Programme equalisers have expanded, beyond their original use as distance correction devices for film and vision, into highly creative tools that represent a leading part of the sound engineer’s artistic palette. A great many EQ designs have been developed over the years that have been attributed with qualities that lend themselves to particular uses and sounds. The Sonnox Oxford EQ plug-in is designed to be flexible enough to address as many of these generic types as possible from a single application by presenting a variety of types to the user.

The following text is presented as a general explanation of many of the factors that affect EQ performance and to illustrate how we have addressed these issues with the Sonnox Oxford EQ plug-in.

Control Ranges & Interaction (types of EQ)

There are many different types of EQ, which differ in many areas. One of the most important areas is the issue of control ranges and interaction. Whilst it is true that with a parametric unit with continuous controls (i.e. not quantised) any response could be obtained by matching their curves, many of the popular EQs have control dependencies that lean towards a specific application. One of the main areas where EQs differ is Gain / Q dependency. Most analogue EQ has Gain / Q dependency as a result of the circuits used. This factor can greatly affect the artistic style that an EQ presents by facilitating certain parameter settings and encouraging particular uses when the unit is operated. In the Sonnox Oxford EQ plug-in we have covered this situation by providing 3 different styles of EQ that take account of Gain / Q dependency as well as overall control ranges.

Sonnox Oxford EQ Types

There are 4 types of EQ as standard in the Sonnox Oxford EQ, plus an option for a fully approved GML 8200 emulation, for Pro Tools and HD. The differences between the types are reflected within the curve characteristics of the bell settings. The shelving curves are the same for all 4 types. They include the use of the 'Q' controls allowing and amount of 'undershoot' to be dialed in for boost settings, and overshoot when a shelf is used in cut settings. As an example, when applying an HF shelf, adding Q will cause the mid range just below the shelf to be cut, whilst simultaneously increasing the slope of the rise to the shelf. This has the effect of reducing perceived harshness, sweetening the sound, much like the legacy Neve and SSL G Series EQs.

EQ Type 1

This EQ can be regarded as a general and multi-purpose 'sharp' or clinical tool. Its response curves are very similar to that of the EQs in the SL4000E consoles, popular in the 80's. Characterised with minimal 'gain' verses 'Q' dependency, the shape of the peak of the boost and cut curves, when in 'bell', remain virtually constant according to the Q setting, no matter what level of boost or cut is in use. Even so, it is possible to mimic many other EQ types with Type 1, due to the flexibility of the control ranges. The boost and cut curves are mirror images of each other, termed reciprical.

EQ Type 2

The boost curves are identical to Type 1, whereas the cut curves are tighter. In fact this is a true 'constant Q' equaliser where the cut curve is 3 times sharper than the boost curve, ideal for removing troublesome resonances.

EQ Type 3

This is a reciprical EQ which has a moderate amount 'gain' verses 'Q' dependency. This means that at lower boost and cut settings, the shape of the curve is broader, becoming progressively sharper with increased boost or cut. This characteristic feels very comfortable to the ears and this type of EQ is often deemed musical, resembling older well-loved Neve types and the SSL G-Series which came along in the late 80's.

EQ Type 4

This type has the greatest 'gain' verses 'Q' dependency. It's characteristics are very soft and gentle, likely to be extremely useful in mastering situations.

GML Option (TDM & HD only)

This EQ emulates the GML-8200 rack EQ unit, but still uses the control same interface as the Sonnox Oxford EQs. It has the same highly accurate control range and law matching in order to retain the exact operational characteristics of the analogue units. It ’s an extremely accurate emulation of the 8200, fully endorced by George Massenburg, with an HF centre frequency going all the way up to 26kHz, just like the real thing.