ArpStacker
4-Voice MIDI Arpeggiator
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Arp Stacker is available on Gumroad: https://brettdooley.gumroad.com/l/arpstacker
It is free. Enter $0 and download it.
If you feel like supporting it, donations are appreciated. I promise to buy coffee
with it.
Music is structure fighting chaos.
Arp Stacker lets the chaos win: just enough.
Three voices run free, each stepping through its own chord at its own speed,
feeding a constantly shifting pool of notes to a fourth voice that fires on a
locked grid. The rhythm stays put. The notes never quite repeat.
The result sounds planned. It wasn’t. That’s the point.
What It Does
Arp Stacker is a 4-voice MIDI arpeggiator with an internal chord engine and a
grid-locked output.
Voices 1, 2, and 3 each run independent arpeggiators against their own chord
type and root. They do not output MIDI. They exist to feed Voice 4.
Voice 4 watches that shifting note pool and fires on a quantized grid with
swing, Euclidean rhythm, and probability filtering. It is the only voice you
hear.
The three source voices can:
- Run at any rate: continuous, not grid-locked
- Step through any chord shape across up to 4 octaves
- Move up, down, ping-pong, or randomly
- Contribute silence to the pool via a narrow gate range
Voice 4 can:
- Fire on any standard grid division
- Apply swing for a shuffle feel
- Use Euclidean rhythm distribution for organic spacing
- Drop notes randomly via probability filtering
- Control note length, velocity, and octave spread
How It Works
Insert Arp Stacker on a MIDI track. Route the MIDI output to your synths. Start
your DAW transport.
Set Voices 1 through 3 to different chords, different rates, and different
modes. Keep their gates low (around 0.08 to 0.12) so they spend most of each
step silent. Voice 4 will turn that silence into rests nobody programmed.
Set the three source voices to irrational rate ratios and the note pool shifts
in patterns that never quite repeat. The Euclidean rhythm gives Voice 4
structure. The gate silence gives it breath. Together they produce something
that has a pulse but never sounds mechanical.
Global controls manage humanization and a panic button that kills everything if
something gets stuck.
Compatibility
Windows only. VST3. Verified in Reaper.
Arp Stacker is a MIDI effect plugin: MIDI in, MIDI out, no audio. Not every DAW
routes MIDI through plugins correctly. If you are not on Reaper, it may work or
it may not. You will need to sort that out for your setup.
I built this because I wanted structured unpredictability: a rhythm generator
that felt alive without being random noise.
If it produces something you wouldn’t have written yourself, that’s the whole
idea.
Brett Dooley
See my other midi vst: https://brettdooley.com/midivst/