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Geonkick - a free software percussion synthesizer
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Geonkick - a free software percussion synthesizer.

Geonkick is a synthesizer that can synthesize elements of percussion. The most basic examples are: kicks, snares, hit-hats, shakers, claps, sticks.

License: GPLv3

Version: 1.8

Author: Iurie Nistor

Source code repository:

Latest releases can be found on tags.

Latest stable features added are on "master" branch

The development is going on "develop" branch or feature (feat/feature_name) branches



Geonkick 64-bit, GNU/Linux, LV2 & standalone


  • Monophonic
  • 3 layers
  • Layers Mixer
  • 2 oscillators per layer
    • sine, square, triangle, saw-tooth
    • initial phase control
    • amplitude & frequency envelope
    • low, band and high pass filter, cutoff envelope
  • FM synthesis
    • OSC1->OSC2
  • One noise generator per layer
    • white & brownian
    • amplitude envelope
    • low, band and high pass filter, cutoff envelope
  • General
    • amplitude envelope & kick length
    • low & high pass filter, cutoff envelope
    • limiter
    • compression
    • distortion
  • Jack support:
    • 1 MIDI in, key velocity sensitive
    • 2 audio out
  • Export
    • stereo & mono
    • WAV: 16, 24, 32 bit
    • FLAC: 16, 24 bit
    • Ogg Vorbis
  • Open & Save preset in JSON format
  • Standalone
  • Plugin
    • LV2
  • Platforms:
    • GNU/Linux
  • Build system:
    • CMake

Demo & Examples

Here a is list of videos about how it works.

Under the directory geonkick/examples, it is gathered some example presets that can be opened and play with.


In order Geonkick to run and operate correctly there is a need for:


  • GNU/Linux operating system
  • Jack server installed and running at 48000 sample rate


  • GNU/Linux operating system
  • LV2 host. For example, a DAW that supports LV2 plugin format.


Install dependencies

In order to build Geonkick there is a need to install the following development packages:

  • Redkite GUI toolkit. See the documentation of Redkite toolkit how to install it.
  • libsndfile
  • RapidJSON (version >= 1.1)
  • JACK Audio Connection Kit (optional if building only for LV2)
  • LV2 development library

On Debian, Ubuntu, Ubuntu Studio install:

apt-get install build-essential
apt-get install cmake
apt-get install qjackctl libjack-dev libsndfile-dev
apt-get install rapidjson-dev
apt-get install lv2-dev
Build & install Geonkick

Clone the code repository, compile and install

    git clone
    mkdir geonkick/build
    cd geonkick/build
    cmake ../
    make install

Note: after every update from the repository over the old code there is a need to clean the build in order to generate the resources and the static API library used by the project:

 cd build
 rm -fr ./*
 cmake ../


Here is a list of tests of the application on various GNU/Linux distributions in order to see if it builds with dependencies installed from repository, installs, runs, and if there any issues.

Distribution Dependences Build Install Run Comments
Debian 10.0/64bit repository OK OK OK
Ubuntu 18.10/64bit repository OK OK OK
Fedora 29 / 64 bit repository OK OK OK
Ubuntu Studio repository OK OK OK


Road map

Here is a list of planned milestones and issues opened for them, dates when will be started and finished.


Short user guide

Shortcut Keys
  • Ctrl + r - reload default state, clean everything
  • Ctrl + k - play
  • Ctrl + h - hide envelope, only the graph is shown
  • Ctrl + o - open file browser dialog
  • Ctrl + s - open save dialog
  • Ctrl + e - open export dialog
  • Ctrl + a - open about dialog

Note: especially when running as plugin be sure the focus to be on the main Geonkick window.

Working with envelopes
  • Left double click to add a new point
  • Left click on the point and move the point
  • Right click on the point to remove it
Play the sound

Geonkick standalone uses Jack and will create two audio outputs and one MIDI input. If audio outputs are connected there are three ways to play the sound:

  • MIDI input, for example, MIDI keyboard. This also will be key velocity sensitive, i.e. lower velocity corresponds to lower sound volume.
  • pressing the key 'Ctrl + k'
  • by means of a DAW if used as LV2

Other technical notes

The block diagram of the synthesizer.


  • Geonkick synthesizer is designed for percussion, i.e. makes use of the fact that percussion instruments don't generate lasting sounds, and most of the time percussion is periodic. Thus, the workflow of the sound synthesis is optimized to this, and differs from the synthesizers that are designed for synthesis of other kinds of instruments.

  • Filters become unstable for some extremal combination of cutoff frequency and Q parameter. If the filters become unstable the percussion graph may show a maximum continuous line or various kinds of distortion. There is a need to work with Q factor in order to use the cutoff in the desired range.

  • If the sound exceeds the range -1.0 - 1.0, the sound is hard limited to value 1.0 or -1.0. This can also be seen in the percussion graph.

  • Compressor and drive are applied per total (compressor is the last one), and there is a need to work with general settings amplitude envelope to make the input right for these two effects. For now it is recommended to use a dedicated drive or compressor instead if the result of using them is not the desired.

  • When a key is pressed, there no synthesis is going on, Geonkick plays the generated percussion that is kept in memory. Synthesis takes place only if some controls are changed.

  • If the key is released before all the percussion length is played, Geonkick will apply a 30ms linear decay to avoid sharp cut of the sound.

  • If the controls are changed during the play of the beat, there will not be any change in the sound during the play of the current beat, the next beat/beats will contain the change, i.e. the next press of the keys. This is done to avoid distortion of the shape of the current generated beat (percussion). This effect of no change is more evident when the percussion length is big, like 4 seconds.

  • FM Synthesis is enabled by pressing OSC1->OSC2 for evrey layer separtely. When pressing OSC1->OSC2 the output of Oscillator 1 will be redirected to modulate the frequency of Oscillator 2. Oscillator 2 must be enabled in order to see the result in the graph.

  • Geonkick is monophonic. Pressing more keys at once will not result in the desired sound or even no sound.

  • Geonkick is not sensitive to key pitch. Pressing keys with different pitch will result in the same percussion sound.

  • Geonkick does not support multichannel.

Thank you!

Here is the list of people that contributed with features ideas that significally improved Geonkick.

unfa - for multiple noise layers

David Runge - for cutoff filter envelope

Christopher Arndt - for band pass filter

Robin Gareus - for many suggestions regarding real-time audio

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