In previous articles, we’ve looked at the foundations of EQ and some basic applications in the mixing process. This broad topic can be broken down into great detail for any specific instance, so covering it all is not possible. Still, we can take an overall, generalized look at the concepts to understand their particular uses. Depending on the types of music that you’re into, you can take this information and apply it to your session accordingly because aside from the niche areas in your mix that require particular equalization treatment (like vocals, bass guitars, or SFX), the devices all do similar things and being able to use each type correctly will be hugely beneficial.
In the ‘Fundamentals of EQ,’ we looked at the foundation of equalization, where we touched on frequencies and the various essential areas of the spectrum. This helped clarify why we need EQ, what it is, and when, where, and how to use it. Following on from that, we looked at technical elements of equalization (such as the controls and parameters) and a few typical applications in the mixdown (like additive, subtractive EQ, and some creative applications). In this article, we’ll dive into even more detail about when and where to use specific devices, take a look at some cool plugins, and talk about what makes different EQs unique and desirable to use.
So, to make this a digestible topic, we’ll break it down into sub-categories to help with the flow of information and make sure that this helps solidify the basic concepts behind equalization. To help illustrate differences in character and functionality behind the different EQs, we’ll look at several free and paid plugins along the way. Applying the correct type to achieve specific goals is essential. So is being critical of your actions in the mix because realizing you’ve gone wrong and fixing the mistake is crucial (sometimes in your plugin choice).
Without further ado, let’s take a look at the categories for today – bear in mind, we’re taking more of a broad view than a genre-specific one, so you’ll have to apply it to your mixes and figure out what works best for you.
High/Low Pass Filter
The first decision you’ll need to make will be regarding which frequency/region needs treatment. Depending on the type of EQ you’re using, the selection of frequencies can be made in several ways where some types allow for greater control, and others have fixed bands (or regions) that can be affected. A parametric EQ allows for the greatest level of flexibility since all of the parameters can be customized to create precise EQ points and shapes.
Secondly, you’ll have to figure out if you’re adding or cutting frequencies (most of the time, you’ll be cutting). This will be determined by either increasing or decreasing the gain (volume, loudness level) of a specific frequency or frequency range. You’ll turn up or down the gain to add or cut at a specific point. All EQs have this feature, whether it’s in a fixed band or not.
The Bandwidth, or Q, refers to the number of frequencies affected by the specific filter (A notch filter on a parametric EQ will be most apparent in such a scenario). It can be altered to affect either a sharp, narrowband or a broader region of frequencies, depending on your requirements.
A shelving EQ will be most commonly applied to a track (or the entire mix) to either boost or cut an entire range of frequencies above or below a chosen point. This would be useful if you wanted to increase the energy in the low end of the entire mix – you could apply the EQ onto the mix bus (or master channel), allowing you to raise the low-end volume equally across the whole mix.
It’s handy because it will also equally affect the harmonics across the entire selected frequency range, which is exceptionally convenient when adding gain because of the excitement generated from all of the new harmonic characteristics coming through.
Remember, this differs from a high/low pass filter in that it does not entirely filter out the sound beyond a certain point but instead allows us to control how much we want to cut and enable us to add.
Shelves are very common and can be found on almost all EQs (even in your car stereo system). However, once again, the amount of control you have over these regions depends on the EQ as some will be fixed, and others will allow for full customization.
A notch refers to a region of frequency that will either be filtered or boosted depending on your needs. As briefly mentioned earlier, it is widespread to use notch filters on parametric EQs due to the extensive level of control one has over each of the parameters. However, notch filters can be found on many EQs; they might offer fixed bands.
This allows us to affect a specific point along the spectrum without affecting anything on either side of the chosen area. If you’re faced with an EQ that offers this feature with fixed bands, there is no need to worry because the provided regions will be common areas that often need tweaking, so you’ll be able to get pretty close. On the other hand, if you have a parametric EQ, this feature becomes a fully-tailored tool at your disposal, allowing you to make highly accurate and narrow regions.
The majority of the time, this will be used to eliminate unwanted sounds by cutting them out, but it is not uncommon to boost specific points in the mix or on a track. For example, on the mix bus or master channel, you might discretely boost the central vocal region, kick and snare hit to establish more clarity. On the other hand, you might want to clean up the boxy or muddy-sounding lower-end by making cuts to specific points without losing too much bass energy.
High/Low Pass Filter
The infamous HPF/LPF, otherwise known as High and Low Pass Filters, are crucial tools in your mixing arsenal as they are mainly used to clean up or get rid of entire frequency regions. As you can imagine, this is crucial when clearing up the low-end to make room for the bass and kick as any unnecessary sounds seeping into that region are not recommended, as we went over in the previous articles.
This is a Band Pass Filter that filters both ends of the spectrum (highs and lows), leaving a band of frequencies to come through in between these points.
And once again, depending on what type of EQ you’re using, you might have either more or less control over where you can place these points along the spectrum. You might even have seen these controls on various microphones.
When it comes to mastering, this is applied to ensure that the low-end cuts off at the right place as anything below a certain point are either a low rumble that can only be felt through subwoofers, or it could be completely inaudible to us. The same can be said for the high-end as most adults cannot interpret sound above 19KHz (or lower even) due to ear damage over time, so this can confidently be filtered out as it isn’t beneficial.
As we begin diving into the various types of EQ, we’ll get to understand the differences between them. Hopefully, this will aid in our decision-making process when selecting a device suitable for any situation.
We’ll start with the parametric EQ because this is the most commonly used type due to the level of control you have when making adjustments. We have, in most cases, absolute control over the device’s parameters (including the frequency, gain, and ‘Q’), making it fully customizable and suited to any scenario. The majority of these EQs are very clean and won’t add much character of their own to the sound, which makes them an excellent tool for cleaning up audio and adding specific boosts.
Your DAW of choice will have a parametric EQ for you to use that comes built-in and a part of the package.
If you’re willing to spend a little bit of money on this venture, the Fabfilter Pro-Q2, Q3, and the Voxengo PrimeEQ have outstanding reputations on the market for various reasons and are undoubtedly powerful devices to have access to.
If you’re a little ‘strapped’ and free versions are what you’re after, then check out the ColourEQ.
Semi-parametric EQs are pretty self-explanatory if you think about it knowing what you do about parametric EQs. Essentially, you’ll have a certain level of control over the parameters, but it is not entirely customizable, unlike a more liberal friend.
However, these EQs often have something extraordinary to bring to the table – be it amazing sounding character, interesting harmonics, or just simply everything about what they do to the sound.
For instance, the Waves PuigTec EQs and audio Pultec EQs are very similar products with subtle differences. These are rather costly items to add to your toolbox, but you cannot go wrong if you have the money. They’re very popular devices to have on mix busses and master channels. They add beautiful character to the sound and have an additional ‘attenuation’ control, which can have interesting effects on the sound.
However, if you can’t afford these options, check out the free SonEQ for similar results.
For the last of the EQ types, we’ll explore the Graphic EQ. You might have come across something like this on an old hifi set that your parents had or even if you’ve explored your computer music software’s advanced settings.
Essentially, here we are given access to affect a specific number of regions along the frequency spectrum – however, these points are fixed and cannot be changed. Essentially, you have control over the gain on whichever frequency band you decide to affect but not much else.
Given the complexity and extensive control that you’re afforded with the other types of EQ, you might wonder why anybody would use something like it. One of the main reasons is its simplicity, which can be very helpful in speeding up decision-making processes as you’re not having to go in and tweak every single parameter each time. Another reason might be the desirable tonal qualities and character that come with these devices.
All of the different types of EQ have their strengths and weaknesses depending on how, when, and where you decide to use them. Understanding what each of them does will allow us to make the correct decision when it comes down to it in the mix. For example, if you’re trying to find and clean up a precise problem frequency in the mix, choosing a parametric EQ over a graphic EQ will get you the results every time rather than on occasion when the problem coincidently arises in one of the available bands. On the other hand, if you’re looking to add character and energy, you’d choose a device that adds tonal qualities to the sound rather than a clean, pristine sounding EQ.
This is a very broad topic that can be expanded on in almost any instance, so it’s essential to grow your knowledge and understanding to succeed when mixing and achieving your goals.