StepPolyArp Unit Is A Real-Time Polyphonic & Polyrhythmic MIDI Sequencer With AUv3 Support

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StepPolyArp Unit is the AUv3 version of the best-known StepPolyArp polyphonic & polyrhythmic MIDI sequencer for iOS.

If developers decide to offer AUv3 versions of their apps, it usually comes as a free update. It rarely happens that companies ask money again for this update. Laurent Colson has decided to offer an AUv3 version of his excellent MIDI sequencer StepPolyArp as a separate app. This means, users must buy the app again if they want to use it as AudioUnit plugin on iOS.

It’s certainly a decision that will polarize because many users have expected a free update. On the one hand it’s always nice to see if an App receive a free update with AUv3 support but on the other hand you also have to see that developers put a lot of work into this development. This work must also be paid. Personally, I’m polarized with this decision because I want to see free updates but also that developers can live from their activity.


“StepPolyArp Unit” is a real-time polyphonic and polyrhythmic MIDI step arpeggiator and step sequencer. It can be used as a standalone application or an Audio Unit MIDI effect plug-in. The application and the plug-in can operate as a step arpeggiator by automatically generating melodic patterns from played notes or chords, or as a step sequencer that doesn’t require MIDI input to play. Unlimited presets can be saved on a local device and synchronized to iCloud. Each preset contains 16 patterns, 5 customizable polyrhythmic step controllers, and a 32 steps event matrix with 11 polyphonic and polyrhythmic lines driving the arpeggiator engine.

The application supports full internal and external MIDI connections for input and output, Audiobus MIDI sender, MIDI filter routing, Ableton Link sync, and MIDI clock source sync. An internal sound bank is included. The Audio Unit MIDI effect plug-in supports multiple instances. A compatible host is required to run the plug-in. The host needs to support the Audio Unit MIDI effect format.


  • Standalone application and Audio Unit MIDI effect plug-in
  • Arpeggiator and step sequencer mode
  • 1 to 32 steps programmable matrix
  • 11 configurable transposition lines
  • Polyrhythmic lines
  • 16 patterns by preset
  • Automatic chaining patterns
  • 8 octaves resizable keyboard
  • Multitasking
  • Sample-accurate timing
  • Internal sound bank
  • Tap tempo
  • Receiving MIDI from external MIDI sources
  • Receiving external MIDI sync (MIDI clock)
  • Ableton Link support
  • Internal routing of inputs, outputs, and MIDI sync
  • Send MIDI to a virtual port that can be used as MIDI input by other “Core MIDI” compatible applications
  • Default velocity, modulation, pan, volume, aftertouch, and pitch bend steps controller
  • Customizable steps controller MIDI setup
  • Arpeggiator and sequencer conform to the selected scale
  • 6 arpeggiator modes
  • 1 random mode
  • 1 chord mode
  • Random patterns creation
  • Presets manager
  • “Program Change” support
  • Native iCloud support
  • “Files” application support
  • Full support of “Split View” and “Slide Over”
  • 128 Undo / Redo levels
  • Copy and paste
  • Lockable keyboard (latch mode)
  • Compatible hosts supporting Audio Unit MIDI effect: Cubasis AUM

Supported MIDI connections:

  • Virtual “Core MIDI” connections between applications
  • iOS compatible MIDI interface
  • MIDI over Wifi
  • MIDI over Bluetooth
  • Ableton Link (sync and transport)
  • Audiobus (MIDI, transport, state saving)

StepPolyArp Unit is now available for $14.99 USD on the App Store.

Available here: StepPolyArp Unit 

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