Tuesday, November 3, 2009

Get Your Freq On: Getting Started with EQ

Next to compression, equalization (or EQ, as it is more commonly called) is perhaps one of the toughest mixing concepts for most beginners to get their heads around. The concept is pretty simple to understand - you use controls to emphasize or attenuate specified frequencies in a sound, thus allowing you to alter the overall tonal balance of the sound. The bass and treble knobs on your car stereo are examples of a very crude equalizer. Where EQ can be difficult to grasp is in the actual practical application; not just the how, but the why. So today, I'm going to share some tips I hope beginners will find useful in getting them on the right track with this often-misunderstood effect.

• Get Your Hertz Sorted
As you may remember from your elementary school science class, a sound's frequency is measured in Hertz (abbreviated Hz). A Hertz measures the number of wave cycles per second in a sound. Thus lower frequencies, which have longer wavelengths, are found at the lower end of the scale, and higher frequencies which have shorter wavelengths and thus more cycles per second, are found at the high end. A human's hearing range is generally believed to be between 20Hz to 20,000Hz (aka 20k - 1k = 1,000 Hz). Your mixes will generally be in a much narrower range, though.

A good thing to do when you are starting out with EQ is to play around with an equalizer on an audio track just to see what boosts and cuts in different frequency ranges sound like. Just by doing this, you should start to get a good idea of basic frequency ranges - what boosts make a sound bassier, which make them brighter, etc. As time goes on, you should make an effort to learn more specific ranges and useful frequencies to improve your ability to hear what cuts or boosts need to be applied to a sound. For instance, you'll find the rumbly sub bass frequencies around 60Hz... a boost around 150Hz can help warm up a bass sound... a boost around 1.5k can make a vocal more intelligible, etc. There are no absolutes when it comes to EQ. Each application might require its own, unique solution. But if you take the time to learn some basics about the frequency ranges various instruments or sounds generally fall into, you'll be able to narrow in on the problem spots faster and more efficiently.

• Trim the Fat
Just about every sound under the sun contains a much wider range of frequencies than is typically needed in a piece of music. You might be playing a high register synth string patch, but if you look at the signal through an analyzer, you'll see that while most of the sound energy is in the upper range, there are probably a bunch low frequencies in there, too. This sounds great when you play it by itself, but when you place it in a mix, those low frequencies are suddenly put in competition with the low frequencies in your synth bass and your kick drum. Frequencies are very selfish. They don't like to share their space very much and if you have too many instruments inhabiting the same frequencies the result is audio mud. The solution here is to cut out the frequencies you don't need in each track so they are no longer clashing with those same frequencies in instruments that DO need them. Likewise, with your bass sound, you can probably cut some of the higher frequencies. While these EQed tracks will probably sound "wrong" when soloed, in a well-balanced arrangement, each instrument contributes to the over all tonal balance and everything sound full without being muddy. You'll note that you can have way more parts going on at once without it sounding bad if you practice subtractive EQing. Obviously you don't need (or want) to go overboard here. You're not trying to totally eliminate different tracks from having some of the same frequencies, you're just trying to minimize the overlap as much as practically possible.

• Never Boost When You Can Cut
All mixes have what is known as "Headroom". Headroom is basically a limit to the amount of signal in your mix (or individual track) before clipping and distortion occur. Any time you boost something in a mix, whether it is the actual track volume or making a boost in EQ (which boosts the volume of a frequency range and thus the volume of the track itself), you are putting yourself closer to that limit. Therefore, it is always preferable to make a cut instead of a boost when it comes to EQ. Not only are you giving the sounds more of their own space, but you're opening up room in your mix as a whole. Let's say you have a guitar and a vocal that are clashing. Instead of boosting 1.5k on your vocal to help bring out the midrange, try cutting that same range in the guitar track to create a 'hole' for the vocal to sit in. Finding the right places to cut holes and doing it transparently takes time and experience, but you'll end up with much cleaner, more open mixes if you get in the habit of utilizing this practice.

• The Eyes Have It
First and foremost, you should be making EQ adjustments using your ears. Remember the credo: if it sounds right, it is right. However, using visual aids such as frequency analyzers can be extremely helpful, especially if you are new to this and aren't yet familiar with the general frequency ranges different sounds occupy. Frequency analyzers represent the frequency content that makes up a sound in the form of a real-time graph. Frequencies that are in abundance are the higher points on the dancing line, while the ones that are more scarce are in the lower regions. This gives you a way to see the overall frequency picture of your sound and take an informed approach to applying EQ to achieve the end you are after. Some EQ plug-ins have built-in frequency analyzers, but there are several dedicated frequency analyzers out there as well.

• Not Everything Needs EQ
It's REALLY easy to go overboard when you are just starting out with EQ. Always stop yourself before you are about to EQ and ask yourself why you're doing it. If you don't have a specific answer, maybe you don't really need it. In fact, a well-arranged track may need very little EQ at all on its individual tracks. Always have a purpose in doing what you're doing. Don't EQ just to EQ.


Anu said...

Rule of thumb:
If you want your element to fit into your track better, CUT

If you want your element to stand out more, BOOST

Anonymous said...

Thanks a bunch for the useful material. Do something on using reverberation followed by delay effect processing...

Tom said...

Anonymous - What specifically would you like to know?