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Update: 2024-01-02

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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.

full package contains following builds.

Linux build is built on Ubuntu 22.04. If you are using distribution other than Ubuntu 22.04, plugin will not likely to run. In this case, please take a look at build instruction.

macOS package is recommended for macOS user. I can’t purchase Apple Developer Program, therefore installation requires a workaround to bypass Gatekeeper. Details of workaround are written in Installation -> macOS Specific section.


Feel free to contact me on GitHub repository or

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Move *.vst3 directory to:

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


Notice: Some plugins don’t have presets provided by Uhhyou Plugins.

Presets are included in the plugin package linked at the top of this page. To install presets, follow the steps below.

  1. Download plugin from a link at the top of this page.
  2. Extract downloaded zip file.
  3. Open presets directory placed in extracted package.
  4. Move Uhhyou directory into an OS specific preset directory (see below).

Below is a list of preset directories for each OS.

Preset directory name must be the same as the plugin. If preset directory does not exist, create it.

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 22.04, 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

Important: full package is not confirmed working. When using full, try removing following files.

macOS package doesn’t contain above files. Also, all packages are in “ad-hoc signing” state set by codesign command.

Remove Quarantine

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 one or both of following command to unzipped .vst3 directory. Replace /path/to/PluginName.vst3 according to your install location.

xattr -rd /path/to/PluginName.vst3
xattr -rc /path/to/PluginName.vst3

Bypass Gatekeeper

Plugin may be considered as unsigned/un-notarized application. In this case, open System Preferences, go to Security & Privacy → General, then click the Open Anyway button. The offcial Apple help page linked below has screenshots for the procedure. See “If you want to open an app that hasn’t been notarized or is from an unidentified developer” section.

If the plugin is still not working, try changing install location to /Library/Audio/Plug-ins/VST3/ or /Users/$USERNAME/Library/Audio/Plug-ins/VST3/ whichever still haven’t tried.

If all the above methods do not work, 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.

Applying codesign

Note This section may not relevant to macOS packages. However it’s not verified. (GitHub issue)

To use full package, following command might be used.

sudo codesign --force --deep -s - /path/to/PluginName.vst3

codesign might not be available without installing Xcode.


GUI Style Configuration

At first time, create color config file to:

style.json will be loaded for each time a plugin window opens.

Several color themes are available on the link below.

Below is a example of style.json.

  "fontFamily": "Tinos",
  "fontBold": true,
  "fontItalic": true,
  "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"

Font Options

Following is a list of font options.

To use custom font, place *.ttf file into custom font path: *.vst3/Contents/Resources/Fonts.

Notice: If the combination of fontFamily, fontBold, fontItalic is not exists in custom font path, default font of VSTGUI is used.

If fontFamily is set to empty string "", then "Tinos" is used as fallback. If the length is greater than 1 and the font family name doesn’t exists, default font of VSTGUI is used.

Styles other than bold, italic or bold-italic are not supported by VSTGUI. For example, “Thin”, “Light”, “Medium”, and “Black” weights cannot be used.

Color Options

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.

Following is a list of color options. If an option is missing, default color will be used.


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

Knob and slider provides following controls:

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)
Middle Drag Draw Line
Shift + Middle Drag Edit One Bar
Ctrl + Middle Drag Reset to Default
Ctrl + Shift + Middle 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
2-4 Decrease 2n-4n
5-9 Decimate by holding 2n-5n

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.

Some BarBox has scroll bar to zoom in. Scroll bar has handles on left end and right end. To control zoom, use Left Drag on one of the handle. Scroll bar also has following controls:


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.



Gain, Boost

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

masterGain = Gain * Boost

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


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.


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


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.



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)

Amount of stereo spread for a unison.


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


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


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


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


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


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.



A, D

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

Turning A knob to right makes sound softer.


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.


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


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


Connection type of strings.

A, D, S, R

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


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


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

If the link above doesn’t work, please send email to

About VST

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