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Update: 2023-12-02

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FeedbackPhaser is a phaser but the modulation source is feedback signal rather than an LFO. It sounds more like a distortion rather than a phaser most of times.

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

You can fund the development through Current goal is to purchase M1 mac for better macOS support. 💸💻



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:


It is recommended to always insert limiter after FeedbackPhaser. Output amplitude can exceed +140 dB, depending on the values of Feedback Amount and Safety Clip.


Quick Start

Below is an example setup steps.

  1. Launch FeedbackPhaser.
  2. Lower Output depending on the amplitude of input.
  3. Change Feedback Amount.
  4. Change Modulation Amount.
  5. Change Safety Clip.

Output amplitude is mostly determined by above steps. After that, start changing other parameters.

Note that the character of Modulation Amount changes depending on Modulation Type. It consequently changes the output amplitude.

Taming Feedback

Safety Clip is the most important parameter to limit output amplitude. if feedback amplitude exceeds Safety Clip amplitude, the text indicator:

Output is clean.

changes to:

Too much feedback.

Distortion will be added when “Too much feedback.” is displayed. If distortion is not desired, increase Safety Clip, and decrease Output.

Sometimes increasing Safety Clip can’t stop distortion. In this case, reduce Feedback Amount and/or Modulation Amount.

Where to Automate

Following parameters might be fun to automate.

Also, note event can be used to control Allpass Center.

More Allpass Stage adds more resonance for feedback. However, it also dilutes the texture of input signal.

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.


Characters inside of square brackets [] represents unit. Following is a list of units used in FeedbackPhaser.


Output [dB]

Output gain.

Highpass [Hz]

Cutoff frequency of highpass filter that is applied right before output.

This highpass filter is used to remove direct current.


Mixing ratio of input and output.

Intensity of Feedback -> Amount changes depending on value of Mix.



Amount of feedback.

Feedback signal may be hard clipped when absolute value of Feedback -> Amount is high.

Safety Clip [dB]

When amplitude of feedback signal exceeds Safety Clip, feedback signal will be hard clipped internally.

FeedbackPhaser applies hard clipping on feedback signal to prevent blowing up. Distortion will occur when hard clipping is engaged.

To get clean sound, increase Safety Clip until text indicator in the Feedback section stays to Output is clean., and no longer changes to Too much feedback. Beware that increasing Safety Clip sometimes drastically increases output amplitude. To compensate, turn down Output at the same time.

Highpass [Hz]

Cutoff frequency of highpass filter that is applied to feedback signal.



Number of allpass filters to serially connect.


Value to determine allpass filter cutoff frequency distribution.

When Spread is 0, all of cutoff frequencies become as same as Center. When Spread is 1, cutoff frequencies becomes higher for later index, as in Center * 1, Center * 2, Center * 3, and so on.

Below is the formula to calculate cutoff frequency of allpass filter.

allpassCutoffHz = modulation * Center * (1 - Spread * (index - 1)).
Center [Hz]

Cutoff frequency of allpass filters when not modulated.



Type of modulation scaling.

The formulas on the list above aren’t directly used in implementation. Range restrictions and other things are also performed to avoid invalid values.


Amount of modulation by feedback signal.

Modulation is applied to cutoff frequency of allpass filter.

Mod. Asym.

Mixing ratio between raw and full-wave rectified modulation signal.

Post LP [Hz]

Lowpass filter cutoff frequency.

This lowpass filter applies to allpass filter cutoff frequencies after modulation.


Transpose [st.]

Note event transpose amount in semitones.

To Allpass

Multiplier to pitch of a note.

When To Allpass is 1, pitch is used without scaling.

Note that FeedbackPhaser uses relative pitch represented by note, not absolute frequency represented by note.

Slide [s]

Pitch slide time when receiving a note-on before receiving a note-off of another note.

Release [s]

Approximate time to return to Center from pitch of last note.


Side Chain

When lit, uses sidechain input as modulating signal.

Smoothing [s]

Time to reach new value after change of parameter.


Oversampling ratio.

Increasing oversampling ratio may suppress gritty noise that appears when modulation is high. However, CPU load increases with higher oversampling ratio.

Change Log

Old Versions


FeedbackPhaser 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.