Equalisation, more commonly refereed to as EQ, is the process of balancing frequencies to give a more pleasing overall sound to an individual track, group of tracks or master. It’s a mandatory part of music production used in tracking, sound design and mixing and you’re probably more familiar with it than you realise.
Graphic equalisers were a common feature of old stereos/boom boxes, splitting the frequency range into bands that you could attenuate or amplify. On mixing desks the EQ section is normally 3 or 4 rotary pots that adjust the spectrum more broadly. However, I want to focus on digital EQs, as they’re far more widely available and (arguably) easier to use than their analog forefathers.
EQs are a staple of every commercial DAW. Although there are variations, most adhere to a similar structure; a ‘shelf’ at either end of the spectrum, sometimes with a low/high cut either side of that, and a number of bell-filters in the middle of them. Other types of EQ include graphic EQs (mentioned above), linear-phase EQ, mid-side, parametric, and various filter types like notch and bandpass.
This wont really serve as a guide as to how to EQ. Mixing your music is very specific and whilst you can read some suggested dos and don’ts, you really need to use your ears and A/B your work against other commercially released records within the genre you are working in. With that in mind I’m going to try and briefly sum-up the plug-ins I’ve run into recording and mixing, this is certainly not all of them, but hopefully serves as a useful guide.
An absolute staple in every DAW and incredibly useful for what’s called corrective EQing. With digital technology we can fine-tooth-comb our mixes with these. The common parameters found on these are the peak or trough defined by the frequency (fairly self explanatory), Q or resonance, which refers to the width and gain, which can either be +/-, and is measured in dB.
These are perhaps the most useful filters for corrective and creative EQing, as you can quickly identify problematic frequencies and attenuate them. There are several ways of doing this if you can instantly identify those areas.
Firstly, you can use the age-old method of sweeping a high-Q resonant peak. If this means nothing to you, then don’t worry. Q is the amplitude applied to the point at-which we are attenuating or amplifying. A wide Q (like the image above) makes broad strokes, a narrower Q makes more surgical incisions.
It’s more common to boost wider Qs but attenuate narrower ones, but this is just a rule of thumb and I am sure someone will find exceptions!
Sweeping an amplified narrow Q band across the spectrum will help you isolate harsh sounds, as when the band rests on one of these, you will hear it resonate or distort. This is a really useful method for helping identify troublesome frequencies in a complex sound or mix.
Another method is using a spectral analyser as many digital EQs have these built into them now (e.g Logic’s EQ, Ableton Live’s EQ Eight, FabFilter’s Pro-Q etc). This can help you visualize peaks particularly in the higher frequencies that may be harder to first hear. Let’s look at an example.
Where to Cut? Think (About It)
Lyn Collins’ 1972 hit Think (About It) is probably one of the most sampled breakbeats of all time. It’s been used on countless record (some of which you can read about here). It’s popularity in the sampling world is largely down to its various drum breaks in the record at 1.21, 1.34, 2.02, 2.14 and 2.21.
The break is characterized by the instantly recognisable vocal shouts and tambourine part. Let’s pickup on the first break at 1.21, here it is without any EQ applied:
N.B These examples aren’t going to sound all that impressive on laptop speakers, so to hear what’s going on properly I would suggest half-decent headphones or studio monitors.
Nothing seems untoward about this at all. However let’s look at at that with a spectral analyser. Normally I’d reach for Voxengo SPAN at this stage (as free and very customizable) but Live’s own EQ Eight has a built-in spectral analyser.
The tambourine has thrown up a couple of sharp peaks at 8.7 kHz and 11.4 kHz. These may not sound that offensive as is, but let’s amplify them to hear what’s really going on there, one by one:
As you can hear there’s quite a squeal there. Let’s drop both frequencies down then compare the original with the EQd versions:
A marked improvement if you ask me, and using the spectral analyser helped us get there in half the time. Of course this should be no replacement for a good musical ear, but sometimes visual tools can help us EQ our material, especially in higher frequencies where it’s much tougher being as accurate as low mids, for example.
There is of course more we could do with this break, but we’ll leave it there for now, what we might do next would largely depend on the style of music, what (if anything) it’s being layered with, how present it is in the mix, what the bass is doing, other percussion, reverbs etc.
Some love has to be shown for FabFilter’s Pro-Q 2 which allows you to isolate frequencies and actually audition them, so you can hear in solo what you are removing, using an extremely tight band-pass filter; a very clever idea!
If you want to read more about spectral analysis, you can have a look here.