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KMI K-Board-C & QuNexus RED

MPE Controller Keyboards By Nick Rothwell
Published November 2023

KMI K-Board-C & QuNexus RED

KMI’s latest keyboards offer MPE control in compact and colourful packages.

For quite some years now, Keith McMillen Instruments (KMI) have been producing an assortment of MIDI and audio devices with LED‑backlit pressure‑sensitive pads. Here it’s the turn of two small, affordable keyboard controllers: the K‑Board‑C and the QuNexus RED, each the latest revision of earlier K‑Board and QuNexus products.

The K‑Board and QuNexus are pretty much identical in terms of shape, size, construction and features. The QuNexus sports some extra sockets that the K‑Board is missing, and much more labelling on the top panel. The K‑Board is available in a variety of colours, but thankfully, my review unit was a rather conservative slightly metallic‑looking grey. The case is plastic, though it seems pretty solid and tough. The QuNexus RED is, as its name suggests, bright red in colour making it look more toy‑like than the K‑Board, even though it’s the more expensive and capable model.

Each device sports a two‑octave C‑to‑C keyboard of mini‑key pads, all white‑ish in colour; these light up when played, the naturals in white and the sharps/flats in blue (which is the closest that modern technology comes to lighting up in black). The left‑hand side of the playing surface provides controls for octave shift, pitch‑bend and various programming options, such as selective enabling of velocity, aftertouch and key position or ‘tilt’. Both devices are USB powered and connect to a host via a USB‑C socket on the left‑hand edge.

K‑Board Meeting

We’ll start with the K‑Board, which is the simpler of the two models. The ‘keys’ don’t actually move, except for a very slight compression under pressure. Despite the lack of physical movement, the keys do generate MIDI velocity which feels pretty responsive and authentic. Channel aftertouch is supported, but since the keys operate by pressure, playing a key with high ‘velocity’ will trigger a note with considerable aftertouch at its onset.

Settings in the K‑Board Editor.Settings in the K‑Board Editor.Pitch‑bend is less than ideal. There’s a small dedicated pitch‑bend pad providing fiddly and not very accurate pitch control; I think if the physical pad were longer, it might work better. Rounding off the controls, there’s a momentary Sustain button, and a Toggle button, which turns the keys into note toggles, useful for holding chords or setting up drones. There’s a pair of octave up/down buttons, but they are rather small and rather too close to the bend pad and bottom C key, so it’s a bit too easy to accidentally trigger something when switching octave, or to accidentally switch octave while playing.

To unlock the full expressive power of the K‑Board, it needs to be switched into MPE mode in the dedicated editor app (and, of course, you need an MPE‑capable DAW and/or instrument). Polyphonic pressure works fine, with the proviso that notes trigger with some pressure already applied, as noted earlier, so fine control is difficult — some kind of pressure ‘dead zone’ would be useful here. MPE Glide (polyphonic pitch control) is something of a mixed bag: the K‑Board and QuNexus don’t have side‑to‑side sensing, and so have to use front‑to‑back ‘tilt’ instead. Pitch transmission seems to be based on absolute finger position on the key (or possibly difference in pressure between top and bottom), so triggering a note with no pitch modification is pretty much impossible, as is fine‑tuning the pitch once triggered: some kind of dead zone for pitch would have been useful here as well. ‘Tilt’ mapped to pressure is a lot more practical: more so than using actual key pressure, which works best for generating note velocity. If you’re not put off by the rather unruly pitch control, or don’t need it, the K‑Board is eminently playable and expressive.

Thank QuNexus

Compared to the K‑Board, the QuNexus RED is a much more sophisticated beast. The word ‘nexus’ in the name hints at this, as do the labels on the top panel and the sockets on the sides of the case, primarily dedicated to CV/pitch interfacing (which, unfortunately, I was not equipped to test). The editing app is also a lot more detailed. The QuNexus can do everything that the K‑Board can, and although it’s missing a sustain button an actual sustain pedal can be used instead.

The QuNexus sports three internal MIDI tracks, and at any time the keyboard is attached to one of them. Each track can have its MIDI messages routed to the USB port, like a standard controller, or to its ‘expander’ port, or both. The expander port is a mini‑USB socket on the right‑hand edge of the device, and the QuNexus comes with an adaptor to turn this into a 5‑pin MIDI output. Hence, the QuNexus can operate as a bare MIDI controller without a computer (though it still needs USB power). Or, should you wish, you could route one track to USB (into a DAW) and another purely to the physical MIDI output, with further options to route to/from CV and gate. Track 1 can operate in MPE mode, in which case, as per the MPE specification, it allocates a number of MIDI channels to support polyphonic expression. Tracks 2 and 3 are non‑MPE and can each use a spare remaining channel.

KMI QuNexus RED MPE controller keyboardKMI QuNexus RED.

At this point I feel I should mention the QuNexus user interface, which could be described as inscrutable. Enter edit mode by holding Shift and you’re faced with various patterns of flashing note keys to tell you what’s going on, and assorted key‑press sequences to change things. After a bit of practice it all starts to make sense: there are the helpful labels on the device, and muscle memory kicks in pretty soon. But if you really want a clear visual indication of every detail of what’s going on, the QuNexus editor app shows everything on screen and stays synchronised with the device.

There’s an arpeggiator and a step sequencer, per track, and a global clock for timing, with play, stop and record controls. Each track is in one of two modes: arpeggiating or sequencing. When the device’s global clock is stopped, the keyboard just plays notes to its chosen destination. When playback is started, the three tracks start arpeggiating or sequence playing in time and in parallel. It’s not generally possible to have a sequencer or arpeggiator running on some of the tracks and not others: either the clock is running and they’re all active, or the clock is stopped and they are not. Only a track in sequence mode with no sequence data recorded will behave like a dumb keyboard.

With the device’s transport stopped, notes are entered into the sequencer step by step after pressing Rec. You can also go back into Rec mode to add more notes. There’s also a real‑time mode: with the transport running, hitting Rec will let you record what you play, and will punch in over the current sequence data in the style of a looper. Eight sequencer patterns can be saved per preset.

The arpeggiator supports a standard selection of patterns (including both random and Brownian motion, the latter being particularly good for generating meandering melody lines) and a repeat range of up to four octaves. It has not one hold mode but three: the first mode holds or sustains notes until all keys are released, the second turns keys into toggle switches for notes, and the third allows active notes to be ‘replayed’ to change velocity or expression settings. The step sequencer is also subject to pattern selection and octave repeat, a useful source of musical ideas.

MIDI clock quantising seemed a little hit and miss: arpeggios appeared to start synchronised to the first note played, not the downbeat of the clock, making DAW synchronisation tricky, and it wasn’t clear how sequence playback was aligned. Letting the QuNexus be master clock and the DAW follow it was much more predictable.

Keyboard settings in the QuNexus Editor.Keyboard settings in the QuNexus Editor.

QuNexus Editor

Although a lot can be achieved using the keyboard and button shortcuts on the QuNexus itself, for really detailed editing you have to fire up the editor. The editor window is a bit small and fiddly, and the overall design looks rather dated: this could do with an update and a design refresh.

One important function of the editor is that it manages and saves presets. Any of the named presets can be loaded into any of the four preset slots on the device.

The editor allows for more detailed configuration such as response curves, key priority, CV/gate configuration, and a totally distinct mode called ‘controller’, where each key can be given its own static MIDI output settings: as well as note pitch and velocity, a key can be a toggle, with controller output as well. Keys can be taken out of the standard ‘keyboard layer’ and made part of this controller layer instead — or in addition. These controller mappings are per preset. This feature is probably most useful if you want to partition off a group of keys on the QuNexus to make MIDI bindings to control an instrument or effect such as a looper.

While the K‑Board provides a no‑nonsense set of features for basic MPE keyboard control, the QuNexus is a sophisticated controller with arpeggiator, sequencer and a varied selection of I/O options.


There’s a lot to like about the K‑Board and the QuNexus. They are robust and portable, and while the K‑Board provides a no‑nonsense set of features for basic MPE keyboard control, the QuNexus is a sophisticated controller with arpeggiator, sequencer and a varied selection of I/O options. The K‑Board is hard to fault as a solid bare‑bones controller, if you can get along with the fact that the keys are pressure pads with little movement or physical feedback, and are forgiving when it comes to pitch control. The QuNexus is a more complex offering, and while its keyboard‑based interface is somewhat obscure, I got used to it quickly. I found some features to be a bit temperamental, but it worked well as an ideas generator and was fun to use. I think my preference leans toward the QuNexus for the sequencing and arpeggiation features, although I’d have liked a bit more timing precision when using them. In any case, the form factor and construction makes both models useful to have in your studio toolkit.


  • Both keyboards are light, super‑portable MPE‑capable controllers.
  • The QuNexus packs a rich selection of performance features and interfacing into its compact form.


  • Keys are pressure‑sensitive only and don’t move.
  • Position sensing (tilt) for pitch can be a bit hit‑and‑miss.
  • QuNexus clocked notes don’t always seem to hit the beat.


The K‑Board is a bare‑bones, MPE‑capable MIDI mini‑keyboard in a form factor that makes it super‑portable. The QuNexus has the same form factor but includes CV/gate and MIDI expander connections and includes a multitrack arpeggiator and step sequencer.


K‑Board‑C £129, QuNexus RED £199. Prices include VAT.

K‑Board‑C $119, QuNexus RED $199.