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Ben Eklund
Equalization serves several purposes. In a live setting, EQ can be utilized to correct unbalanced frequency response in the house speakers. In other words, if the speakers heard by the audience are bass- or treble-heavy, a graphic equalizer will help balance (flatten) the speakers’ frequency response. Also in a live setting, feedback can be drastically reduced by pinpointing the frequency of the feedback and cutting, or lowering, that band of frequency on a graphic equalizer. In these scenarios, a 25- or 31-band graphic equalizer is typically used, in order to provide a high level of control over frequency response.
In a studio setting, applying EQ to a single instrument or mix of instruments has several effects. I found a great video demonstration on the internet of the EQ III 7-band equalization plug-in bundled with Pro Tools 10. The engineer in the video, Joe Gilder, who runs a website called Home Studio Corner, outlined several key points about using EQ on multiple instruments in a mix.
- Attenuate (cut) bad frequencies when necessary; do not simply boost the good.
- Some instruments do not need the full 20 Hz to 20 kHz range. Anything below 100 Hz can typically be cut from a guitar track. Apply a high pass filter at this frequency. Anything above 10-12 kHz is generally not necessary for a kick drum. Apply a low pass filter around that frequency.
- You can search for a “good” or “bad” frequency by boosting a frequency range, narrowing the bandwidth, and sweeping it horizontally across the frequency band. This is useful for pinpointing a particularly pleasing sound that can be given a little boost, or a harsh sound that can be attenuated.
- When mixing similar-sounding instruments, you can cut a frequency range on one track and boost the same frequency on the second track to allow the latter instrument to come through the mix better.
- The ear is the best judge when applying EQ.
To practice a couple of these tips, I made a one-minute recording of the song “12:51” by the Strokes. I recorded rhythm and lead guitar tracks. I have posted two versions of this recording in the audio section of my blog, one without EQ, and one with the adjustments.
I applied a high pass filter on the rhythm track at 100 Hz to roll off the low end. I also used the sweep technique to attenuate a harsh frequency. In this case, I cut the 4 kHz band by three decibels. Using the same technique, I boosted the frequency range around 360 Hz to add presence to the low end.
On the lead track, I again applied a high pass filter, but at a slightly lower frequency because I didn’t want to lose too much of the low end in the guitar riff. Rolling off anything higher than 94 Hz was too noticeable for my liking. I wanted to give some warmth to the higher end as well as boost the lower end a bit, so I again swept for the right frequencies. I ended up boosting at 220 and 1500 Hz. I liked the way the two frequencies contrasted and complemented each other. The adjustments didn’t sound out of place with the rhythm track.
In the photos section of my blog, I have posted screen captures of my adjustments. The changes are subtle, as they should be. Drastic changes in studio EQ should usually be addressed during the recording phase, possibly by using a different microphone, or by simply tweaking the tone knobs on the amplifier for an electronic instrument.
