buy a new, reliable version of the Pro-One in desktop form for $349 new, I would have been among the first to sign up, years ago. The fact that it’s now here and available to the masses means only one thing—there’s really no excuse for not getting back to the studio!
Leo Maymind is a producer, DJ, and writer living in Los Angeles, CA. He is obsessed with sound, and you can reach him at lmaymind@gmail.com.
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