Mixing : Equalizers

Eq it is one of the least understood aspects of recording and mixing probably

EQ is a change in the volume of a particular frequency of a sound, similar to the bass and treble tone controls on a stereo. it is one of the least understood aspects of recording and mixing probably because there is such a large number of frequencies - from 20 to 20,000 HZ. The real difficulty comes from the fact that boosting or cutting the volume of any one of these frequencies depends on the structure of the sound itself: Each one is different. But even more complex is the fact that different sounds are equalized differently depending o the type of music, the song, end even the people you are working with.

First you m st learn all the frequencies or pitches by name. Then, you will see how boosting or cutting a certain frequency affects different instruments in different ways.

Types of equalizers

There are three main types of equalizers found in the recording studio: graphics, parametrics, and rolloffs (highpass and lowpass filters).

Graphics

Each frequency can be turned up or down by using the volume sliders on a graphic equalizer. The voume controls on an equalizer are called bands. There are different kinds of graphic equalizers that can divide frequencies from five bands up to 31 bands. Five to 10 band graphic equalizers are commonly found in car stereos. Thirty-one band graphics (which will change the volume at 31 different frequencies) are common in recording studios and live sound reinforcement.

Band Graphic EQ

The primary advantage of a graphic equalizer is that you can make changes in a volume at a number of different frequencies. Graphic EQs got their name from the visual display that's easy to read for reference. (However , these days, you get a much nicer display on a digital parametric EQ.) Also, since the frequencies are mapped out visually from left to right, it is easy to find and manipulate the volume of any particular frequency.

Many people don't realize that when you turn up a particular frequency from a graphic, you are actually turning up a range of frequencies preset by the manufacturer. For example if you turn up 1000 hz, you might actually be turning up a frequency range from around 300 to 50000Hz.

Bandwidth on a graphic EQ

This range of frequencies is called the bandwidth and is preset by the manufacturer. You have no control over the bandwidth on a graphic. Generally, the more bands (or volume controls) there are, the thinner the bandwidth. Therefore a 31-band graphic EQ will have a more precise frequency range for each slider than a 5-band graphic. If you turn the volume of 1000Hz on a 5-band graphic you could be turning up from 100 to 10,000Hz.

Frequency works as a function of up and down, so higher frequencies are reproduced by the tweeters in our speakers and these are placed higher than the subwoofers who usually go at the bottom.

Parametrics

Engineers want to be able to control the range of frequencies, or bandwidth, they are turning up or down. With a parametric, the bandwidth knob gives you control over the width of the frequency range being manipulated. The knob is usually called "Q" because the word "bandwidth" won't fit on the knob ("Q" stands for "quality", which is an electrical term for bandwidth). A thin bandwidth is normally labeled with a peak, whereas a wide bandwidth is often labeled with a hump. Sometimes ranges of musical octaves are used to define the bandwidth - for example from 0.3 octaves to 3 octaves wide. Sometimes a scale of 1-10 or 10-1 (it's not standardized on consoles) is used.

Wide and narrow Bandwidths on Parametric EQ

On a graphic equalizer, you select the frequency by moving your arm left to right to place your hand on the correct volume slider. On a parametric EQ, you select the frequency by turning the "frequency sweep" knob with two fingers. A separate volume knob is then used to turn the chosen frequency up or down.

Paragraphics

Some less expensive consoles have equalizers with frequency sweep knobs but do not have bandwidth knobs. This type of equalizer is commonly referred to as semi-parametric, or paragraphic. Be careful, though; these days some manufacturers and certain salespeople are now using the term "parametric" to refer to a paragraphic or semi-parametric, even though it has no bandwidth control.

Rolloffs

A rolloff EQ turns down the volume of low or high frequencies. They are commonly found on consoles as highpass and lowpass filters. Larger consoles often have sweepable or variable rolloff knobs so that more of the lows or highs are rolled off. Smaller consoles often have only a button that rolls off a preset amount of lows or highs. A highpass filter rolls off the low frequencies but does nothing to the highs; it passes them.

Highpass filters are especially helpful in getting rid of low-frequency sounds, such as trains, planes, trucks, air conditioners, earthquakes, bleed from bass guitars or kick drums, and serious foot stomping.

Highpass filters can be found on microphones and smaller mixing consoles as switches that simply roll off the lows when the switch is engaged.

A lowpass filter rolls of the hight frequencies and is especially helpful in getting rid of hiss on sounds that don't have a lot of highs in them, such as bass guitar. Lowpass filters are also used to roll off the high frequency attack (click) of a kick drum in order to make it sound more like the classing rap kick drum sound.

You can read more about the most important things you need to know about mixing, and how to setup the compressors properly depending on the task you want to realize in Dave Gibson's book "The Art of Mixing 2nd Edition" A visual guide to recording engineer and production.