Mix Mondays is our weekly mixing help column, which aims to take the sting out of Monday with a little audio talk.

Equalization is probably one of the easier kinds of processing to understand, but it can be a little daunting at first because there’s so many controls and often not enough explanation of what the knobs are actually doing.

Most plugins make it easy to see what’s happening: you make bumps and dips and hear changes in your sound.  However, most old-school engineers (and quite a few new-school engineers) will tell you that the visuals of your Eq are just there to help you along your way.  There’s limits to what all those displays, RTA’s (real time analyzers), and meters can show you.  They approximate what is happening to your sound, and how you’re affecting it.  But that’s really a deep topic for another time.

Suffice it to say, like everything else in the world of music production, you’re really only limited by what you can hear, not what you can see. So do yourself the educational favor of closing your eyes while making some Eq changes, and see if you can learn to hear what different changes sound like.  

OK, I’ll get off my soapbox now and get into it.  The basic idea of Equalization is something called “Frequency-specific gain.”  Being able to change the volume of just one frequency out of the entire audible range (20Hz – 20,000Hz) isn’t really possible…or useful.  However, Eq’s let you make broader changes to ranges of frequencies, which is really useful in music production.  The mechanics behind how Eq’s do this is complex and varied.  In fact the way in which Eq’s are designed to select and process bands is what gives each one its particular “sound” or “character.”  

Most Eq’s allow you to select a band of frequencies by giving you a knob to choose the center frequency of the band.  Basically when you create a bump or dip in your Eq, the center of that bump or hill is your “center frequency.”

 

Here, you can see that I’ve setup a simple Eq curve selecting 1180Hz as the center frequency for the boost.  The Eq is also boosting frequencies around 1180Hz.  

How skinny or wide the curve is, depends on the Q of the curve.  A Q value isn’t directly applied like a measurement, but rather it is used to derive the width of your frequency band.  Here’s a good explanation of Q from AstralSound.com if you really want to know the math.  

Here, you can see that I’ve raised my Q value from 0.71 in the first picture to 11. The two Eq curves are vastly different in how they look, but more importantly, they sound very, very different.  The main change is that the Eq has honed in more precisely on the center frequency of 1180 Hz.  This generally sounds more obviously processed, and can induce a kind of “ringing” at that frequency.  

On a side note, if you want to hear what wah pedals basically do, setup a high-Q, high-gain eq curve and grab that frequency selector and sweep back and forth as you’re playing back.  Funky times.

The last control you’ll encounter is the Gain, which I hope is pretty obvious.  You can turn things up and down as you please with this control, but be warned, most Eq’s give you a far larger range of gain than you’ll ever really need.  This makes it far too easy to apply all sorts of crazy, over-the-top, distorting Eq’s without even noticing it.  I can’t tell you how many times I’ve opened someone else’s session to find a track compressed, limited, and then Eq-ed with 12dB boosts all over the place.  How loud do you want it? 

Even my example’s gain of +8dB is kind of over-doing it no matter what track it is on.  I only used a large gain for this article because its more visually obvious.  In dealing with actual mix situations I’d suggest trying to keep things within the +/- 5dB range if you can.  If you’re trying to make something sound exaggerated or unreal, then by all means gain-away.  Just be advised that if you’re trying to get a “transparent” Eq sound, then less is more.  

Another thing to note is that a subtractive Eq, is almost always more transparent than an additive Eq. It just tends to be more obviously distorting to turn up a frequency band than to turn it down. 

My Eq Process

Most of the time when I’m mixing, I’m using Eq to “clean-up” a sound and even it out.  Trying to turn down some “problem frequencies,” which might be too harsh or stand out too much is the major work of Eq’s in my mixes. 

To do this, I usually listen to the signal without any processing and try to estimate what needs changing.  To start you might try to think, “does this track fit in the mix right?”  If there’s a million things fighting for space in mid-range, you might try asking yourself, what part of the sound is more “characteristic” for this track and what can cut away for the sake of other tracks? The decision making process is really where you get to be creative in your mixing, so I won’t tell you what to turn up or down on which track, but be thinking as you listen. That’s the best way I’ve found to make my hours of tweaking worthwhile.  

After I’ve listened hard to my track both soloed an in context with the mix,  I setup an Eq with just one band active, make the Q very high, and turn up the gain by about 6 to 8 dB.  The second picture above is actually a good example of how I start out.  

Then I slowly move the curve around in the frequency range as the track plays back.  When I’m doing this, I’m hunting for things that either help or hurt the sound.  Keep in mind that this Eq curve is more extreme and stark than you’ll finish with, so don’t expect it to sound great as you’re hunting.  Instead, really look for frequencies that jump out at you as you sweep.  Some of those that aren’t helping the sound can be turned down a bit to help smooth out your mix and make space for other things.  

Once I feel like I’ve located the frequencies I want to process, I bring the gain down to a reasonable level, usually between +/- 3dB and lower the Q value.  This gives me a less obvious tweak to the sound, which might be hard to hear on its own, but placed into the mix, it’ll make a big difference.  

Here you can see an example curve that I might end up with: Small gain change and a wider Q than the Eq curve I was using to hunt through my sound.  

There’s a million other things to be said about Equalization and how to get the most out of it.  There’s also hundreds of other ways to use Eq’s and reasons to do so beyond what I wrote here, but those will have to wait for another time.  Hopefully, though, I covered the basics behind what your Eq controls are and good basic technique for hunting down “problem frequencies.” 

Until next time, happy sound hunting.