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Keith McMillen K-Board Pro 4, Reviewed

Marty Cutler



Expressive synthesis is literally under your fingertips on keys that don’t actually move.

The Keith McMillen K-Board Pro 4 is one of the latest generation of MPE controllers. The formal adoption of MIDI Polyphonic Expression (MPE) into the MIDI protocol prompts new playing techniques. It also challenges the capabilities of conventional MIDI controller hardware and the synthesizer’s abilities to express modulation on a per-note basis. A diverse crop of controllers and synths now provides as many modes of expression as you have appendages.

By distributing MIDI events over multiple MIDI channels in much the same way many MIDI guitars do, MPE lets you articulate individual notes in ways that would otherwise affect all MIDI notes. Examples include bending individual notes or different amounts of vibrato or resonance per note, even when applied to a chord. (For more information on MPE, see the story in our first issue, “Roger Linn Digs into MPE Controllers.”)

Keith McMillen’s take on a proper MPE controller is the K-Board Pro 4 (KBP4), a four-octave keyboard with a few new wrinkles. To begin with, the KBP4 uses raised keys, which undoubtedly can help ease players moving into MPE from a conventional MIDI controller. Don’t expect the feel of a typical synth-action keybed, though, as KBP4 has no moving parts. Instead, the keyboard is simply a silicon overlay to McMillen’s Smart Fabric sensors. They are slightly narrower than conventional keys; nonetheless, I grew accustomed to them quickly.

Let’s Connect

A red anodized aluminum base anchors the six-pound KBP4. Above the base, a second tier of black aluminum houses the keys and horizontal controller strips, dubbed sliders. Overall, the build feels solid and stable.

At the rear of the second tier, a Micro-B USB port conducts MIDI to and from the KBP4 and draws power from your computer’s USB ports. Two jacks for sustain and controller pedals sit adjacent to the USB port. A Mini-B USB port accommodates the optional Keith McMillen MIDI expander ($70), which can route MIDI from the KBP4 to hardware MIDI devices. It can also serve as a power supply, making it easier to power the unit away from a computer.

The K-Board Pro 4’s keys transmit note data, strike and release velocity, and poly or channel aftertouch. They also sense side-to-side (X-axis) and forward-and-back (Y-axis) movement, essential for controlling MPE-capable instruments.

The four illuminated sliders are independently programmable. They can send MIDI control change (CC) and pitch-bend data. You can also use the sliders to select programs and transpose notes in octave increments across the entire MIDI note range. If you play multiple MPE-enabled synths, you’ll especially appreciate the ability to send pitch-bend range messages in real time from a slider to your target instrument, in order to match sources. Like the keys, the sliders are bidirectional.

Control à la Carte

The keyboard takes its cues from Keith McMillen’s’ K-Board Pro 4 Editor software which is available for the Mac, for Windows, and as a web app. It detects the KBP4 upon launching and uploads the instrument’s patch memory in a couple seconds.

The GUI is elegant and easy to navigate. All the file and preset-management tools appear at the top, and you can see the keyboard’s connection status on the right. The presets in the KBP4’s memory are accessible from a pull-down menu at the top. Just beneath that, the software provides a batch of handy presets that can work off the bat. Most importantly, they also provide excellent springboards for customizing your controller.

Once you understand how the controls are mapped, it’s easy to configure them for any synthesizer. Keith McMillen Instruments also supplies a license and download link for an 8-track version of Bitwig Studio, along with templates to accommodate MPE controllers.

Testing, One, Two

You can configure the K-Board Pro 4 as an MPE controller for practically any DAW, with the caution that not all DAWs are as easily configured as others. Ableton Live, MOTU Digital Performer, and Reason Studios Reason, for instance, require the creation of multiple tracks to support polyphonic expression. Apple Logic Pro X, Bitwig Studio, and Steinberg Cubase are superbly MPE-ready; just launch an MPE synth into a track and make sure the track’s MIDI input is set to all channels. 

Standalone synths that support the MPE protocol are a joy to play. In FXpansion Strobe2, an MPE-ready clavinet patch yielded satisfyingly expressive results, with faster release velocities speeding up the release times for those rhythmic, percussive, barely tonal notes that clavinets do so well. Vertical maneuvers on the Y-axis provided funky glides in the instrument’s lower ranges, and X-axis wiggles spiced up an occasional note with vibrato.

Arturia Pigments 2 has a button to enable MPE, and the factory MPE settings give you perfect control over subtle timbral changes and vibrato. UVI Falcon has a nice bank of MPE-enabled presets that spring to life with the K-Board. EastWest’s Play engine brings MPE to its extensive sample library, as well. You can, of course, also use the KBP4 as a conventional MIDI keyboard over a single channel.

Just Ask the Axis

Comparisons with other MPE controllers are inevitable. I ran KBP4 side-by-side with my ROLI Seaboard Rise 49. Most obviously, the physical design of the KBP4 differs from the “keyless” design of the Rise. As a result, using pitch bend across the X-axis is limited to vibrato effects, as gliding across the keys will trigger additional MIDI notes, rather than the continuous sweep of pitch that the Rise can produce. Compared with competing MPE controllers, you may consider that a disadvantage.

For my part, I found remapping bends to the KBP4’s Y-axis more manageable than the Rise’s default (and hardwired) X-axis. I’d recommend trying both to see which instrument suits your keyboard technique, as the feel of the keys is as different from each other as it is from a piano keyboard.

A major feature of the KBP4 is the ability to create zones, which can assign different controller sets to the keys and sliders. For example, you can set pitch bend to the Y-axis’s lower zone and CC74 for filter cutoff to the Y-axis’s upper zone. When MPE mode is disabled, you can assign different MIDI channels to the zones, thereby creating your own keyboard splits.

The Seaboard Rise offers a couple more onboard controls, but the K-Board Pro 4 lets you connect two foot pedals in contrast to the Rise’s single jack and an expander module for addressing external synths. The Seaboard requires purchasing a USB MIDI hub to play hardware synths without a computer. Both have their strengths and limitations. I often find myself shuttling back and forth between the KBP4 and the Rise. Because of the KBP4’s clearly defined keyboard, though, I find it easier to land on the right notes.

Whether you will acclimate to the KBP4’s keys from piano, organ, or synth keys is a difficult call; most of the difficulty is the lack of a mechanical action. For my part, I found it liberating, and my facility, accuracy, and speed improved. Single-key tremolo was easier to articulate, and glissandos were smoother and less painful. Despite the absence of key travel, with a bit of adjustment, I found the KBP4’s keys to be very sensitive to dynamics. The K-Board Pro 4 Editor will let you edit velocity and all modulation curves, including thresholds for any modulation to kick in so you don’t generate unintended modulation with an overzealous attack.

RE: Animator

The K-Board Pro 4 gets my enthusiastic recommendation. It’s an amazing tool for wresting as much life out of synthesis as possible, and certainly more than I imagined. Calling it a controller seems inexpressive and not in keeping with what the instrument really does. To me, it’s a re-animator. Paired with an MPE-compatible synth, it could bring more life and color to any electronic music production.


Price: $895

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