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Blue Cat's FreqAnalyst Multi User Manual
Blue Cat's FreqAnalyst Multi User Manual
Blue Cat's FreqAnalyst Multi - Real Time Multi Tracks Spectrum Analyzer (AU, VST, AAX and VST3 Plug-in)
"A unique multi-track spectral analysis tool for mixing or mastering."
MacOSUniversal BinaryWindows Vista or newerWindows x64 (64-bit)VSTVST3AAX64-bit AAXAudio Unit


Blue Cat's FreqAnalyst Multi is a unique multiple tracks real time spectrum analyzer: it lets you visualize the spectral content of several audio tracks on the same screen with extreme smoothness and high resolution, for both time and frequency.

FreqAnalyst Multi is the ideal solution for mixing: you can use it as a frequency overlap detector and actually see which part of the spectrum every single instrument uses. It is now also possible to easily compare the spectrum of several instances (for EQ matching or response curve measurement) thanks to the new 'Diff' view which displays the difference between several curves.

Just like with Blue Cat's FreqAnalyst Pro plug-in, the frequency analysis can be fine tuned in details, and three modes are offered for each channel: instant, peak or average response of several audio tracks can be displayed on the same graph (the plugin supports up to 16 curves). Zooming capabilities and coordinates display let you exactly measure the characteristics of the spectrum for each audio track. Thanks to the advanced routing capabilities you can define different settings for each track and thus adapt the analysis for each audio signal you want to analyze. Our multiple tracks tutorial shows you how simple multiple tracks spectrum analysis can be.

The four memory slots let you store any curve in memory: it helps you make comparisons between several setups or portions of your audio project very easily.

Thanks to included window opacity management feature and advanced layout customization capabilities, you can adapt the plug-in user interface to your personal needs and enhance your workflow. It is also possible to create a completely custom user interface using Blue Cat's skinning language.

If you are looking for a single track spectrum analyzer with a spectrogram view and audio to MIDI capabilities, check our Blue Cat's FreqAnalyst Pro plug-in.

Blue Cat's FreqAnalyst Multi - Enlarged display lets you increase the level of details. Blue Cat's FreqAnalyst Multi - Real Time Multi Tracks Spectrum Analyzer (AU, VST, AAX and VST3 Plug-in) Blue Cat's FreqAnalyst Multi - Multi tracks spectrum analysis with Blue Cat Audio's exclusive data sharing technology.

Typical applications: frequency overlap detection, EQ matching, frequency response measurement, spectral balance measurement.

System Requirements


  • An Intel or Apple Silicon processor.
  • Mac OS 10.9 or newer.
  • Any VST / Audio Unit / AAX compatible application (64-bit) .


  • An SSE2-enabled processor (Pentium 4 or newer).
  • Microsoft Windows Vista, Windows 7, 8 or 10.
  • Any VST / AAX compatible host software (32 or 64 bit).

For more information about supported platforms, see our Knowledge Base.

Demo Limitations:

  • Three instances of the plug-in per session.
  • The plug-in is frozen for a few seconds every 40 seconds.


The plug-ins versions 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.

Before installing one of the plug-in versions, you should close all your host applications.



All versions of the plug-in provide an installation program. Follow the steps of the wizard to install the software on your machine. During the installation you will be asked where you want the software 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. For other plug-in types, you should just use the standard path.

Some applications will not automatically rescan the new plug-ins, so you might have to force a refresh of the plug-ins list.


When a new version of the software is released, just launch the new installer: it will update the current installation.


To uninstall the software, 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.



On Mac the plug-ins are available as drive images with an installer. After download, double click on the dmg file to open it. You can then double click on the installer (.pkg file) to install the package.

Note for Mac OS 10.15 Catalina or newer: you may have to right click on the installer and select "Open" instead of double clicking on the file to launch the installation if your computer is not connected to the Internet.


When a new version of the software is released, just launch the new installer: it will update the current installation.


To uninstall the software, simply remove the component(s) from their install location (move them to the trash):

  • AAX plug-ins are installed in the /Library/Application Support/Avid/Audio/Plug-Ins/ folder
  • Audio Units (AU) are installed in the /Library/Audio/Plug-Ins/Components/ folder
  • RTAS Plug-ins are installed in the /Library/Application Support/Digidesign/Plug-Ins/ folder
  • VST plug-ins are installed in the /Library/Audio/Plug-Ins/VST folder
  • VST3 plug-ins are installed in the /Library/Audio/Plug-Ins/VST3 folder

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.
  • ~/Library/Preferences/Blue Cat Audio/[Plug-in name]: license information
  • ~/Documents/Blue Cat Audio/[Plug-in name]: user data, such as presets, additional skins and user-created plug-in data.

Please be aware that these directories may contain user data that you have created. Remove these directories only if you do not want to reuse this data later.

First Launch

Blue Cat Audio plug-ins cannot be run standalone, they require a host application (see the System Requirements chapter for more information). Some host applications will require you to scan the plug-ins before they are available in the application.

If the plug-in is not available in the application, please check that it has been installed in the appropriate directory (with no host application running), and that the host application has scanned it.

Using Blue Cat's FreqAnalyst Multi

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.


The FreqAnalyst Multi plugin is bundled with a single skin. You may want to create your own or download new ones from The included skin is composed of three panels:

  • The spectrum view where you can see the spectrum of the curves shared by all the instances of the plug-in.
  • The Diff pane when you can compare several spectra by visualizing their difference.
  • The routing pane where you can choose which analysis curve you want to display and share with other plug-in instances.

The main elements of the user interface are described below:

  1. Select the screen size (small, medium or large).
  2. Choose between spectrum and difference panes (to be displayed in (B)).
  3. Choose the display mode (single or dual screen, and row or column). In dual screen mode, you can show both the spectrum and the diff panes at the same time.
  4. Show/Hide the controls pane (A): The controls pane can be collapsed to gain real estate on the screen. This changes the size of the user interface of the plug-in. Some host applications may require you to close and reopen the user interface of the plug-in to take this update into account.
  5. Show the routing matrix to select and rename the curves routed from this instance of the plug-in.
  6. You can freeze all curves (for all instances) in order to get a snapshot of all the curves.
  7. Synchronize all instances. This is particularly useful when using the difference view: you may need to synchronize the multiple instances of the plug-in so that they compute the spectrum at the exact same time, to improve the accuracy of the difference computation.
  8. Reset the average or peak curves for all instances.
  9. Select the stereo operation mode for the current instance. In mono mode, the plug-in will compute the spectrum only for the first available channel (left)
  10. Curves display settings:
    • Filled: show filled curves. This option may become CPU-heavy when you have multiple curves to display with a large screen setting.
    • Antialias: antialiased curves look better (smoother), but you may want to disable this option if you prefer "old style" display.
    • Name: display the name of the curve on the graph (overlay).
    • Show List: display the list of available curves at the right of the current pane.
  11. These two sliders let you control the x and y zoom for the graphs in both views. Once zoomed, you can drag the rulers with the mouse (click on the vertical or horizontal ruler when the cursor is a small hand and drag to move in the graph). It is also possible to zoom the screen by selecting an area with the mouse. You can then right click on the graph to unzoom.
  12. At any time, right click on the graph to unzoom.
The main parts of the user interface are the following:
  • (A) The controls displayed at the bottom of the user interface let you modify the parameters for the audio analysis of the current instance or all other instances at the same time.
  • (B) Current display (spectrum or diff pane).
  • (C) This is the place where the coordinates of the mouse cursor are displayed when the mouse is over a graph.

Routing Pane

In order to route curves to the display and share them among instances, you need to open the routing pane (by clicking on the “Routing” button). It is displayed by default when you first open the plug-in.

  1. List of available curves for the current instance. These are the curves you can route to a shared curve numbered from 1 to 16. The plugin proposes three types of analysis curves for each of its four channels. The four channels are the left and right (or mid and side, depending on the “Mid/Side” setting), and the combination of these channels (max or average). The instant spectrum is the real time view of the frequency content, the peak is the maximum of the spectrum and average is the average of the spectrum over time. This last type of analysis is particularly interesting when comparing tracks for EQ matching.

  2. Select a shared curve slot to display and share the curve corresponding to the row.

  3. When a slot is not available it means that it is already in use by this instance or another instance. You can click on the 'X' button to free the slot occupied by the curve corresponding to the row.

  4. Use this button to reset all curves affectations for this instance of the plugin.

  5. You can assign a name to each analysis curve. It will be displayed in the main pane when the curve is connected to a bus:

You can close the routing pane by clicking on the little cross at the top right, or by clicking anywhere in the background behind.

Spectrum View

  1. Select the shared curves to display. No curve will be shown on this view until you select the curves you want to share in the routing pane. The curve names can be customized (see the routing pane).

  2. The four “A B C D” buttons let you store the curve to one of the proposed memory slots. The curves stored into these slots can be shown/hidden with the buttons available in (4).

  3. Show/Hide curves stored in memory.

  4. Both the frequency/gain pair representing the coordinates of the mouse cursor and the note information are displayed when the mouse is hovering over the graph. The note information shows the name (A, B, C...), the octave (A0, A1,...) as well as the number of cents below or above the note.
  5. This slider lets you change the absolute threshold for the current instance (see the parameters section).

Diff View

This view shows differences between selected spectra. It is very handy to compare several spectra. For example you can compare the left and right channels of a single track to check the its spectral balance (repartition of frequencies across the left and right channels), or you can have an instance compute the average spectrum of a reference commercial track and compute its difference with the average spectrum of your current mix. The resulting difference curve will show you the EQ you need to apply to your track so that your mix “sounds like” your commercial reference, as far as spectrum is concerned.

  1. Show/hide a difference curve.

  2. Select first spectrum for the difference.

  3. Select second spectrum for the difference.

  4. Store the difference to one of the memory slots.

  5. Show/hide curves stored in memory slots.

The resulting curve shows the difference between the first and the second curves. This means that when the difference curve is above 0, the first curve is greater than the second.

For a more accurate visualization it is recommended to compare curves that have similar precision settings. When comparing different tracks you will usually not be interested in absolute values but in the shape of the curve: both tracks may have a different absolute level.


The settings described in the parameters section are available at the bottom of the user interface. The absolute threshold can also be controlled by the vertical slider on the right of the display.

Apart from the reset buttons, all these parameters control the analysis for the current instance of the plug-in only. To modify the settings for other instances, you can either push the values used in the current instance to all others, or open the user interface of each other instances you want to modify.

It is possible to push the value for each parameter to other instances of the plug-in independently (using the small red arrow close to the control) or to push all the settings of the current instance to all others with the large blue arrow on the left of the controls pane.

Memory Curves

As shown earlier, it is possible save several types of curves in memory slots. Clicking on the little blue arrow below each memory slot opens a menu to manage these curves: they can be copied and pasted to other slots (even in another application), or be saved as files to be reloaded later:

Memory slot menu

This lets you make multiple measurements and reuse them elsewhere as references.

Screen Configurations

The plug-in is setup by default to work in single screen mode, but there are two other modes available, using the display mode button:

Dual screen / column mode

Dual screen / row mode

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.


The Principle

Blue Cat's FreqAnalyst Multi uses our unique data sharing technology to share complex information between several instances of the plugin. This lets you visualize the spectrum of several audio tracks in the same plugin instance:

Each analyzer is both able to produce and display shared curves. With the 'Diff' view it is now possible to compute and display the difference between several curves:


The procedure to see and compare frequency contents is the following:

  • Insert the plugin on one or several audio tracks in your sequencer

  • For each instance, open the routing pane and select the curves you want to see and share.

  • Adjust the settings for the audio analysis in each instance.

  • Open the user interface of an instance of the plugin and select the shared curves you want to see.

  • Watch the result!


A few examples of application:

  • Checking overlapping frequencies when mixing: when doing your mix it might be difficult to hear overlapping frequencies across tracks and a bit of visual help can be handy, especially if your monitoring environment is not ideal. In this case the FreqAnalyst Multi can be of great help: instantiate the plugin on the tracks you want to check and look at the spectra on the main spectrum view. Overlapping frequencies can be easily detected on the graph (zoom in if necessary) and corrected with a little bit of EQ.

  • Comparing your mix with a commercial reference (EQ matching): sometimes you want to approach the sound of song you like or a precise style. In order to obtain a similar spectrum, import your favorite track in your host application, instantiate the FreqAnalyst Multi on this track and on the track for your own mix. Route the average curves for both tracks and compare them in the diff view. The resulting curve shows you the EQ you need to apply to your mix to obtain the same average spectrum, the “sound signature” of this track.

  • Measuring an effect chain: it's sometimes good to know what is exactly happening to your audio signal while applying audio effects, to detect defects or imply understand what it does. By measuring the spectrum before and after an effect is applied to a track and compute the difference, you can exactly reproduce the dynamic frequency response of the effects. It's also a good way to measure the frequency response of a room, a monitoring system or any gear you may have.

  • Spectral balance measurement: measuring the left and right channels of an audio track and displaying the difference between these curves in the diff view will let you see the balance of each frequency bin. This can be useful to check how balanced you mix is or on the contrary to see left/right differences that might be required for stereo widening. In the latter case, using the mid/side channels and their difference might be even more appropriate.

For more information about how to use this plugin in your favorite host application and for more practical usage examples, have a look at the Blue Cat's FreqAnalyst Multi Tutorials.

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 FreqAnalyst Multi 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:

Smooth Bypass

On the left, the power button can be used to smoothly bypass 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.

Using the knob on the bottom right of this area, you can reduce the opacity of the window, and make it transparent (the actual result may depend on the host application). Additional messages may appear in the area next to this knob, depending on the plug-in.

Some plug-ins may also propose you to manually select the audio I/O inside the plug-in (bottom left of the presets area), regardless of the host configuration. It can be useful for example to save CPU by selecting mono to stereo configurations (instead of full stereo sometimes chosen by default by the host), or add extra channels to manage side chain internally, when the host does not provides any side chain input. Please note that this does not change the number of I/O seen by the host application.


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
Control Settings Display the controls settings menu (to manage automation and MIDI control, as described here).
Undo Undo
Redo Redo
Manual User Manual
About About
Zoom Scale the user interface (from 70% to 200%).

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.
  • Preset Skin: opens the skins menu to choose the skin for the current preset and manage alternative skins for the software.
  • 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 settings window. It lets you change the skin, MIDI and automation settings that are used by default in all instances of the plug-in (if not overridden 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.



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

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.


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)


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


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.
  • MIDI Program Change: activate MIDI Program Change support (see below).
  • Load: load preset from file.
  • Save: save current state to last loaded user preset.
  • Save As: save current preset to a file.
  • Copy copy preset to the system clipboard.
  • Paste paste preset from the system clipboard, if available.
  • Save As User Default: save the current state as the default preset. This preset is used every time a new instance of the plug-in is created.
  • Clear User 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 Program Change

It is possible to load presets remotely using MIDI "Bank Select" and "Program Change" messages. To enable this feature, select a MIDI channel to receive the events from in the MIDI Program Change menu item from the presets menu:

This setting is saved for each plug-in istance with your session but not in presets (except for the default preset, using the "Save as User Default command"). Once activated, the plug-in menu will display the bank number followed by the preset number for each preset:

Every root folder is considered as a new bank, starting with the factory presets (bank 0). Program and bank numbers may change while you add folders and presets, so you should be careful when naming them if bank and program numbers matter to you. It is recommended to use folders to make this task simpler. As a side note, sub folders do not define additional banks (all presets contained in sub folders are associated with the current bank.

As specified by MIDI, bank select messages are not used until a program is actually selected.

MIDI Implementation note: the software supports all types of Bank Select methods. You can use either MIDI CC 0 or MIDI CC 32 to select banks. If both are used simultaneously, they are combined together so that you can use more banks (in this case CC0 is LSB and CC32 is MSB, and actual bank number is 128*CC0+CC32).

MIDI and Automation Control

Blue Cat's FreqAnalyst Multi 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

The main menu

Most skins also provide the ability to change MIDI and automation settings directly in the main user interface. Clicking on the control settings icon in the main toolbar opens the following menu:

  • Show Control Settings: show direct access to individual control settings for each parameter in the user interface (see next paragraph).
  • Lock Control Settings: lock the current controls settings for MIDI and automation so that they remain unchanged when loading presets.
  • Use Global Control Settings: ignore the current MIDI/automation settings and use the global settings instead.
  • Control Settings Window: display the control settings window, to change control settings for all parameters.
  • Save As Global Control Settings: save the current settings as global settings (used by default, when no specific MIDI/Automation setting has been set for the cuirrent preset).

Individual Control Settings

When this feature is activated using the "Show Control Settings" item in the MIDI and Automation Settings menu, dropdown menu buttons appears next to the main controls displayed by the plug-in:

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.
  • Control Settings: launches the advanced settings panel described below. This controls the settings for the current preset.
  • All Control Settings: display the control settings window, with access to all parameters.

Advanced 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:


Check our online tutorial for more screenshots and more examples of our plug-ins user interfaces.

Blue Cat's FreqAnalyst Multi 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.

The input parameters of this plug-in are described below. They affect the spectrum analysis for the current instance of the plug-in. Each instance has independent parameters for the audio analysis.






Bypass the plugin.


Precision of the audio to frequencies transform. The higher the setting, the higher the frequency precision, and the higher the CPU consumption



Rate of the audio to frequencies transform. The higher this value, the better time resolution (and perceived smoothness). Beware that above 100% CPU consumption might increase, especially when the precision is high.



Attack time for the frequencies envelope follower.



Release time for the frequencies envelope follower.

Peak Reset


Rate of the peak curve reset. If set to 0, the peaks will never decrease and will represent the maximum value.

Abs Threshold


Absolute threshold for spectrum display. All frequency bins which value is below this threshold are set to -120 dB)

Rel threshold


Relative threshold for spectrum display (percentage of the maximum value). All frequency bins which value is below this threshold are set to -120 dB)



Slope added to the frequency response curve. Can be used to correct the response curve (for example tune the plug-in so that pink noise frequency response is flat)



Offset added to the frequency response curve. Can be used to correct the response curve.

Reset Peak

Command to reset peak curves (value changes are considered as reset commands)

Reset Average

Command to reset average curves (value changes are considered as reset commands)

Stereo Mode

Stereo operation mode for the plug-in: stereo (left/right), mono or mid/side.

Blue Cat's FreqAnalyst Multi Curves

The FreqAnalyst Multi plug-in provides visual feedback about the frequency content of the audio signal thanks to output curves that can be routed to one of the 16 display curves. The plugin provides two channels. In stereo mode, channel 1 is left and channel 2 is right. In Mono mode, channel 1 is mono and channel 2 is fed with silence. In Mid / Side mode channel 1 represents the mid channel (mono part of the signal) and channel 2 the side channel (stereo part of the signal).

Curve id




Instant Spectrum(1)

Instant frequency content for channel 1.


Peak Spectrum(1)

Maximum value of the frequency content for channel 1 over time.


Average Spectrum(1)

Average value of the frequency content for channel 1 over time.


Instant Spectrum(2)

Instant frequency content for channel 2.


Peak Spectrum(2)

Maximum value of the frequency content for channel 2 over time.


Average Spectrum(2)

Average value of the frequency content for channel 2 over time.


Instant Spectrum(Avg)

Instant frequency content (channels average).


Peak Spectrum(Avg)

Maximum value of the frequency content (channels average) over time.


Average Spectrum(Avg)

Average value of the frequency content (channels average) over time.


Instant Spectrum(Max)

Instant maximum values of the frequency content for both channels.


Peak Spectrum(Max)

Absolute maximum values of the frequency content for both channels over time.


Average Spectrum(Max)

Average maximum values of the frequency content for both channels over time.

These output curves can be routed to one of the 16 display curves that are shared among plug-in instances. The ids for these curves are shared.curve1 to shared.curve16.

Plug-in Settings

In addition to the controls offered in the main user interface, Blue Cat's FreqAnalyst Multi 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 overridden in the presets settings. Consider these settings as “default” settings.


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.

(generic screen shot, does not correspond to the actual plug-in parameters)

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:

"Send MIDI events when parameters values change": activate this option when using a control surface that accepts MIDI events as input. MIDI messages will be sent to the output of the plug-in when the user change the parameters values in the user interface, to keep the software and the controller in sync. MIDI is only sent for parameters that are activated for MIDI control.

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.

(generic screen shot, does not correspond to the actual plug-in parameters)

About Skins

Blue Cat's FreqAnalyst Multi integrates Blue Cat's skinning engine that allows you to customize the user interface. You can download alternate 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 custom one, you can choose to create your own skin.

Choosing the Skin

There are two ways to select the skin of your plug-in: you can change the default (or 'global') skin, 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 (choose this one if you want to use the skin used by default, regardless of the session or preset), whereas the current preset skin only applies to the current preset of the current plug-in instance (use this one if you want to change only the skin for the current session/preset).

Note: in some host applications, 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.

The Skins Menu

The skins menu can be opened from the main menu. It displays the list of skins available for the plug-in as well as commands to manage the skin used by default when no preset skin has been selected:

  • First Section - Factory Skins: shows the list of factory skins delivered with the plug-in ("Default" and "Light" in this example).
  • Second Section - User Skins: shows the list of user skins that have been installed in the Documents Skins folder for the plug-in (see below).
  • Use Global Skin: use the global skin for the current preset/session (unloads any custom skin previously selected for the current preset).
  • Load: opens a file browser dialog to manually select the skin from the file system.
  • Save As Global Skin: use the current preset skin as the global skin (loaded by default if no preset skin has been defined).

Installing User Skins

To select user skins directly from the skins menu, install them in the "Skins" directory available in the plug-in's documents folder:

[Your Documents Folder]/Blue Cat Audio/[Plugin Name]/Skins/

The skin engine will scan this folder for new skins (xml files) and display them in the menu. The skin files should be in the root skins folder or in a subdirectory inside this folder: subdirectories are not scanned recursively.

Other Methods to Select Skins

You can also select the skins in the settings panels available from the main menu:

The global skin (used by default if no preset skin has been selected) can be changed in the global settings pane. The current preset skin can be changed in the preset settings page .

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 You can get ready to create your own skins in a few minutes. You can then share your skins on our website.


This manual only covers the main aspects of Blue Cat's FreqAnalyst Multi. Our website offers many additional resources for your Blue Cat's FreqAnalyst Multi plug-in. It is constantly updated, so keep an eye on it!


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 FreqAnalyst Multi has been updated, or subscribe to our Newsletter to be informed of the latest news about our products.

Note: minor version updates are available from the same location as the original full version download (link received by email upon purchase). The demo version publicly available on our website will not let you register.

You can also follow us on twitter, facebook and instagram for almost real time updates notification, and subscribe to our YouTube channel to watch the latest videos about our software.

Versions History

V2.41 (2022/12/12)

  • Added Apple Silicon support for AAX Plug-in Format.
  • Fixed VST3 version not always loading properly in Ableton Live 11.
  • Improved VST parameter value display in some host applications.
  • Added an option in global & preset input settings to send MIDI events when MIDI-enabled parameters are modified in the plug-in (to update control surfaces accordingly).
  • Improved undo management and automation when using the mouse wheel to move knobs.
  • AAX: Fixed erratic mouse behavior in Pro Tools on Mac.
  • Mac: installers and plug-ins have been notarized to avoid security warnings on Mac OS Catalina and newer.

V2.4 (2021/10/19)

  • Single Installer on Mac (all plug-ins formats).
  • Apple Silicon (M1 processor) support.
  • Dropped 32-bit support on Mac.
  • Now requires MacOS 10.9 and newer.
  • Arrow keys can now be used to navigate presets.
  • Added MIDI control support (MIDI CC messages) for Next and Previous Preset commands, with MIDI learn.
  • Improved MIDI & automation control settings with lock, reset and "save as global setting" capabilities.
  • Improved smooth plug-in bypass (faster and smoother transition).
  • Unicode support.
  • Reduced the number of threads used by the plug-in.
  • Reduced memory footprint.
  • Windows: improved GUI loading performance.
  • VST3: fixed random crash in Ableton Live 11 upon load.

V2.32 (2020/11/12)

  • New high resolution graphics for knobs.
  • Reduced disk footprint.
  • Mac: fixed GUI performance issues on native P3 displays and improved performance on other displays.
  • Mac: fixed mouse wheel that required large movements to change parameter values.
  • Mac: fixed mouse cursor flickering issues.
  • Mac: fixed Esc key not closing fine edit parameter dialog.

V2.31 (2020/04/28)

  • Fixed plug-in layout not properly saved and restored.
  • Mac: faster GUI rendering on recent Mac OS systems (up to 8x faster).
  • Mac: fixed user interface not properly shown on retina displays in some applications built with the 10.14 Mac OS SDK.
  • Mac: fixed settings panel rendering issues in dark mode on Mac OS Mojave and newer.
  • Mac: fixed registration dialog not working in some applications (LUNA, Garage Band, Gig Performer).
  • Mac: fixed demo version causing Logic to freeze when reloading a project.
  • Mac: fixed Audio Unit plug-in listing in some host applications (Plogue Bidule...).

V2.3 (2019/06/12)

  • Refreshed GUI design, with improved usability and touchscreen support.
  • The GUI can now be zoomed from 70% to 200%.
  • Spectrum analysis is now performed in the background and does not affect audio performance.
  • Precision now goes up to 11.
  • Last loaded preset is now remembered in session and displayed in the presets menu.
  • Plug-in state can now be reverted to the last loaded preset.
  • Now supports retina displays on Mac (text and graphs using high resolution).
  • VST3: added support for MIDI program change messages to change presets via MIDI.
  • VST3: fixed audio output muted in some host applications.
  • VST: the user interface is now properly resized in Cubase on Windows.
  • Mac: new installer.
  • Mac: fixed minor compatibility issues with Mac OS High Sierra and Mojave.
  • Dropped support for Windows XP and Mac OS X 10.6 and earlier.
  • Dropped support for legacy RTAS and DirectX plug-ins formats.
  • Fully compatible with previous versions of the plug-in (except for VST3 on Mac, as explained below).

Warning: because of a bug of the initial VST3 release, this new version may not work with existing sessions that used the VST3 format. See this blog post for more details and how to fix it.

V2.2 (2016/03/03)

  • VST3 plug-in format support.

V2.1 (2015/09/07)

  • Save each memory curve as a file that can be reloaded later as a reference.
  • Copy and paste memory curves between instances using the system clipboard.
  • Last loaded preset can now be saved directly from the presets menu without having to select the file.
  • Fixed demo version popup window freezing Pro Tools in some situations.
  • Presets can now be selected using MIDI Program change and bank select messages (can be activated with the presets menu/MIDI Program Change item).
  • Factory and user skins can now be selected directly from the plug-in menu.

V2.03 (2014/01/09)

New Features:
  • Copy/paste the plug-in's current state from the presets menu using the system clipboard.
  • Reduced the plug-in's memory usage.
  • Windows VST Installer now remembers where the plug-in was initially installed to simplify upgrades.
  • (Mac) plug-in version number is now available when using "Get Info" in the Finder.
  • (Mac) Improved display of Audio Unit parameters in most host applications.
Bug Fixes:
  • Fixed window frame not showing with Cubase 7.5 (32-bit) on Mac.
  • (Mac) About window does not show up first in the corner of the screen anymore.
  • (Win) Alt-Click on a control now resets the value to default in Pro Tools, as expected.
  • Fixed version number reported to host application for VST and Audio Unit versions.

V2.02 (2013/06/21)

  • 64-bit AAX support for Pro Tools 11.

V2.01 (2013/05/14)

  • Pushing all parameters to other instances does not push the stereo configuration anymore.
Bug fixes:
  • Fixed AAX version not showing up in Pro Tools 10.3.5 on Windows.
  • (RTAS) Fixed parameters control with EUCON control surfaces in Pro Tools.
  • Fixed user interface issues in Final Cut Pro X.
  • Fixed compare button issues in Pro Tools.
  • Mac-VST: Fixed window resize issues on Cubase and Nuendo (Mac).
  • Mac: Fixed user interface display issues when first opened in Ableton Live 9.
  • Mac: Control MIDI settings dialog now brought back to front when already opened in the background.
  • Mac: fixed copy/paste keyboard shortcuts for plug-in registration that did not work in some hosts.

V2.0 (2012/07/06)

New Features:
  • Brand new fully customizable user interface:
    • New look and feel.
    • Show/hide what you need.
    • Curves names can now be displayed on the graph (overlay).
    • Single or multiple displays modes.
    • Multiple display sizes
    • Improved readability.
    • Animated transitions.
  • All instances can now be forced to synchronize.
  • New integrated presets manager:
    • Load/save presets from the plug-in's user interface.
    • Organize presets with folders.
    • Customize the default preset.
    • Exchange presets easily.
  • Automation range and response curve can now be customized for each parameter.
  • Automation and MIDI settings (channel, MIDI learn etc.) are now accessible from the main user interface.
  • AAX plug-in format is now also supported on Windows (Pro Tools 10.2 required).
  • Improved note display (now uses a +/-50 value for cents).
  • Improved Graph rulers display when zoomed.
  • Routing matrix automatically displayed when opening the plug-in for the first time for easier setup.
  • New presets to make setup easier.
  • Plug-in name has been shortened for a clearer display in mixer view for most host applications.
  • Changed the default VST install path on Windows.
  • License is now shared between plug-ins types (register only once for all formats).
  • Added new presets.
  • Improved value display in fine edit window.
Optimizations and Performance Improvements:
  • Reduced VST plug-in loading time.
  • Improved parameters precision (now stored as 64-bit).
  • More compact presets format (uses less space and loads faster).
  • Smaller binaries on Mac (dropped PowerPC support).
Bug Fixes:
  • Fixed presets-related crashes in Cubase on Mac.
  • Fixed user interface display issues in Wavelab on Mac.
  • Fixed keyboard stealing issue in Digital Performer 7 on Mac.
  • AAX/RTAS on Mac: Fixed audio engine freeze or error issue with Pro Tools on some Mac configurations.
Note: this new version can be installed side by side with the previous version for backward compatibility reasons. Installing this new version won't break your previous projects.

V1.91 (2011/07/11)

  • Output data rate can now be customized, from 20 to 500 Hz.
  • Increased the default output data rate (from 20 to 50 Hz) for smoother spectrum display.
  • Note value for the current mouse location is now displayed, in addition to the frequency.
  • Windows: improved settings dialog loading time.
  • Mac: user interface performance improvement (up to 30% lighter on cpu).

V1.9 (2011/05/23)

  • Difference curves can now be saved for easier comparisons and stereo spread matching tasks.
  • Windows uninstaller now proposes to remove preferences as an option.
  • Misc minor user interface and windows installer changes.

V1.82 (2011/02/10)

  • Fixed keyboard focus stealing issue in Pro Tools and several other host applications.
  • Controls visibility is now persistent.

V1.81 (2010/11/29)

Fixed incompatibility issues with older presets in the previous version.

V1.8 (2010/11/18)

  • Analysis parameters can now be pushed from one instance to others to simplify the workflow.
  • 64-bit Mac VST support.
  • User interface enhancements:
    • Improved readability.
    • Zooming is now animated.
    • Controls can be collapsed to reduce the size of the user interface and focus on the analysis.
    • Improved consistency with our other analysis tools.
    • Drag the rulers to move the curve when zoomed (can keep measurement/selection mode and still drag the curves).
  • Improved synchronization of curves within a single instance.
  • Default release time is now shorter.

V1.7 (2010/06/19)

Performance Improvements (all platforms):
  • Improved user interface performance and increased graphs display refresh rate.
  • Improved signal processing performance (up to twice faster on some systems!). The plug-in now requires a processor supporting SSE2.
  • Reduced memory footprint.
  • Faster skin loading.

V1.61 (2010/02/25)

  • Demo version now displays a nag screen only once per session, and only when opening the user interface of the plug-in.
  • Fixed a crash on Mac and 64-bit Windows that randomly occured when opening and closing the user interface multiple times.
  • Mac: fixed crash with demo version in Ableton Live 8.1.1.

V1.6 (2010/02/15)

  • RTAS plugin format support for Pro Tools (Mac and Windows).
  • 64-bit applications support for Windows DX and VST under Windows x64.
  • Mac AU 64-bit format support (compatible with 64-bit Logic 9.1 on Snow Leopard)
  • Fixed MIDI learn issues.
  • Space bar does not trigger plug-in buttons anymore (avoids conflict with transport control in most applications).
  • Mac: fixed user interface crashes in some hosts under Snow Leopard.
  • Mac: fixed keyboard/mouse focus issues in some hosts.
  • Mac: fixed user interface crashes in some hosts, when used with particular display settings.
  • Mac: fixed multiple screens issue.
  • Mac-AU: fixed user interface resizing issue when changing skin in some hosts (Logic).
  • Mac-AU: fixed settings lost issue when doing offline rendering in some applications.

V1.51 (2009/05/05)

Mac VST update: fixed incompatibility issues with Cubase 5 on Mac.

V1.5 (2009/02/27)

  • Mac Audio Unit support.
  • Improved Performance.
  • New Windows Installer (you should uninstall any previous version before installing this new one).
  • New documentation format.

V1.4 (2008/12/10)

  • Now available for Mac in VST format.
  • Minor user interface changes.
  • (Bug fix): keyboard shortcuts are no longer forwarded to host application when entering the names of the curves in edit boxes.

V1.3 (2008/05/26)

  • New diff view to compute and visualize the difference between several spectra.
  • Graphics rendering has been improved for smoother analysis curves display in some hosts (such as Cubase).
  • Minor user interface changes (fonts, layout).

V1.2 (2008/02/25)

  • Fixed a crash on certain configurations while opening the global settings window.
  • Settings window is now faster to open.

V1.1 (2007/12/13)

  • User can now define a name for each curve which is displayed in the main view.
  • Non connected curves are now easy to identify.
  • Improved display refresh rate: analysis is now even smoother!
  • New "zoom by selection" feature.
  • Spectrum analysis normalization improvement: absolute values comparison with different precision settings is now more accurate.

V1.0 (2007/10/04)

First version.

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