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DSP tonewheel organ
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A DSP Tonewheel Organ emulator.

setBfree is a MIDI-controlled, software synthesizer designed to imitate the sound and properties of the electromechanical organs and sound modification devices that brought world-wide fame to the names and products of Laurens Hammond and Don Leslie.


  • start jackd [] or configure JACK autostart
  • run setBfree-start
  • connect JACK Audio/MIDI ports (using qjackctl or you favorite JACK connection manager -- note: enable JACK-MIDI or use a2jmidid to expose MIDI-devices to JACK, alternatively run setBfree midi.driver=alsa)


setBfree is based on the code of Fredrik Kilander's Beatrix organ emulator. He gave permission to Will to use the Beatrix code in a GPL app. Robin Gareus changed the OSS based code to a JACK interface and moved the overdrive, reverb, and leslie functionality into LV2 plugins. The LV2 plugins allow users to mix and match any of the components with any other JACK supported app. Robin also added a TCL/TK GUI for testing and added leslie cabinet simulation using Ken Restivo's IR sample.

While this works now in its first beta release, we are using this as a starting point for building a high quality emulator players familiar with the great Hammond organs of the past will enjoy. There will be two major milestones to reach this goal. The first is to clean up its first beta functionality including improving and cleaning up the current code, and adding a slicker GUI interface. For the second milestone, we will modify much of the code to make the organ more dynamic. A user will be able to adjust to taste from the 'like a bird' quality of chill players to the knocking, screaming organ sounds of gospel vamps, and rock and roll.


Run setBfree -h for a quick overview. setBfree --help will output a lengthy list of available options and properties than can be modified.

setBfree is the synthesizer engine. It responds to MIDI messages (JACK-MIDI or ALSA-sequencer) and outputs audio to JACK. The engine does not have any graphical user interface (GUI). It is usually started from the commandline.

The GUI vb3kb is a standalone application that simply sends MIDI messages to setBfree. setBfree-start is a shell-script that launches both and connects the GUI to the synth.


setBfree midi.driver="alsa" midi.port="129" jack.connect="jack_rack:in_"
setBfree jack.out.left="system:playback_7" jack.out.left="system:playback_8"
setBfree-start midi.driver="alsa"

Getting started - standalone app

You'll want reliable, low-latency, real-time audio. Therefore you want JACK. On GNU/Linux we recommend qjackctl to start the jack-audio-server, on OSX jack comes with a GUI called JACK-pilot.

To be continued..

Getting started - LV2 plugins

To be continued..

Internal Signal Flow

     +--------+    /-----------\    /--------\
     |        |    |           |    |        |
MIDI | Synth- |    |  Preamp/  |    |        |
--=->|        +--->|           +--->| Reverb +--\
     | Engine |    | Overdrive |    |        |  |
     |        |    |           |    |        |  |
     +--------+    \-----------/    \--------/  |
  |  /--------\ Horn L/R  /-----------\
  |  |        +---------->|  Cabinet  +-----*--> Audio-Out Left
  |  |        +---------->| Emulation +--\  |
  \->| Leslie |           \-----------/  |  |
     |        +--------------------------|--/
     |        +--------------------------*-----> Audio-Out Right
     \--------/ Drum L/R

Render diagram with A pre-rendered image is available in the doc/ folder.

Each of the stages - except the synth-engine itself - can be bypassed. The effects are available as standalone LV2 plugins which provides for creating custom effect chains and use 3rd party effects.

The preamp/overdrive is disabled by default, reverb is set to 30% (unless overridden with reverb.mix, reverb.dry or reverb.wet). Note that a stopped leslie will still modify the sound (horn-speaker characteristics, angle-dependent reflections). Bypassing the leslie (whirl.bypass=1) will mute the drum-output signals and simply copy the incoming audio-signal to the horn L/R outputs. The cabinet-emulation is an experimental convolution engine and bypassed by default.

The LV2-synth includes the first three effects until and including the Leslie. The effects can be triggered via MIDI just as with the standalone JACK application. The cabinet-emulation is not included in the LV2-synth because it depends on impulse-response files which are not shipped with the plugin.

The Vibrato and Chorus effects are built into the synth-engine itself, as are key-click and percussion modes. These features are linked to the tone generation itself and can not be broken-out to standalone effects.

Summary of Changes since Beatrix

  • native JACK application (JACK Audio, JACK or ALSA MIDI in)
  • synth engine: variable sample-rate, floating point (beatrix is 22050 Hz, 16bit only)
  • broken-out effects as LV2 plugins; LV2 wrapper around synth-engine
  • built-in documentation

see the ChangeLog and git log for details.


Install the dependencies and simply call make followed by sudo make install.

  • libjack-dev - required - - used for audio I/O
  • tcl-dev, tk-dev - optional, recommended - - virtual Keyboard GUI
  • libasound2-dev - optional, recommended - ALSA MIDI
  • lv2-dev - optional, recommended - build effects as LV2 plugins
  • libzita-convolver-dev - optional - IR leslie cabinet-emulation
  • libsndfile1-dev - optional - needed to load IR samples for zita-convolver
  • liblo-dev - optional - - used only in standalone preamp/overdrive app.
  • help2man - optional - re-create the man pages
  • doxygen - optional - create source-code annotations

If zita-convolver and libsndfile1-dev are available you can use

make clean

to enable experimental built-in convolution reverb used for leslie cabinet simulation (at some point down the road this will be enabled the default).

The Makefile understands PREFIX and DESTDIR variables:

make clean
make install ENABLE_CONVOLUTION=yes PREFIX=/usr DESTDIR=mypackage/setbfree/

Packagers: see debian/rules in the git-repository. LDFLAGS can be passed as is, CFLAGS should be specified by overriding the OPTIMIZATIONS variable. The packaging also includes a desktop-file to launch setBfree from the application-menu which is not included in the release.

Mac/OSX: The same instructions apply. Tcl/Tk is included with OSX. The JackOSX packages available from provide neccesary header and development files. The setBfree git-repository includes a script to build universal binary and create a DMG. However this script assumes that universal (PPC, i386, x86-64) versions of the JACK-libraries as well as zita-convolver and libsndfile are available in /usr/local/ on the build-host.


Many thanks to all who contributed ideas, bug-reports, patches and feedback. In Particular (in alphabetical order): Dominique Michel, Fons Adriaensen, Jeremy Jongepier, Julien Claasen and Ken Restivo.

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