Introduction

The MPC Spectral Compressor is a dynamics processor that allows you to apply compression selectively across 18 frequency bands. These compression bands can either be spread out across the full range of the spectrum, or focused on a specific frequency range for more precise control.

The MPC Spectral Compressor includes the following features:

• Master Threshold control
• Frequency Range selection
• Band Depth controls
• Gain Reduction graph
• Compressor Knee
• Output Trim

Overview

The Depth sliders below the graph control the maximum amount of gain reduction that can be applied to the corresponding frequency bands determined by the current Range setting. The Range can be set to focus on specific areas along the frequency spectrum (Low, Mid, High, etc.), or it can be set to Full Range mode to allow control over the entire spectrum. The Threshold sets the input signal level where the overall compression begins to take effect. Additional controls include compressor Knee and output Trim.

Controls

Threshold

The slider attached to the input meter on the left is the Threshold control. The Threshold sets the input signal level where the overall compression begins to take effect. The Threshold can be set anywhere between -60 and 0 dB.

Frequency Range

The Frequency Range section allows you to select the specific frequency range that gets processed by the compressor. The 18 compressor bands will be distributed across whatever range is selected. For example, with Mid selected, all 18 bands will be focused on the Mid range, allowing for more precise control over the frequencies within that range.

The available Frequency Range options are as follows:

Depth Controls

The 6 sliders below the graph set the Depth for their corresponding bands. The 18 compressor bands are divided among the 6 sliders so that each slider controls the Depth for 3 of those bands.

The range of frequencies affected are shown below each slider.

The Depth determines the maximum amount of Gain Reduction that can be applied within each slider’s control range. Possible Depth values range from -24 to 0 dB. Setting a Depth slider to 0 dB will prevent any attenuation from occurring within that slider’s control range.

Knee

The Knee value determines how far the input signal must exceed the threshold in a given band, to incur the full depth for that band. Possible Knee values range from 1 to 30. With a low Knee value (Hard Knee), the compression will activate more abruptly as the signal passes over the Threshold. A high Knee value (Soft Knee) will apply the gain reduction more gradually as the signal passes the threshold.

Output Trim

The Output Trim adjusts the level of the compressor’s output signal anywhere from -10 dB to +10 dB. It can be used to increase or decrease the output level as needed for gain compensation.

Gain Reduction Graph

The Gain Reduction Graph provides a visual representation of Gain Reduction across the frequency spectrum. The Reduction curve (red) is displayed above the Input curve (orange-yellow) indicating the amount of Gain Reduction applied and its location along the spectrum. The red line inside the Input curve indicates the level of the compressed signal relative to the input signal.

Additional Features

At the top-right corner of the plugin window are the Momentary Bypass and Settings buttons.

Momentary Bypass

The Momentary Bypass button bypasses the plugin for as long as it's held. This is useful for auditioning A/B comparisons quickly. 

Settings

The Settings button reveals a pop-up menu where the window size can be adjusted. It also contains a link to the plugin manual and version info at the bottom.

Control Behaviors & Shortcuts

Various mouse & keyboard shortcuts can be used to perform certain actions on the following controls:

Sliders/Knobs

Labels

Combo Boxes (Drop-down menus)

Band Controls

Graph Rulers

System Requirements

Your system must meet the following requirements in order to run Harrison plugins:

• Windows 7 or higher
• Mac OS 10.9 or higher
• Linux GCC 5 compatible systems
• OpenGL 3.2 or higher
• libcurl-gnutls on Linux

macOS M1/ARM Support: This plug-in is provided as a universal binary for macOS and features native M1 support.

Note for Pro Tools users: Pro Tools 11 or higher is required on Mac, 10.3.5 or higher is required on Windows.

Additional requirements on Windows

Harrison plugins require the “Windows C++ Universal Runtime” to be installed on your computer.  Universal runtime is part of the system’s core libraries on Windows 10. On Windows versions Vista to 8.1,  it will be automatically installed via Windows Update. It is also possible to install the runtime manually, but that is outside the scope of this manual.

Note for Linux Users

If you’re experiencing issues with the plugin’s graphics or the GUI isn’t showing up correctly on Linux, make sure your system’s graphics driver supports the minimum required OpenGL version of 3.2 or higher. To check this, run glxinfo | grep Max in a terminal window and make sure that the value listed for the OpenGL core profile version string is at least 3.2 or greater.

If your core profile version meets this requirement but you are still experiencing graphics issues like the ones mentioned above, it is likely that your system is reporting an OpenGL version lower than 3.2 to ensure backwards compatibility with deprecated OpenGL functions. To work around this, you can force the system to report an OpenGL version of 3.2 or higher by setting this environment variable: MESA_GL_VERSION_OVERRIDE=3.2

You can use this as a prefix when opening your DAW from a terminal command like so:

MESA_GL_VERSION_OVERRIDE=3.2 {command_to_launch_program}

This will set the environment variable for that particular terminal session only, so it will be reset once the session is ended. If you don’t want to run this command every time you launch your DAW, you can set the environment variable in your profile script so that it automatically gets set every time you login.

Installation & Licensing

Licensing on macOS & Windows

This plugin is licensed through iLok on macOS and Windows. Visit iLok, Licensing and Activation for guidance on activating your Harrison plug-in. 

Licensing on Linux

This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit (http://www.openssl.org/)

In DEMO mode, after using the plugin for a certain amount of time, it will display a message:

This message will come up periodically unless a license is provided. You can purchase a license directly from Harrison’s web store or from an authorized plugin reseller. Once you’ve purchased a license, install it by entering your license key into the designated field on this screen. Continue to the next section for detailed instructions on how to obtain your license key. 

Obtaining your License Key

After you purchase a license, you will receive a license key that will look something like this:

{your  name}*AVA-BF*DC-138971-151520-1|gGLbnvCZJe386ULohzfQN6cIsoZ71n7c+AUg==|

This license key is required to install your license and activate the full version of the plugin. The way to obtain your license key varies depending on where you purchased the license from.

If you purchased the license from Harrison’s web store, you will receive an email with a link to download a text file containing your license key. If you purchased the license from a reseller, you will receive an email containing the license key text.

Licensing your Plugin

When prompted by the plugin, copy and paste your license key into the designated text input field. This will automatically install your license and register it with the plugin.

Once installed, Harrison’s license files are simple text (.txt) files which are stored in the user’s HOME folder. The HOME folder is the folder that contains your Desktop, Downloads and other folders. The location of your HOME folder is different for each operating system:

• Linux: /home/{your username}

You may keep a copy of this file for your own use. The license is a per-user license and you may install the license file on all of your computers. To install the file on a new computer, simply save the file to a USB key or other transferable disk; then transfer the license file to the new computer’s HOME folder. The license file has your name encrypted in it, so you should not share it with other people. Your name will appear on the top of the plugin’s control panel to indicate that it is licensed to you.

The plugin will automatically detect your license key as long as the license file is stored in the HOME folder of the computer you are using. After transferring the license file to a new computer, it may be necessary to close and re-open your DAW in order for the plugin to detect the license.

If you don’t want to keep your license in your HOME folder for whatever reason, you may also store it in the following alternative location:  ~/.config/harrisonconsoles

Finding the plugin in your DAW 

DAW operations vary tremendously. Generally speaking, to use the plugin you must follow these steps:

1. Install the plugins, using the provided plugin installer application.
2. Follow your DAW’s instructions to “scan” for new plugins.

Please refer to your DAW manual to see which plugin formats (AAX, AU, VST, or VST3) are supported by your workstation.

Most plugin formats require that plugins are installed to a specific location on the system. In these cases, the installer will place the plugins in the default locations.

For VST format, on Windows, it is normally expected that the user defines the location of VST plugins, and tells the workstation where to find the plugins. The default location for VST plugins is C:\Program Files\Steinberg\VST.  The plugin installer will save the VST (.dll) files to that location if a custom VST path is not provided by the OS.  If you are having trouble, you should verify that the path is included in your DAW VST scan paths.

Thank you for purchasing this Harrison plugin!

Harrison has been making products for the audio engineering industry since 1975. We continue to make these products, with intense dedication, from our Nashville, Tennessee factory.  

As the audio industry has changed through the decades, Harrison has too. Originally launched to provide mixing consoles for music recording studios, the Harrison brand has extended to provide products for live broadcast, live sound, theater installations, post-production, film dubbing stages, and bedroom studios. We’ve lived through the launch of the commercial music industry, the maturation of analog, the digital revolution, the establishment of the internet, and now the acceptance of computers as the de-facto platform for the audio industry. In our pursuit of audio excellence, we’ve developed our own analog circuits, digital I/O solutions, digital DSP engines, control surfaces, audio workstations, and nearly every aspect of pro-audio technology.

“If you asked a hundred engineers, mixers and producers to define the “perfect console” you would probably get a hundred answers. The answers, however, would all contain the same salient points.”
“The “perfect console” would have totally transparent sound, capturing the true musical quality of all performances. It would have unlimited features, facilities, and functions. It would perform all required tasks with a minimum of operator effort. It would be totally reliable and require no preventive or corrective maintenance…
You can spend the rest of your life looking for the “perfect console”. You’ll never find it. You will find, however, that we have what you need.”- quote attributed to Dave Harrison;  Harrison MR20 brochure; circa 1982

True-er words were never spoken; indeed every year there are many products and technologies that seem tantalizingly necessary for audio excellence. Our lasting experience has proven that simple, straightforward, well-engineered, and great-sounding tools are the only necessity.

These plugins represent the pinnacle of Harrison’s engineering practices for digital audio sound & workflow. We sincerely hope that you enjoy using these tools as much as we enjoyed creating them. Your continued support is greatly appreciated!