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User Guide - MPC Channel Strip

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Introduction

The MPC Channel is an all-in-one signal processing suite for mixing and editing audio in post-production film. It is equipped with six essential mixing tools that use the same powerful DSP found in Harrison’s renowned MPC (Motion Picture Console) used in high end film studios around the world.

The tools provided are:

  • A parametric 8-Band Equalizer with a wide range of RTA options.
  • A pair of multi-pole Filters with various selectable shapes.  
  • A 2-Band De-Esser based on the X-Tool DSP found in Harrison MPC digital consoles.
  • A 2-Band Denoiser for cleaning up unwanted background noise.
  • Compressor with a variety of adjustable parameters and a selectable Program Dependent mode.
  • Routing, Trim & Polarity section for re-arranging the order of signal flow, toggling Polarity, and adjusting input/output Trim.

The processing sections (referred to as modules) can all be monitored simultaneously in one resizable window, so everything that's happening can be seen at a glance. Other useful features include rearrangeable signal flow, fully automatable parameters, and advanced RTA displays. Altogether, the MPC Channel is an invaluable tool that will take any post-production workflow to the next level.  

 

Module Controls

Each module can be individually resetsoloed, or bypassed using the corresponding buttons listed below. These three buttons can be found along the top bar of each module.

 

image12.pngThe RESET button resets all of a module’s parameters to their default states (with the exception of RTA controls).

 

image9.pngThe SOLO button bypasses all processing outside of the module being soloed. This allows individual modules to be auditioned exclusively without any other processing. 

 

image7.pngThe IN button toggles the enablement of each module. If disabled, a module’s processing is bypassed and its effects will not be heard. 

 

The SOLO and IN buttons work differently depending on how they are clicked. Single clicking these buttons will simply toggle between the two button states. Clicking and holding these buttons will only change the state for as long as the button is held. Once released, the button will return to its previous state. This lets you quickly audition the inclusion or removal of each module individually.

 

 

 

 

 

 

Equalizer

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The MPC’s Equalizer module is a parametric 8-band EQ with an additional pair of filters and an optional RTA display. This module consists of 4 sections:

  • Graph: Shows a visual representation of the EQ curves over the RTA display
  • Band Control: Controls the parameters for each of the 8 bands
  • Filter Control: Controls the parameters for the high and low filters
  • RTA Control: Controls the RTA display

Each band/filter has adjustable FrequencyGainShape, and parameters, as well as a button for toggling its enablement. All of these parameters can be adjusted in the control sections below the graph. Band/filter parameters can also be controlled by interacting with the corresponding “bubble” icon on the graph.

When activated, the RTA (real-time analyzer) shows the distribution of energy across the frequency spectrum for a given audio signal in real-time. The Equalizer’s RTA controls can be found in the bottom right corner of the module, but they will not be covered in detail in this section of the manual. For information on RTA controls, see the RTA section on page 13.

 

 

 

Equalizer Band/Filter Controls

The band and filter control sections below the graph contain parameter controls for the 8 bands and 2 filters. image10.png

Enablement

Each band/filter can be individually enabled or disabled by clicking the IN button at the top-left corner of its control. On the band controls, the IN button is a circular icon marked with the corresponding band number. On the filter controls, it is a square button marked “A” for the low filter and “B” for the high filter. You may notice that these buttons also match the corresponding icons on the graph for each band/filter.

If a band/filter is OUT (disabled), its bubble on the graph will turn dark gray and it will have no effect on the overall EQ processing.

NOTE: Clicking and dragging a disabled band/filter on the graph will automatically re-enable it for use.

Frequency, Q, and Gain

The FrequencyQ, and Gain can be controlled by the 3 corresponding label boxes in each band/filter control. These labels display the current values of their parameters and can be adjusted by clicking them and dragging in any direction (left/down to decrease, up/right to increase) or by scrolling the mouse wheel up or down over them. These parameters can also be set by typing new values directly into the label boxes. For ease of use, these will accept bare numbers such as “500” or numbers with units such as “500Hz”, “1k”, “1kHz”, “20dB”, etc.

All bands and filters have a Frequency range of 20 Hz to 20 kHz, a Q range of 0.09 to 100, and a Gain range of -24 dB to +24 dB. Note that some parameters may be disabled with certain shapes selected. For example, a band in Low Pass mode has no controllable Q or Gain parameters, so the label boxes for these parameters will be disabled in that mode.

Shape

The Shape menu to the right of the IN button will open a dropdown menu listing the selected band or filter’s available curve shapes to choose from. The Shape can also be changed by hovering the cursor over the menu and scrolling the mouse wheel up or down, allowing you to browse through shapes quickly without opening the dropdown menu. The available shapes and pole (slope) options for the bands and filters are listed below.  

Bands 1-8:

  • Low Pass (6, 12 dB/octave)
  • High Pass (6, 12 dB/octave)
  • Low Shelf (12 dB/octave)
  • High Shelf (12 dB/octave)
  • Bell
  • Notch
  • Search*

Filter A:

  • High Pass (6, 12, 24, 36, 48 dB/octave)
  • Low Shelf (12, 24, 36, 48 dB/octave)
  • Wide Notch

Filter B:

  • Low Pass (6, 12, 24, 36, 48 dB/octave)
  • High Shelf (12, 24, 36, 48 dB/octave)
  • Wide Notch

Search is the inverse of the notch shape. It attenuates all frequencies outside the range of the selected band by surrounding it with High and Low pass filters. This shape is ideal for sweeping across the spectrum to identify wanted or unwanted frequencies or tonal ranges.

Equalizer Graph

The Equalizer graph provides a visual representation of the EQ curves and allows for hands-on control of each band and filter. The circular “bubble” icons control each of the 8 bands and are numbered accordingly. The two square icons labeled “A” and “B” control the low and high filters. These icons also match the IN buttons in the control sections.   image2.png

The Gain and Frequency of a band/filter can be adjusted by clicking and dragging its icon on the graph to the desired position. There are rulers on the left and bottom of the graph which mark the Gain and Frequency values of each position (you may have noticed that there’s also a ruler to the right of the graph. This will come into play once we get to the RTA controls).

The Gain ruler on the left can be dragged up or down to adjust the vertical position of the EQ curve. By default, the maximum and minimum gain values shown on this ruler are 12 dB and -12dB, but moving a band past these values will automatically scale the vertical axis of the graph to accommodate gain values up to 24 and -24 dB. This can also be done manually by right-clicking and dragging the Gain ruler up or down. The scale and vertical position can be reset to their default states by OPT-clicking or double-clicking the Gain ruler.

The Q of a band/filter can be adjusted by right-clicking or SHIFT-clicking its bubble on the graph and dragging it up or down. This can also be done by simply hovering the cursor over it and scrolling the mouse wheel up or down.

OPT-clicking a band or filter will reset its FrequencyGain, and Q to their default states, while double-clicking will only reset its Gain back to zero.

Holding CTRL while hovering the cursor over a band on the EQ graph will temporarily put that band into Search mode.

Denoiserimage5.png

The Denoiser is an effortless tool for removing unwanted noise from recorded audio. While it can be used on any input source, this Denoiser is optimized for processing speech. The cutoff frequencies of the high and low filters are preset to best accommodate the frequency range of the human voice and the envelope is set to match the rate of normal speech.

 

The Denoiser functions like an expander for frequencies outside the range of the human voice. The HIGH and LOW sliders control the maximum amount of Gain reduction applied to signals within each band’s respective Frequency range. The maximum Gain reduction set for each band will only be applied to signals below the Threshold. All Signal levels above the Threshold will be allowed to pass through with variable Gain reduction based on the dynamic characteristics of the signal.

You can think of the Threshold as setting the level that separates noise from the desired signal. Properly set, any noise present in the input signal should be just below the Threshold (where the maximum Gain reduction is applied) and the level of the desired part of the signal should average above the Threshold (where less or no Gain reduction is applied).

The “curtain” display in the center shows a visual representation of the max Gain reduction set by the HIGH and LOW sliders compared to the actual Gain reduction happening in each band. The two white diagonal lines represent the max Gain reduction while the red reduction indicators fill the area above the lines based on the amount of Gain reduction being applied to the input signal.  

De-Esserimage1.png

This module contains a simple and intuitive implementation of Harrison’s renowned De-Esser algorithm. It is primarily used to attenuate harsh frequencies caused by sibilance in human speech.

 

The two circular markers on the graph display, labeled “S” and “H”, are the controls for the Ess and Hi bands (S = Ess, H = Hi). These controls can be dragged horizontally or vertically to set the Bandwidth and Depth of their respective bands.

A band’s horizontal range, or Bandwidth determines the range of frequencies subject to attenuation within that band. The low cutoff Frequency for the Ess band has a range of 200 Hz to 8 kHz, while the Hi band control has a range of 2 kHz to 12 kHz for taming any additional frequencies above that.

The vertical Depth of a band sets the maximum Gain reduction in dB that can be applied to the frequencies in its Bandwidth. A lower Depth means greater possible attenuation. Both bands have a maximum Depth value of -12 dB and can go up to 0 dB, where no attenuation occurs.  

Clicking and dragging in the open portion of the graph (rather than on a specific band control) allows you to control both bands simultaneously. This is useful for adjusting the Frequency or Depth of the bands without altering the Bandwidth. To adjust the overall Bandwidth, you may use the mouse wheel to easily move the bands closer together or further apart.

 

To the left of the graph display is the Level Meter and Threshold control. The Level Meter displays two values: the level of the input signal (dark green) and the Ess signal (light green). The Ess signal is the level of signal present in the Frequency range of the Ess band. The attached Threshold slider sets the level in which Gain reduction starts to be applied to the input signal.

The Attack knob controls how long it takes for a signal to become fully attenuated once it exceeds the Threshold. Possible Attack times range from 0.2 ms to 20 ms.

Located above the Attack knob is the Auto Solo button. With Auto Solo activated, clicking and dragging either of the band controls on the graph will automatically solo the corresponding band. This lets you hear only the parts of a signal that are within the Frequency range of the soloed band so sibilant frequencies can be easily identified.

NOTE: Holding CTRL will temporarily solo the selected band even if Auto Solo is off.

The De-Esser also includes an RTA which can be controlled from the RTA section in the bottom right corner of the module. For detailed information on RTA controls, see the RTA section on page 13.

 

 

 

 

 

 

 

 

 

 

Compressorimage11.png

The MPC’s Compressor module is optimized for vocal compression (speech and singing). But its flexible controls allow it to meet a variety of other needs as well.

Although the controls in this module are fairly standard among compressors, a brief description of each is listed below.

 

The Ratio knob controls the Ratio of Gain reduction applied to a signal that exceeds the Threshold. For example, a Ratio of 2:1 means that an input signal exceeding the Threshold by 2dB will result in an output signal that is only 1dB over the Threshold level. Possible Ratio values range from 1:1 to 100:1.  

The Knee adjusts the area of the Threshold point, which affects how quickly the input signal transitions from being below the Threshold (not compressed) to above the Threshold (compressed) and vice versa. Its possible values range from 1.0 to 30.0. A low Knee value (hard knee) means that the transition through the Threshold point will be more abrupt. A higher Knee value (soft knee) will create a smoother transition through the Threshold.  

The Depth determines the maximum amount of Gain reduction that can be applied to signals above the Threshold. The possible Depth values range from 0 dB to 30 dB.

The Attack time controls how long it takes for a signal to become fully attenuated once it exceeds the Threshold. Possible Attack times range from 0.1 ms to 100 ms.

The Release time controls how long it takes for the signal to return back to its original, uncompressed state once it falls back down below the Threshold. Possible Release times range from 5 ms to 500 ms.

The Program button located between the Attack and Release knobs will enable Program Dependent mode when selected. This option will automatically adjust the Attack and Release times based on the dynamic character of the input signal. In many cases this can help to avoid compressor “pumping”. 

On the right side of the module, you’ll find the Input Meter/Threshold control, Gain Reduction Meter, and Makeup Gain. The Input Meter shows the level of the incoming signal compared to the Threshold level, which is controlled by the attached slider. The Gain Reduction Meter shows the amount of Gain reduction being applied to the input signal in dB. The Makeup Gain can be used to increase the Compressor’s output level up to 30 dB (the same as the maximum Depth value), in order to compensate for lost gain.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Routing, Trim, & Polarity

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This last module provides controls for re-routing signal flow, adjusting Trim, and toggling Polarity.

The order of signal flow between the six elements can be rearranged by dragging an element’s marker to its desired position along the signal chain, which flows from top to bottom. Dragging an item to another slot will swap the positions of the two items. Dragging an item to one of the arrow indicators in between each item will push all other items down (if placing higher from a lower position) or up (if placing lower from a higher position) and place the dragged item in the newly opened spot.

If a module is disabled, its corresponding element markers in the signal chain will become greyed-out.

The signal routing is fully automatable, so the order of signal flow can be automated to accommodate various scene changes in real-time.  

The Trim fader can adjust the Gain of the signal passing through it (-20 dB to +20 dB). This is also a routable item, so it can serve as an input or output Trim depending on its position in the signal chain.

The Polarity switch inverts the phase of the output waveform (flips it 180°) when selected.  

 

 

 

 

 

 

RTA

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An RTA (Real-Time Analyzer) is included in the Equalizer and De-Esser modules to help users visualize spectrum data for a given audio signal in real-time. The RTA is calculated using a Discrete Fourier Transform, which provides high resolution data even in lower frequency ranges. The Equalizer and De-Esser modules each have sections for controlling their RTA displays. The controls described here apply to the RTAs in both modules, unless noted otherwise.

The circular button at the top-left corner toggles the RTA on or off (Green = on).

The Type dropdown menu selects between the 4 modes of operation:  GraphScrollBar, or Lightning. Note that the Graph and Lightning modes are only available in the Equalizer RTA.

For multi-channel configurations, the Channel Mode dropdown menu will allow you to select individual channels for the RTA to listen to. This option defaults to “Sum” mode, which sums all the available channels together for the RTA to read from. The Channel Mode selector will be disabled if the channel configuration is mono.

NOTE: Summing multi-channel audio may produce misleading RTA measurements due to the potential phase difference between signals. Selecting an individual channel for the RTA channel mode will provide the most accurate RTA measurements.

The Post button sets the input signal to the RTA from Pre-EQ to Post-EQ. If you want the RTA measurements to be affected by your EQ adjustments, you should enable this option (Available in the Equalizer RTA only).

The Decay time determines how long RTA measurements are displayed before they ramp back down to zero. If the RTA display is changing too rapidly to be useful, you should increase the Decay value. Likewise, if the display appears to be “frozen”, try decreasing the Decay as this might be the result of an excessively high Decay value.

The Length slider is only available in Scroll mode and essentially controls the scroll speed of the spectrum data. If the display is scrolling too quickly or if you would like to see more of the spectrum’s history, you should increase the Length value.  

RTA Trimimage4.pngimage13.png

The Gain Trim of the RTA’s input signal can be adjusted on all RTA types by clicking the ruler to the right of the display and dragging it up or down. This can be used to increase or decrease the RTA’s sensitivity to the signal being fed to it.

When the RTA is in Bar or Scroll mode, the ruler will display the levels of brightness that correspond to each intensity value along the vertical axis. The levels of brightness displayed on the ruler will change accordingly when the Trim is adjusted.  

In Graph and Lightning modes, the scale of the vertical axis can be zoomed by right-clicking the ruler and dragging up or down.

The RTA Trim / Zoom can be reset to their default states by OPT-clicking or double-clicking this ruler.

 

RTA Graph Mode

In Graph mode, energy is represented by the vertical position of the RTA across the horizontal frequency spectrum. High-energy points can be easily recognized as “peaks” in the RTA graph.image19.png

 

RTA Scroll Mode

In Scroll mode, the RTA is displayed as a vertically-scrolling spectrogram, providing you with additional time to recognize and target certain spectral characteristics of the audio signal.image17.png

 

 

 

RTA Bar Mode

In Bar mode, the distribution of energy is represented by the brightness level of the vertical bands that flash across the spectrum.image6.png

 

RTA Lightning Mode

In Lightning mode, the RTA is displayed as a horizontal curve which is the calculated average of the actual curve. Bright flashes occur along the spectrum in areas where the peaks are greatest above average.image8.png

 

 

 

Tool Tips 

This section describes some helpful shortcuts and control modifiers that can be used throughout the plugin. Even though some of these are mentioned earlier in the manual, they’ve all been included in this section as well so they can be found easily.

The following terms denote various combinations of keyboard/mouse actions listed below.

  • OPT-click: Left mouse click while holding the Option (Alt) key on a keyboard
  • CMD-click: Left mouse click while holding the Command (⌘) key on a keyboard
  • CTRL-click: Left mouse click while holding the Control key on a keyboard
  • SHIFT-click: Left mouse click while holding the Shift key on a keyboard
  • Double-click: Two consecutive left mouse clicks
  • Right-click: Right mouse click

Resetting Parameters: OPT-click any control to reset it to its default value. This includes sliders, knobs, menus, labels, rulers, and band controls on the EQ/De-Esser graphs. Double-clicking can be used to reset knobs, sliders and rulers only.

Double-clicking a band control on a graph will only reset its Gain.

Menu Scrolling: Quickly browse through options in a dropdown menu by scrolling the mouse wheel over it. This applies to the menus controlling EQ Shape, RTA Type, and RTA Channel.

Adjusting Faders: You do not need to grab the fader cap to control a slider. The entire slider area operates as the grab-able control.  As you hover over a slider, the slider area will highlight and you can click and drag (or mouse wheel) in any part of the highlighted area.

You can also scroll the mouse wheel over sliders and label boxes to adjust their values.

Fine Adjust Mode: CMD-click / scroll to fine tune any slider or knob value.

 

 

 

Equalizer Graph Controls

The Q of a band/filter can be adjusted by right-clicking or SHIFT-clicking its bubble on the graph and dragging it up or down. This can also be done by simply hovering the cursor over it and scrolling the mouse wheel up or down.

Double-clicking a band/filter will reset its Gain back to zero, while OPT-clicking will reset its Frequency, Gain, and Q to their default states.

Holding CTRL while hovering the cursor over a band on the EQ graph will temporarily put that band into Search mode.

 

Denoiser Graph Controls

The Low and High values can be adjusted simultaneously by the same amount by clicking or scrolling the mouse wheel in the center of the visual display and dragging up or down. This can also be done by scrolling the mouse wheel in the center of the display.

The Low and High values can be adjusted simultaneously by the same amount by clicking the center of the visual display and dragging up/down or by scrolling the mouse wheel. Dragging left/right here will adjust the Low and High values inversely to each other, meaning one will increase as the other decreases and vice-versa.

 

De-Esser Graph Controls

Dragging in the open portion of the graph (rather than on a specific band control) allows you to control both bands simultaneously. This is useful for adjusting the Frequency or Depth of the bands without altering the Bandwidth. To adjust the overall Bandwidth, you may use the mouse wheel to move the bands closer together or further apart.

Holding CTRL while hovering the cursor over a band on the De-Esser graph will temporarily Solo that band.

Usage Notes

Special Equalizer Shapes

The EQ bands feature two specialized shapes that can be instrumental for EQ-ing in post-production: Notch and Search.  

Notch is a shape designed to help eliminate unwanted noises commonly found in production recordings such as camera noise, lighting hum, or servo motors from auto focus units.

Notch has no gain setting. It is an absolute notch down to the noise floor.

Notch maintains a phase coherent signal even when multiple notches are applied on voice recordings.

Search is the inverse of the notch shape. It attenuates all frequencies outside the range of the selected band by surrounding it with High and Low pass filters. This shape is ideal for sweeping across the spectrum to identify wanted or unwanted frequencies or tonal ranges.

Once you have identified the Frequency and Q using Search, you can then apply any other shape while maintaining the same Frequency and Q values.

Search is a valuable post production tool that can also be used to create various SFX such as radio filter futz and radio tuning sweeps.

Noise Reduction

Placing the Filters prior to Denoiser in the Routing section and applying judicious pre-filtering of the Low and High frequencies can yield more effective noise reduction with less artifacts. This works particularly well on dialogue.

For low Frequency hum or rumble, a steep High Pass filter will help optimize noise reduction in the Denoiser.

In the event of high frequency buzz or tones, pre-filtering with a Wide Notch shape on one of the filters can be very effective.

 

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

Truer 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.

Our 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.