What are the different types of EQ?
In the top drawer of every producer and mix engineer’s toolbox is a plugin seemingly sent from the gods.
EQ's are a gorgeous feat of engineering used to sculpt the frequencies in your recordings and sounds.
But what are the differences between Parametric, Graphic, and Dynamic EQs? What is Linear Phase EQ and when should you use it?
We’ll answer all these questions and help to provide you with a better understanding of EQ and its intricacies.
If you want to understand more about the basics of EQing, read our Beginners EQ Advice first.
The most common and arguably most useful of the EQs is Parametric.
It is a multi-band variable EQ, which in short means your frequency spectrum is split up into bands, and you have control of each band’s frequency, amplitude and Q value (also known as bandwidth).
Parametric EQs allow you to boost or cut the amplitude, move this boost or cut up or down the frequency spectrum, and widen or narrow the bandwidth of each band.
The frequency spectrum is usually divided into 3-7 bands, depending on which Parametric EQ you are using.
Some prime examples of Parametric EQs are:
Parametric EQs are useful for everything because you can be as broad or as surgical as you need to be.
You can narrow the bandwidth into a single frequency then boost or cut. You can widen a bandwidth to cover multiple bands, boosting or cutting through the lows, mids and highs at the same time.
The flexibility of Parametric EQs allows you to use it on single tracks or on the master chain sculpting the entire mix. It’s the best all rounder, I use it on everything as standard.
The simplest EQ type in this article is probably Graphic EQ.
Normally Graphic EQs come in 31-, 15- or 10- band sizes. They are made up of one bell filter per frequency band, and you can subtract or add to the signal. These bell filters are also usually fixed frequency, so you don’t have the freedom to sweep the boost across the frequency spectrum.
Instead, you choose the frequency band individually and boost or cut as close as you can get to the desired frequency. Clearly, 31-band graphic EQs offer the most control, and mathematically it usually works out that: three frequency bands cover one musical octave.
The Q value or bandwidth is usually fixed at 4, and you have up to 12 or 15 dB of gain adjustment for boosting and cutting. The biggest difference Graphic EQs pose is the fact you cannot visually see the sound on a graph, and where you’re cutting or boosting. Because of this, you’ll need an experienced ear to know what frequency you need to cut or boost at and wherein the frequency spectrum the potential issues you can hear live.
Graphic EQs are popular for live music, as the sound engineer has a great deal of control and can boost or cut quickly. Which is ideal for those quick stage changes.
The API 560 is a classic example of a graphic EQ.
The most recent type of EQ to enter the mix is Dynamic EQ.
It’s like a mixture of a standard EQ and multi-band compressor. It will only affect the signal once a certain threshold is reached. Dynamic EQ allows you to be selective and apply EQ only when it needs to be applied, instead of affecting the tonal quality of the individual track throughout the whole song.
For example, let's say you have a falsetto vocal occupying the upper mids and higher frequency bands in the chorus, but the clarity in your high end is skewed because your hi hat pattern is occupying the same frequency bands, making the vocal sound a little lost and unclear.
You can set your dynamic EQ’s threshold to trigger in the chorus and cut some of the competing frequencies of the hi hat pattern out, making space for your vocal to be heard clearly and most importantly; when it needs that clarity.
Surfer EQ2 is a prime example of Dynamic EQ, with iZotope’s Neutron 3 and Fabfilter’s Pro-Q 3 also featuring a dynamic mode.
Linear Phase EQ
Finally we hit a lightly debated type of EQ.
You may have heard discussions on Linear Phase EQ vs Minimal Phase EQ. Is one better than the other? Is Linear Phase pointless? Will using one type over the other make an audible difference to your mix?
You can make your own decision on whether you stand with or against Linear Phase EQ, but a lot of people just cannot hear the difference or benefit of its use.
Breaking it down, essentially all EQs that are nonlinear are called minimal phase EQs and experience phase shifts.
This is due to a latency created from changing the amplitude of specific frequency bands. This latency/delay of the frequencies causes what’s known as ‘phase smear’. This can create audible artefacts in the track you are EQing, creating an unwanted distortion or strange colour of the tone.
For the majority of the time, you won’t be able to hear these artefacts and they will go unnoticed. Ask yourself if you have ever heard an example of phase smear in your personal mixing experience.
If the answer is no, you are probably for team ‘Non-linear EQ’. If your answer is yes and you’ve heard an artefact in your signal, linear phase EQ will bypass these unwanted artefacts in your track, getting rid of phase issues caused by this EQ latency.
On the flip side, linear phase EQs are CPU intensive. So you’ll experience latency, especially when recording with a linear phase EQ on the channel, and in a big CPU intensive mixing project, your computer will struggle. Linear phase EQs also bring about an issue called pre-ringing. This is when you hear the transient before the transient hits.
The sound of pre-ringing can become quite irritating, for example hearing the click from your kick drum before it hits could be enough to throw anyone off their mixing game, and close the project.
Many mastering engineers opt for Linear Phase in their chains to avoid phase issues and keep the natural tone of the track.
Waves’ ‘Linear Phase EQ’ is one of the most renowned Linear Phase EQs on the market, Logic also has a Linear Phase EQ plugin.