What Does A Graphic Equalizer Do
Marine Farinha
A graphic equalizer (graphic EQ) is a high-fidelity audio control that enables the user to improve sound quality. Sound quality captured by sources, such as microphones and instrument pickups, is adjusted by changing the individual frequency bands of the audio.
Audio equalization itself is a process of adjusting the frequency balance within an electrical signal. The primary use of EQs is to adjust the frequency response of audio, which is done by boosting or cutting the energy of different frequency ranges -- or bands. This process is generally simple and can affect the quality of the audio. Musicians or audio engineers use EQs to balance different elements of a song and create more clarity within the audio.
The graphic equalizer got its name for the way its slide controls resemble a graph -- with the EQ's response and frequency on the Y and X axis accordingly. Graphic EQs are commonly found in car audio speaker systems, home theaters, recording studios and middle- and high-end stereophonic audio systems. Graphic equalizer programs are also available for use in fine-tuning sound in a PC. They are well-suited for live sound environments, where an engineer can make quick decisions with clearly marked sliders.
Graphic EQs work by boosting or cutting predetermined bands to improve sound quality. The bands are set within a fixed range. Graphic EQs send incoming audio to a set of filters that pass audio based on their assigned band. The user moves up or down the slide controls labeled in decibels to boost or cut the energy passed through each band. The slide potentiometers for each channel are placed side by side, with the lowest frequency on the left and the highest frequency on the right. In this way, the positions of the buttons appear to follow a graphical curve. There are also various types of EQs, with graphic EQs being just one type.
A typical graphic equalizer consists of several audio filters or amplifiers, each centered at a specific frequency in the audio range. Most graphic EQs have two identical sets of filters or amplifiers, one for each channel in a stereophonic sound system. Incoming audio is sent to a set of filters that pass audio based on frequency range. The user can boost or cut the energy passed by each band by using the slider controls.
Graphic EQs typically divide sound into six or 31 bands of frequency, with a slider controlling each band. The number of filters used depends on the EQ. For example, EQs with filters spaced one-third of an octave apart with three filters to an octave would be a one-third octave equalizer. The more filters per octave, the more control the user has over EQ responsiveness. For example, the center frequency of each band in a 31-band graphic equalizer is one-third of an octave apart from the center frequencies.
If the treble is too loud on a track, for example, cutting one of the higher frequency bands can soften it. Likewise, if there is too much bass, lowering a slider on one of the lower frequency bands will fix it. However, making just slight adjustments can change the sound significantly.
High-pass and low-pass filters are used to set limits. High-pass filters cut low frequencies while letting high frequencies pass through, and low-pass filters cut high frequencies while enabling low frequencies to pass through. So, for example, producers can use high-pass filters to cut the low basses, while using low-pass filters to avoid higher frequency sounds like cymbals from bleeding. Bleeding occurs when one audio source output leaks into another audio source's input.
Parametric equalizers are multi-band variable equalizers that enable the user to control each band's amplitude, center frequency and bandwidth. Parametric EQs boost and cut amplitude, shift the center frequency up or down, and widen or narrow the bandwidth of each band. This type of EQ enables precise adjustments and audio engineers can pinpoint particular frequencies in recording and mixing studios.
Parametric EQs are more complex than graphic EQs, since they can make more fine-tuned and specific adjustments. Where a graphic EQ only has control over a fixed set of frequencies, parametric EQs can control the following:
This article was co-authored by Jason Williams and by wikiHow staff writer, Travis Boylls. Jason Williams is an AV & Security Specialist and the Owner of Williams AV & Security. With more than 35 years of experience, he specializes in home automation and home theater system installations. Jason is an AVIXA Certified Technology Specialist, a CEDIA Certified Cabling & Infrastructure Technician, a Pakedge Certified Network Administrator, and holds a Georgia Low Voltage Unrestricted License.
This article has been fact-checked, ensuring the accuracy of any cited facts and confirming the authority of its sources.
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A graphic equalizer, more commonly known as an EQ, is used to change the frequency response of selected sounds, such as particular instruments or vocals in an audio track. It can be used to enhance the bass, reduce the treble, highlight a saxophone, or just make your audio sound better overall. EQs can be used in home audio or live sound. An EQ can be connected to audio equipment or physical hardware, or it may be a program on your computer. Once you get a handle on the basic operation of your EQ model, you can use it to make simple audio adjustments, then get into more detailed audio fine-tuning. This wikiHow article teaches you how to use a graphic equalizer.
Equalization, or simply EQ, in sound recording and reproduction is the process of adjusting the volume of different frequency bands within an audio signal. The circuit or equipment used to achieve this is called an equalizer.[1][2]
The concept of equalization was first applied in correcting the frequency response of telephone lines using passive filters; this was prior to the invention of electronic amplification. Initially, equalization was used to compensate for the uneven frequency response of an electric system by applying a filter having the opposite response, thus restoring the fidelity of the transmission. A plot of the system's net frequency response would be a flat line, as its response at any frequency would be equal to its response at any other frequency. Hence the term equalization.
Later the concept was applied in audio engineering to adjust the frequency response in recording, reproduction, and live sound reinforcement systems. Sound engineers correct the frequency response of a sound system so that the frequency balance of the music as heard through speakers better matches the original performance picked up by a microphone. Audio amplifiers have long had filters or controls to modify their frequency response. These are most often in the form of variable bass and treble controls, and switches to apply low-cut or high-cut filters for elimination of low-frequency rumble and high-frequency hiss respectively.
Graphic equalizers and other equipment developed for improving fidelity have since been used by recording engineers to modify frequency responses for aesthetic reasons. Hence in the field of audio electronics the term equalization is now broadly used to describe the application of such filters regardless of intent. This broad definition, therefore, includes all linear filters at the disposal of a listener or engineer.
A British EQ or British style equalizer is one with similar properties to those on mixing consoles made in the UK by companies such as Amek, Neve and Soundcraft[4] from the 1950s through to the 1970s. Later on, as other manufacturers started to market their products, these British companies began touting their equalizers as being a cut above the rest. Today, many non-British companies such as Behringer and Mackie[5] advertise British EQ on their equipment. A British style EQ seeks to replicate the qualities of the expensive British mixing consoles.
Filtering audio frequencies dates back at least to acoustic telegraphy[6] and multiplexing in general. Audio electronic equipment evolved to incorporate filtering elements as consoles in radio stations began to be used for recording as much as broadcast. Early filters included basic bass and treble controls featuring fixed frequency centers, and fixed levels of cut or boost. These filters worked over broad frequency ranges. Variable equalization in audio reproduction was first used by John Volkman working at RCA in the 1920s. That system was used to equalize a motion picture theater sound playback system.[7][8]
The Langevin Model EQ-251A was the first equalizer to use slide controls.[when?] It featured two passive equalization sections, a bass shelving filter, and a pass band filter. Each filter had switchable frequencies and used a 15-position slide switch to adjust cut or boost.[9] The first true graphic equalizer was the type 7080 developed by Art Davis's Cinema Engineering.[when?] It featured 6 bands with a boost or cut range of 8 dB. It used a slide switch to adjust each band in 1 dB steps. Davis's second graphic equalizer was the Altec Lansing Model 9062A EQ. In 1967 Davis developed the first 1/3 octave variable notch filter set, the Altec-Lansing "Acousta-Voice" system.[8]
Daniel N. Flickinger introduced the first parametric equalizer in early 1971. His design leveraged a high-performance op-amp of his own design, the 535 series[11][failed verification] to achieve filtering circuits that were before impossible. Flickinger's patent from early in 1971[12] showed the circuit topology that would come to dominate audio equalization until the present day, as well as the theoretical underpinnings of the elegant circuit. Instead of slide potentiometers working on individual bands of frequency, or rotary switches, Flickinger's circuit allowed arbitrary selection of frequency and cut or boost level in three overlapping bands over the entire audio spectrum. Six knobs on his early EQs would control these sweepable filters. Up to six switches were incorporated to select shelving on the high and low bands, and bypassing for any unused band for the purest signal path.
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