Firefly Synth
Firefly Synth
Firefly is a freeware semi-modular synthesizer and effects plugin that builds on the ideas introduced in InfernalSynth, expanding them into a deeper, more flexible sound design environment.
Developed by Sjoerd van Kreel, Firefly is aimed squarely at producers who enjoy experimental synthesis, FM-heavy architectures, and hands-on modular-style routing without the visual clutter of full virtual Eurorack systems.
Available for Windows and Linux in CLAP and VST3 formats, Firefly is still evolving, but even in its current state it offers a powerful foundation for aggressive digital tones, abstract textures, and highly modulated synth patches.
System Requirements:
- 64 bit
- VST / AU
- Windows
- macOs
A semi-modular engine built for experimentation
At its core, Firefly features four oscillators per voice, each capable of operating in multiple synthesis modes.
Alongside classic waveform generation, the oscillators support FM, AM, and Karplus-Strong style synthesis, allowing Firefly to move easily between percussive plucks, metallic timbres, and complex evolving tones.
Rather than relying on fixed signal paths, Firefly embraces a semi-modular philosophy. Oscillators, envelopes, LFOs, filters, and distortion stages can be freely routed using a comprehensive modulation matrix.
This encourages exploratory sound design and rewards users who enjoy building patches from the ground up.
Modulation, distortion, and per-voice control
Firefly places a strong emphasis on per-voice processing. Each voice includes its own DAHDSR envelopes, LFOs, filters, and distortion stage, making it possible to create animated, expressive patches that respond dynamically to velocity, note changes, and modulation sources.
The distortion being applied per voice is particularly notable, allowing harmonics and saturation to evolve differently across voices instead of being flattened at the output stage.
While Firefly currently ships without a large preset library, this design choice reinforces its identity as a synth for users who prefer shaping sound manually rather than browsing finished patches.
Key Features:
Firefly is a semi-modular synth featuring 4 oscillators per voice with FM, AM, and Karplus-Strong synthesis. Build complex patches with a deep modulation matrix.
- Semi-modular synthesizer and FX plugin
- Four oscillators per voice with multiple synthesis modes
- Supports FM, AM, Karplus-Strong and classic waveforms
- Per-voice DAHDSR envelopes
- Per-voice LFOs and filters
- Per-voice distortion stage
- Flexible modulation matrix for custom routing
- CLAP and VST3 plugin formats
- Designed for experimental and advanced sound design
FAQ
Firefly is primarily designed for manual sound design and does not focus on preset browsing. Demo patches and project files are available via the GitHub repository.
Firefly works well in hosts such as Bitwig, FL Studio, Reaper, and Studio One. Renoise is currently not supported.
Yes. FM is one of Firefly’s strongest areas, with deep routing options and per-voice processing that allow for complex, evolving FM textures.
Yes. Firefly can operate as both a synthesizer and an FX plugin, making it useful for processing external audio with its modulation and distortion engine.
A 64-bit CPU with AVX support is required. Firefly is available for Windows and Linux only.
