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:

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.

Front Panel Controls

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.

Dynamics Control

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.

Basic Dynamics Architecture

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:

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 feed forward 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:

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.

Compressor