A synth that sounds expensive.
Halcyon Swarm is a polyphonic virtual-analog synthesizer: two oscillators with up to eight detuned voices each, a ladder filter that growls when you push it, analog-style envelopes, and chorus, delay and reverb built in. Warm pads, snappy basses and gliding leads, from one clear window. It runs as an Audio Unit in Logic Pro, and as VST3 or CLAP in most other music software.
Free while in beta. Version 0.2.14, built 16 October 2026. By downloading you agree to the licence agreement.
Find your next sound
Browse the factory library by sound type, search by name or tag, and preview each patch before loading it. Save your own sounds as presets and keep favourites close at hand.
Shape the sound by hand
Grab the dot on the filter curve and drag it: left and right sweep the cutoff, up and down raise the resonance, and the curve shows you exactly what the filter is doing. On the envelope page, drag the corners of the amp and filter envelopes to make a sound pluck, swell or hang in the air.
Every knob drags up and down (hold Shift for fine moves), resets with a double-click, and records into your host's automation like any other control.
Built the way commercial synths are
The engine skips the shortcuts that make hobby synths sound thin or harsh. Oscillators are band-limited and run at twice your sample rate, so high notes stay clean instead of fizzing. The filters stay smooth and stable however fast you sweep them, and the ladder can scream into self-oscillation without blowing up.
Envelopes follow the curved shape of analog circuits, so plucks snap and pads breathe. Every knob is smoothed, so moving it never clicks.
- Unison Up to 8 voices per oscillator, detuned and spread across the stereo field.
- Filters 24 dB ladder with drive, plus 12 dB low-pass, band-pass and high-pass.
- Voices 16-voice poly, or mono legato with glide.
- Effects Ensemble chorus, ping-pong delay and a lush 8-line reverb.
Six modules, one window
The tiles on the left bring each module into focus, with its picture in the middle and its controls on the right. The performance row along the bottom always stays in reach: detune, sub, cutoff, resonance, attack, release, LFO rate, reverb and volume.
Oscillators
- Wave
- Saw, pulse, triangle or sine, with pulse width.
- Unison
- Up to 8 voices with detune and stereo spread.
- Mix
- A sine sub an octave down, and noise.
Filter
- Type
- Ladder LP 24, or LP, BP and HP 12.
- Cutoff, Res, Drive
- Drag them on the curve or turn the knobs.
- Env, Key, Velocity
- How much the envelope, the note and how hard you play open it.
Envelopes
- Amp, Filter
- Attack, decay, sustain and release, from half a millisecond to 20 seconds.
- Velocity
- How much playing harder gets louder.
LFO & Voice
- LFO
- Five shapes to pitch, cutoff and pulse width, per note or free-running.
- Voice
- Poly or mono legato, glide and pitch-bend range.
Effects
- Chorus, Delay
- Wide ensemble chorus and ping-pong echoes.
- Reverb
- Size, decay and damping, from rooms to long washes.
Installing the beta
The beta installers aren't signed by Apple or Microsoft yet, so your computer asks you to confirm once.
macOS 11 or later
- Open
HalcyonSwarm-0.2.14-macOS.pkg. - If macOS says it can't check the file for malicious software, click Done. Then open System Settings, go to Privacy & Security, scroll down and click Open Anyway.
- Follow the installer. It adds the Audio Unit, VST3 and CLAP versions for all users.
- Restart Logic Pro. On a Software Instrument track, you'll find it under AU Instruments, then Halcyon Audio.
Windows 10 or 11, 64-bit
- If your browser says the file isn't commonly downloaded, choose Keep. In Edge it's under the … menu next to the download.
- Run
HalcyonSwarm-0.2.14-Windows-Setup.exe. If Windows says it protected your PC, click More info, then Run anyway. - Pick VST3, CLAP or both, and finish the installer.
- Rescan plugins in your music software. The VST3 goes to
C:\Program Files\Common Files\VST3.
About this beta
- This is the first public beta of Halcyon Swarm.
- Formats: Audio Unit (macOS only), VST3 and CLAP. A software instrument: MIDI in, stereo out.
- The Windows version is brand new and hasn't had much testing yet. If it doesn't show up or misbehaves in your host, we'd like to hear about it.
- Projects you make with this beta should reopen in later versions, but keep backups while things settle.
- Planned: presets, more modulation routings and more oscillator shapes.
File checksums (SHA-256)
db50cc715e6403496ed15ab64370577d6efe776910281570b4305c472ee72b81 HalcyonSwarm-0.2.14-Windows-Setup.exe 59375339e9a1ca8f444942f8e669a685fdc8b7030ead1349628772039a38ec36 HalcyonSwarm-0.2.14-macOS.pkg