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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


Go to for builds.


If you want to build AAX plugins You'll need its SDK located in ~/srcs
For AU on the Mac you'll want to put the CoreAudio SDK in /Applications/
Nothing extra is needed for building VST/LV2 plugins


To build and install the standalone, lv2 and vst plugin:

sudo make install

Other make commands:

# Build just the Linux standalone executable:
make standalone

# Build just the Linux LV2 plugin:
make lv2

# Build just the Linux VST plugin
make vst

# Install just the Linux standalone executable:
sudo make install_standalone

# Install just the Linux LV2 plugin:
sudo make install_lv2

# Install just the Linux VST plugin
sudo make install_vst

The standalone executable is built to standalone/builds/linux/build and installed to /usr/bin The LV2 plugin is built to builds/linux/LV2 and installed to /usr/lib/lv2 The VST plugin is built to builds/linux/VST and installed to /usr/lib/lxvst


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


Open /standalone/builds/vs15/Helm.sln for standalone version
Open /builds/vs15/Helm.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 unison oscillators each
  • Sub oscillator with shuffle waveshaping
  • Oscillator feedback and saturation for waveshaping
  • 12 different waveforms
  • Blending between 12 or 24dB low/band/high pass filter
  • Low/Band/High Shelf filters
  • 2 monophonic and 1 polyphonic LFO
  • Step sequencer
  • Lots of modulation sources including polyphonic aftertouch
  • Simple arpeggiator
  • Effects: Formant filter, stutter, delay, distortion, reverb

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