The EQ stage of mixing is vital in finding space for each instrument, making important moments punch through and eliminating clutter. Here’s is an awesome guide by Music Tech to getting it right.
1: Watch the very top
Watch the very top common procedure when editing or mixing audio is to try to get rid of hiss on recorded audio tracks. These very high frequencies can often be found between 5kHz and 20kHz in the frequency range, depending on the material, so applying a high-cut filter with a narrow Q value should enable you to knock out the hiss while leaving other high frequencies that you want to keep intact.
As ever, this is a matter of careful experimentation. Systems such as Dolby Noise Reduction used to get rid of hiss, but also usually made the whole track sound dull as a side effect. Since digital files don’t suffer from the same physical problems as tape, you can be fairly sure that if you get your top end sounding clean, it should be reproduced as such whatever it’s played back on.
2: Control your body
More than any other tool, EQ is able to control the ‘body’ of a sound. Compression can play around with levels and presence, but to control the weight of a sound it’s usually to EQ that you will turn. For some parts, this means reducing bottom end and lower mids to reduce clutter in the mix, and for others it’s about adding weight by increasing those same frequencies.
3: Add bass weight
To add weight to a track, try looking around the bottom end of the spectrum, gently boosting with an amount of around 10dB as you move around, until you find a point that seems to add the most body. Then find a frequency either double or half that value – so if it was 110Hz, go to 55Hz – and add a dB or two of boost there as well.
4: It’s the ensemble that matters
In a dense or complex arrangement, you may well find that two or more elements of a track are fighting to occupy the same frequency space. It might be impossible to EQ them to sound the same as they originally did and still make enough space for both of them. One trick is to EQ them in slightly different directions while keeping them sounding good in the context of a track.
This doesn’t necessarily have to be extreme; for example, you could make one guitar part more bass-heavy and one more top-heavy. Solo’d up, they might sound odd, but the main thing is that they sit well in the context of the track. If there are parts of a track where a sound plays solo or with less accompaniment, you can always automate the EQ to behave differently at those points, or duplicate the track and treat it separately.
5: Understand vocal requirements
Vocals almost always need to cut through a mix, or at the very least be prominent and audible, and EQ is key to this – along with compression, of course. There are some good rules of thumb to observe.
A lot of male vocals will, prior to treatment, have too much bass end on it to sit well in a mix, so rolling off some of this is usually a good tactic. A vocal that is too nasal or top-heavy on the other hand, might benefit from the addition of some lower mids, and perhaps even bass. As vocals can sometimes vary over a large part of the frequency spectrum through the course of a song, you need to pay particular attention to their EQ. Multi-band compression can also help to control unexpected peaks if a single band compressor isn’t quite doing it.
6: Pre-treat certain sounds
When you are recording certain sounds, particularly vocals, it can be advisable to do a little EQ’ing on the channel into which the vocal is going to be recorded. Close-up vocals, in particular, can sound boomy in the singer’s headphones and lead to them not performing to their full potential. Knocking some bottom end off will help their vocal sit better in the headphone mix.
Remember, however, the difference between doing this using a software channel strip where the EQ is not part of the take, and thus can be changed afterwards, and on your mic pre or interface, where the changes are a permanent part of the recording. It’s usually wise to record relatively clean and then EQ afterwards, but if a sound is particularly problematic at the low or high end, for example, it doesn’t hurt to mitigate this prior to recording.
7: Order matters
As with any effect used as an insert, the point at which you apply EQ can have an effect on the end results. Imagine you applied an EQ that cut out a lot of bottom end, and then in the next insert slot applied a compressor. That would cause the compressor to behave in a specific way because it would be compressing a signal without much bass end. If the EQ was applied after the compressor, the EQ would be working on the compressed sound – the full frequency spectrum – rather than the compressor working on the EQ’d sound.
The differences can be subtle or more noticeable, depending on the plug-ins you are using. If you are using EQ in your DAW’s mixer, rather than as a plug-in, be aware of what path the signal is taking on its journey from timeline to speakers.
8: Compare and Contrast
When it comes to getting a production right, you’ll do a lot of tweaking. Many EQ modules give you the ability to A/B between two presets, and sometimes as many as four. With almost any effect used during music production, this can be a really helpful thing to do, as it lets you non-destructively audition different treatments and flip between them.
After extensive periods of listening, your ears get used to the way something sounds, and so sometimes a fresh perspective can be helpful. Consider, also, muting the EQ from time to time to remember exactly what you are adding or taking away from a part. EQ presets, whether in the form of plug-in or track presets in your DAW’s mixer, are also a good way to try different treatments while being able to roll back easily.
9: Get up close
Between about 4 and 6kHz, you will find frequencies that control the clarity and ‘up-front’ quality of a track, so boosting in this range can make the music seem closer to the listener. At the very top end, from 6 to 16kHz, you get the ‘air’ that can be used to add sparkle to tracks. Pushing the very top end too hard can result in sibilance on vocals, or too much hiss, so be careful. Some EQ plug-ins even have an “add air” preset.
10: Investigate channel strips
All major DAWs feature EQ of some description on channels, often in the form of a channel strip. These usually contain some handy presets that you can dial in quickly to see how something will sound. One good use for this is to pull up a ‘telephone line’ or ‘old radio’-style EQ setup to quickly alter the sound, rather than having to spend time working out for yourself how such a curve might be set up. You can flip through presets to quickly audition different treatments; of course, every vocal is different so it’s unlikely a preset will be perfect from the get-go, but it’s usually a great starting point. Some third-party plug-ins take the form of channel strips, notably Izotope’s Alloy and various models from Waves.
11: Get in the Q
Many EQ modules, particularly parametric models, have a Q control for EQ points, and this is just as important in tailoring the character of the EQ as setting the frequency. Q controls the width of the EQ curve, and hence how much of the area around the frequency point is affected.
With a narrow Q, one example of which would be a notch filter, only a very specific frequency is affected – and this makes it good for trying to pinpoint individual sounds within an audio signal. A wider Q value, on the other hand, affects more of the the frequencies around the main EQ point, often tailing off gently. This is better for pulling a broader frequency range up or down. Narrow Q values are often used for more surgical EQ, whereas gentler Q values are used commonly in mastering.
12: Less can be more
Different EQ modules and plug-ins have different numbers of bands, and when they do you can often switch different bands on or off. Normally, you might find anything from two to 30 bands available to you. There are cases where you need to be specific and try to isolate a certain frequency that can be found only by using a 30-band model, but more often than not, around six might be a good number to use. This stops you from over-complicating what need only be a fairly simple task. Sometimes, you might only need to use a high or low shelf, which involves just one EQ point, for the purposes of rolling off top or bottom end. When you start getting into 30-band territory, it can be overkill.
13: Strip it back
When EQing a whole track during mastering, some people like to start by knocking off the bottom end so that they can hear the middle and top in isolation. They adjust the lower and upper mids to get the sound good and firm, and the top so that it is bright but controlled. Then, bringing the bottom end back in will bolster the overall sound and you can EQ it accordingly.
This stops you focusing too much on the bass end all the way through the EQ process. Of course, the end goal is a perfectly balanced sound, and how you go about it is less important than achieving it. Remember not to use EQ to compensate for volume – that should be done with compression, or multi-band compression if necessary.
14: Make space for competing sounds
When EQ’ing during mixing, there are tricks to make elements in a similar frequency range sit together. The kick drum and the bass are two things that often get in each other’s way, so you could try cutting one at a specific frequency and boosting another at exactly the same frequency. You need to try to avoid situations where you have two EQ modules boosting at the exact same frequency. Ideally, you should create a space for each instrument to live in within the mix. Sidechained compression can also be used effectively here.
15: Get deep down
Sub bass lives between around 16 and 60Hz, and these sounds are often felt more than heard. Too much emphasis on them can make a track seem muddy and confused, so if this is happening, try using EQ to roll them off. Regular bass is somewhere between 60 and 250Hz, so playing around with these frequencies can add weight to the track or thin it out a little if it is sounding too boomy.
16: Keep it simple
A lot of virtual instruments have EQ controls on them, and it’s important to remember that any presets you use may already have EQ applied. The same goes for presets on other effects plug-ins that you may have called up on other tracks. Try to EQ in as few places as possible, as this keeps the signal path a little simpler, and if you are troubleshooting it means fewer places to look to find a culprit.
17: Understand curve shapes
Some EQ modules, such as Fabfilter’s Pro-Q, let you set the shape of the EQ curves applied at different frequencies. These let you quickly dial in EQ characteristics without having to play around with lots of dials. The most common types of curves are bell, high and low shelf and high and low cut. By mixing and matching curve types on different frequencies within a single EQ module, you can more precisely control the character of the sound.
18: Choose an EQ type
Parametric EQ is the kind that may come as part of your DAW, and offers a number of bands and usually the ability to draw in EQ points with the mouse and make Q settings. Graphic EQ is more often – though not exclusively – found in hardware form, and features a large number of physical sliders that can be used to control the shape of the sound. Linear Phase EQ is found only in software form, and allows EQ’ing without colouration of the sound.
19: Master the mids
A lot of information in music exists in the mid range and it’s important to understand the difference between lower and upper mids. Simple EQs sometimes have a single mid control, but having two or even three for different parts of the mid range is much more flexible. You can generally set the crossover points of these sections on a more flexible EQ unit to tailor the boundaries to the material you are working with.
20: Use hands-on controls
Some EQ plug-ins can be made to learn from MIDI input, and where this is available you can connect a MIDI control surface and assign knobs to the EQ dials. While playing back, this would allow you to tweak EQ points and curves by hand, which can feel much more natural and intuitive than using the mouse. Some control surfaces are designed specifically for tasks such as this.