Helm - a free polyphonic synth with lots of modulation
C++ C Objective-C++ Makefile Java Objective-C
Latest commit 352fba3 Jan 7, 2017 @mtytel committed on GitHub Merge pull request #110 from Hodorgasm/master
Assume there exists lround if compiling with g++ in C++11 or later



Helm is a free, cross-platform, polyphonic synthesizer that runs on GNU/Linux, Mac, and Windows as a standalone program and as a LV2/VST/AU/AAX plugin. Release is in beta so there are outstanding bugs. Please send any bugs found to matthewtytel@gmail.com


Go to tytel.org/helm for builds.


If you want to build VST/AAX plugins You'll need their SDKs located in ~/srcs
For AU on the Mac you'll want to put the CoreAudio SDK in /Applications/Xcode.app/Contents/Developer/Extras/CoreAudio
Nothing extra is needed for building LV2 plugins



The standalone executable is located in standalone/builds/linux/build
The LV2 plugin is located in builds/linux/LV2

To build a GNU/Linux VST plugin:

make vst

The VST plugin is located in builds/linux/VST as an .so file.


Open /standalone/builds/osx/Helm.xcodeproj for standalone version
Open /builds/osx/HelmPlugin.xcodeproj for plugin versions


Open /standalone/builds/vs12/Helm.sln for standalone version
Open /builds/vs12/HelmPlugin.sln for plugin versions


  • 32 voice polyphony
  • Interactive visual interface
  • Powerful modulation system with live visual feedback
  • Dual oscillators with cross modulation and up to 15 oscillators each
  • Unison and Harmony mode for oscillators
  • Oscillator feedback and saturation for waveshaping
  • 12 different waveforms
  • 7 filter types with keytracking
  • 2 monophonic and 1 polyphonic LFO
  • Step sequencer
  • Lots of modulation sources including polyphonic aftertouch
  • Simple arpeggiator
  • Effects: Formant filter, stutter, delay
  • Still more...

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