The KeyStep Pro (2020): 37 slim keys with velocity and monophonic aftertouch and an LED above every key, a four-track polyphonic step sequencer (Track 1 switchable to a 24-part drum sequencer, Tracks 2-4 switchable to arpeggiators), 16 patterns per track up to 64 steps with up to 16 notes of polyphony per step, Scenes and Chains, a Looper, five touch-sensitive encoders, an OLED screen, pitch/mod touch strips, and hybrid connectivity — 1 MIDI in / 2 MIDI out, four CV/Gate/Mod voices, eight drum gate outputs, clock in/out/reset, a metronome output with a built-in speaker, a sustain input and USB (also outputs 1.2V/oct for Buchla alongside the usual 1V/oct). The KeyStep Pro Chroma is the same instrument in a black colorway. It sits above the single-track KeyStep and KeyStep 37, and shares its sequencing DNA with the pad-based BeatStep Pro. There is no KeyStep Pro 'mk2'.
Arturia's KeyStep Pro is the big-brother sequencer the company's fans spent years asking for: take the popular single-track KeyStep, cross it with the multi-track, CV-rich sequencing of the pad-based BeatStep Pro, and put a three-octave keyboard on the front. The result is a 37-slim-key controller that's really a four-track polyphonic sequencer — one track flips to a 24-part drum machine, the others to arpeggiators — wrapped around some of the most complete hardware connectivity in its size class: MIDI, USB, four voices of CV/Gate, eight drum gates and clock, all at once.
Since 2020 it's been a fixture of DAWless and hybrid rigs — widely treated as the brain that clocks and sequences a whole desk of synths, modular and a computer together. Where opinion genuinely splits is reliability: the launch firmware was famously buggy, a big 2021 update fixed most of it, and a stubborn minority still report lockups or an outright dead unit. It's also frequently discounted well below its $499 list.
