Understanding Equalizers

Understanding Equalizers

Every day I see posts on Facebook, Twitter, and various other social media platforms that look like this “What is a good EQ for a kick drum,” or “How do I EQ a guitar.” Everyone that I reach out to and train all has the same issue: they don’t understand EQ and what it is. So many people working in church sound have no idea what an equalizer is and how it can be used to help control sound. In this article I want to break down exactly what an EQ is and how they can be used.

What is an Equalizer?

First off we need to discuss what an Equalizer, or EQ, is. An EQ is essentially a set of filters that are used to remove certain frequencies from your audio signal path. There are 3 types of filters that are used to create a traditional equalizer: Hi-Pass, Low-Pass, & Bandpass.

Hi-Pass Filters

A Hi-Pass filter is sometimes referred to as a “Low Cut” filter. A Hi-Pass filter allows high frequencies to pass through the filter, anything below the filter cut off is removed from the signal path. Here is a picture of a Hi-Pass Filter curve.

HPF.png

You can see that the Hi-Pass filter is removing low frequencies from the signal starting at 100 hz. A Hi-Pass filter is great at removing unwanted low end from certain instruments such as Vocals, Guitars, & Cymbals. This can really help clean up your mix and keep instruments from sounding muddy.

Low Pass Filters

Low pass filters are the exact opposite of Hi-Pass filters. Instead of allowing high frequencies to pass through the filter, they only allow low frequencies to pass through the filter. Any frequencies above the filter cutoff will be removed from the audio signal. Here is a picture of a Low Pass Filter curve

LPF.png

You can see that the Low Pass filter is removing all of the high frequencies from the signal starting at 7.3 kHz. A Low Pass filter is great for removing unwanted high end from certain instruments such as kick drums, and certain floor toms. Be wary of Low Pass Filters, however, because removing too much high end can remove clarity and punch from instruments. If there are problematic frequencies in the high end then remove them but if there isn’t a problem, don’t try to fix it. NEVER use a low pass filter for vocals, unless you want to have a vocal that sounds like an adult in Charlie Brown.

Bandpass Filters

Bandpass filters are a combination of Hi-Pass and Low Pass filters. They only allow a certain range of frequencies to pass through. Here is a picture of a Bandpass Filter Curve.

BPF.png

You can see that this bandpass filter is only allowing a narrow band of frequencies to pass through. Only frequencies between 132 hz and 1.9 kHz are allowed to pass through. This is great for creating a telephone vocal effect, but isn’t very useful in a musical context. I don’t, personally, use bandpass filters unless I’m trying to create some kind of special effect.

Notch Filters

A Notch filter is a filter that adjusts a specific frequency, or band of frequencies. Sometimes notch filters can have a variable bandwidth allowing them to affect a wider, or narrower, range of frequencies. Below is an example of a notch filter with both a narrow, and wide bandwidth.

Notch Filter with Narrow Bandwidth

Notch Filter with Narrow Bandwidth

Wide Notch.png

Shelving Filters

Shelving filters resemble the shape of a shelf, hence the name. Shelving filters raise, or lower at a specific frequency, and tapers off at a specific level and continues at that level throughout the rest of the frequency spectrum. This may sound confusing, but here is a picture to show what a shelving filter looks like.

EQ Controls

Now that you understand the 3 filter types that combine to create an equalizer we need to discuss some different controls and parameters that EQs have. Different types of equalizers will have different controls but these are some of the basic parameters that you can adjust on an EQ: Frequency, Q (Ratio), & Gain.

Frequency

Frequency changes where the center of your filter is in the frequency spectrum. This can change the focus of your filter from high frequencies, low frequencies, low-mid frequencies, etc.

Q (Ratio)

The Q factor adjusts the bandwidth of your filter. This can make the filter affect a wider range of frequencies or it can me the filter affect a very narrow range of frequencies.

Gain

Gain is probably the easiest of all of the parameters to understand. Gain adjusts how loud, or quiet, the frequencies in your filter are. If you boost the gain, the frequencies in your filter will get louder and stand out against the rest of the frequencies. If you remove gain, the frequencies in your filter will get quieter and will be hidden against the other frequencies. While gain is probably the easiest parameter to understand it causes the biggest debate when trying to understand EQs. Should you always boost the gain to make good sounding frequencies stick out more, or should you always reduce the gain to make the bad frequencies stick out less? This will be addressed later in the article.

Graphic Equalizer

Graphic Equalizer

Types of Equalizers

Graphic Equalizers

Graphic equalizers give you a graphical representation of what is going on in the frequency spectrum. They come with a preset number of filters that have the option of adjusting gain. Graphic equalizers don’t have the option to adjust Q, or Frequency. The most common graphic equalizers usually have 31 bands eq available and each band is spaced 1/3 of an octave apart from each other. Each frequency band is a filter that can be adjusted to get the sound that you want. These usually serve the purpose of Room EQ, which we discussed in a previous article Getting Great Church Sound.

Parametric EQ

Parametric EQ

Parametric Equalizers

Parametric EQs are usually what most people are familiar with. These are the types of EQ found on analog mixers and digital mixers alike. Parametric EQs allow you to adjust all parameters previously mentioned on the EQ. You can adjust the frequencies that you wish to filter, the bandwidth of the filter, and how much gain you either want to add or take away. These are commonly used for mixing, and these are most likely what you are using in your church on Sundays.

How to Use an EQ

Now that you’ve read through all of the boring theory behind equalizers you’re ready to understand how to use this tool to better your mixes. Understanding all of the different filters and how they work can help give you a better idea on how to use these to create great sounding mixes. First, lets dive into the two main schools of thought surrounding EQ: Additive vs Subtractive EQ.

Additive vs Subtractive

Additive EQ is a mindset that, essentially, says this: “This track is sounding a bit muddy, I’m going to add some extra high end to help bring up the clarity.” At first glance there isn’t anything wrong with this, in fact, many professional mixing engineers and front of house engineers use this technique. However, issues can arise when only boosting frequencies. In a live sound environment there is one problem that we want to avoid at all cost: FEEDBACK! Everyone hates it when you have a high pitch squeal coming through your speakers right? If we’re only boosting frequencies then we are essentially just turning up the fader, but only for that frequency. This can give us a greater risk for feedback in a live environment. In the studio, I don’t care as much about adding because there is no risk for feedback but in live sound feedback can ruin a great show, especially in a worship service.

Subtractive EQ is the opposite mindset. It says: “This track is sounding a bit muddy, I’m going to remove some of the low mids so that they don’t stick out as much, this way the high end can have room to cut through.” Both of these mindsets are trying to accomplish the same goal, but are going about doing so in different ways. One says “I don’t have enough of something, I’m going to add it,” while the other says “I have too much of something, I’m going to take it away.” It is important to understand that neither of them are 100% right. Allow me to break down my steps to EQ.

  1. Listen to the instrument with no EQ & Identify problem frequencies

  2. Use Subtractive EQ to remove problem frequencies

  3. Listen to instrument again

  4. Use additive EQ sparingly to add extra color to the instrument and bring out nuanced sounds.

Utilizing these four steps really helps me use the best of additive and subtractive EQ. I want to remove the frequencies that are too present and are muddying up the track first before I do any kind of additive EQ. This way I don’t have to add as much, reducing my risk for feedback.

Use Your Ears

EQ is not a science, it is an art. So much of mixing is thought to be science when it isn’t. Mixing engineers and Front of House engineers are as much artists and the musicians on stage. When you sit in the sound booth at church on Sunday you are an artist, not a scientist. There isn’t a magic formula for how to EQ a kick drum. Your ears decide how you EQ. If it sounds good, it is good. No ifs, ands, or buts. Make sure you are listening to your instruments before you apply any EQ. Sometimes the best EQ is actually no EQ. There are many times that the only EQ I do on a vocal is apply a Hi-Pass filter to remove unwanted low end. That’s it. Use your ears and figure out what sounds good, then stick with it.

Don’t Always EQ in Solo

So many times I see people that only EQ their instruments in Solo. This means they set the EQ for an instrument by itself, not in the mix. EQ-ing in solo can be really good when trying to identify problem frequencies, but always make sure you are setting your EQ with a full mix as well. Sometimes you’ll notice that the things you hear in solo don’t show up in the mix. Sometimes something that sounds bad in solo, will sound great in the mix. Use EQ to help blend the mix together, don’t get so caught up in having a perfect vocal tone or perfect guitar tone that you miss out on getting a great sounding mix.

Conclusion

In this article we have discussed everything regarding Equalizers. Hopefully now you have a better understanding of what an equalizer is, how it works, and how you can use an EQ to get great mixes for your church on Sunday. As always if you have any questions feel free to email us at worshipinnovation@gmail.com, or message us on facebook @worshipinnovation and instagram @wrspinno. We’d love to talk to you and help you learn more about running sound at your church. I hope you have a great day!

God Bless,

Tyler

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