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IK Multimedia UNO Synth Pro X

IK Multimedia UNO Synth Pro X

IK Multimedia’s new UNO Synth Pro X is a statement of intent.

The last iterations of IK Multimedia’s UNO Synth series saw the Italian company’s paraphonic UNO Synth Pro and UNO Synth Pro Desktop commit to the trajectory set in motion by the first UNO Synth, throwing down the gauntlet as serious contenders in the analogue synth game. In my review of those instruments back in late 2021, I noted that they were surprisingly powerful, that their onboard effects were surprisingly good, and maybe the takeaway from this is that we just shouldn’t be surprised anymore. In any case, I was therefore not surprised, upon unboxing the UNO Synth Pro X, to see that IK have demonstratively sought to up their synth game and extend the appeal of the series ‘upwards’; in other words, this time around it feels like the company have, you might say, more ‘serious’ synthesists in their sights. Make no mistake: these are quality electronic instruments by any standard, even if their names do sound like a jumble of all the marketable terms IK could think of. Including the word ‘synth’.

I say ‘more serious’ carefully, because that doesn’t necessarily mean ‘better’ — Teenage Engineering for one blew that notion out of the water long ago with the gloriously dumb yet generation‑definingly good OP‑1. It’s by no means esoteric, but nonetheless a sense of accessibility doesn’t seem to be at the top of the UNO Synth Pro X’s agenda, at least in the way it was with the UNO Synth Pro. For one thing, the Synth Pro came in two iterations: a Desktop version (with a form factor exactly the same size as the Pro X), and a keyboarded version that I should point out boasted a very nice‑feeling Fatar keybed. With the Pro X, IK Multimedia have forgone the keyboard and committed to one desktop version, presumably on the assumption that anyone wanting that dimension of playability will have their own MIDI keyboard. No hand‑holding on that front, then.

Far from its predecessor’s panel’s minimal interface, ostensibly consisting of four assignable knobs and grid of parameters, the Pro X’s matte‑finish panel is replete with controls. It’s bold and upfront with its functions, many of which are carried over from before, though there are a raft of additions and improvements to speak of as well. It’s not far off a knob‑per‑function layout, and those used to conventional subtractive synth architecture will find themselves on ostensibly familiar ground.

Logic Pro X users may raise eyebrows at the name — as we’ve come to expect from IK Multimedia the Pro X is set to pair famously with your computer, with USB‑C connectivity and a brand new deep‑diving digital editor that can also assume software plug‑in form (side note: you can’t transfer presets from the Synth Pro to the Pro X). But as far as I can tell there’s no particular persuasion toward Apple’s DAW. In fact, in one interview IK product manager Enrico Dell’Aversana lightheartedly referred to the ‘X’ as standing for ‘experimentation’, and in fairness it’s easy to see why. The Pro X’s interface invites sonic exploration in a manner we’ve not seen from the Synth Pro series up to now, and it’s streamlined many features to make the whole process that bit more fluid and enjoyable as well. It’s also worth noting that the Synth Pro X’s price is the same as that of the keyboarded Synth Pro, and significantly higher than the Synth Pro Desktop. The message is clear: IK Multimedia mean business.

Transport Is Arranged

Users of the Synth Pro Desktop will notice that the Pro X has changed things around a little — or a lot — when it comes to panel priority. Where the Synth Pro had a two‑and‑a‑half octave capacitance‑sensing keyboard taking up at least a third of the overall panel space, with a miniature sequencer squeezed above it, the Pro X prioritises its sequencer with generously‑sized buttons and pops a miniature single‑octave keyboard just above. This is a good move — not least because I don’t think anyone will miss that keyboard (I’m yet to see a single person ever actually play a capacitive keyboard musically), but also because it emphasises the value of the Pro X’s sequencer as central to its character and playability. In many ways it serves to render the Pro X more a bona fide sequencing instrument in the tradition of Elektron or Roland (more on that anon) than a keyboard‑controlled synth that happens to have a sequencer included. The little keyboard is still useful for programming sequences and auditioning sounds, of course, but I’m of the view that on an instrument this size you really don’t need any more than that. I also feel the Pro X’s look and layout brings it into a more Korg‑ish territory, perhaps because of its faint aesthetic shades of the Electribe or Drumlogue.

Sequences of up to 64 steps can be punched in step by step, recorded in real time with the keyboard (the Synth Pro’s recording metronome is carried over to the Pro X) or even imported from the 10‑mode arpeggiator. Usefully, when loading up a preset the Pro X offers the choice of loading the sound, the sequence, or both, so you don’t need to recreate any sequences to play them with different voices. There’s more here than I have space to cover, but it’s a big tick in the ‘sequencer’ box.

The UNO Synth Pro’s rear panel hosts an input for an external power supply, a USB‑C port, 3.5mm sockets for CV/gate, audio input and headphone out, a pair of quarter‑inch audio outputs and full‑size MIDI I/O ports.The UNO Synth Pro’s rear panel hosts an input for an external power supply, a USB‑C port, 3.5mm sockets for CV/gate, audio input and headphone out, a pair of quarter‑inch audio outputs and full‑size MIDI I/O ports.

Engine Room

The left half of the panel is taken up by the Synth Pro X’s three oscillators and dual filters, building on the design of the Synth Pro (which itself greatly expanded on the original UNO Synth’s dual oscillator, single filter design). It can operate in paraphonic, legato or mono modes, selectable via a Voice button in the top left corner of the panel. This is as good a time as any to say I’m a big fan of paraphony, particularly when it comes to sequencing: it maintains the limitation of a monosynth and its emphasis on sound sculpting, but still allows the odd unexpected chord to appear in a sequence, or the occasional overlapping of notes in a melody line.

Singular knobs for wave morphing (from triangle through saw to square and, finally, pulse), tuning and level are switchable between oscillators 1, 2 and 3 with a button that can also be held down to edit all three together. As on the Synth Pro, to my ear the oscillators don’t have buckets of character, but they sound very nice and very clean. The two filters, meanwhile, each get their own panel controls for cutoff, resonance and envelope amount. Filter 1 is OTA‑based, while filter 2 is SSI chip‑based. A column of buttons allow for a range of various modes: you can link the two to be controlled by filter 1’s controls, switch filter 1 between low‑ and high‑pass modes, switch filter 2 between 2‑ and 4‑pole modes, and put the two in either parallel or series in the signal chain. Right out of the gate there’s a real emphasis on the filters as the Synth Pro X’s primary sound sculpting tool; much more than on the Synth Pro. It’s a bigger and more detailed section than that of the oscillators, even if the oscillators do also offer FM, sync, noise and ring modulation.

Ring modulation? Dual filtering? Of course the Korg MS‑20 springs to mind. No complaints here, of course; the MS‑20’s pair of filters is one of the reasons it has a place in the hearts of synthesists the world over, and I was happy to see its architecture nodded to here, since it’s surprisingly rarely seen in other instruments. The Synth Pro X’s filters don’t have the same analogue snarl as the MS‑20’s in and of themselves, but as a pair there’s something rather brilliant about them — much more than the sum of their parts. It’s also worth pointing out that the Synth Pro also had dual filters, but it goes to show how much interface design can influence a player’s approach: on the Synth Pro it felt more like a handy bonus feature. This time, with the two ready and waiting on the panel for hands‑on tweaking, it feels positively crucial to the workflow. I will also say that they magnificently work to channel the filter of the now‑legendary TB‑303, and were more than capable of imparting the kind of tasty acid house throatiness I was hoping for from them.

This is not lost on IK Multimedia, who cite the 303 as the inspiration behind one of the Synth Pro X’s more intriguing features: Bassline mode. This mode makes a few nudges across the board to alter the Pro X’s character in the name of fluid low‑end sculpting, for instance reducing the upper frequency limit from 20kHz to 5kHz and limiting the envelope to just the attack and decay stages. It also enables an Accent feature on the envelope for emphasising certain steps in a sequence. While this mode certainly does a brilliant job of channelling oodles of watery, distorted 303 energy, one frustration came with the fact that, at least on the loan unit in front of me, Bassline mode doesn’t seem to be a simple on/off affair: hit the button to enter the mode; hit it again and you’ll exit the mode but with a smattering of parameters changed, with no immediately clear way of going back to where you were. Perhaps this will be addressed in [cough] a future firmware update? Part of me feels that this kind of bass‑building is already inherent to the Synth Pro X’s character; surely it could have been worked into the overall workflow (via a button to remove the latter two stages of the envelope, for example) instead of being spoon‑fed via its very own global mode. It’s a fun feature, though, to be sure, and at the end of the day there’s no mandate to use it.

In The Deep End

The top right of the UNO Synth Pro X is home to a small OLED screen and grid of master control buttons for preset storage, tempo adjustment, arpeggiator toggling and more. Happily, with the panel of the Pro X providing so many controls at my fingertips I found myself deferring to the screen and its encoder surprisingly little — which isn’t something I could say of the Synth Pro. In fact, Enrico Dell’Aversana has previously chalked up the Synth Pro as a ‘preset machine’ compared to the Pro X. Don’t look at me — his words, not mine — but I will say there’s far less dreaded menu diving to speak of this time around. What the screen does do very nicely is display values, allow for global settings, enable preset naming and recall and the like. At the end of the day, I’d say IK Multimedia have got the screen‑to‑panel balance about right.

To the left of this section is a single envelope generator, switchable via a button between amplitude and filter control. Said button also allows for the editing of a handy third envelope, which can be assigned to go almost anywhere. Another very nice touch, again rarely seen on an instrument like this, is the option to have the envelope’s attack and decay stages loop like an LFO. Beneath this is the LFO proper, with a single set of controls for both LFO 1 and 2; once again switched between via a button. Frequencies can be freeform or sync’ed to a clock division at the push of a button, which is another nice, sequencer‑friendly addition, and there’s also the option for the LFO to fade in with a truly languid maximum fade time of 10 seconds.

When it comes to modulation at large, I was extremely impressed by the Synth Pro’s capacity for incredibly deep and flexible routing. Three unassuming Source, Destination and Amount buttons in a section labelled Matrix on the far left of the panel allow for slick, upfront modulation programming. Push the Source button, turn a knob to assign; push Destination and turn another, then adjust the amount using the Pro X’s data encoder. It’s quick and phenomenally creative, not to mention open‑ended. Parameter changes can also be recorded in real time across a sequence, and there’s even step‑by‑step parameter ‘locking’ for truly articulate, synth‑wide sequencing with automated parameters and effects.

When those two filters start to move and grind against one another, when waves morph to and fro, when effects swell and die down across a sequence, it all amounts to something rather special.

Effective Communication

As with the Synth Pro, the effects on the Pro X do a good job of punching a fair way above their weight. The three effect categories of modulation, delay and reverb are squeezed into the same four‑knob section beneath the LFO controls, with — you guessed it — a button to toggle between them, while the post‑filter, twin‑diode drive circuit is positioned on the other side of the panel beside the main volume knob. This I’m an advocate for: one‑knob analogue drive is never unwelcome, and for me it almost always does something to reiterate the joy of using hardware and bring out some real character. While I would have loved the option to place the drive pre‑ or post‑filter — which doesn’t feel like a stretch given the amount of flexibility on offer here — the Pro X’s drive nonetheless sounded great and gritty to my ear, adding genuine value to the overall result. Further, placing it alongside the volume knob makes a great pairing for broad‑strokes gain and tone control; between the two of them there’s a lot of scope.

Meanwhile the other three effects, as mentioned, are grouped. Their shared controls aren’t the most intuitive, with labels for the reverb effect (Time, Size, Filter and Amount) given priority on the panel over those of the other effects for some reason. In fact, I would probably have preferred the knobs to simply be labelled ‘param 1’, ‘param 2’, etc, so I could know from the outset simply to reach for the screen and data encoder for all my info, effect‑wise. As it is there is a lot to choose from with the Synth Pro X’s effects, but some scanning of the manual is almost certainly needed to figure out how to access it all. Shift‑Amount, it turns out, is used to choose from a host of sub‑categories per effect. Reverb offers a choice of hall, plate or shimmer. Delay offers mono, stereo, doubler, ping‑pong or LCR (a mode that cycles the delay signal from the right channel through the centre and into the left channel). Modulation effects have been given a reboot: there’s chorus as before, but the Pro X’s eschews the phaser and flanger offered by its predecessor and instead opts for a uni‑vibe effect. Given the option, I would probably have preferred the previous effect selection, but that’s a matter of preference. There isn’t much to complain about here; the OLED screen means things don’t take too long to adjust and at the end of the day the effects sound very good, particularly when one starts to bring modulation into the picture.

More Than The Sum Of Its Parts

On that note of modulation, all things considered it’s the sheer depth of features like this that really constitute the heart of the Synth Pro X. It certainly sounds good in a static mode of operation, but when those two filters start to move and grind against one another, when waves morph to and fro, when effects swell and die down across a sequence, it all amounts to something rather special. What gives the UNO Synth Pro X its edge isn’t so much its raw sonic power — as I’ve said, its oscillators didn’t stagger me but they certainly get the job done, and the same goes for its filters. Its functionality, however, is excellent. Suffice to say: three oscillators, dual multimode filtering and such a deep modulation matrix on a synth this size — and at this price — is impressive, and to further furnish it with some quality effects and analogue drive is laudable.

I mentioned that the Pro X feels aimed at more serious synthesists than the Synth Pro, but at the same time I don’t believe IK are trying to placate purists here. The UNO Synth Pro X is a powerful and multifaceted instrument that will reward hours of experimentation, yet it still manages to stay fun and light on its feet in all the ways that matter. Explorative enough for the studio and upfront enough for the stage, it’s very much a success for IK Multimedia.

Going Soft

IK Multimedia UNO Synth Pro X

The UNO Synth Pro X welcomes a brand new software editor, building on the one that came with the Synth Pro. While it’s not possible to transfer presets from the Synth Pro to the Pro X, it has become a lot easier to edit and store sounds thanks to an updated interface that both mirrors and expands the hardware unit’s panel. The workflow is therefore nicely transferable between the two, while oscillators, envelopes and more are rendered in a knob‑per‑function layout, with automated parameters moving in real time. Its modulation matrix and effects page also break out a host of the Pro X’s functions and present them on a platter, while the librarian page allows for easy storage and management of presets. The Pro X can be bus‑powered, so I can easily imagine it becoming best friends with your laptop; entailing all the flexibility and portability of working in software while sculpting sounds in the analogue domain.


  • Hugely improved panel layout.
  • Excellent range and depth of modulation.
  • Intuitive and flexible sequencer.
  • Quality effects and drive.
  • Oodles of preset storage with independent sound and sequence recall.


  • ‘Bassline’ mode feels a touch superfluous.


IK Multimedia have shown just how serious they are about their synth game with the greatly improved UNO Synth Pro X: a characterful, classy and highly functional instrument that will prove as valuable in the studio as it is on stage.


£519.99 including VAT.

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