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Update: 2020-09-02

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CollidingCombSynth

CollidingCombSynth is an experimental synthesizer which sounds like bowed string. Equipped with 24 Karplus-Strong string models which collide to each other. Tuning of pitch is possible, but difficult. So mostly suitable for sound effects.

CollidingCombSynth requires CPU which supports AVX or later SIMD instructions.

The package includes following builds:

macOS build isn’t tested because I don’t have Mac. If you found a bug, please file a issue to GitHub repository or send email to ryukau@gmail.com.

Linux build is built on Ubuntu 18.0.4 and tested on Bitwig and Reaper. If you are using distribution other than Ubuntu 18.04, plugin will not likely run. In this case, please take a look at build instruction.

Installation

Plugin

Place *.vst3 directory to:

DAW may provides additional VST3 directory. For more information, please refer to the manual of the DAW.

Presets

Extract preset zip, then place preset directory to the OS specific path:

Preset directory name must be the same as the plugin. Make Uhhyou directory if it does not exist.

Windows Specific

If DAW doesn’t recognize the plugin, try installing C++ redistributable (vc_redist.x64.exe). Installer can be found in the link below.

Linux Specific

On Ubuntu 18.0.4, those packages are required.

sudo apt install libxcb-cursor0  libxkbcommon-x11-0

If DAW doesn’t recognize the plugin, take a look at Package Requirements section of the link below and make sure all the VST3 related package is installed.

REAPER on Linux may not recognize the plugin. A workaround is to delete a file ~/.config/REAPER/reaper-vstplugins64.ini and restart REAPER.

macOS Specific

When trying to run plugin first time, following message may appear on macOS.

<PluginName>.vst3 is damaged and can't be opened. You should move it to
the Trash"

In this case, open terminal and try running following command to unzipped .vst3 directory.

xattr -rc /path/to/PluginName.vst3

Plugin may be considered as unsigned/un-notarized application. In this case, try following the steps below.

  1. Open terminal and run sudo spctl --master-disable.
  2. Go to System Preferences → Security and Privacy → General → Allow apps downloaded from, then select “Anywhere”.

Beware that steps above degrades security of your system. To revert the settings, follow the steps below.

  1. Go to System Preferences → Security and Privacy → General → Allow apps downloaded from, then select option to “App Store and identified developers”.
  2. Open terminal and run sudo spctl --master-enable.

Reference

Color Configuration

At first time, create color config file to:

Below is a example of style.json.

{
  "fontPath": "",
  "foreground": "#000000",
  "foregroundButtonOn": "#000000",
  "foregroundInactive": "#8a8a8a",
  "background": "#ffffff",
  "boxBackground": "#ffffff",
  "border": "#000000",
  "borderCheckbox": "#000000",
  "borderLabel": "#000000",
  "unfocused": "#dddddd",
  "highlightMain": "#0ba4f1",
  "highlightAccent": "#13c136",
  "highlightButton": "#fcc04f",
  "highlightWarning": "#fc8080",
  "overlay": "#00000088",
  "overlayHighlight": "#00ff0033"
}

Hex color codes are used.

First letter # is conventional. Plugins ignore the first letter of color code, thus ?102938, \n11335577 are valid.

Do not use characters outside of 0-9a-f for color value.

Controls

Right Click on the controls pops up a context menu provided by DAW.

Knob and slider can do:

There is an additional control for number sliders used for Octave, Seed etc.

Control with many blue vertical bars (BarBox) have some keyboard shortcuts. LFO Wave on Main tab and Gain, Width, Pitch, Phase on Wavetable tab are using BarBox. Shortcuts are enabled after left clicking BarBox and mouse cursor is on the inside of BarBox. Cheat sheet is available on Infomation tab.

Input Control
Left Drag Change Value
Shift + Left Drag Change Value (Snapped)
Ctrl + Left Drag Reset to Default
Ctrl + Shift + Left Drag Change Value (Skip Between Frames)
Right Drag Draw Line
Shift + Right Drag Edit One Bar
Ctrl + Right Drag Reset to Default
Ctrl + Shift + Right Drag Toggle Lock
a Alternate Sign
d Reset Everything to Default
D Toggle Min/Mid/Max
e Emphasize Low
E Emphasize High
f Low-pass Filter
F High-pass Filter
i Invert Value (Preserve minimum)
I Invert Value (Minimum to 0)
l Toggle Lock under Mouse Cursor
L Toggle Lock for All
n Normalize (Preserve minimum)
N Normalize (Minimum to 0)
p Permute
r Randomize
R Sparse Randomize
s Sort Descending Order
S Sort Ascending Order
t Subtle Randomize (Random walk)
T Subtle Randomize (Converge to 0)
z Undo
Z Redo
, (Comma) Rotate Back
. (Period) Rotate Forward
1 Decrease
2-9 Decrease 2n-9n

Snapping is not available for all BarBox. If you’d like to have snapping for certain BarBox, feel free to open issue to GitHub repository.

Edit One Bar with Shift + Right Drag holds a bar under the cursor when mouse right button is pressed. Then only changes that one bar while holding down mouse right button.

Toggle Lock with Ctrl + Shift + Right Drag behaves as line edit. When right mouse button (RMB) is pressed, it holds the opposite state of the bar below mouse cursor, then use the state for the rest of bars. For example, if RMB is pressed on a locked bar, dragging unlocks bars while holding down RMB.

Caution

Output amplitude varies a lot, even if Compressor is turned on. Recommend to always insert limiter after CollidingCombSynth.

Block Diagram

If the image is small, use Ctrl + Mouse Wheel or “View Image” on right click menu to scale.

Diagram only shows overview. It’s not exact implementation.

Parameters

Gain

Gain, Boost

Master gain. Value of Gain and value of Boost will be multiplied.

masterGain = Gain * Boost
Compressor

Turn on/off the comporessors. Each voice has a compressor.

Time

Attack/Release time of compressor.

Larger Time value may sound more natural, but compression becomes leaky. In this case, try turning down the value of Threshold.

Threshold

Compressor starts compressing the signal when input amplitude exceeds Threshold. Usually, Threshold is set to less than 1.0.

Tuning

Octave, Semi, Milli

Changes master pitch.

ET, A4 [Hz]

Changes tuning.

ET stands for equal temperament. Note that when ET is less than 12, some notes may become silent due to frequency becomes too high or too low.

A4 [Hz] is frequency of note A4.

Unison

nUnison

Number of voices used by unison.

To avoid interruption of release, increase the number of Poly in Misc. section. Note that increasing Poly consumes more resources.

Detune, Random Detune

Detune is the difference of pitch between voices used in a unison.

When Random Detune is checked, amount of detune changes for each note-on.

random = RandomDetune ? rand() : 1
detune = pitch * (1 + random * unisonIndex * Detune)
Spread

Amount of stereo spread for a unison.

Gain

Amount of randomization of gain for voices used in a unison.

Random

Random section has configurations for 4 random number generators (RNG).

Amount

Amount of randomization. Randomization is disabled when Amount is set to 0.

Seed

Seed value. Different seed generates different sequence of pseudo random number.

Retrigger

When checked, the synth resets seed for each note-on.

Exciter

Configuration of exciter. Excitation is some force to start physical model. For example, picking of guitar, impact of piano string and hammer, impact of stick and drumhead, are excitation.

The exciter of CollidingCombSynth consists of sawtooth/noise oscillator and serially connected 8 comb filters.

LP Cutoff

Cutoff frequency of lowpass filter which applies to oscillator output. Unit of display value is Hz.

Gain

オシレータの音量です。

A, D

A is the attack time of oscillator. D is the decay time of oscillator.

Turning A knob to right makes sound softer.

Saw/Noise

Mixing ratio of sawtooth and gaussian noise in oscillator output. When set to leftmost, oscillator only outputs sawtooth. When set to rightmost, oscillator only outputs gaussian noise.

Comb Time

Delay time of comb filter. Unit of display value is seconds.

String

Configurations of Karplus-Strong strings.

LP Cutoff

Cutoff frequency of lowpass filter which is inserted in feedback path of string model. Unit of display value is Hz.

HP Cutoff

Cutoff frequency of highpass filter which applies to string output. Unit of display value is Hz.

Distance

Distance between strings. When an immediate amplitude of a string exceeds Distance, exceeded amplitude will be propagated to a neighbouring string.

Propagation

The value of Propagation changes the loss of force when strings are collided. The bounce will be weaken if Propagation is smaller.

Connection

Connection type of strings.

A, D, S, R

Envelope parameters which modulates LP Cutoff. This envelope basically works as the gain envelope of CollidingCombSynth.

Frequency

Fundamental frequency of string. The final frequency of a string is calculated by multiplying note pitch by Frequency.

noteFrequency = A4Hz * pow(2, Octave + (Semi - 69) / ET + Milli / (ET * 1000))
stringFrequency = Frequency * noteFrequency

Change Log

Old Versions

N/A.

License

CollidingCombSynth is licensed under GPLv3. Complete licenses are linked below.

If the link above doesn’t work, please send email to ryukau@gmail.com.

About VST

VST is a trademark of Steinberg Media Technologies GmbH, registered in Europe and other countries.