What is a Sound Equalizer?
An in depth guide to sound equalization.
I. What is a Sound Equalizer?
II. Using Sound EQ in Your Projects
III. Different Types of Sound Equalizers
IV. Forming a Good Audio Mix
V. Instrument Specific Equalization
“Learning which frequencies to boost and which ones to cut can completely transform your mix.”
————-)>Jump to “Quick EQ Reference Guide”
Sound Equalization Guide – Part 1:
Equalization is essential for mixing audio tracks. Using equalization correctly can turn a dull sound into a bright sound, hide irritating frequencies, and make your kick drum hit so hard it’ll literally blow peoples minds (or their speakers)! The first thing you need to understand before tackling EQ is this:
The sound we hear is actually travelling waves which we percieve as different pitches depending on the “frequencies” of the wave. Every musical note corresponds to a specific frequency. Frequencies are measured in hertz (or hz) and are typically audible to humans in the range of 20hz to 20,000hz.
Equalization (EQ) is defined as the change in volume of a frequency or a set of frequencies in a sound, kind of like turning the treble or bass knobs on your stereo system. Using equalization you can mold an instruments sound to you’re preference by boosting and cutting frequencies in the sound. Lower frequencies consist of lower or deep pitch and higher frequencies consist of higher pitches.
Before I get into how you use equalization in your mix, you need to know the different types of equalizers. First off there are hardware sound equalizers and software equalizers. Both can come in one of the 3 main types of sound equalizers which include graphics, parametrics and rolloffs (high/lowpass filters). These all work by cutting or boosting frequencies of a sound passing through them, but use different methods to do so. Graphics equalizers can be used to change the volume of predetermined frequency points called bands. The amount of bands on different graphics equalizers that I’ve seen have ranged anywhere from just a few all the way up to 31. The more bands available the more control you have over the sound.
Parametric EQ’s provide even more control and flexibility because unlike graphic eq’s, they allow you to set the location of the bands and the width of the bands. When you boost the volume of a frequency you are actually raising the volume of frequencies around it as well. Being able to change the width of a band allows you to specify exactly what frequencies you are boosting or cutting on each band or raise/lower a wide range of frequencies with one band.
The third type of EQ is a Rolloff. These consist of simple lowpass and highpass filters that cutoff lows or highs at one specific point, or more advanced units that allow you to set the amount of lows/highs that are rolled off. A highpass filter basically allows only high frequencies through and cuts off (rolls off) low frequencies, while the a lowpass filter does the opposite (rolls off highs). Some microphones such as the Electrovoice re20 include a highpass filter switch used to rolloff lows when the switch is activated. This is especially helpful when you have a vocalist with a real boomy voice causing unwanted bass in a track. On the other end, lowpass filters can help remove some high frequencies from instruments like a kick drum to give it a real nice low sound.
Now that you have the basic understanding of what EQ is, its time to get into actually using it. You don’t have to be a genius to learn how to use EQ you just have to learn how to listen. And no, not like listening to your wife, you can keep tuning her out and nodding your head. I mean listening to the sounds (or frequencies) of instruments, not only by themselves but mixed together with other instruments. This is something that comes with practice like most things, and you’re going to have to put in some time to get it down.
“Forming Your Mix”There are no set in stone rules when using a sound equalizer. Every instrument (and every mix) is different.
The first thing you want to do before you start turning knobs is listen. Try to figure out what needs to change in the sound of the instrument, if anything. Also listen to all the instruments in your mix together. Find out where you need to make room for instruments being masked, what needs to be cut and what needs to be boosted. If your kick drum isn’t standing out, chances are the lows of your other instruments (more than likely your bass guitar/synth is the culprit) are drowning out the kick. If you’re mix sounds too dull you might need to increase the “brightness” of some instruments (5000-8000hz). If you have irritating frequencies in an instrument making you cringe and grind your teeth, you probably need to cut some of the mids out (800-5000hz). Listening is critical, and you always want to know what the problem is before you try to fix it. If you just start cutting and boosting frequencies without understanding what you’re doing you’ll probably end up making things worse.
Sweeping isn’t cheating:
So how do you find out what needs to change? You do a method called sweeping. Raise the volume way up on one of your bands (be careful not to blow your speakers or your eardrums), and sweep the frequency control until you hear what you’re looking for. If you’re looking for an area that needs to be boosted, listen for what frequency sounds the best while you’re sweeping. If you’re looking for an area that needs to be removed, listen for the most irritating area while you’re sweeping. Once you’ve found the frequency that needs to be adjusted, change the volume control accordingly.
Quick Reference Guide for a Sound Equalizer – Common Instruments:
Like I said before every mix is different, and there are no specific ways to EQ for every mix. Although you’ll still have to use your ears and make your own changes to each instrument here is a reference guide to provide a “typical” EQ for common instruments:
Kick Drum EQ Guide – How to Apply Equalization to Kick Drums:
- Roll off “muddiness” around 250-350hz. Remember to use a narrow band so you’re not removing your lows.
- Boost your highs at around 5000hz to make it a little brighter. When boosting highs you typically want to use a wider band to get a more natural sound.
Snare Drum EQ Guide – How to Apply Equalization to Snare Drums:
- If your snare sounds weak try to boost 1-2dB between 60-120hz.
- Sweep for irritating frequencies in the midrange and slightly reduce the volume. Try not to remove too much mids or your other instruments will drown out the snare in the mix.
- Boost about 2-5dB in the highs around 6000-7000hz.
Hi-Hat EQ Guide – How to Apply Equalization to Hi Hats:
- Reduce muddiness around 250-350hz. Muddiness is also considered warmth and removing too much can make the instrument sound distant or “hollow”.
- Sweep for irritating frequencies in the midrange and slightly reduce (remove 2-5dB).
- Boost your highs around 11,000-12,000hz about 5 dB.
- Sometimes I like to just throw a highpass filter on my HH instead of messing around with all the EQ. It’s quick and easy, but not always the right thing to do depending on the mix.
Bass Guitar EQ Guide – How to Apply Equalization to Bass Guitars:
- Cut your mud at 250-350hz if nescessary. Remember to keep your band thin when cutting mids so you don’t remove all your lows. A slight boost at 60-80hz can help but try not to drown out your kick.
- A slight boost (2-4dB) around 1,000-3,000hz can add some presence if you’re having trouble hearing your bass.
I actually like to record my high octave and low octave piano sections on seperate tracks and EQ them seperately, although you can effectively EQ a piano on one track.
- Piano EQ Guide – How to Apply Equalization To Pianos:
- Reduce muddiness around 250-350hz.
- Reducing your mids around 1,000-2,000hz can help take out the “cheap” sound of a piano (sometimes called honkiness or chunkiness).
- A boost in 5,000-8000hz can add clarity and give you a crispy sound (bacon)
Vocals are the big dog that you really don’t want to get bit by. Through the years sound engineers have used thousands of different techniques to get their vocals right for the mix, and some have turned out great while others sound terrible. EQ’ing your vocals really depends a variety of things: The song, the mix, the vocalist, and the microphone. You don’t do the same thing with a country singer that you would for a hip-hop artist simply because the instrumental behind them is going to be mixed entirely different. Try playing around with different techniques (not just EQ but all kinds of effects) to get vocals to sit right in your mix. The key is to make them very clear and easy to understand. Don’t let your mix overwhelm your vocals or there’s no point in having lyrics (unless of course the lyrics are so awful you’re trying to hide them).
Vocal EQ Guide – Applying Sound Equalization to Vocals:
- Be very careful when modifying the midrange of vocals (800-5000hz). The human voice is very well known to humans (make sense?) so any changes in the main range of the human voice stands out more than most EQ changes. Boosting or cutting in the midrange of vocals should be done about 1/3rd as much as any other instrument (if you would normally cut 3dB only cut 1dB).
- An important thing to keep in mind is that changing an instrument in the mix can directly effect how other instruments sound. So a good approach for vocals is changing the other instruments as opposed to directly changing the vocals. If you still can’t get your vocals to sit right after making room for them in your other instruments, THEN move on to EQ the vocals.
- If you need more vocal presence boost around 5,000-6,000hz about 2dB.
- As always sweep for irritating frequencies in the mids (800-5000hz) and slightly reduce.
- Try boosting around 300hz. If it sounds worse try to cut around 300hz. Use a narrow band so you’re only changing a small range of frequencies.
Wrapping it up (Summary…not protection):
Sound equalization is something that take’s a lot of practice to get used to. Most people’s ears aren’t real sensitive to small boosts and gains in frequency and can’t hear exactly what they’re doing even if they do hear a difference at first.
Now you have a basic understanding of what EQ is, the different types of equalizers, and how to use them. Reading a EQ guide can’t make you good at EQ but taking your new understanding of it and practicing is a good step. Before I end the guide to EQ I’ll leave you with one final tip:
After making your EQ changes to your mix, take a break and go listen to some commercial music for a while. Get your ears back attuned to the standard industry sound AND THEN go back and listen to your mix with your fresh set of ears. This can help you spot anything you missed. Good luck.
Also read Sound Equalization on wikipedia for a more in depth look into sound EQ.
Other Articles related to Sound Equalization:
Best Music Production Software For Your DAW - An Article about music production software, many of which include sound equalizer plugins.
Common Sound Processing Effects used in Mixing - This page offers brief descriptions of the common audio/sound processing effects used in mixing, including sound EQ.
Additional Sound Equalization Notes:
Sound equalization is something that take’s a lot of practice to get used to. Most people’s ears aren’t real sensitive to small boosts and cuts in frequency and can’t hear exactly what it is they’re doing even if they do hear a difference at first. There’s a reason why you see questions all over forums like “how do I EQ my BD or kick drum?” or “what frequencies should I cut from my bassline with my sound equalizer?”. Training your ears to hear muddiness and brightness and learning what to boost and cut to fix different issues with different instruments takes time. You’ll get the hang of it, just keep practicing and apply some of the things you learned in “What is a Sound Equalizer?“.