Basic Equalization (MetaPop)

One of the most important aspects of a mixdown is equalization. It’s a simple concept that works by using filter circuits to alter frequency response. In this article we’re going to take a further look at what Equalization is and the basics of using filtering to alter sounds. 1. What is the Frequency Spectrum? https://drive.google.com/file/d/0B4I-xZfEjcKJV19BZUdRY2psOHM/view?usp=sharing (Image) What’s commonly referred to as the Frequency Spectrum is the range of frequencies the human ear can hear. 20 hertz (lowest) to 20,000 hertz (highest) is the standard range of audible frequencies. We often see this represented in audio software on a graph, the x-axis representing frequency (20hz-20khz) and the y-axis representing amplitude (level). In the above chart you can see a suggestion of the fundamental position for several instruments on the frequency spectrum. Something like the bass will typically be comprised of all low sounds and won’t have much presence in the high frequencies where the vocals are. Consequently these two elements often mix together easily and don’t compete for space in a mix. Drums and Bass however often occupy similar regions of the frequency spectrum and need to be managed with equalization and filtering. 2. What is Equalization and Filtering? https://drive.google.com/file/d/0B4I-xZfEjcKJNEs3MVE4VFdORjg/view?usp=sharing (Image) Equalization is the use of audio filters to alter the frequency response of an audio signal. A “filter” is an analog circuit designed to boost or cut audio at a specific frequency, a digital filter simply models this behaviour. Each “band” of an EQ is a filter, almost like a frequency specific volume knob. There are several different types of filters for each band. Here’s a video that utilizes several of the filter types on Ableton’s EQ Eight device to process a vocal: 3. Using EQ in Your Mix There are a few situations in which we will use EQ in almost every mix. The most common of these is likely using High Pass and Low Pass filtering to eliminate unnecessary frequencies. These types of filters reduce everything above or beneath a set cutoff point, literally letting lows or highs “pass through”. In the frequency spectrum example above you see the guitar fundamentally occupying the mid frequencies. The term “fundamental frequency” gets used a lot in reference to EQ and it typically pertains to the lowest frequency of a sound, which is also the basis for the harmonics of that sound (we’ll save this for an advanced EQ article). However, in this example we’re talking about the range of frequencies that give a sound it’s identity, the range that is most crucial for a clear reproduction of the sound. Because the guitar example above is most crucially heard in the mid range, we can utilize high pass filtering to cut out the unnecessary low frequencies and make more space for sounds that primarily occupy the low end (see below). https://drive.google.com/file/d/0B4I-xZfEjcKJZmY5RHpNaVB3ZFU/view?usp=sharing (Image) Alternatively we could use what’s called a “low shelf” (see below) which won’t entirely cut out the low end, but instead reduce everything beneath a specified cutoff point. https://drive.google.com/file/d/0B4I-xZfEjcKJMmpFTEFLa0w1RG8/view?usp=sharing (Image) This same concept applies for low pass filtering and high shelf eq. In the example of the guitar, we could likely utilize a gentle high shelf reduction to make more room for our percussion and vocal. Another common use for EQ is eliminating a specific frequency from a sound using a “bell” filter (shaped like a bell). Say we’ve located the frequency that best defines the thump of our kick sample, and we want to cut this frequency in the bass to blend the two sounds together. Here we could utilize a bell filter to slightly reduce a specific band of frequencies in the bass sound (see below). https://drive.google.com/file/d/0B4I-xZfEjcKJTEI5ZHBld3BoSGc/view?usp=sharing (Image) Alternatively, a few of the filter types mentioned above (low shelf, high shelf and bell) can also be used to boost the frequency range of a signal. In theory it makes more sense to cut out what you don’t want from sounds, rather than attempt to add to the sound by boosting frequencies. However, in some situations it can be critical to the overall balance of a sound to make slight boosts to compensate for cuts made elsewhere in our mix. 4. Further Learning These concepts outline some very basic ways in which we can use EQ. For further information and learning check out this overview tutorial below and continue reading some of these linked guides to advanced EQ and mixing techniques. Equalization Video:

Further Reading:

https://www.soundonsound.com/techniques/whats-frequency
https://www.uaudio.com/blog/multiband-eq-mix-fix/
http://downloads.izotope.com/guides/iZotope-Mixing-Guide-Principles-Tips-Techniques.pdf

Fonte: MetaPop: Basic Equalization – By su na