Equalizers are audio devices used to tailor the sound from an amplifier, including home stereo systems, PA (public address) systems, and car audio. Equalizers give more control over a sound's tone than can be achieved by using simple treble and bass controls. The audio spectrum is divided into various bands of frequencies, allowing custom volume control of each band. Simple equalizers may have as few as five bands, while more advanced models can divide up to 31 bands (1/3 octave) for pinpoint-accurate control.
Equalizer Uses
Equalizers can be used to adjust a sound's tone to the preference of the listener. Many people like accented bass or brighter high frequencies. This depends on the listener and the type of audio material that is being played. Equalizers are also used to compensate for poor recordings. For example, if a vocal was recorded too low in volume, boosting the mid-range frequencies may bring it more to the forefront. One of the traditional applications for equalizers is to compensate for acoustic characteristics of the listening environment. In a home stereo system, an equalizer can overcome specific frequency problems that a room may affect. Thick carpet, drapes on the walls, large glass window surfaces, upholstered furniture and other room elements affect how audio material will sound in a room. An equalizer can boost or cut various frequency bands to compensate for room acoustics.
Graphic And Parametric Equalizers
With graphic equalizers, the center frequency of each band is fixed. Knobs or sliders control the volume within that specific band. Parametric equalizers allow the center frequency within each band to be changed, in addition to the band's volume. This gives extremely fine control over the shape of a sound.
Analog And Digital Equalizers
Analog equalizers typically have a front panel with vertically mounted slide controls, each dealing with a specific band of frequencies. Controls go from left to right, adjusting low to high frequencies. The vertical center position of each slider is for a "flat" response, that is, no change to that particular band. Lowing a slide control "cuts" or reduces the volume of frequencies in that band, and raising it "boosts" or amplifies them. Due to this physical front panel layout, analog equalizers make it easy to visually see the EQ curve setting at a glance. Digital equalizers for professional use can be computer-based software designed to work alone or can be built within digital audio recording systems, such as ProTools and Apple's Logic programs. Alesis manufactures a rack-mounted digital equalizer that has the appearance of a front panel analog unit, with lights indicating the level position of each band. Levels are changed by simply pushing buttons, and presets can recall complete setting quickly. Digital equalizers can also be found on CD and stereo players for cars, using an LCD screen to make adjustments to the various bands.
Equalizers For Car Audio
Listening to music in a vehicle creates a unique set of environmental characteristics. Cars that have a lot of glass surface areas, which are reflective, will accent high frequencies. Thick carpeting absorbs sound, and some truck cabs are lined with carpet. The rumble of the road adds low frequency sounds to the listening environment. Traffic and other outside noise also makes a low "signal-to-noise ratio," that is, the level of the audio material compared to the level of ambient sounds. All of these factors make equalizers for vehicles an especially useful tool. Car equalizers are available for mounting under or in the dash, and some models are universal, while others are designed to work with specific manufacturers. Often, newer car audio systems will have digital equalizers built in.
Proper Settings
Often, people like to boost highs and lows, as a personal preference, which creates a "smiley face" pattern on the front panel of an analog equalizer. However, this may not necessarily be what sounds best. Your ears are good tools for setting the controls on an equalizer. Start by placing all controls at the "flat" position. Play several songs representing the type music that you usually listen to, while slowly adjusting each frequency band a little at a time. Boosting a band is not always an improvement. Sometimes cutting helps, as in the case where recordings have excessive high frequencies already boosted on a vocal. Don't make drastic changes to levels without giving your ears some time to listen to the results of new settings.
Tags: each band, front panel, high frequencies, audio material, center frequency, control over