The original Arturia KeyStep launched in 2016 and became one of those rare pieces of gear that refused to leave people’s desks. I’ve seen it at modular shows, in bedroom studios, on live rigs — often used by people who had already “upgraded” to something else but kept coming back to it. So when Arturia followed their KeyStep mk2 announcement last November with the Arturia KeyStep 37 mk2, I wasn’t surprised. I was relieved.
If you read our Arturia KeyStep 25 mk2 review, you’ll know the 25-key version impressed us for its thoughtful generative additions and hardware-forward workflow upgrades. The KeyStep 37 mk2 takes that same foundation and gives it the extended physical toolkit that more expressive players have been waiting for.
A Bigger Canvas for the Same Ideas
The Arturia KeyStep 37 mk2 builds on everything that made the mk2 family compelling — the generative tools, the OLED display, the upgraded sequencer and arpeggiator — but wraps it in a more expansive body. You get 37 slim keys with velocity and aftertouch, five more than the standard mk2, and a 39-LED light guide strip above the keybed that shows notes played in real time. That last detail sounds minor until you’re chaining patterns mid-set and actually need to see what’s happening without counting keys.
The four additional encoders are also a significant upgrade over the 25-key version. Rather than navigating sub-menus on the OLED screen, these are mode-aware knobs for fast Seq/Arp/Chord/Mutate editing — hardware-direct, the way most of us prefer for live use. There’s also a dedicated MIDI CC button with 16 assignable CCs across 4 banks, mapped to those same encoders. That transforms the KeyStep 37 mk2 into a capable hands-on controller for external gear, not just a sequencer hub.
What’s New
The KeyStep 37 mk2 is not a straight port of the 25-key mk2 into a larger body. There are real additions:
- 37-note Slimkey keybed — velocity and aftertouch, five more keys than the standard mk2
- 39 LED light guide over the keybed for real-time note and sequence feedback
- 4 additional encoders with a Control button for mode-aware, menu-free editing
- MIDI CC button + 4 banks — 16 assignable CCs mapped to the encoders
- Mutate button — one-press melodic and rhythmic mutation, shapeable with a dedicated encoder
- Phrase Arpeggiator with 16 modes including generative pattern arps
- Pattern chaining and unquantized recording in the sequencer (up to 64 steps, 8-voice polyphony)
- Spice & Dice sliders alongside Gate Length for live tweaking
- 4 CV outputs — Pitch, Gate, Mod 1, Mod 2 — all assignable to velocity, aftertouch, mod wheel, and more
- USB-C (class-compliant bus power + USB MIDI), MIDI DIN In/Out, Sync I/O, sustain/expression jack
- Dedicated power switch on the rear panel
The Features Worth Your Time
The Mutate button is the headline feature — and not just because it’s new. What it does is reshape sequences and arpeggios with melodic and rhythmic variation, live, without stopping the music. You can dial in the depth with the dedicated encoder. It’s not a randomizer that throws everything at the wall — it’s controlled mutation with a musical result. If this had existed when I was spending hours manually editing step sequences looking for fresh directions, I’d have been considerably less frustrated.
The Phrase Arpeggiator is equally interesting. Beyond the standard up/down/random modes, the generative pattern styles (accessible on keys 7–15) loop original melodic ideas based on the notes you’re holding. Add Spice via the slider to inject rhythmic variation on top of that, and patterns start evolving in ways that feel like you’re performing rather than babysitting a loop.
Why This Matters Right Now
Arturia released the 25-key mk2 in November 2025, and the community immediately started asking about the 37. Reddit threads and Elektronauts forums were full of people holding off purchases specifically for this. As we noted in our [KeyStep mk2 review](https://audionewsroom.net/2025/11/arturia-keystep-mk2-review-its-the-little-things-that-make-a-classic-even-better.html), the generational upgrade was well-executed — and the 37 mk2 arriving so soon after feels like the planned second half of a product family launch.
DAWless and hybrid setups have gone from niche to normal, and compact controllers with deep CV connectivity are in higher demand than ever. Four fully assignable CV/Gate outputs at this price point is still genuinely rare. Arturia is doubling down on hardware-first workflows, and the 37 mk2 is the most complete expression of that in the KeyStep line.
Official Video
Pricing and Availability
The Arturia KeyStep 37 mk2 is available now directly from Arturia. Pricing is set at $199 USD / £175 GBP. The 25-key KeyStep mk2 sits at $139, so the premium for five extra keys, four encoders, and the MIDI CC engine feels about right.
How about you — are you a compact-and-portable mk2 user, or does the extra real estate of the 37 change your setup?
