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A software synth (WORK IN PROGRESS)

Wobbler is a software FM synthesiser. It can be controlled by the user in a number of ways:

  • GUI and computer keyboard
  • MIDI keyboard
  • Scriptable command line interface

Although Wobbler is still under heavy development, most of the core features have been implemented:

  • User selectable waveforms (sine, square, sawtooth, triangle)
  • Detune
  • FM synthesis
  • ADSR (Well, attack and release)
  • Low pass filter
  • LFO for lowpass filter cutoff
  • MIDI note input
  • Command line parameter and note control

Wobbler is a GUI for Mick Grierson's Maximilian, a C++ DSP and synthesis library. However, due to some bugs in Maximilian's library, synthesis functions will be rewritten from scratch for Wobbler (at some point).


  • SDL2
  • rtmidi

How to use (Mac)

  • Install dependencies: brew install sdl2 rtmidi
  • Clone the repo:
  • Enter the director: cd Wobbler
  • Build: make
  • To run in GUI mode: ./wob
  • To run in CLI mode: ./wob --no-gui

Note: Currently there is no Makefile for Linux, but a slight bit of tweaking and it should compile fine.

What is Wobbler for?

In short, it is to enable quick experimentation with synthesis parameters, in a way that mimics the experience of a hardware synth. In addition to offering a typical GUI, the synth can also be controlled via MIDI and your terminals standard input. This opens up allows the synth to be easily scripted.



Notes can be played by connecting a MIDI keyboard to your computer before starting Wobbler, changing synth parameters via CC will be added soon.


Currently the GUI controls aren't labeled, however, here is a reference:

Carrier waveform Carrier detune Modulator waveform Carrier/modulator ratio Attack time Release time Cutoff frequency LFO rate

Computer Keyboard

If you don't have a MIDI keyboard, you can use your computer's keyboard to play notes and change octave:

Command line

Additionally, the synth can be controlled via the command line, below is a list of commands:

Command name Arguments Description
rand n/a Randomise synth parameters
help n/a Display a list of commands
quit n/a Quit the program
noteon midi note Turn a note on
noteoff midi note Turn a note off
car_wave 0.0 - 1.0 Set the carrier wave
detune 0.0 - 1.0 Set the detune amount
mod_wave 0.0 - 1.0 Set the modulator wave
mod_ratio 0.0 - 1.0 Set the modulators ratio w.r.t. carrier frequency
attack 0.0 - 1.0 Set the attack time
release 0.0 - 1.0 Set the release time
cutoff 0.0 - 1.0 Set the cutoff
lfo 0.0 - 1.0 Set the LFO speed

If you are soley interested in using the synth via scripting or command line, it is possible to start the program without a GUI, in order to do this, run ./wob --no-gui


As Wobbler accepts commands from standard console input, is possible to script sequences and synth changes using any language you'd like. To see an example of this, please check out


  • Sometimes notes will randomly be dropped, especially when notes are played very fast. This is due to a bug in Maximilian's envelope function. Currently there is little that can be done about this, however, eventually Maximilian's synthesis functions will be replaced by custom Wobbler specific functions, remedying this issue.
  • Currently there is no Linux Makefile, however Wobbler should compile fine on any Linux machine given a bit of tinkering. One will be added shortly.


A software FM synthesizer for macOS and GNU/Linux (WORK IN PROGRESS)






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