This document introduces cesSynth2, a VST2 plugin which models a
drawbar organ. The synth offers the following features:
- Polyphonic - up to 64 notes can be played, with a polyphony
- Nine harmonics, with individually selectable levels. There is
an additional a detuned oscillator for each harmonic, with a user
selectable detune level.
- Full ADSR control of the amplitude.
- Stereo output, with pan controls for each oscillator, and an
- Control of the detuned oscillators
- Click simulation
- Percussion simulation
- Resonant LP filter
- A custom GUI
A free version of the plugin can be downloaded from here
for Macintosh and here
for PC. The plugin comes with a default sond bank. The free version
is released under the feedbackware
licence agreement. In addition, a version can be purchased for $20
from here which adds sample
If you have any comments of this documentation, or the plugin,
please contact me.
Optimising the synth performance
It is possible to configure cesSynth2 to produce some very
complicated sounds. Some aspects of the sound are computationaly
expensive, and similar results can be achieved with significant
The synth operates in the following modes:
No detune or pan
With the Pan Rate and Pan Depth set to 0, and the Tune
Rng and Tune Lvl set to 0, the no detune or pan mode is
selected, which offers the most polyphony.
No detune with pan
Tune Rng and Tune Lvl set to 0.
No pan, but individual drawbar detunes used.
Detune with pan
All synth features used.
From the above table is should be noted that there are significant
performance gains to be had from not using detune, and not using pan.
If a very simple pan is required (the same pan position for all
drawbars), an external plugin can be used to provide this facility.
This will offer better performance than the internal pan effect,
since this calculates the pan for each drawbar separately.
It should be noted that the use of percussion, click or the ADSR
filter do not affect the synth mode, or the synth performance.
- The synth provides 9 harmonics. In the GUI, there is a slider
for the output level of each harmonic. Under the slider is a knob
providing a detune control for the harmonic, and under that a pan
control. The overall width of the pan is controlled by the Pan
- The envelope section provides a standard ADSR for the overall
- The pan section allows a pan depth (from mono to full stereo
width) and an autopan rate. The pan rate moves the position of the
harmonics within the stereo image at the indicated rate.
- The tune section allows the range of the detuned oscillators
to be selected (maximum setting is 1 semitone), and the level of
the detuned oscillators. It is therefore possible to produce
'beat' type effects by setting the level at maximum and detuning
the oscillators by only a few hz. With large range settings,
richer harmonic sounds can be produced.
- The Click controls give control over the total time of the
click (in ms) and the click intensity. The click is applied to the
signal before the envelope, so if you have a slow envelope attack,
you won't get to hear the click.
- The percussion controls provide a time control, and a level.
The level control runs from -100 to 100. Negative values add the 2
2/3' pipe, whilst positive values add the 4' pipe to the output.
The percussion is not affected by the envelope, or the level
selected for the given harmonic.
- The filter section provides a cutoff frequency and a feedback
- The poly control limits the maximum number of voices.
- The volume control controls the overall volume control of the