









Table Of Content
Introduction
Description
From a light ensemble to a deep destructive modulation effect, Blue Cat's Chorus can just do anything, for free!
The Chorus effect was originally designed to simulate several voices, just as if several persons were playing together the same notes, but with a variable delay between them. This is one of the typical effects that you can get with Blue Cat's Chorus.
But this plug-in also enables you to drastically change the original sound and create deep pitch modulation or crazy 'bubbling' effects.
With the additional "Spread" control on the stereo version, the famous stereo widening and head spinning chorus effects are a few click away.
Features
Main Features
- Single voice vintage chorus effect.
- Stereo spread control.
- Sine or triangle LFO shapes.
- In or out of phase mix control.
Blue Cat Audio Standards:
- Available as: Mac-AAX, Mac-AU, Mac-RTAS, Mac-VST, Win-AAX, Win-DX, Win-RTAS, Win-VST, Win x64-DX, Win x64-VST.
- Native DSP code for optimal performance.
- Full MIDI control and automation support with silent, zipper-free parameters update, advanced response control and MIDI Learn.
- No CPU load on idle: when the plug-in is fed with silence, the processing smoothly shuts down, to optimize the CPU usage of your Digital Audio Workstation.
- Skinnable and customizable user interface with transparency management.
- Smooth Bypass: activate/deactivate the plug-in with absolutely no noise.
- Undo/Redo.
- Full featured integrated presets manager.
- Any sample rate supported.
System Requirements
Windows
- An SSE2-enabled processor (Pentium 4 or later).
- Microsoft Windows XP, Vista, Windows 7 or 8.
- Any DirectX / VST / RTAS / AAX compatible host software (32 or 64 bit).
Mac OS X
- An Intel processor.
- Mac OS X Moutain Lion (10.8), Lion (10.7), Snow Leopard (10.6), or Leopard (10.5).
- Any VST / Audio Unit (32/64-bit) / RTAS / AAX compatible application.
For more information about supported platforms, see our FAQ.
Installation
Blue Cat Audio plug-ins cannot be run standalone, they require a host application (see the System Requirements chapter for more information). Depending on which host application you use, you might need to install the plug-ins in different locations.
Windows
Install
All versions of the plug-in provide an installation program. Follow the steps of the wizard to install the plug-in on your machine. During the installation you will be asked where you want the plug-in(s) to be installed. For the VST version you should install the plug-in inside the VST plug-ins folder used by your host application(s). The default path set in the installer should work for most applications, but you should check your host software documentation to know where it looks for VST plug-ins.
Some applications will not automatically rescan the new plug-ins, so you might have to force a refresh of the plug-ins list.
Upgrade
When a new version of the plug-in is released, just launch the new installer: it will update the current installation.
Uninstall
To uninstall the plug-in, simply launch the "Uninstall" program that is available in the start menu or in the configuration panel. It will take care of removing all files from your computer.
Mac
Install
On Mac the plug-ins are available as drive images. After download, double click on the file to open it. You can then drag and drop the plug-in file(s) to the shortcut that is provided within the image. It will install the plug-in(s) for all users on the machine.
In case you do not have admin rights on your Mac or if you want to install the plug-in(s) to another directory, just copy the files to the appropriate location. If required, more information is available in the README.txt file that is included in the package.
Upgrade
When a new version of the plug-in is released, open the new image and copy the files over the previous ones. The new version will replace the older one.
Uninstall
To uninstall the plug-in, simply remove the plug-in components from the folder where you have copied them during install (move them to the trash).
If you want to completely remove all settings and configuration files, you can also remove these additional directories that may have been created on your computer:
- ~/Library/Preferences/Blue Cat Audio/[Plug-in name and TYPE], where TYPE is VST, AU, RTAS or AAX: global preferences.
- ~/Documents/Blue Cat Audio/[Plug-in name]: user data, such as presets, additional skins and user-created plug-in data.
Using Blue Cat's Chorus
The User Interface
Note: The main toolbar, menus and basic features available with all our plug-ins are detailed in the Blue Cat Audio Plug-ins Basics section.
Overview
Blue Cat's Chorus is bundled with two skins. You may also create your own or download new ones on www.bluecataudio.com.
The user interface consists in a row of actionable knobs and buttons that control the parameters described in details in the parameters section.

The various elements of the user interface (knobs, sliders, buttons...) are simple and intuitive to operate, but more information about how to interact with them is available in the "Plug-ins Basics" chapter of this manual.
Blue Cat Audio Plug-ins Basics
This chapter describes the basic features that are common to all our plug-ins. If you are already familiar with our products, you can skip this part.
User Interface Basics
About Skins
Like all Blue Cat Audio plug-ins, Blue Cat's Chorus uses a skinnable user interface. It means that the appearance and behavior of the user interface can be entirely customized.
Especially with third party skins, the experience may be quite different from the one offered by the default skins that we provide. However, our plug-ins and our skinning engine have several standard features that will be available whatever your favorite skin.
More information about custom skins can be found in the skins section.
The Main Toolbar
In most skins, an optional toolbar at the top of the user interface gives you access to the main options and settings of the plug-in:
Presets Area
At the center of the toolbar, you can see the current preset area (the "Default Settings" box). It displays the name of the current preset, with a "*" at the end if it has been modified since loaded.
The arrows on the left and right let you navigate thru the (factory and user) presets available for the plug-in.
Clicking on the preset name opens the presets menu which lets you manage the presets of the plug-in.
Commands
The icons in the toolbar give you access the to the following commands that are detailed in the next paragraph:
| Icon | Name | Function |
|---|---|---|
|
|
Menu | Open the main menu |
|
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Undo | Undo |
|
|
Redo | Redo |
|
|
Manual | User Manual |
|
|
About | About |
The Main Menu
The main menu is available from the main toolbar, or if you right click anywhere on the background of the plug-in:

- Presets: opens the presets menu to manage presets.
- Set Preset Skin: change the skin for the current preset.
- Use Global Skin: use the skin defined in the global settings for the current preset. This item is enabled only if a skin has been defined for the current preset.
- Undo/Redo: undo or redo the latest modifications. This includes all changes made to the current preset settings such as MIDI or automation preferences.
- Presets Settings: open the presets settings window. It lets you change the skin, MIDI and automation settings for the current preset.
- Global Settings: open the global settingswindow. It lets you change the skin, MIDI and automation settings that are used by default in all instances of the plug-in (if not overriden by the current preset).
- User Manual: open this user manual.
- Check for Updates: opens up our website to let you check if any update for this software is available.
- Get More Skins: get more skins for this software.
- Legal Information: browse licensing and misc legal documents.
- About: displays the “about” dialog box.
The Title Bar
In most skins, an icon bar is located below the main toolbar. The first commands are the same for all plug-ins:
From left to right:
- Smooth Bypass: smoothly bypass the plug-in (just like a power button).
- Window Opacity: reduce the opacity value by turning the knob, and make the the plug-in window transparent. (the result may depend on the host application).
- Show/Hide MIDI and Automation Control Settings: show/hide the buttons that give access to direct MIDI/Automation setup for each parameter in the user interface. This button will show or hide dropdown menu buttons that popup a MIDI/Automation setup menu described here.
Controls
Examples
Here are a few examples of typical controls you will encounter in the user interface of our plug-ins:
| slider | slider | knob | button | Text control |
|
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Interacting with Controls
You can interact with the controls of the plug-in interface either with the mouse or the keyboard.
Setting the keyboard focus on a control (so that it responds to key strokes) may be automatic (when you pass the mouse over it it gets focus) or manual (you have to click on the control to set the focus on it). Note that all host applications behave differently regarding keyboard handling. In some applications you may not be able to use all keys described later in this manual to interact with our plug-ins. It is usually made obvious to you to know the active surfaces of the skin (the places where you can click with the mouse): the mouse cursor usually changes when you can do something on a control. In the default skins delivered with the plug-in, the cursor changes to a small hand or an arrow to tell you when your mouse is over an active control.
Mouse
Various mouse movements will let you interact with the controls:
| Mouse Interaction | Action |
|---|---|
| Left Click | Acquire focus and start dragging or push (button) |
| Left Click + Alt Key | Set the value to default |
| Left Double Click |
Acquire focus and launch the “fine
tuning” edit box (except button):
![]() |
| Right Click | Set the value to default |
| Mouse Wheel | Increment or decrement the position (focus required) |
| Mouse Drag | Change the control position depending on mouse movement (except button) |
Keyboard
All control widgets support the following keys (note that some of them are caught by the host and thus never forwarded to the control. For example in Steinberg Cubase SX you cannot use the arrow keys to control the plug-in):
Keys Common to All Controls
| Key | Action |
|---|---|
| Up Arrow | Small increment of the position (up or right) |
| Down Arrow | Small increment of the position (down or left) |
| Left Arrow | Same as Down Arrow |
| Right Arrow | Same as Up Arrow |
| Page Up | Large increment of the position (up or right) |
| Page Down | Large decrement of the position (down or left) |
| + | Small increment of the value of the control |
| - | Small decrement of the value of the control |
| d | Set to default value (same as mouse right click) |
| e |
Opens the 'fine tuning' window to precisely
set the parameter:
![]() |
| SHIFT | When the key is down, the fine tuning mode is on, and you can modify the value with better precision when moving the mouse, the mouse wheel or using the keyboard. Just release the key to get back to the normal mode. |
Keys Specific to Buttons
| Key | Action |
|---|---|
| Enter | Pushes the button |
Presets
To get started with the plug-in and discover its capabilities, a couple of factory presets are provided. You can also save your own presets and recall them later for other projects. Our plug-ins propose a full-featured preset manager to let you save, browse, organize and recall its presets.
The Presets Menu
The presets menu can be opened from the main menu or the main toolbar. It displays the list of presets available for the plug-in as well as commands to load, save or organize presets:

- Factory Presets: shows the list of factory presets delivered with the plug-in.
- "Folder A" to "User Preset Z": user presets and categories.
- Load: load preset from file.
- Save As: save current preset to a file.
- Save As Default: save the current state as the default preset. This preset is used every time a new instance of the plug-in is created.
- Reset Default: reset the default preset to its factory state: this makes the plug-in forgets the custom settings you might have saved as a default preset.
More about Presets
There are two types of presets: factory presets (read only) that are provided with the plug-in, and user presets that can be created and stored by the user.
The user presets are stored in a subdirectory of the documents folders of your profile ("Documents" on Mac, and "My Documents" on Windows): Blue Cat Audio/[Plug-in Name]/Presets. Each preset is stored as an individual file. You can create folders and subfolders in the Presets directory to classify your presets, as shown in the example below:

If you save a preset named "Default" in the root Presets directory, it will override the factory default preset (that's what "Save As Default" does). To restore the factory default preset, you can just remove this file or use the "Reset Default" command.
MIDI and Automation Control
Blue Cat's Chorus can also be remotely controlled via MIDI using MIDI CC ("Control Change") messages or automation curves, if your host application supports it. It is possible to customize the channel, control numbers, range and response curve used for each parameter in the settings panel available from the main menu (see the Plug-in Settings chapter for more details).
MIDI and Automation Settings Menu
Most skins also provide the ability to change MIDI and automation settings for each parameter directly in the main user interface. When this feature is activated using the corresponding title bar button, dropdown menu buttons appears next to main controls:

Clicking on this button shows the MIDI/Automation settings menu:

- MIDI Learn: launches MIDI learn mode for the control: touch your MIDI controller and the control will learn from it the MIDI channel and CC number. To end the learn mode, reopen this menu and deselect the option.
- MIDI Unlearn: deactivates MIDI control for this parameter.
- Settings: launches the advanced settings panel described below. This controls the settings for the current preset.
Andvanced MIDI and Automation Settings
You can completely customize the way the plug-in is controlled by automation and MIDI. For a global view of all parameters at a time, you can use the Plug-in Settings window for the current preset which is available from the main menu.

MIDI Settings:
- Enable MIDI: enable/disable the MIDI control of the parameter.
- Channel: MIDI Channel for the parameter control. If set to 0, the plug-ins will accept Control Change Messages from all MIDI Channels (MIDI Omni mode).
- CC: Control Change Number.
- Learn: click on this button to activate the MIDI learn functionality. When it is activated, you can move your MIDI controller, and the plug-in will automatically set the MIDI Channel and CC Number.
MIDI and automation settings:
- Response: response curve of the MIDI or automation control: from very fast to slow control.
- Min: minimal value of the parameter when MIDI controlled or automated.
- Max: Maximum value of the parameter when MIDI controlled or automated.
Note: if the Min value is higher than the Max value, the response curve will be reversed: increasing the control value will decrease the parameter value.
Note: if you double click on the parameter text control boxes for the max and min values, a “fine tuning” edit box will appear and let you change the min and max values with more precision:

More
Check our online tutorial for more screenshots and more examples of our plug-ins user interfaces.
Blue Cat's Chorus Parameters
All parameters described below can be automated and controlled via MIDI if your host application supports it. You can precisely define this behavior in the settings panels described later in this manual.
Input
|
Name |
Unit |
Description |
|---|---|---|
|
Bypass |
|
Bypass the effect. |
|
Gain |
dB |
Input gain. |
|
Dry |
% |
Amount of dry input signal. |
|
Wet |
% |
Amount of wet signal (signal modified by the variable delay). |
|
Delay |
ms |
Average delay applied to the signal. |
|
Depth |
% |
Depth of the effect: amount of delay variation around the average delay. |
|
Rate |
Hz |
Rate of the LFO. |
|
Spread |
% |
(Stereo version only) Amount of stereo effect. Set this parameter to 0 if you want a mono chorus effect. |
|
Shape |
|
Selects one of the two available shapes for the LFO: sine (0) or triangle (1) waveform. |
Plug-in Settings
In addition to the controls offered in the main user interface, Blue Cat's Chorus has various settings that let you fine tune the behavior of the plug-in. You can choose to change these settings either for the current preset or globally for all instances of the plug-in.
The Global Settings Window
The settings available in this window apply to all instances of the plug-in, for all presets, if not overriden in the presets settings. Consider these settings as “default” settings.
General
You can change the default skin for all instances of the plug-in: write the skin file path in the text edit box or click on the button to open a file chooser dialog. If you have several instances of the plug-in opened in your session, you will have to re-open the user interfaces of these plug-ins to see the skin change.

The output data refresh rate can also be customized for all instances of the plug-in. It controls the refresh rate of non-audio data produced by the plug-in (parameters, curves...). It also controls the refresh rate of output MIDI CC messages or output automation data. The higher the refresh rate, the better precision, but also the higher cpu usage (some host applications may also have trouble recording MIDI data at high refresh rates). The default value is 50 Hz.
Global Control Input Settings (MIDI and Automation)
The plug-in offers a couple of settings that affect the way it is controlled by MIDI messages or automation. While the first settings only apply to MIDI control, the "Control Response", "Min" and "Max" settings apply to both automation and MIDI control.
For each parameter you can define a default MIDI channel and CC number. You can then control the plug-in with an external MIDI controller or one of our plug-ins that generate MIDI messages.
The settings below are available for each plug-in parameter.
MIDI Settings:
- Enable MIDI: enable/disable the MIDI control of the parameter.
- Channel: MIDI Channel for the parameter control. If set to 0, the plug-ins will accept Control Change Messages from all MIDI Channels (MIDI Omni mode).
- CC: Control Change Number.
- Learn: click on this button to activate the MIDI learn functionality. When it is activated, you can move your MIDI controller, and the plug-in will automatically set the MIDI Channel and CC Number.
MIDI and automation settings:
- Response: response curve of the MIDI or automation control: from very fast to slow control.
- Min: minimal value of the parameter when MIDI controlled or automated.
- Max: Maximum value of the parameter when MIDI controlled or automated.

Note: if the Min value is higher than the Max value, the response curve will be reversed: increasing the control value will decrease the parameter value.
Note: if you double click on the parameter text control boxes for the max and min values, a “fine tuning” edit box will appear and let you change the min and max values with more precision:

The Current Preset Settings Window
In this window you can change the settings for the current preset of the current instance of the plug-in only.
Preset Skin
You can choose to use the global skin setting or to change the skin for the current preset. This way you can have different skins for different instances of the plug-in in the same session in order to differentiate them.

Preset Control Input Settings (MIDI and Automation)
Use the global settings or override them for the current preset. The parameters are the same as for the global input settings.

About Skins
Blue Cat's Chorus integrates Blue Cat's skinning engine that allows you to customize the user interface. You can download new skins for your plug-in at the following address:
If you don't find a skin that fits your need or if you want a really custom one, you can choose to create your own skin.
Changing the Skin
You have two ways to change the skin of your plug-in: you can change the default (or 'global') skin in the global settings, or change the skin for the current preset only (either in the preset settings page or from the main menu). The global skin applies to all plug-in instances, whereas the current preset skin only applies to the current preset of the current plug-in instance.
See the main menu for more information about how to access these options.
On some hosts the plug-in window won't resize automatically when you choose a skin with a different size. In this case, just close the window and re-open it: it will be displayed with the right size.
Create a Custom Skin
You can create custom skins for your plug-in in order to adapt it to your exact needs. You can change its look and feel and make it completely integrated in your virtual studio!
Just read the Blue Cat's Skinning Language manual and download the samples for the tutorial on http://www.bluecataudio.com/Skins. You can get ready to create your own skins in a few minutes.
You can then share your skins on our website.
FAQ
Plug-ins Formats
Here is a list of host software and the version we recommend you to use. Many other applications are supported, check your application user manual to choose the best version (AU stands for "Audio Unit" and DX for "DirectX"):
| Host Application | Plug-in Version |
|---|---|
| Cakewalk Products (Sonar, Project5...) | DX |
| Sony Products (Vegas, ACID, Soundforge) | DX for old versions, VST for new |
| Steinberg Products (Cubase, Nuendo, Wavelab) | VST (Mac or PC) |
| Ableton Live | VST (Mac or PC) |
| Adobe Audition | any |
| EnergyXT | VST |
| Magix Samplitude | VST |
| Avid (Digidesign) Pro Tools | RTAS |
| Apple applications (Logic Pro, Logic Express, Garage Band...) | AU |
| Cockos Reaper | VST (Mac or PC) |
| ... |
Installation
Most software you can purchase on this website is plug-ins for host applications. It means you need another application to use it. See the "Plug-ins Formats" section in this FAQ for more information.
First check that you application supports DirectX, Audio Unit or VST plug-ins.
If you are using the DirectX version, check that your host application supports DXi plug-ins (MIDI enabled DirectX plug-ins). If it does not, it may remove it from the DirectX plug-ins list (some applications such as Sony Vegas 5 and Cool Edit Pro are known to do this). In this case, use our DXi Manager free utility and disable the MIDI capabilities of the plug-in. You may need to reinstall the software again before it shows up into your host application. For more information about this topic please read our DXi in Sony Vegas tutorial (it is applicable to other applications than Sony Vegas).
If you are using the Direct X version and your host application supports DXi, check that the plug-in does not appear in the 'virtual synth' or 'synthesizers' category. If you wish not to use the MIDI capabilities of the plug-in and use it as a regular Direct X plug-in, you can download the freeware DXi Manager and disable the MIDI capabilities of the plug-in.
You are probably running a 32-bit application. If that's the case, you need to install the 32-bit version of the plug-in: the choice for 32 or 64-bit is not determined by the operating system (64-bit windows can run both 32 and 64-bit applications), but by the host application that you are using.
Our plug-ins require several additional files for default settings, skins and miscellaneous data. We provide an installer for our customers' convenience. Our installers do not modify the system settings or the Windows registry, except for the DirectX versions registration. Our installers won't harm your system.
Software Version
Upgrade
Automation
More...
This manual only covers the basics of Blue Cat's Chorus. Our website offers many additional resources for your Blue Cat's Chorus plug-in and is constantly updated, so keep an eye on it! You will find below a few examples of available resources.
Extra Skins
We encourage our customers to propose their own skins for our products and we often propose alternative skins to let you choose the one that best suits your needs. You can check Blue Cat's Chorus skins page to get the latest skins.
Aqua
![]() | Product: Chorus Description: Simple Mac OS X Aqua-style skin. Author: Blue Cat Audio Download: Skin_Aqua.zip |
Aqua Brushed
![]() | Product: Chorus Description: Mac OS X Brushed Metal style skin. Have your plug-in look like iTunes! Author: Blue Cat Audio Download: Skin_AquaBrushed.zip |
Audiofanzine
![]() | Product: Chorus Description: (French) Une skin aux couleurs du formidable site www.audiofanzine.com. Author: Anonymous ('Audiofanzine Fan') Download: Skin_Audiofanzine.zip |
FL Studio
![]() | Product: Chorus Description: FL Studio style for your plug-in. Author: Blue Cat Audio Download: Skin_FLStudio.zip |
FL Studio Knobs
![]() | Product: Chorus Description: A very small skin with FL Studio style, using tiny knobs. Author: Blue Cat Audio Download: Skin_FLStudioKnobs.zip |
Bronze
![]() | Product: Chorus Description: Author: Limeflavour (www.flavoursoflime.blogspot.com) Download: Skin_LimeFlavourBronze.zip |
Gray
![]() | Product: Chorus Description: Author: TSV (www.tsvdesign.net) Download: Skin_TSVGray.zip |
Yellow
![]() | Product: Chorus Description: Author: TSV (www.tsvdesign.net) Download: Skin_TSVYellow.zip |
Windows XP
![]() | Product: Chorus Description: Windows XP look for your plug-in. Author: Blue Cat Audio Download: Skin_WinXP.zip |
Black Beauty
![]() | Product: Chorus Description: Author: satYatunes (satyatunes.blogspot.com) Download: Skin_satYatunes_blackbeauty.zip |
Metal Beauty
![]() | Product: Chorus Description: Author: satYatunes (satyatunes.blogspot.com) Download: Skin_satYatunes_metalbeauty.zip |
Tutorials
Many Tutorials are available on our website. They cover a wide range of topics and host applications. You will find below a list of tutorials that are related to the Blue Cat's Chorus plug-in. An updated list is also available online.
Tutorial - Using DXi plug-ins in Sony Vegas
![]() | This tutorial will teach you how to use any DXi plug-in in Sony Vegas: Sony Vegas does not support MIDI automation, so if your plug-in supports the MIDI Dxi protocol, it is removed from the plug-ins l...[Read More...] |
Tutorial - Export Plugin Presets to Share them with the Community
![]() | This tutorial shows you how to export your presets in order to share them with the community on the Blue Cat Audio website. This tutorial uses Blue Cat's Stereo Triple EQ for the demonstration bu...[Read More...] |
Tutorial - Getting Started with Plug-ins User Interface
![]() | Get used to the user interface features of Blue Cat Audio products! They have been designed for an optimal workflow, so here are the tips and tricks to save time. All these functionalities are explain...[Read More...] |
Tutorial - Using MIDI Control in Sonar
This tutorial will help you understand how to use parameters MIDI control in Cakewalk Sonar. It is applicable to any DXi plug-in (MIDI enabled DirectX plug-in)....[Read More...] |
Tutorial - How to Use the Free Presets Available on this Website
![]() | This tutorial shows you how to get and load free presets for your favorite Blue Cat Audio plugin. This tutorial uses Blue Cat's Dynamics for the demonstration but is applicable to all our plugins...[Read More...] |
Updates
As you can see in the history log below, we care about constantly updating our products in order to give you the latest technology available. Please visit our website often to check if Blue Cat's Chorus has been updated, or subscribe to our Newsletter to be informed of the latest news about our products.
You can also follow us on twitter and facebook for almost real time updates notification, and subscribe to our YouTube channel to see the latest videos about our software.
Versions History
V4.01 (2012/04/23) |
Bug Fixes:
|
V4.0 (2012/03/28) |
New Features:
|
V3.63 (2011/02/10) |
|
V3.62 (2010/03/19) |
This update only concerns the RTAS version of the plug-in:
|
V3.61 (2010/02/25) |
|
V3.6 (2010/01/30) |
|
V3.5 (2009/11/20) |
|
V3.4 (2009/09/21) |
|
V3.31 (2009/05/05) |
| Mac VST update: fixed incompatibility issues with Cubase 5 on Mac. |
V3.3 (2009/02/03) |
| Mac Audio Unit Support. |
V3.3 (2008/11/21) |
|
V3.2 (2006/11/29) |
|
V3.1 (2006/09/27) |
|
V3.0 (2006/08/30) |
|
V2.0 (2006/02/26) |
|
V1.3 (2005/01/15) |
|
V1.2 (2004/12/21) |
| Minor GUI fixes. |
V1.1 (2004/12/16) |
| First VST Version. |
V1.0 (2004/09/21) |
| First DirectX Version. |
See you soon on www.bluecataudio.com!

















