How do you choose the right EQ?

At the fundamental level, equalisation is a straightforward enough concept: the attenuating and/or boosting of targeted frequencies in an audio signal in order to improve it in both its own right and the context of other sounds playing at the same time (ie, ‘the mix’). Within that remit, though, there are certain things to consider when deciding which EQ to deploy for a particular purpose, relating to both the technical specifics of the equalisation method itself and the sonic characteristics of the circuitry powering it, be that virtual or physical.

Of course, there are no hard and fast rules here, and what appears to be the ‘wrong’ EQ for a given role might turn out to work wonders; but gaining an understanding of where to start the EQ selection process for the most commonly encountered tracking and mixing tasks is an important stage in any producer’s development.

Parametric EQ

By far the most flexible member of the EQ family, the parametric EQ enables adjustment of one or more independent frequency bands in terms of centre frequency, bandwidth (Q) and gain. This is the type to reach for when you need to fix issues in the mix or make detailed changes to individual sounds – that’s most of the time, then. The ability to cut or boost narrow bands by precise and sizeable amounts is essential for resolving clashes between signals operating in the same frequency ranges – vocals and guitars, for example – and tamping down unwanted resonances or emphasising underpowered components within a sound.

The latest generation of parametric EQ plugins, with their interactive graphical displays and scalpel-sharp filters, are limitless in their sculpting capabilities. What’s more, most of them (Sonnox Oxford EQ, DMG Audio Equilibrium, iZotope Neutron 3 EQ, FabFilter Pro-Q 3 et al) even let you select different filter types and models for each band, further increasing their versatility and effectiveness.

At the other end of the timeline, though lacking the adjustable Q control essential to a parametric EQ, with their ‘indented’ knob-based controls, emulations of vintage EQs such as the Neve 1073 (Sonimus Burnley 73, IK Multimedia EQ 73), semi-parametric API 550A (UAD API 500 Series Collection, IK Multimedia EQ-PA) and others offer less precision than their modern descendants, but impart an inherent musicality and warmth thanks to their faux analogue architecture.

Parametric is also the EQ weapon of choice for mastering – check out iZotope Ozone and PSP Audioware MasterQ 2 for starters, both suitably tooled up with linear phase filter options and CPU-intensive algorithms.

Other conventional EQ types

Particularly notable in the classic EQ pantheon is the revered Pultec EQP-1A, which is well represented in software form (UAD Pultec Passive EQ Collection, Softube Tube-Tech Equalizer Collection, IK Multimedia EQP-1A) and features the unique ability to boost and cut its low and/or high bands at the same time, which has a quasi-magical bolstering effect on kick drums, basses and vocals.

Although none of them are as universally useful as the trusty parametric, there are a few other standard EQ types that you’re likely to come across in your musical endeavours – namely, shelving, graphic and tilt EQs, and standalone filters (low-pass, high-pass, etc).

Shelving EQ applies an upward or downward broadband slope above or below the dialled-in frequency which flattens off - hence “shelf”, and is a great choice for applying sweeping curves to the master bus – the classic ‘smile’ EQ, for example. Dedicated shelving EQ plugins aren’t really a thing, as pretty much all parametrics include shelving bands, but there are a few Baxandall-type (very broad Q for shallow slopes) models on the market, among the best of them Brainworx Dangerous Music BAX EQ.

Graphic EQ is a definite oddity in the 21st century studio, being most often found in the live sound arena; but manipulating a set of fixed-frequency gain sliders on the mix bus can make for a refreshingly direct and straightforward alternative to the parametric approach. Taking graphic EQ in a futuristic new direction, Newfangled Audio’s EQuivocate gives you 26 bands to wrangle, with filters modelled on the human auditory system for a sound that’s described as “as natural as possible”.

Encountered even less frequently than the graphic EQ, the tilt EQ ‘see-saws’ its response curve/line on a central fulcrum frequency, shelving the frequencies above and below it in opposite directions to each other. It’s good for quickly brightening or darkening a signal, and Universal Audio’s Tonelux Tilt EQ for UAD-2 and Apollo systems is a quality example.

With low-end energy build-up being an issue in many mixes, high-pass filters are another go-to for corrective EQing. Slinging one on every channel that isn’t actively intended to provide bass content (ie, potentially all but the kick and bass), set to roll off everything below the point at which the sound makes its presence felt, can dramatically enhance the clarity and space of any track.

Dynamic, Pitch Tracking and ‘intelligent’ EQ

Recent years have seen the rise of the dynamic EQ, which literally combines equalisation with compression in a powerful hybrid of the two. Having set your band frequency, Q and gain, you then dial in a threshold that has to be exceeded by the input signal for the cut/boost to begin to be applied to that band. Dynamic EQ is ideal for quelling occasional peaks or dips in crucial frequencies that don’t otherwise require EQing – vocals, guitars and drum overheads are prime targets – and is brilliantly realised by the likes of FabFilter Pro-Q 3, Sonnox Oxford Dynamic EQ, McDSP AE400 and AE600, and Tokyo Dawn’s free TDR Nova.

Pushing the dynamic EQ concept a step further, so-called intelligent EQs are ‘trained’ to find problem resonances and spectral issues on their own, getting signals of all kinds more mix-ready with minimal effort on the part of the user. They really work, too, as evidenced by the wild popularity of Oeksound Soothe 2 and Soundtheory Gullfoss. Some intelligent EQs incorporate AI to guide your EQ decisions in a way a preset never could, for example check out the FAST Equaliser from Focusrite.

Last but not least, let’s not overlook pitch tracking EQ, a category dominated by Sound Radix’s SurferEQ. This amazing feat of software engineering tracks the pitch of the input signal and shifts its seven bell, shelving and LP/HP filters automatically to maintain their relative musical positions, thereby sorting out pitch-variable issues in vocals and monophonic instruments that would otherwise require automation of a regular EQ.

I can’t afford any of these fancy EQs – is my DAW’s stock EQ good enough?

We’ve highlighted a number of top-notch commercial third-party offerings (and one must-have freebie) here, but the EQs built into most DAWs these days are at least pretty good, if not quite excellent, albeit largely limited to parametrics and multimode filters. As long as you don’t expect much in the way of character, Pultec-style trickery or mastering-grade viability, your stock DAW EQ will more than suffice for bread-and-butter frequency-shaping, so don’t feel like its an inferior option – as ever, if it sounds good, is it good. Indeed, onboard EQ plugins can actually bring their own benefits in the shape of low CPU usage and handy response curve thumbnails embedded in mixer channels.