ABOUT EQ

WHAT IS EQ?

EQ is an essential tool during mixing for defining the low-end, adding sparkle to vocals or percussion, and for separating tracks with similar frequency ranges. It’s also useful for correcting recordings. For example, if a guitar has an annoying resonance, you can reduce the resonating frequency with EQ.

Almost all EQs work the same way: select a frequency or frequency range, then adjust the level up or down. EQs are often described as having 'bands'. This means that the whole frequency curve is split into sections — a 3-band EQ lets you manipulate three sections of the curve individually.

Parametric EQs also have a ‘Q’ control in addition to Gain and Frequency. Q refers to the width of the curve used for the adjustment — the bandwidth. A high Q setting means a low bandwidth and a narrow curve — more like a spike. A low Q setting gives you a wide curve, covering a wide range of frequencies.

As a rule, it sounds more natural if you use a low Q (wide bandwidth) when boosting, and a high Q (a narrow spike) when cutting.

TYPES OF EQ

  • Parametric — Refers to the adjustable parameters. Fully-parametric = Q, frequency and gain. Semi-parametric = frequency and gain only. Not parametric = only gain is adjustable.

  • Shelving filter — Raise or lower a frequency and everything above or below it. A low shelf has a plateau at the bottom end, a high shelf at the top. This is the kind of EQ behind the 'Bass' and 'Treble' knobs on your HiFi amplifier.

  • High-cut, Low-cut filter — Cuts the frequencies above or below a certain frequency. Also called high-pass and low-pass filters, the important aspects are where the cut (or pass) starts, and the slope of the downward curve. A steep slope sounds less natural, but can be more precise.

  • Graphic equalizer — Divides the frequency-spectrum into (usually) 31 bands, each with a gain control only. Often used live to equalize room-resonance on a PA.




TIPS AND TRICKS

LOW-CUT ON VOCALS

Before you do anything else, use a low-cut (or high-pass) EQ setting on your vocals. Remove the entire low end, and audition the signal until you can hear the vocal track getting thin — then roll back a little.

REMOVING RESONANCE

Using a full-parametric EQ, choose a high Q setting and increase gain up to 10 db. Now sweep through the frequencies and listen out for the point where the signal resonates — it might sound buzzy or boomy. Once you've got it, drop the gain to anywhere between -3 db and -12 db, depending on how annoying the resonance is.

A QUICK GUIDE TO THE FREQUENCY SPECTRUM

  • Bass: from about 40 Hz to 200 Hz: Booming, full, solid

  • Low Mids: from about 200 Hz to 800 Hz: Body, fatness, fullness, warmth

  • Mids: from about 800 Hz to 5,000 Hz: Clear, present, forward

  • Highs: from about 5,000 Hz to 8,000 Hz: Bright, alive, brilliant

  • Ultra Highs: above about 8,000 Hz: Crisp, radiant sparkling

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