MonkSynth

A monophonic vocal synthesizer that sounds like a monk chanting. Built using formant-wave-function (FOF) synthesis, inspired by the classic Delay Lama VST plugin by AudioNerdz (2002).

Download the latest release — available for Windows, macOS, and Linux.

MonkSynth running in Ableton Live 12 with the classic Delay Lama theme

MonkSynth v0.0.1-beta.1 in Ableton Live 12, with the classic theme imported from the original Delay Lama DLL

Features

FOF synthesis engine producing realistic vocal formants
XY pad for real-time pitch and vowel control
Built-in stereo delay effect
MIDI support: note on/off, pitch wheel, CC1 (vibrato), CC5 (glide), CC7 (volume), CC12 (delay), CC13 (voice)
Automatable Pitch Bend parameter (±12 semitones). The hardware pitch wheel is routable to either Vowel (Classic / Delay Lama compat, the default) or Pitch via right-click → Pitch Bend
ADSR envelope with configurable attack, decay, sustain, release
Unison mode with up to 10 detuned voices and voice spread
Theme system with right-click context menu for custom themes
Import classic theme from the original Delay Lama DLL
5 factory presets
VST3 plugin format (Windows, macOS, Linux) and Audio Unit (macOS)

Building

Prerequisites

CMake 3.20+
C/C++ compiler (MSVC, GCC, or Clang)

Build

cd cpp
cmake -B build
cmake --build build --config Release --target MonkSynth

The VST3 SDK is fetched automatically by CMake. The built plugin is placed in your system VST3 directory.

macOS Audio Unit

To also build the AU plugin, install the AudioUnit SDK and configure with:

cmake -B build -G Xcode -DSMTG_AUDIOUNIT_SDK_PATH=/path/to/AudioUnitSDK
cmake --build build --config Release --target MonkSynth-au

DSP unit tests

The pure-C DSP layer (dsp/) has a small unit test suite exercising ADSR envelope boundaries, the note stack, unison detune math, pitch-bend propagation, and delay-line feedback stability. Tests are opt-in so they don't affect normal plugin builds:

cd cpp
cmake -B build-tests -DMONKSYNTH_BUILD_TESTS=ON
cmake --build build-tests --config Release
ctest --test-dir build-tests --output-on-failure

CI runs the test suite on the Linux job before packaging each release, so any DSP regression blocks the build.

Installation

macOS: Run the .pkg installer — installs both VST3 and AU plugins
Windows: Run the .exe installer — installs the VST3 plugin
Linux: Extract and copy MonkSynth.vst3 to ~/.vst3/

Linux compatibility

The Linux build is verified on each release to load cleanly under strict loader semantics (Bitwig-style dlopen(RTLD_NOW)) on these distro families:

Ubuntu 22.04 / 24.04 LTS (and derivatives: Linux Mint, Pop!_OS, Elementary, KDE neon)
Debian 12 (and derivatives: KX Studio, AV Linux, MX Linux)
Fedora (latest)
Arch Linux (and derivatives: Manjaro, EndeavourOS, CachyOS)

If your distro isn't listed it most likely still works — these are smoke-tested in CI to catch the missing-shared-library class of bug, not an exhaustive support claim. The plugin is built on Ubuntu 22.04 (glibc 2.35), so any distro with glibc ≥ 2.35 should be compatible. Reports from other distros are welcome via GitHub Issues.

Themes

MonkSynth ships without a built-in theme. On first launch, it shows a setup screen where you can import the classic look from the original Delay Lama DLL (available as freeware from audionerdz.nl).

You can also load custom themes via right-click on the plugin GUI. A theme folder contains a theme.json manifest and any combination of these PNG files (missing ones fall back to 1x1 placeholders):

background.png — main background (360x510)
monk-strip.png — animation sprite sheet (5x6 grid, 311x311 frames)
knob-left.png / knob-right.png — rotary knob filmstrips (50x3000, 60 frames)
fader-down-large.png / fader-down-sm.png / fader-right-sm.png — fader handles
info.png — info overlay (253x275)

Looking for fresh default themes to ship with the plugin. If you design a theme you're proud of, open a PR — I'd love to include contributed themes in the next release. The right-click menu has an "Open Themes Folder" item that reveals where themes live on disk.

Translations

The plugin UI (setup screen, info overlay, right-click menu, and DLL-importer error messages) is available in English, Japanese, and Korean. The language auto-detects from your OS locale; you can override it via right-click → Language.

Japanese and Korean translations were generated by a large language model as a starting point. Native-speaker contributions are very welcome — please open a PR editing cpp/src/strings_ja.h or cpp/src/strings_ko.h. Every string is indexed by the StringId enum in cpp/src/i18n.h; keep entries in the same order and leave any you're unsure about as empty strings to fall back to English.

Parameter names (shown in your DAW's automation lanes) stay English on purpose — tutorials, presets, and community discussion all assume the English names.

Code Signing Policy

Free code signing provided by SignPath.io, certificate by SignPath Foundation.

The Windows VST3 plugin and installer are signed as part of the release build in GitHub Actions. Signing requests are submitted to SignPath only for tagged releases built from this repository, and each request is manually approved in the SignPath UI before the certificate is applied.

| Privileged role | Signer | |-----------------|--------| | Author | Jonathan Taylor | | Reviewer | Jonathan Taylor | | Approver | Jonathan Taylor |

Privacy Policy

This program will not transfer any information to other networked systems unless specifically requested by the user or the person installing or operating it.

Acknowledgments

Delay Lama by AudioNerdz (2002) — the beloved freeware VST plugin that inspired this project
Xavier Rodet (IRCAM) — formant-wave-function (FOF) synthesis technique
stb_image_write by Sean Barrett — single-header image writing (MIT / public domain)
VST3 SDK by Steinberg — plugin framework (MIT)
SignPath Foundation — free Windows code signing for open source projects

License

MIT

--- Tranlated By Open Ai Tx | Last indexed: 2026-06-24 ---

monksynth