Developer Joe Landers has released Profligacy, an experimental emulator that runs the original firmware ROM of the Korg Prophecy — the 1995 monosynth that was Korg's answer to the Yamaha VL1. It is free, it is an early alpha, and it is available on GitHub.
It is also, for anyone who plays an MPE controller, a useful reminder of what expressive synthesis looked like before the protocol existed.
What Landers Actually Built
Most of the recent wave of ROM-accurate synth emulators are forks of Gearmulator, the open-source project from The Usual Suspects that targets Motorola 68k-based instruments. Landers used it for his Elektron Monomachine and Machinedrum emulators, released the same week.
The Prophecy could not take that route. Its hardware runs on three Texas Instruments TMS57002 DSP chips, alongside an NEC V55 microcontroller and a Toshiba H8 processor — a completely different architecture. So Landers analysed the chips and wrote his own emulator from scratch over recent months.
The plugin's interface is modelled closely on the hardware, with six sections: panel, matrix, program, arp, global and dev.
Two important caveats, both of which Landers states plainly himself:
- It requires the original ROM. The project is explicitly aimed at people who already own Prophecy hardware and can dump their own firmware. No ROM is distributed.
- It is an early alpha. Expect unfinished areas and bugs. CPU load is heavy — roughly half a core on an Apple M2, and around 80% on an Intel iMac.
If you want a Prophecy you can actually finish a track with, Korg's own official emulation is the sensible choice. It is polyphonic, needs no ROM, and is available as part of the Korg Collection.
Why the Prophecy Matters to Expressive Players
The Prophecy was monophonic by design, which in MPE terms sounds like a dead end. It is not. The instrument is interesting precisely because Korg had to solve the expression problem without per-note channels — and the solutions they landed on are the direct ancestors of the axes we use today.
The engine paired two oscillators, one of them a physical modeling oscillator, across a set of selectable synthesis models: analog modeling, noise plus comb filter, variable phase modulation, modulation synthesis, and physical modeling proper. Behind them sat two multimode resonant filters, four LFOs, onboard effects and patch storage.
Physical modeling engines of that era shared a trait with today's: they sound dead without continuous input. A plucked or blown model that receives only note-on and velocity produces one gesture and then decays. Korg's answer was to put a large, visible, continuously variable controller directly under the player's left hand and route it deep into the model — not to a filter cutoff, but to the physical parameters of the simulated resonator.
That is the same design instinct behind MPE's slide and pressure axes. The difference is that MPE distributes the gesture per note rather than per instrument. What the Prophecy did to one voice, a Seaboard, LinnStrument or Osmose does to every voice independently.
Playing It From an MPE Controller
Because Profligacy emulates a monophonic instrument, you will not get per-note expression from it — and no amount of channel configuration will change that. But it is still worth driving from an expressive keybed rather than a conventional one.
Set your controller to single-channel MIDI mode rather than MPE mode, and map pressure to whichever modulation destination the patch uses for its main timbral control. On a physical modeling patch, that generally means a parameter inside the model rather than the filter. The result is closer to how the instrument was meant to be played than any velocity-only approach.
It is also a good calibration exercise. Playing a genuinely monophonic expressive engine makes very clear what per-note expression actually buys you — and where it does not matter. A solo lead line played with continuous pressure control does not need MPE. A chord where each voice moves independently does.
The Wider Trend
Landers' Prophecy work sits alongside a broader 2026 surge in ROM-accurate emulation — Gearmulator forks, the Roland SC-88 Pro and SRV-330 recreations from The Usual Suspects, the open-source Ensoniq EPS-16+ project, and more. Most of these instruments predate MPE by decades and will never support it.
Their value to expressive players is historical rather than practical: they document a period when manufacturers were solving expression with ribbons, joysticks, breath inputs and mod strips, one gesture at a time, because the protocol offered nothing better. Understanding those constraints makes it considerably easier to see what modern per-note expression is actually for.
Profligacy is available now as an experimental VST3 for macOS (Apple Silicon and Intel) and Windows from GitHub.
Sources: Joe Landers on GitHub · Synth Anatomy