Sonnox Oxford Dynamics User Manual
Contents
1 Introduction 4
2 FrontPanelControls 6
3 DynamicsControl 7
3.1 Basic Dynamics Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4 Compressor 9
4.1 Compressor Threshold Control . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.2 Compressor Ratio Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.3 Compressor Soft Ratio Control . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.4 Compressor Make-Up Control . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.5 Using Level Control Functions . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.6 General Programme Compression . . . . . . . . . . . . . . . . . . . . . . . . 12
4.6.1 ‘Least Possible’ Approach . . . . . . . . . . . . . . . . . . . . . . . . 13
4.6.2 ‘Overall Compression’ Approach . . . . . . . . . . . . . . . . . . . . . 15
4.6.3 Combined Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.6.4 Maximum Loudness . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.6.5 Minimum Obtrusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.7 Timing Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.7.1 Compressor Attack Control . . . . . . . . . . . . . . . . . . . . . . . . 19
4.7.2 Compressor Release Control . . . . . . . . . . . . . . . . . . . . . . . 20
4.7.3 Compressor Hold Control . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.8 Compressor Timing Laws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.8.1 Exponential/dB timing (Normal and Classic types) . . . . . . . . . . . 23
4.8.2 Linear/dB timing (Linear type) . . . . . . . . . . . . . . . . . . . . . . . 24
4.9 Using Compression Timing Functions . . . . . . . . . . . . . . . . . . . . . . 25
4.9.1 Fast as Possible Approach . . . . . . . . . . . . . . . . . . . . . . . . 26
4.9.2 Natural Dynamics Approach . . . . . . . . . . . . . . . . . . . . . . . 26
4.9.3 Slow and Gentle Approach . . . . . . . . . . . . . . . . . . . . . . . . 26
4.9.4 Artistic Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5 Limiter 28
5.1 General Limiter Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.2 Maximising Loudness with the Limiter . . . . . . . . . . . . . . . . . . . . . . 30
6 Expander 31
7 Gate 32
8 SidechainEQ 33
8.1 Sidechain EQ Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
9 Warmth 35
9.1 Max Trim Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
10 Dither 36
11 BusCompressor(TDM andAAX DSP only) 37
11.1 Description of Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
11.2 Buss Compressor Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . 40
11.3 Description of Sub Channel Controls . . . . . . . . . . . . . . . . . . . . . . . 41
12 DescriptionofControls 43
13 ‘ACCESS Follows’modes(AAX only) 46
14 Specifications 47
14.1 Control Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
14.2 Pro Tools | HDX – Instances per chip . . . . . . . . . . . . . . . . . . . . . . . 48
15 PresetManagerToolbar 48
16 SupportedPlatforms 49
17 SystemRequirements 49
18 CopyrightandAcknowledgements 50
1 INTRODUCTION
1 Introduction
The Oxford Dynamics plug-in is a direct emulation of the extremely flexible and capable
unit used in the OXF-R3 professional mixing console. Resulting from many years research
into professional dynamics applications, it offers separate Compressor, Limiter, Expander,
Gate and sidechain EQ functions, with fully independent control of all parameters.
Features such as selectable time constant curves and variable soft compressor functions
allow the user to confidently tackle all common uses of compression, from subtle
unobtrusive level control and mastering functions to the creation of great artistic
effects.
The use of a feed-forward architecture with logarithmic sidechain processing, and the use
of look-ahead techniques, ensures exemplary sonic characteristics and dynamic
accuracy, with an artistic capability simply unavailable from any other single unit,
analogue or digital. This highly sophisticated and professional product has the power and
flexibility to obviate the need for many of the separate applications that most users keep
for specific tasks. The Oxford Dynamics features include:
• Separately controlled sections for Compressor, Limiter, Gate and Expander,
providing an extremely wide range of dynamic control
• Fully featured 2-band sidechain EQ with audition function
• Additional surround format Compressor and Limiter with selectable Sub channel
filtering and sidechain gain contribution control
• Selectable linear and exponential time constant curves
• Highly accurate logarithmic sidechain processing
• Fully variable soft ratio function for extreme programme tolerance and highly
musical compression operation
• Variable harmonic enhancement for extra loudness, presence and ‘punch’
• Selectable re-dithering function for word length reduction in mastering situations
• Extremely low signal path insertion noise and distortion, below -130dBr
• All functions are fully automatable
• Automatic mono-stereo detection and adaptation as appropriate
• Mono-only versions to allow processing of one side of a stereo track
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1 INTRODUCTION
Dynamic signal level control has grown in complexity and popularity from humble
beginnings to an essential part of the sound production process. Originally conceived as
a method to automatically correct for performance variation and broadcast transmission
limitations, dynamic control has evolved beyond this to engender complete artistic
cultures and idioms, resulting from the continuous expansion of the artistic effects
provided by such processes. As a result of these trends, many diverse types of
compression mechanisms have been developed over the decades aimed at a very wide
range of uses and effects.
By providing an unusually wide range of control, along with multiple timing laws and
operational subtlety, the Oxford Dynamics section can achieve impeccable results in the
widest range of uses, from sensitive almost imperceptible dynamic compression on
vocals and programme material to harmonic enhancement of instruments and dramatic
artistic audio effects.
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2 FRONT PANEL CONTROLS
2 FrontPanelControls
The separate dynamics functions have their own control sets that are available at any time
by operating the appropriate ACCESS button for that section. Operating the IN button for
any section will force the controls for that section to the foreground of the GUI for
convenience. The IN buttons can be used to toggle the contributions from each section
on and off, for comparison purposes. Button illumination displays indicate which sections
are in and which control set is being accessed. Control setting parameters are
permanently available during operation, and specific values can be typed into the
parameter windows at any time. Where functions apply to the overall dynamics rather
than single sections, their parameters and buttons are visible permanently.
Overall input/output levels and section contribution meters are permanently visible for
reference. The four section gain contribution meters (top centre of the display), GATE,
EXP, COMP, LIMIT display the gain reduction contribution of each section separately,
the maximum of which at any time will determine the instantaneous gain reduction of the
complete dynamics plug-in.
A live graphic display of the overall level transfer function is permanently displayed (in the
lower right) for reference, and all setting parameter values are visible for any section that
is being accessed.
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3 DYNAMICS CONTROL
3 DynamicsControl
The Dynamics section comprises of four separate applications: Compressor, Limiter, Gate
and Expander.
Although these applications contain several different control types that have common
functions, the operation, ranges and laws of these controls have been optimised carefully
for maximum flexibility within the intended specific use of that section. The very wide
control ranges offered within the applications are accommodated in the user interface by
employing specific control laws that encourage experimentation over a very wide
parameter set, without the loss of finer control sensitivity and detail. Careful consideration
has also been given to the dynamic behaviour of the time constants, as this factor is
largely responsible for the sonic character of any dynamics application.
In order to make best use of this application, it is necessary to acquire a basic
understanding of dynamics processing in general, and the particular architecture of the
Oxford Dynamics plug-in. The following sections address these issues.
3.1 BasicDynamicsArchitecture
There are two basic types of dynamics architecture in common use; these are often
termed as feed-forward and feedback types. The feedback type uses its own output to
compute required gain reduction:
GAIN CONTROL
..
.
X
LEVEL DETECT
AND SIDECHAIN
.
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3.1 BasicDynamicsArchitecture 3 DYNAMICS CONTROL
This method had an advantage in early analogue compressors because the complex and
largely unpredictable laws of early gain reduction elements could be somewhat
decoupled from the total level transfer characteristic of the application (because the
design made use of level feedback). With the introduction of better solid state VCAs and
accurate logarithmic sidechain processes, this method has largely been abandoned in
favour of the feed forward model since it has a much greater degree of control parameter
separation and intrinsic accuracy.
The Oxford Dynamics section is a feedforward type processor. By this we mean that the
gain controlling sidechain element of the processor works by evaluating the programme
level at the input, and calculating the required output gain by dead reckoning:
GAIN CONTROL
..
.
.
X
LEVEL DETECT
AND SIDECHAIN
This widely conforms to the architecture of most popular modern analogue dynamics
sections employing voltage-controlled amplifiers. In a digital design the feed-forward
model has additional advantages, which include the possibility of extremely well
controlled and variable time constant laws and sonically accurate gain control elements.
Also look-ahead processing (using delay) allows gain control to be initiated in advance of
the signal, without losing signal quality.
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4 Compressor
4 COMPRESSOR
There are two main factors that describe the function of a compressor: alevelversus
gainfunction, which is generally assumed to be independent of the time constants, and
a dynamicgainfunction which exhibits more complex dynamic behaviour over time. To
explain the operation of the compressor section, it is useful to split these two categories.
The following section refers to the level versus gain behaviour of the compressor
application in the Oxford Dynamics plug-in.
The Oxford plug-in employs logarithmic sidechain processing, which means that all signal
parameter setting (and time constant action) occurs in the ‘decibel’ domain. This makes it
possible for all control functions to remain independent and therefore provides the
greatest level of control for the user. To get the best results from the compressor, it will be
useful to gain an understanding of the specific effects of its control parameters by reading
the following pages carefully.
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4.1 CompressorThresholdControl 4 COMPRESSOR
4.1 CompressorThresholdControl
The threshold control sets the level (referred to dB FS) at which compression and gain
reduction will begin. The control has a linear decibel law over the range. The following
graph illustrates the threshold control operated in 5 dB increments with the ratio at max
(1000:1) to –20 dBr.
4.2 CompressorRatioControl
The ratio control sets the rate at which gain reduction will occur when the input level goes
beyond the set threshold level. The control has a 1/Ratio law so that gentle compression
can be achieved despite the wide range of the control. So, from 1:1 to 2:1 ratio occurs
over the first 50% of the control range and 4:1 ratio occurs at 75% control rotation etc.
Full limiting is achieved with the control at 100%.
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4.3 CompressorSoftRatioControl 4 COMPRESSOR
4.3 CompressorSoftRatioControl
The soft ratio function provides a gentle, minimum rate transition between the region
below the threshold and the compressed region of the curve. A further threshold, below
the main threshold control setting, defines the start of the soft curve. The program signal
is therefore compressed progressively harder as it gets louder within this region, until the
full compression defined by the ratio control is achieved. Adjustment is made via the
SOFT button, which provides fixed settings from 0 dBr to –20 dBr in 5 dB
increments.
4.4 CompressorMake-UpControl
The MAKE-UP control allows manual compensation for level loss during compression up
to a maximum of +24 dBr. The gain makeup is applied to all Dynamics functions but
operates only when the compressor is IN.
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4.5 UsingLevelControlFunctions 4 COMPRESSOR
4.5 UsingLevelControlFunctions
Since all level control functions in the Oxford Dynamics Compressor operate entirely
separately, a very high degree of control for a wide range of common use is possible, in
particular the plug-in does not impose any particular style constraint on the user. This
section explains some of the commonly used techniques, and how they may be achieved
using the Dynamics plug-in.
In the most general terms, the extremes of compression usage fall into two main
categories: dynamiclevelcontrol and audioeffectgeneration. For simple level control,
such as controlling performance variation in vocals, instruments and final programme
material, we most often require the most transparent compression with minimum artefacts
caused by the dynamics’ control. However, to generate audio effects and distortion the
reverse is true and we need to make the audio character of the compression a dominant
part of the final result.
In order to understand how we achieve these two different styles of result, we must
remember that, in general, we are much more sensitive to the rate of change of level than
we are to relative gain. So in order to generate prominent audio effects using the
compressor, we need to generate a significant rate of change of gain action by using both
hard compression gain curves and the creative use of time constants. However, for
general unobtrusive level control we should be avoiding all of this, and opting for the
gentlest compression gain curves and least obtrusive time constant settings that integrate
well with the programme style.
4.6 GeneralProgrammeCompression
There are two main basic philosophies that underlie approaches to unobtrusive
compression. The aim of the following pages is to explain these concepts, make
comparisons between them, and show how enhanced results can be achieved using the
Oxford Dynamics Compressor.
continuedonnextpage
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4.6 GeneralProgrammeCompression 4 COMPRESSOR
4.6.1 ‘LeastPossible’Approach
The first and most obvious, which we will call the ‘leastpossible’ approach, is to leave
the majority of the programme uncompressed, forcing the compression to deal only with
the louder passages. This method has a definite psychological advantage in that one gets
the feeling that the majority of the programme remains unaffected. There is also some
possible technical merit (especially for legacy designs) in that the compressor is working
‘less often’ and over a restricted range, thereby avoiding some of the potential errors in
the application.
The above graph illustrates this kind of approach. The situation here is that the
programme goes ‘over’ on the loud passages, so we seek to control the loud portion only
by setting the threshold relatively high (-5 dBr) and setting the ratio high enough (ie.
between 3:1 and 4:1) to prevent the ‘over’. With the Oxford compressor, the threshold and
gain make-up controls can be used to accommodate this approach over a 24 dB range of
relative input levels, without change in the sonic character of the programme.
This method has the major disadvantage of risking increased rate of change disturbance
because the transition between non-compressed and compressed programme regions is
sharp. There is therefore a considerable reliance on longer time constant settings in order
to reduce the sonic effects of the compression. In other words, we need to seek to
control the rate of change using time slewing rather than level progression. Whilst this
approach would naturally form a good basis for using the compressor as an audio effect,
it is less suitable for composite programme control.
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4.6 GeneralProgrammeCompression 4 COMPRESSOR
One way to alleviate the compression transition effect is to smooth it out using the soft
ratio function:
The above graph shows the action of the SOFT ratio control set to 5dB applied to the
previous settings. Starting the compression earlier, and increasing the compression ratio
up to the max level point, smoothes out the transition point at the onset of
compression.
The main advantage of this method - oftenreferredtoas‘overeasy’ - is that faster time
constants can be used before the compression artefacts become too obtrusive. This
means that the programme can be made to sound louder and more present without
increasing peak levels, despite the fact that more of it is being compressed. Also, the use
of faster time constants further reduces peak overshoot, so there is less need to employ
limiting in the signal chain.
It should be noted that with the Oxford plug-in, the application of the soft function will
always result in the same maximum output level. This means that you can apply the soft
ratio function at will, with only a minimal need to adjust the threshold and ratio
controls.
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4.6 GeneralProgrammeCompression 4 COMPRESSOR
4.6.2 ‘OverallCompression’Approach
This concept advocates that a more transparent sounding compression can be achieved
if a relatively large portion of the programme level range is under continuous compression.
The rationale here is that the rate of change disturbances are minimised because the
compressor spends less time going over the onset of compression transition range. But
the downside is that peak loudness is less well controlled, therefore quite heavy additional
peak limiting is sometimes required to tailor the performance into an overall mix.
The above graph illustrates this general approach. The threshold is set to around –30 dBr
and the ratio is set to 2:1; the level loss has been compensated manually by the make-up
gain control. In this case we can see that quiet parts of the programme output below –30
dBr are boosted by 15 dB. The most prominent 30 dB range of the programme is
represented by only a 15 dB dynamic range, whilst still maintaining a good representation
of the dynamic information in the performance.
This approach can significantly improve the loudness of programme material over a wider
range, where maintaining a decent dynamic range in the output is an important feature.
Therefore this approach works well for the compression of classical, choral and solo
instrumental work.
4.6.3 CombinedApproach
From the above discussion we can see that the digital compressor, with its sonically
transparent gain control process and very accurate level control, allows very effective
influence over a wide dynamic range of programme material, without incurring some of
the problems associated with analogue units. The range of control provided by the Oxford
Compressor allows the construction of many possible combinations and variations of the
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