ESI Xkey 25 and Xkey 37, new 2024 versions of the polyphonic aftertouch keyboards

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ESI Xkey 25 and Xkey 37 are the new generation of its polyphonic aftertouch keyboards, now with USB-C connectivity and more software.

My first real contact with polyphonic aftertouch was with the CME key keyboard series eight or nine years ago. These are super portable aluminum keyboards with full-size keys with velocity and poly aftertouch but with little key travel. 

The Xkey series is now entering a new 2024 generation made by a new brand and new features.

ESI Xkey 25 Xkey 37


ESI Xkey 25 and Xkey 37

Goodbye, CME, and hello, ESI. The German developer company ESI from Leonberg has taken over the Xkey portfolio from the Chinese company CME and is now continuing it. CME, on their side, is now focusing on the MIDI and USB host interfaces.

ESI is not taking this step alone. They work closely with the San Diego, CA, USA-headquartered company Artesia Pro. 

The new Xkey 25 and Xkey 37 are also mostly the old ones. Most of the specs have remained the same. They are still super portable, ultra-thin, and come in rugged, brushed aluminum metal casings. 

ESI Xkey 25 Xkey 37

Like the previous generation, both versions also keep the same key range (25-key and 37-key versions) with the same specs. The keys are custom full-size keys with little key travel, are velocity-sensitive, and offer polyphonic aftertouch. The latter remains a unique selling point of the keyboards in this price range.

Besides this, they also offer again hardware pressure-sensitive buttons that handle various functions: pitch bend, modulation, octave +/-, and sustain.

ESI Xkey 25 Xkey 37

New In The 2024 Generation

The new 2024 generation has little new to offer. But the only new addition is a great one that makes them more modern for 2024.

ESI killed the micro USB port on the new Xkey 25 and Xkey 37. They now come with a rock-solid USB-C connection. to ensure seamless, class-compliant interfacing with current PCs, Macs, and mobile devices.

Further, the Xkey 37 also hosts a MIDI output, expression, and sustain pedal inputs via an included 5-pin connection. This is unchanged from the original version.

Also new is the included software bundle. Both 2024 generation versions now include licenses of Bitwig Studio 8-track, Steinberg WaveLab LE, and Steinberg Cubasis LE.

On top, you get a cross-platform editor software, enabling comprehensive customization of their MIDI controller keyboard’s parameters. It also brings ESI’s esteemed multi-client, multi-device MIDI driver for Windows.

There is no official video for the new version. Here is a very old one from my friend Corry Banks of BBoyTechReport, now Modbap Modular.

First Impression

I am pleased that the Xkey 25 and Xkey 37 keyboards are now being re-released under ESI. The moment to release these keyboards in a new version is perfect, as many current hardware and software synthesizers now have poly aftertouch support.

This was not the case 10 years ago when the original CME keyboards came out. Before buying it, check the USB connector. If it’s a micro USB, then it is still a CME. With USB-C, it is an ESI. 

ESI Xkey 25 and Xkey 37 MIDI will start shipping in Europe in July for 149€ and 249€, respectively. In August, they will also ship to the US.

More information here: ESI 

Audio & MIDI News


  1. I see no point in them being this thin. Why not make them twice as thick? It would still be smaller than a keystep and twice the travel would be going from nowhere to something.

    • I see no point changing a design after 10 years on the market that sold well. It’s one of the key selling point, plus polyphonic aftertouch and pretty affordable.

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