I’m a big fan of the Sonnox Dynamic EQ. it’s flexible, sounds great and the user interface just lets you get on with the job. Part of the reason why I like it so much is because dynamic EQ makes much more sense to me than multiband compression, which is limited and in most cases is difficult to use. Here are three things about the Sonnox Dynamic EQ, which I think make it one of the best out there.

Trigger Modes

A nice way to present the difference between the four types of dynamic processes:

The most familiar use for a dynamic EQ is as a band of EQ which reduces the gain of a filter when energy in that area increases beyond the threshold. Just think of a de-esser and you’ll know what I mean. To set this up introduce a negative target gain and run the filter in Above Trigger mode. This is familiar stuff and is definitely the most useful way to use a dynamic EQ but there are other options.

To introduce a boost in response to the level exceeding the threshold just dial in a positive target gain in Above mode. This would be Upwards Expansion.

If you want to set up a cut which is applied all the time apart from when the threshold is exceeded then a trigger setting of Below and a negative target gain will achieve that. The ability to invert the action of the equaliser make is very flexible indeed.

Side Chain Flexibility

I’m not talking about an external side chain here, though the Sonnox Dynamic EQ has access to one of these. I’m talking about the internal side chain and how flexible it is. In most broadband compressors it is possible to filter the internal side chain and trigger the compression action in response to a specific frequency. In that case all frequencies get compressed in response to a narrow band of frequencies feeding the detector.

What is less common is being able to affect the gain of a narrow band of frequencies in response to the amplitude of a different narrow band of frequencies. Less common still is the capability to be able to increase the gain of, for example the upper midrange, in response to bass frequencies i.e. keying one set of frequencies from another. This is straightforward in the Sonnox Dynamic EQ

Q/Gain Dependency

One of the least well known aspects of static EQ design is Q/Gain dependency. This is a great deal of the reason why some people prefer one EQ over another and why the differences are more apparent when using the equaliser than when listening to the results. When cutting or boosting a band of parametric EQ it is possible to achieve most filter shapes but the differences are found in how the Q behaves as the gain is changed. An “ideal” filter might be expected to maintain a constant Q as the gain is increased. Constant Q filters exist but many designs favour an action where the Q narrows with increasing cut or boost. In this case the sound is perceived as more consistent.

I wrote a piece about this and how it relates to the different EQ types in the Sonnox Oxford EQ but that is a static EQ. The difference is only perceived by the mixer, not in the finished mix. This isn’t the case with a dynamic EQ where the gain of the filters is changing in response to the program material and it is essential that the Q/Gain dependency of the filters sounds as consistent and natural as possible if a transparent effect is to be achieved.

The filters in the Sonnox Dynamic EQ have a moderate amount of Q/Gain dependency and are similar to the Type 3 found in the Oxford EQ. This type is similar to Neve EQs, praised by many as having a musical character. As 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.