Equalize

Introduction

Equalize 2 is a versatile, user friendly and great sounding equalizer with several unique features. Unlike other equalizers, you can freely adjust not only center frequency, gain and bandwidth, but also the filter slope for each band. The filter slope can be set anywhere from a gentle 3dB to ultra sharp 120dB per octave.

You can operate Equalize as a zero latency processor when using the minimum phase mode or choose to preserve the phase relationships in the linear phase mode. Equalize goes one step further, though, and introduces the unique mixed phase mode that allows you to set the latency freely in the range 5 to 120 milliseconds while preserving the phase relationships as much as possible. This gives a unique control over potential pre-ringing artifacts which is a common problem with linear phase filtering.

Latency values below 20 milliseconds ensure that any pre-ringing is masked by the temporal masking of human hearing while preserving the time-alignment across the audible frequency range.

Great care has been taken to provide a user interface that is straight forward to use. Band parameters can be adjusted using handles directly in the graphical representation of the frequency response, including bandwidths and filter slopes. A flexible real-time analyzer lets you monitor every aspect of the processing. You can easily switch between full, mid, side, left or right channel processing for each band and Equalize automatically routes the audio signal internally to ensure the best results and lowest possible latency.

User Interface and Usage

The graphical user interface of Acon Digital Equalize 2 is designed to hide the complexity of the plug-in and provide an efficient workflow as well as intuitive control over the plug-in parameters.

Adding Bands

You can add up to 12 individual bands in Equalize. Each equalizer band represents a filter type, which can be either low cut, low shelf, bell, notch, high shelf or high cut.

To add an additional band, click the + button below the curve display or double click in the main EQ curve display area.

A bullet shaped handle appears in the curve that you can move around using the mouse. The currently selected band also shows additional handles that you can use to manipulate the bandwidth (if applicable) and filter slope.

Removing Bands

You can remove the band by clicking the x button or by double clicking the handle.

Soloing and Bypassing Bands

You can solo or temporarily bypass an equalizer band in order to monitor its effect on the audio signal. You can enable the solo mode by pressing the Ctrl key while moving an equalizer band handle. The Shift key enables the bypass band mode.

Alternatively, you can use the buttons to enable or disable the solo and bypass modes:

: Solo mode

: Bypass mode

Band Parameter Settings

The parameters that are related to a specific band are placed within the band group and the header indicates which band is currently active. The parameters apply to the currently active band only. To change the currently active band you can either click its bullet handle in the frequency response visualization or use the arrow buttons to browse through the active bands.

• Frequency (Hz)

The center (for peak and notch filters) or threshold frequency of the currently active equalizer band in Hertz.

• Band gain (dB)

The gain of the currently active equalizer band in decibels. This parameter is not available for high or low cuts, or the notch filter.

• Bandwidth (oct.)

The bandwidth of the currently active equalizer band in octaves. This parameter is only available for peak and notch filters.

• Resonance (dB)

Controls the resonance in decibels at the threshold frequency for cut and shelving filters. Resonance occurs in analog filters and results in a boost around the threshold frequency.

• Slope (dB/oct.)

The filter slope of the currently active equalizer band in decibels per octave. This controls the steepness of the filter.

• Gain to Bandwidth Link

The perceived bandwidth of an equalizer band is dependent on the gain setting. You can link the bandwidth to the gain setting, so that the bandwidth is automatically adjusted when you change the gain to preserve the perceived bandwidth.

: Click this button to activate or deactivate the gain to bandwidth link

• Filter Type Buttons

You can choose between six different filter types:

: Low cut, removes frequency content below the band frequency

: Low shelf, boosts or attenuates frequency content below the band frequency

: Peak filter, boosts or attenuates frequency content around the band frequency

: Notch filter, removes frequency content around the band frequency

: High shelf, boosts or attenuates frequency content above the band frequency

: High cut, removes frequency content above the band frequency

• Channel Mode Buttons

You can choose any of the following channel modes for each equalizer band individually:

L : Apply to left channel only

M : Apply to mid channel only. The mid channel is the sum of the input channels multiplied by a scaling factor.

: Apply to both channels

S : Apply to side channel only. The side channel is the difference of the input channels multiplied by a scaling factor.

R : Apply to right channel only

Global Parameters

Master gain (dB)

The master gain controls the overall gain of the equalizer in decibels. Equalize can automatically adjust the overall gain to compensate for any gain changes in the equalizing process. This is based on an average distribution typically found in music and cannot be completely accurate.

To activate the automatic gain compensation, click the button labelled A to the left of the master gain knob.

Phase mode

You can choose between three different phase modes in Equalize. Since Equalize is a 'clean' equalizer in the sense that it doesn't apply any saturation or similar effects to simulate analog artifacts, the resulting filter applied by Equalize is fully described by the amplitude response (which is the visualization of the filter curve response that is shown in the upper part of the plug-in window) and the phase response.

Minimum phase:	This is the way analog equalizers process audio and has the great advantage of zero latency and no pre-ringing. Sharp filters can cause time alignment problems and crosstalk between tracks can cause unpredictable results when tracks are processed separately.

Linear phase:	The advantage of the linear phase mode is that you can process tracks independently even if there is crosstalk between them. Linear phase processing introduces high latencies and can cause pre-ringing effects that aren't desirable.

Mixed phase:	The unique mixed phase mode combines the best of the two phase distributions. You can adjust the latency and hence the maximum pre-ringing time so that it is masked by the temporal masking effect in the human auditory system.

You can read more about the phase modes in the Phase Modes chapter.

Latency (ms)

If the mixed phase mode is activated, you can choose the latency and maximum pre-ringing time freely in the range 5 ms to 120 ms. Low latencies will result in a phase distribution more like minimum phase while higher latencies result in a more linear phase distribution. We recommend to keep this value around 20 ms to ensure that the pre-ringing is masked by the temporal masking effect of the human auditory system while still preserving the time alignment of the signal component in the audible frequency range.

Note: The latency is doubled if you combine mid or side bands with left or right channel bands and use the mixed phase mode.

Analyzers and the Frequency Response Visualization

Equalize visualizes the frequency response of the current equalizer settings and contains two separate spectrum analyzers that you can set up to monitor the effects of the processing.

Analyzer 1 & 2

You can choose to analyze different signal sources using the drop-down lists under the Analyzer 1 and Analyzer 2 headers. Either input or output signals can be analyzed and you can also choose if the left, right, mid or side signal should be analyzed.

Drop (dB/s)

The drop parameter sets how quickly the analyzer adapts to lower signal levels and is specified in decibels per second.

Range Buttons

You can change the range of the frequency response visualization or the spectrum analyzers by clicking the buttons at the lower end of the level axes. A drop down list appears with the alternatives.

Adjusting the Analyzer Frequency Range

The frequency range of the equalizer curve can be altered conveniently thus making it possible to zoom in on specific frequency ranges for more precise control.

Move the mouse cursor to either the left or right edge of the frequency axis below the frequency curve editor. The mouse cursor turns into a left-to-right arrow.

Now click and keep the left mouse button pressed while adjusting either the start or end frequency of the visible frequency range.

You can also scroll the visible frequency range up or down moving the mouse to the center of the frequency axis. The mouse cursor turns into a hand.

Click and keep the left mouse button pressed while dragging left or right to move the visible frequency range up or down in frequency.

Piano Keyboard Display

Equalize can display a piano keyboard in the bottom of the equalizer curve editor. You can find this setting in the Preferences.

The piano keyboard makes it easy to map the band frequencies to the frequency of a specific piano key. Click a key on the piano keyboard to assign the frequency of the currently active band to the frequency of the clicked key.