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Secrets of EQ

January, 19 2009 |
A Discussion with John Mills

Let's start with the most famous question that sound people are asked. "Do you really know what all those knobs do?"

If you can answer that question, you may also know every frequency and its equivalent musical notes. Maybe you know the exact crossover point of every driver in your system, and you might even have calculated the RT60 of the main sanctuary, youth room and gymnasium.

Or maybe not. Whether you're the person who actually DOES know what every knob on the soundboard does, or you are just starting out, the real question is: "How does it sound?"

Starting Out

When I first began doing sound, I bought a great set of headphones. I thought to myself - if I'm going to be expected to make something sound good, I should probably know what I'm shooting for.

So I started listening (like crazy) to CDs. Not just bands or styles I liked, but anything and everything I could get my hands on. I listened to the lyrics, chords, melodies and harmonies, but also to how it all fit together. I concentrated on the space that each instrument was taking up.

I noticed that certain instruments seemed always to be sitting in a certain spot — not to where they were panned, but to the frequencies they occupied.

Instrument Frequency Response

How To Get There

When building a mix, we need to think of the song as a line. Each instrument makes up part of that line. If we have too many instruments or frequencies trying to take up the same space our line gets bumpy and the mix gets muddy.

Listen to each instrument and think of a space for it on the line. Keep other instruments away from it (EQ wise) and you will have an easier time hearing that instrument. You wouldn't want to have a really bassy, heavy electric guitar because it would be taking up a lot of the space the bass guitar really needs. Try to keep each instrument in its place.

Think of each instrument as to what the fundamental piece of it is. For instance the fundamental of a kick drum will be low frequencies. That's not to say you don't need highs to make it cut, but there really isn't much midrange going on with it. Try to carve out some of the midrange of the kick to make room for the low midrange of the bass guitar.

Another example is electric guitar. Many engineers mistakenly try to make the electric guitar huge to get a 'larger than life' sound, but if you really listen to a guitar on a CD and focus on what frequencies are really taking up space in the mix, you'll be surprised at how small the range actually is.

I always tell new engineers never to be "done" with the mix. Listen for changes, and more importantly, listen to make sure that everything is in the mix and working together. Be attentive to the mix and what's going on inside it. It doesn't mean you have to constantly turn knobs. Focus less on the actual sound of the individual instrument and more on how it interacts with other instruments in that same range.

There are no "magic" numbers that work every time because all instruments are a little different. The equation gets more complicated when we use different mics or the instrumentalist changes patches on their keyboard, but trust me… none of that is really important. What is important is that you focus on getting a natural sound that blends nicely with the competitors for the same space.

Bridging The Gap

Here are some general guidelines to consider when you are trying to find your space.

General Frequency Tips

Instrument Frequency Tips

Trust Your Ears

The most important question is "Does it sound natural?" Does it sound like the CDs you've been listening to? More specifically, does it sound like you were sitting in front of the real instrument? I keep this in mind throughout the performance.

I constantly glance down all the channels and think about each input. Kick, does the kick sound right? Bass, does the bass sound right? Guitar, does the guitar sound right? Piano, does the piano sound right? Vocals, do the vocals sound right? Then I think about it all again and ask if the guitar and vocal are walking over each other. Can I hear the piano? Is it because the guitar has too much midrange near the piano part's midrange? Try taking a little low mids our of the guitar instead of turning up the piano. I think you get the picture.

It's almost impossible to make the initial adjustments to instruments or vocals in the mix with the whole band playing. Instead I try to have a snapshot of what I think the instrument should sound like.

Learning to EQ confidently means you know where you are heading. That's why I recommend listening to CDs with a good set of full range headphones. No cheap earbuds here… you need a pair that will allow you to hear the whole frequency spectrum, and preferably a sealed set, like good earphones or sealed headphones. You'll be able to form a mental soundscape of that you can use when you are back behind the console.

Turn, Turn, Turn!

Here's a bonafide "trick of the trade". Turn some knobs. I mean actually get in there and turn the heck out of the EQ knobs and listen to what they do.

Here is a simple technique to use in sound check.

Grab the gain (Figure 1) on the mid EQ of an instrument crank it up a bunch...

Now grab the frequency (Figure 2) of the mid and sweep it up and down.

You will hear a spot where it makes that instrument or voice sound horrible. Once you find it, take the gain back to zero, listen for a second again, and then cut out about 6db of it. You will be amazed how much better that instrument sounds when you "get the junk out" as I call it. This is an amazing way to learn what frequencies sound like and the technique will eventually train your ear to hear the junk without boosting it first.

Becoming a master of EQ is like becoming a master painter. Sometimes you just have to throw some paint on a canvas and see how it works.

About John Mills

A frequent contributor to Shure Notes®, John is an 18-year veteran of the road. He was a frustrated Electrical Engineer who hated college. He left school to pursue a career on the road as a drummer, ended up as a sound engineer and after being blessed to work for many of the top Christian worship leaders, artists and tours, has landed at a job as an audio engineer for a design firm. He says, "I guess Mom was right, she always knew I'd finally got a real job." Check out and for more about what John is up to.
Davida Rochman
A Shure associate since 1979, Davida Rochman graduated with a degree in Speech Communications and never imagined that her first post-college job would result in a lifelong career that had her marketing microphones rather than speaking into them. Today, Davida is a Corporate Public Relations Manager, responsible for public relations activities, sponsorships, and donation programs that intersect with Shure at the corporate and industry level.