Equalisation is the audio engineer's most widely used processing tool. However, the equalisation applied is usually static -- it remains the same over time.
This is often undesirable! For example, a presence boost which was appropriate during one section of a performance may become harsh during another section.
The two most common solutions are automation and multi-band dynamics processing. Automation is only convenient when the spectral changes occur over a long period of time, and aren't repetitive. Typical multi-band dynamics processors work to some extent, but with inconvenient downsides.
Multi-band compressors/expanders and dynamic EQs work in a similar way. They both split the input signal into multiple parallel paths. Each path is filtered to restrict its frequency range, then sent into a compressor or expander.
A dynamic EQ applies the gain reduction/expansion to the gain parameter of a parametric equaliser which processes the original input signal.
Multi-band compressor/expanders apply their gain reduction directly to each filtered signal, then combine them to reconstruct the original wide-band input signal.
This reconstruction approach has some downsides:
When the band-limited signals are combined to reconstruct the input signal, a static phase shift is present at their cross-over point. The band-limiting can be achieved using linear-phase filters, however these incur high latency and can degrade transient response at lower frequencies.
Multi-band processors typically afford less precise frequency adjustment than a parametric equaliser. If steeper filters are used to provide greater precision, phase shift at the crossover points increases.
Some multi-band processors get around the phase response issue, but are still left with a problem -- the bands cannot be overlapped! This can pose significant problems when a combination of gentle character modification and precise correction is required.
But Multi-band processors do have an advantage over most dynamic EQs. As a boost or cut increases, the width reduces. This is similar to the proportional Q response or gain / Q dependency of many well loved analogue EQ processors.
When using an EQ which does not have this gain / Q dependent response, gain changes often require Q changes to maintain the desired effect. Of course, this is highly undesirable if the gain is being modulated dynamically! See Gain-Q Dependency for details.
The Oxford Dynamic EQ combines the benefits of dynamic EQ with the Oxford EQ's Type 3 gain / Q dependency, giving you the best of both!
The Offset Gain determines the resting, or static gain of each equaliser section.
The Target Gain determines the gain which the EQ band will attempt to reach dynamically.
This means that each equaliser section's gain is constrained between these two settings, preventing accidental over-processing which can occur with other dynamic equalisers.
When multiple EQ sections overlap, their combined response can exceed the range defined by each section's Offset and Target Gain settings.
Enable and Disable all processing for this band.
Listen to just the frequency range which will be processed. This can help when fine tuning your EQ settings.
Select the output channel to apply this band's EQ to.
You can select to process:
Select the EQ type which is applied to the output signal.
The available types are:
Set the centre frequency (Bell EQ type), or corner frequency (Shelf EQ types) for this band.
Set the Q (width) of this band's Bell EQ type. The Q control is disabled for the Shelf EQ types.
Drag up/down to set the Target and Offset Gains, retaining their relative levels.
Drag left/right to set the centre frequency of this band.
Toggle the graph dB scale between -/+4 dB, -/+6 dB, -/+12 dB and -/+20 dB scales.
This shows the spectrum of the processed output signal. When a Listen button is enabled, it shows the filtered side chain signal.
The 'side chain' is the signal path which controls the dynamics processor.
The original input signal is copied and filtered to focus on a narrow frequency range. This filtered signal is fed into the band's dynamics processor, which controls the EQ gain applied by that band.
By default the side chain filter matches the EQ band, using the same type, frequency and Q. This provides the easiest way to apply dynamic EQ only when it's needed.
Enable to control the side chain filter independently of the EQ band.
Drag the middle node left/right to set the centre frequency of this side chain filter. Drag the edge nodes left/right to set the Q of this side chain filter.
The nodes are greyed out when the side chain is disabled.
Listen to the side chain signal filtered using the side chain filter settings. This can help when fine tuning the frequency range to react to dynamically.
Enable to route an external signal into this band's side chain path. You'll need to set up the side chain signal in your DAW.
Select the input signal channel to feed into this band's side chain path.
You can select to feed the side chain with:
Select the filter type which is applied to this band's side chain signal.
The available types are:
These correspond to an EQ Type of Low Shelf, Bell, and High Shelf respectively.
Set the centre frequency (Band Pass filter type), or cutoff frequency (High and Low Pass filter types) of the side chain filter.
Set the Q (width) of the side chain Band Pass filter. The Q control is disabled for the Low Pass and High Pass filter types.
Each EQ band is controlled by a powerful dynamics processor, providing upwards and downwards compression and expansion. However, it's not necessary to know the difference between these types of processing. See Trigger for details.
Choose Peak to react to overall peak signal level. Choose Onsets to react only to sudden increases in signal level, while ignoring the overall peak level.
Onset detection is useful for reacting to transients, staccato notes and even sibilance!
In Above mode, gain changes dynamically when the signal is above the Threshold. Use Above mode for downwards compression and upwards expansion.
In Below mode, gain changes dynamically when the signal is below the Threshold. Use Below mode for upwards compression and downwards expansion (gating).
When selecting a Trigger mode, just ask yourself: "Do I want to start applying gain when the signal rises above the Threshold, or when the signal falls below it?""
See Dynamic Transfer Function for more details.
Set the level at which the dynamics processing becomes active (depending on the Trigger setting).
This Threshold level is preceded by a 10dB knee to smooth the transition away from the Offset Gain.
Set how reactive the band's gain is. This is similar to a compressor's ratio control.
At high Dynamics settings, the band's gain is more likely to reach the Target Gain. At 0% the band will stay at the Offset Gain.
Set how slowly the band approaches the Target Gain.
Set how slowly the band recovers to the Offset Gain.
Set the output gain of the plug-in to avoid clipping or match the dry and processed signal levels.
Filters with some amount of gain / Q dependency are sometimes referred to as 'proportional Q filters'. The Oxford Dynamic EQ provides gain / Q dependency which matches the R3 EQ's Type 3 response.
From the Oxford R3 EQ user guide:
This style of EQ has a moderate amount of gain / Q dependency whereby the Q increases as gain gets further from 0dB. This provides the EQ with a softer characteristic as EQ is progressively applied and since the effective bandwidth is increased for low gain settings, it sounds louder and more impressive when used at moderate settings. The gentler Q curve also lends itself better to overall EQ fills and more subtle corrections in instrument and vocal sources. Turning the Gain control seems to produce the effect that the ear is expecting, without needing to adjust the Q control too often. Therefore EQs of this type are often dubbed as ‘more musical sounding’.
This EQ most resembles the older and well-loved Neve types, their modern derivatives and the later SSL G Series. Also many of the more popular outboard EQs have this dependency to some extent.
This gain / Q dependency is highly important for a dynamic EQ, where the gain is modulated dynamically. A dynamic EQ with no gain / Q dependency will tend to sound over-processed or harsh as more gain cut/boost is applied.
| Sample Rate (kHz) | Latency (samples) | Latency (ms) |
|---|---|---|
| 44.1 | 50 | 1.1 |
| 48 | 50 | 1.0 |
| 88.2 | 35 | 0.4 |
| 96 | 38 | 0.4 |
| 176.4 | 70 | 0.4 |
| 192 | 76 | 0.4 |
The differences in latency are due to differences in the oversampling filter used at different sample rates. Lookahead time (in ms) is the same for all sample rates to ensure consistent behaviour.
| 44.1/48 kHz | 88.2/96 kHz | 176.4/192 kHz | |
|---|---|---|---|
| Mono (5 Band) | 5 | 2 | 1 |
| Mono (3 Band) | 7 | 3 | 1 |
| Stereo (5 Band) | 3 | 1 | |
| Stereo (3 Band) | 1 | 1 | 1 |
Sonnox Oxford plug-ins come equipped with their own onboard Preset Manager, which is displayed at the top of the plug-in window. The reasoning behind this is to allow increased portability of your presets across all the host applications, while also providing a consistent and versatile interface. While most host platforms allow creation and loading of presets, those host-created preset files are not portable between different host applications. With the Oxford plug-ins’ Preset Manager, you can create a named preset in one host application and load it when using an alternative application.
The Sonnox Preset Manager is fully described in a companion document — Sonnox Toolbar and Preset Manager User Guide — available for download at www.sonnox.com/docs
For latest System requirements, please visit www.sonnox.com.
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