EQ: A step-by-step example

This section steps you through the EQ process, with both graphic and parametric EQ. We'll assume that this is a male voice track that needs a little bit of sparkle. We're trying to do the following:

- Add a bit of warmth to the bottom end.

- Add a little clarity to the midrange.

- Give the vocal a bit of air, a little extra shimmer.

We're going to assume that you're using a software equalizer, though there's no reason that this couldn't be done using a hardware EQ. Also, the frequencies we're choosing in this example may not be the best frequencies for your audio, although they're probably a good place to start. Remember: Use your ears:

1. First, roll off the extreme low end. Chances are good (unless you have an extremely deep voice) that there is no information down here, except for possibly some room noise. Let's roll off everything below 60Hz.

On a graphic EQ, push down the faders below 60Hz. If you have more than one, start off gradually, rolling off about 3dB at 60Hz and then increasing the roll-off with each lower frequency.

On a parametric EQ, choose a high-pass filter at 60Hz and roll it all off. Shelving EQ has gradual roll-off built in.

2. Listen to your audio. You shouldn't hear much of a difference, if any. That's fine. You may hear a slight clearing up of the sound, and if so, that's even better.

3. Next, work on the midrange, because it's the most important. To give a voiceover a slight lift, you can boost the upper mids in the 2 – 4KHz range.

On a graphic EQ, pick a frequency in this range and boost it significantly, say 6-10dB. Preview your audio. Return that frequency to no gain, and try boosting the frequencies on either side, previewing each time. When you find the frequency that sounds best for your content, boost it 3dB and then boost the frequencies on either side 1.5dB, so there's a nice gentle lift. Preview the audio, and make sure it sounds good.

On a parametric EQ, choose a narrow Q and boost a frequency in the 2 – 4KHz range. Preview your audio. Try moving the frequency setting up and down, until you find the right frequency. Preview the audio each time you change the frequency. After you settle on a frequency, widen your Q to approximately 1.5. Boost 3dB, and give your audio one last preview to make sure you're doing the right thing.

4. Now listen to the low mids. The low mids are roughly where the sounds "er" and "uh" live. (If you've ever seen a sound check before a live gig, you'll hear the audio engineer making these sounds in the mics to check the EQ.) These frequencies give our ears information about the size of a room. You can often clear up a mix by cutting here, but be careful: You can make your audio sound too thin if you cut too much.

On a graphic EQ, you can experiment with cutting around 300Hz. You can do the same on a parametric EQ, with the added benefit that you can make the Q very narrow, to avoid thinning out your mix too much. Be sure to preview your audio to make sure you're making it sound better and not too thin.

5. If you're worried about the bottom end of your audio, particularly after cutting a little at 300Hz, you can add some warmth by boosting the bottom end. We rolled off the extreme low end earlier, but those frequencies are generally inaudible on most systems. To add audible bottom end, you need to boost in the 80 – 200Hz region. Where you boost depends on what (or who) you're EQing. The bottom end of male voices is usually around 100Hz; female voices are closer to 200Hz.

On a graphic EQ, you can find and push the frequency you're looking for. You may want to push the frequencies on either side slightly, as well. And the same goes for parametric; find the frequency, choose a fairly wide Q, and boost a bit. Preview your audio.

6. Finally, you need to decide if your audio needs any final sparkle. You can add this by boosting your high frequencies ever so slightly.

On a graphic EQ, start lifting at around 5KHz and boost the frequencies above 3dB. On a parametric EQ, select 5KHz for your shelving frequency and boost 3dB. Preview your audio. If you're happy with the sound, apply it! You may want to save this as a preset if this is a setting you think you'll be able to reuse.

Figures 1a and 1b show the results of all the preceding steps using graphic and parametric EQ. Your results may be slightly different; in fact, they should be, because you're listening to something different!




Figure 1: The results of the step-by-step example, illustrated on a) a graphic EQ and b) a parametric EQ.

Using a graphic and parametric equalizer

Using a graphic equalizer
Graphic equalizers divide the frequency spectrum into a specific number of bands and assign a fader to each band, as shown in Figure 1. The number of bands varies, depending on the hardware or software. The more bands you have, the narrower the range of frequencies you're affecting when you move a fader up or down.


Figure 1: A typical graphic equalizer (Sony Sound Forge)

Using a graphic equalizer couldn't be easier; you just grab a fader and push it up or down. If you're not sure exactly which frequency you want to work on, don't be afraid to experiment. Grab a fader, push it up, and preview the result. You should be able to hear that frequency being boosted in your file. If you can't hear it, push the fader up even more. Push it up until the frequency is horribly exaggerated. Don't worry; this is how audio engineers do it. Exaggerate to find the frequency, and then scale back the EQ until you've achieved the effect you're after.

This also works when you're looking for a frequency that you want to get rid of. If you can hear a nasty frequency, for example a noisy hiss or even a honking quality to a vocal, hunt for the frequency by boosting until you find the frequency that you're after. Sure, it will make your file sound even worse, but after you find the offensive frequency, you can cut it knowing you're cutting in the right place.

Remember that you want to boost wide and cut narrow. If you're boosting a particular frequency, you should also boost the frequencies on either side — about half the amount you're boosting the target frequency, so you get a nice EQ curve. If you're cutting, cut only the offensive frequency. Don't cut too much; it will make your audio sound hollow and unnatural. If you've ever seen an audio engineer use a graphic EQ, you'll see them adjust their settings to get a nice smooth looking curve, perhaps with one or two nasty frequencies cut.

Using a parametric equalizer
Parametric EQ is slightly different from graphic EQ, because you don't have faders for specific frequencies. Instead, you choose a frequency, how much around your target frequency you want to affect and how much you want to boost or cut. Parametric EQ is usually implemented using knobs, with a separate knob for the frequency, the Q (which is the term used for the width of the effect), and the amount of boost or cut. Some parametric EQ systems don't provide control of the Q; this is known as semi-parametric EQ.

Some parametric EQ also have a little switch that changes the EQ from standard parametric to shelving EQ. Shelving EQ affects all frequencies above or below the frequency setting. Shelving EQ that affects all frequencies below the target frequency is known as high pass, because all frequencies above the target frequency are passed through untouched. Similarly, shelving EQ that affects frequencies about the target frequency is called a low pass shelf, because all the low frequencies are passed.

Tip The EQ knobs on cheaper mixing desks are often fixed-frequency. They're also often shelving, so they're really not precision instruments. If you're going to use the EQ on your mixing desk, use it sparingly. After you've recorded EQ to "tape," it's hard to remove.


Figure 2 shows a software parametric EQ. You can see that it offers four fully parametric controls, along with both high and low pass EQ. Using a parametric EQ is very much like a graphic EQ, with the added ability to adjust the Q. To find the frequency you want, choose a very narrow Q and boost that frequency. Preview your audio, and move the frequency setting back and forth until you hit your target. Next, set your Q (remember: boost wide, cut narrow). Then adjust the boost or cut until your audio sounds the way you want it. If you want to work on another frequency, just use the same approach: Find, set your Q, and apply the right amount of boost or cut.


Figure 2: A software parametric equalizer (Sony Sound Forge)