Uno Synth Pro review: IK Multimedia shows it's serious about hardware

With dual filters, rich oscillators and powerful modulation matrix the Uno Pro is a powerful sound design machine.

Terrence O'Brien / Engadget

The original Uno Synth was IK Multimedia’s surprise entry into the world of budget-minded hardware instruments. It wasn’t just a surprise that the company, best known for its iPhone-friendly MIDI controllers and plug-ins, decided to make a synthesizer, but that it also went full analog — an area where it didn’t have much pedigree. The results were mixed, but the general consensus was that the Uno’s core sound was impressive. Now IK is trying to move up a weight class with the Uno Synth Pro — a three-voice paraphonic synth with its crosshairs squarely aimed at the likes of the Korg Minilogue.

Of course, as with most musical instruments, there is no apples-to-apples comparison. So whether you’re better off spending your synth dollar on an Uno Pro or on something else will depend on your priorities.

The Uno Synth Pro comes in two different flavors: the standard Pro with a 37-key Fatar keybed and a partially metal chassis; and a smaller Desktop model with a set of touch keys and an all-plastic body. The Pro version costs $650, while the Desktop is just $400. I tested the Desktop model, so I can’t tell you much about the feel of the more expensive one, but if you already own a decent MIDI controller and don’t plan on gigging with the Uno Synth, save yourself the cash; they’re otherwise exactly the same instrument.

Under the hood are three oscillators with continuous wave shaping from triangle to saw to square (with pulse width modulation). There are options for hard sync, ring modulation and FM, plus two envelopes, two LFOs, two filters, analog overdrive and a selection of 12 digital effects. In short, there are plenty of options for sound design, especially when you consider the 16-slot modulation matrix.

Engadget · IK Multimedia Uno Synth Pro review

Physically, the Uno Synth Pro Desktop is a bit of a mixed bag. The overall construction is plastic, and certainly feels it, but it’s solid enough. The knobs offer a good amount of resistance and the buttons are decent. The same is true of the screen: It’s small but gives you all the info you need. The gray, black and red color scheme can make quickly spotting the controls you’re looking for a bit difficult, especially the secondary and shift functions. (On a dark stage they’d be impossible to find.)

The four knobs at the top are used to change almost all the parameters by navigating a grid beneath it. I’ll admit that the interface isn’t my favorite. But in order to keep costs down while preserving as much flexibility as possible IK Multimedia went with a light-up grid instead of a knob per-function design. It’s a decision I could quibble with, but one that I can accept. Also, it’s worth noting that if you want to get real specific with a parameter it’s better to use the endless encoder to the right of the screen after selecting your target with the four pots to the left.

Uno Synth Pro Desktop
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The biggest problem, however, is with the touch keys and strips. Now, to be clear, this criticism does not apply to the full-sized version with a proper keybed, only the desktop model. But, to be blunt: The capacitive keys and touch strips are not good. They can feel unresponsive. Occasionally, the Uno Synth would straight up fail to detect my touches. And putting the synth in three-voice paraphonic mode seemed to make things worse. The same is true of the pitch and mod strips; sometimes they’d fail to register my touch or react slowly to it. The mod strip in particular is easy to trip up if you move your finger too fast and it has a tendency to jump between values rather than smoothly glide between them. If you plan to actually play your Uno Synth Pro (rather than use an external sequencer or controller) I highly recommend you spring for the full-sized version with the keybed and pitch and mod wheels.

The Uno Synth Pro does have a pretty solid arpeggiator and sequencer, though, so there’s a chance you can get by without having to ever touch the “keys” on the desktop version. There is also a scale mode in the settings that disables the black keys and maps the white ones to the scale of your choice. Which, at the very least, makes it less likely that you’ll sound out of key if your finger lands three millimeters to the right of where you intended.

Uno Synth Pro Desktop
Terrence O'Brien / Engadget

And look, I get that touch keys are hard to do right. They were bad on the original Uno Synth. They’re bad on Modal’s Skulpt and Craft synths. The Volca’s are slightly better, but still quite cramped. Honestly, the only synth I can think of where the touch keys aren’t a liability is the MicroFreak. (And there are probably people who would disagree with me even on that.)

Many of the frustrations I have with the interface and physical controls are immediately forgotten once the Uno Synth Pro starts making noise, though. In short, it sounds glorious. Especially with all three of its oscillators stacked in mono mode. While the Pro is a three-voice paraphonic instrument, I think it’s at its best when treated as an extremely beefy mono synth. The oscillators have a lot of body and grit to them. The triangle is glassy but dusty and the saw wave just plain rips. Add a bit more dirt from the analog drive circuit and you’ve got a truly gnarly sounding machine for leads and basses.

The oscillators can also be hard synced, there’s pulse width modulation (though no dedicated knob for it), ring modulation and FM for more metallic sounds. The FM function, though, is slightly hidden in the menus, which is a shame. It’s a valuable sound design tool that’s just not as accessible as it should be thanks to some questionable interface decisions.

IK Multimedia Uno Synth Pro Desktop
Terrence O'Brien / Engadget

The dual analog filters are also lovely. The multimode two-pole filter from the original Uno Synth is here and it’s just as juicy as ever. It can be a bit aggressive, but that’s part of its charm and it really hits the spot if you’re into acid basslines. Then there’s a switchable SSI-based lowpass filter with two and four-pole modes. It’s a little subtler than the multimode option, but with the resonance cranked it will self-oscillate and scream.

The two filters on their own are solid enough. But special things happen when you combine the two. They really allow you to start pulling out unique timbres. You can run them in series to create effectively notch or bandpass filters, or in parallel using each to pull out slightly different tones and then combining them into something new. There’s even an audio-in jack on the back, so you can route any instrument you want through the Uno Pro’s filters and effects. It’s just a shame that it’s an ⅛-inch jack instead of a ¼-inch.

IK Multimedia Uno Synth Pro Desktop

Speaking of the built-in effects, they’re pretty good. The reverbs are lush, the delays effective (if nothing special) and the modulation effects add some body. Not all of them are a home run and the controls are limited, but they do add a lot to the already impressive sound crafting tools at your disposal. The phaser and flanger are forgettable, but the Chorus is pretty solid, especially on the “string” algorithm. The reverse reverb, when combined with one of the delays, can even make the Uno Synth Pro a viable pad machine. Which is pretty impressive because, in paraphonic mode you only have a single amp envelope and you only get one oscillator per note, which can sound a bit thin.

I will say, though, that putting the synth in paraphonic mode and then dialing in a different sound for each voice is super fun and adds an interesting dimension to pad and key sounds. Because there’s a single amp envelope it’s hard to get anything really jittery and glitchy that way, but it does help beef up pads.

The final ingredient in the sound design here is the modulation matrix. This is where you can use the two envelopes or the two LFOs, or even the tuning of the oscillators to control everything from delay amount, to filter cut off, to wave shape, to the rate of an LFO. There are 16 modulation slots that you can fill to get subtle tone changes to bonkers EDM sound effects, with a total of 30 modulation sources and 35 destinations to mix and match.

IK Multimedia Uno Synth Pro Desktop
Terrence O'Brien / Engadget

The matrix does require some menu diving, but it’s pretty straightforward and incredibly powerful. Without it the Uno Synth Pro is a solid but unexciting instrument. But once you start delving into the modulation matrix it really starts to standout from the crowd.

Again, though, it does require menu diving to make the most of it. And this is really the biggest knock against the Uno Pro. I’m just not that interested in navigating sub-menus on a tiny screen on my hardware instruments. It makes me less likely to experiment and push the limits of a device.

IK Multimedia has apparently heard this complaint loud and clear and has built an editor app for macOS and Windows. This makes managing presets and programming the modulation matrix much easier. It puts all your options front and center and, other than switching tabs from the sound engine, to the matrix to the effects, there’s really not much menu diving to speak of. The app is also supposed to work as a VST plugin with your DAW of choice, but I couldn’t get that to work. It functioned fine in standalone mode, but every time I fired up Ableton and loaded the Uno Synth Pro Editor plugin, it failed to detect the instrument.

Uno Synth Pro Desktop Editor
Terrence O'Brien / Engadget

Keeping the Uno Synth Pro tethered to a computer over USB isn’t ideal, though. Ground loop hum is a real issue for devices in this price range, and the Uno Synth Pro is no different. I was actually able to hear it quietly recalibrating itself over and over thanks to the interference. The balanced outputs on the instrument can help, but even then it’s still pretty noisy and you need to have the balanced audio cables on hand. Standard “instrument” cables aren’t going to cut it here.

The desktop model even relies on micro-USB for power which is surprising and slightly annoying. The company did that so that you could power it with a battery pack while out and about, but there’s already a micro-USB port for MIDI, so having a second just for power is unnecessary.

The last downside I have to mention is that, just like the Uno Drum, the Uno Synth Pro feels unpolished. It goes beyond the somewhat frustrating interface and the mediocre build quality, though. The firmware is a bit buggy. As I mentioned earlier, the keys and touchstrips are unresponsive and jumpy at times. But I’ve also seen weird behaviors like the screen flickering and the audio getting choppy when I select a new preset. After about 30 second it settles down, but still, it’s worth noting. I also saw a full-on crash and freeze once.

IK Multimedia Uno Synth Pro Desktop

So the question becomes: Does the incredible sound of the Uno Synth Pro make up for its myriad annoyances? I’d say unequivocally yes if you’re looking for a feature-packed monosynth and don’t mind menu diving. There are plenty of other great sounding monophonic instruments out there for about the same price, like the Korg Monologue, but they lack the depth and feature set of the Uno Pro. Then there are high-end monos like the Moog Sub 37 that cost more than twice as much as the Uno Pro at $1,800.

The equation gets more complicated if you’re planning to make use of the Uno Pro in paraphonic mode for pads. I might consider spending your money elsewhere at that point. The original Minilogue still offers an incredible analog bang-for-your-buck and true polyphony. Then there’s the Minilogue XD, which is the same price as the full size Uno Synth Pro ($650), also has excellent effects, a combination of analog and digital oscillators, plus access to sound engines and effects developed by third parties for the ‘logue SDK.

And if you don’t demand analog, there’s the Arturia MicroFreak which offers as much depth on the sound design front as the Uno Pro, but for only $350 and its touch keys don’t make me want to rip my hair out.

My frustrations with the Uno Synth Pro’s interface aside, it’s hard not to be impressed with its wealth of sound design tools. And IK Multimedia didn’t cut any corners when it came to the quality of the oscillators and the filters. I will admit to being skeptical of the Uno Pro, but once I started exploring it I was a convert.

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