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What is an equalizer?

From: Foundations of Audio: EQ and Filters

Video: What is an equalizer?

Even if you don't know it, you've probably used an equalizer or EQ at some point in your life, probably on a car stereo, boom box, or home theater system. I like to think of EQ as frequency-specific level control. While a typical volume or level control in your mixer allows you to increase or decrease the amplitude of an entire channel's signal uniformly, an EQ allows you to increase or decrease the amplitude of a specific range of frequencies relative to everything else in the sound or instrument that you apply it to.

What is an equalizer?

Even if you don't know it, you've probably used an equalizer or EQ at some point in your life, probably on a car stereo, boom box, or home theater system. I like to think of EQ as frequency-specific level control. While a typical volume or level control in your mixer allows you to increase or decrease the amplitude of an entire channel's signal uniformly, an EQ allows you to increase or decrease the amplitude of a specific range of frequencies relative to everything else in the sound or instrument that you apply it to.

Want more bass? Boost the low frequencies. Too much top end? Cut the treble or high frequencies. Sounds simple? In many ways it really is. In audio recording EQs, or filters as some engineers prefer to call them, are most often used to improve a sound's balance or tone, either by itself or in the context of other sounds in a mix. EQ is used to fix sound problems as well as shape or creatively change a sound's tone in wild and unique ways.

We often refer to EQs as filters because they literally filter or isolate a specific portion of the signal's frequency spectrum relative to the rest of the signal. In this course, we'll use the terms equalizer, EQ, and filter synonymously. If this sounds confusing, imagine an EQ as a frequency mixer for a specific track in your mix. In fact, a graphic equalizer is just that, a mixer-like tool that allows you to raise and lower the relative levels of the low- to high-frequency content across the entire range of the instrument.

So if you want a more snap in a snare simply raising the entire level of the snare in the mix isn't going to achieve that; you need to use EQ to turn up or boost the relative levels of the snap frequencies, which might be somewhere between 3 and 5 kHz. When volume and pan aren't enough to shape a track in the mix, an EQ can help you reshape or refocus a track's frequency bounce, adding more amplitude to certain frequencies or taking away amplitude from others.

This enables you to push the sound forward, pull it back, or otherwise hone its place in priority amongst the other instruments in the mix. In many cases EQ is used in an attempt to improve mistakes or compromises made during the recording process, where the original recording has left something to be desired, like on a guitar recorded with too much low end or a vocalist recorded through a less-than-ideal mic that has an unflattering EQ curve. But EQ can also be used to make already-great-sounding instruments work better together in context.

For example, an acoustic guitar's fundamental and lower overtone frequencies may be masking or obscuring the same frequencies shared by the lead vocal. Reducing the entire level of the guitar would not be an ideal solution, as some of the higher overtones and harmonics may be providing a nice melodic and rhythmic complement to the tune that we want to maintain. An EQ would allow us to reduce or turn down only the lower fundamental frequencies while leaving the higher overtones and harmonics intact, helping it sit correctly in the mix against the vocal and other elements.

(music playing) Ultimately, we'll find that EQ can be used for creative tasks as well as for corrective ones, but for whatever the reason, when you don't like the current frequency makeup or tone of a specific track or tracks, you can reach for an EQ or filter to change it.

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This video is part of

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Foundations of Audio: EQ and Filters

36 video lessons · 12505 viewers

Brian Lee White
Author

 
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  1. 3m 28s
    1. Welcome
      1m 36s
    2. What you should know before watching this course
      35s
    3. Using the exercise files
      58s
    4. Using the "Get In the Mix" Pro Tools and Logic Pro session files
      19s
  2. 15m 46s
    1. What are frequency and amplitude?
      2m 27s
    2. Measuring frequency
      1m 48s
    3. Measuring amplitude
      1m 58s
    4. The perception of frequency and amplitude
      4m 18s
    5. Frequency and pitch
      5m 15s
  3. 36m 10s
    1. What is an equalizer?
      4m 14s
    2. Hardware and software EQ
      1m 58s
    3. Understanding frequency and gain EQ controls
      3m 41s
    4. Using the bandwidth, or Q, EQ control
      5m 35s
    5. Parametric equalizers
      2m 36s
    6. Shelving filters
      5m 11s
    7. High- and low-pass filters
      5m 42s
    8. Putting it all together with multiband EQ
      3m 43s
    9. Using graphic EQ
      3m 30s
  4. 46m 13s
    1. Creating focus
      3m 47s
    2. Get in the Mix: Using EQ to fix problems and place elements in the mix
      8m 30s
    3. Get in the Mix: Creating complementary EQ curves
      9m 7s
    4. Get in the Mix: Creative EQ with the telephone effect
      5m 30s
    5. Get in the Mix: Frequency bracketing with filters
      5m 44s
    6. Get in the Mix: Automating EQ
      6m 18s
    7. Learning to listen
      3m 10s
    8. Balancing expectations from the recording process
      4m 7s
  5. 41m 14s
    1. Get in the Mix: EQing FX returns
      4m 29s
    2. Using common vintage-modeled EQs
      5m 2s
    3. Using frequency analyzers
      3m 44s
    4. Using harmonic generators to excite frequency content
      5m 44s
    5. EQ or compression first?
      3m 3s
    6. EQ and room acoustics: Is your room lying to you?
      6m 15s
    7. Boost or cut? The relative nature of EQ and headroom
      4m 0s
    8. Building healthy EQ strategies
      8m 57s
  6. 19s
    1. What's next and EQ summary
      19s
  7. 5m 51s
    1. A session with Brian Lee White
      5m 51s

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