Previously, we dove into the fundamentals of EQ by looking at some essential sound characteristics, cheat sheets, and some standard terms to establish a basic understanding of the topic. In this edition, we will take it a step further by exploring some technical elements of EQ and looking at various applications in the mixing process. The main areas of focus will be on subtractive and additive EQ. With these two topics enlarged, we’ll be able to cover a lot of information and come out with a clearer understanding of how to approach it at different stages of the mix adequately.
Most of the equalization that you’ll end up doing will be subtractive because, as we concluded in The Fundamentals of EQ, space is limited when it comes to frequencies, so we need to carve away to generate sufficient room for them to coexist without overcrowding the whole mix. This means determining where each of your instruments/sounds prime frequency ranges are and highlighting them by cutting away unwanted regions. The more accurately you do this, and the better you fit all the tracks together will mean that you lessen the chances of overcrowding, and you’ll end up with a clear-sounding mix.
This really can’t be stressed enough, so let’s explore an analogy where we look at EQing a song as if it were compared to creating a drinking goblet out of wood. When making a goblet, you’d probably start with a solid piece of wood such as a branch or trunk of a tree, much like the untreated tracks at the start of a session. From here, you would begin carving and chipping away at the wood to establish the shape of the goblet before hollowing it out, filing it down smoothly, and varnishing to perfection. It would be tough to create a wooden goblet by building it from scratch (like sticking random pieces of wood together), and so this is the best option. The same analogy can be applied to the process of EQing in the mix as most of the work done will be subtractive EQ to carve and shape the mix into a desirable product before additive EQ is applied – this would be much like the process of carving and chipping the wood away until the shape of the goblet is achieved. The final EQ touches will include adding some volume to specific frequencies that sound good in the mix and cleaning up any bad spots – much like the final filing and varnishing of the wood into a finished goblet.
Additionally, we’ll look at some features and functions of a basic EQ to establish familiarity with the concepts of using and applying it effectively. Without further ado, let’s get stuck into the juicy stuff.
Features and Functions of A Basic EQ
There are many types of EQs, and we’ll dive into more detail about them all in the next article, but for now, here is a list of them:
Each of these EQs has unique functionality in some way which we’ll cover in the next article (as mentioned); however, for now, we’ll look at a parametric EQ and three distinct features for controlling the parameters.
The High and Low Pass Filters are extremely useful tools in the mixing process because they allow you to cut out entire regions of unwanted frequencies above or below a certain point. This point can be controlled and manipulated according to the track at hand, meaning that you’d be able to cut out everything above 700Hz or below it, if you wanted and control the steepness of the curve. Whether you’re cutting above a point or below a point will be determined by the filter you use. A high pass filter (much as the name suggests) allows frequencies of a higher nature to pass through while cutting out lower ones and vice versa for a low pass filter – you can set the point, or frequency, where this occurs.
This is extremely useful when clearing up the low-end as you can apply this to every track that isn’t associated with the bass frequencies to give the mix clarity from the get-go.
The shelf set acts similarly to the HP/LP filters in that it either cuts or boosts above or below a certain point (depending on your use). However, the difference is that it does not cut or boost entirely, where a HP/LP filter cuts everything in comparison.
This could be used if you wanted to boost the entire low-end of a track or, opposingly, if you wanted to cut it. It is not limited to the bass; whether this happens in the low-end or the high frequencies depends on your choices and settings. Essentially, it’s suitable for broad application as you’re working with entire regions rather than specific zones.
The Q represents the bandwidth – how much of a frequency band you’ll be affecting – most common in notch filter scenarios. This parameter is available on each ‘band’ of the EQ and allows you to control how narrow or wide the area you’re affecting is.
This is useful in all situations as it allows for greater control of the areas we want to process.
As was made clear at the beginning of this article and in the previous one, subtractive EQ will likely be the most commonly applied technique when mixing. This is the case for several reasons: the need for clarity in the low-end for bass and kick and cleaning up each track in the mix to create space. The reasons for it are pertinent so let’s explore some techniques that we might employ to subtract frequencies.
Due to the imperative nature of having a clear low-end in the mix, one should visit each track in the session to determine whether treatment is necessary. Excluding the bass and kick (or any low-end sounds), there should be no other frequencies occupying the low frequencies due to the nature of the soundwaves (as discussed in The Fundamentals of EQ). This means that we should ensure that every other track in the session is cut in this range.
A great way of doing this is by setting a high pass filter to cut out the problematic frequency range and copying this onto every track that requires it. Immediately, you’ll notice much more clarity in your mix by doing so, and you can take the time at a later stage to go and treat each channel individually for maximum control.
The low-end always provides a relevant example to discuss. However, it is equally applicable in the higher frequencies with a low pass filter. Overcrowding in the high range can be fatiguing to listen to because of its harsh nature and can spoil a mix too. There needs to be a lot of presence in the high-end of your mix, but it should be clear and crisp, much like the opposing low-end frequencies, for it to sound good.
Shelving is another cogent method of subtractive EQ in a scenario where you might not want to cut frequencies entirely or if you’d like to affect a group of tracks simultaneously.
A notch filter allows you to narrow in on specific frequency bands along the spectrum and make independent cuts anywhere you decide. Using the Q parameters, we can create very tight bands for surgical cuts or set them wider for broader cuts.
For the examples above, a parametric EQ will complete the various applications as most of them come equipped with these options.
Adding frequencies can be touchy business because it’s effortless to get wrong, resulting in things just not sounding the way you’d imagined or how you’d like them to, as well as the potentially damaging effect it can have on your mix.
It’s safe to say that you shouldn’t be adding in frequencies unless you’re sure it’s having a positive impact on your mix – you can only really tell this once you’ve done most of your subtractive EQing (housework) and the mix has been nicely shaped. The reasons for this could be that adding frequencies that don’t need to be there can sound terrible or that it’s likely you’ll have to revisit this decision as you advance towards a finished product.
However, there are some exceptions, of course, and it’s up to you to use your discretion and be sure that whatever you’re doing is benefiting the mix as a whole. You might want to establish the dominant frequencies in the kick and add a bit there and in the bass, vocals, guitar, or any instrument. All sounds have a sweet spot, so distinguishing and highlighting can be very beneficial when carving out the best shape for your mix.
Many mix engineers will employ EQs that have something special about them and can add interesting sonic characteristics when applied. A reason for this is because a clean EQ might not be as desirable as one that adds some sonic warmth to the tone (which may not be desirable when your focus is subtracting frequencies).
As with almost anything in our technologically advanced world of audio mixing, there are few limits to what we can achieve, and being creative when utilizing devices will always give you an upper hand because there’s so much to be discovered.
However, if you need some direction, we’ll take a look at some applications in the creative realm of EQ. When it comes to creating movement in the mix, using either HP/LP filters to sweep across the frequency spectrum can be very effective – this can be achieved by automating the EQ parameters. You might want to either cut or boost specific frequencies more or less at different stages in the mix, which is possible and will mean you have even more control.
EQ can be a great tool when it comes to isolating specific regions for compression. Sometimes you only want to compress a certain area of the sound’s frequency spectrum which means you’ll need to isolate that region. This requires using subtractive EQ first. Next, you’ll add a compressor into the chain, followed by another EQ, which will be used in an additive fashion to bring back the previously cut frequencies (before the compressor), resulting in a more natural sound. It’s likely that a shelf filter will be used in a scenario such as this.
We’ll explore some more creative uses in another article, as well as take a look at some great plugins.
To conclude, it’s clear that EQing wears many hats in the mix process; however, most commonly, it appears to be that of the subtractive style. It’s a crucial starting point in any mixdown and will need to be tweaked accordingly along the way to establish the best possible shape for all frequencies to coincide with each other. Clarity in the mix is the ultimate goal unless you’re dabbling in the creative side of things, so be sure to make decisions that will get you there.