Equalizer

Equalizers (EQ) essentially, help modify the frequency envelope of a sound, though this term is sometimes applied to audio filters. Equalizers help balance and clear distorted signals during their transmission. Depending on the pattern of attenuation or boost, there are different kinds of equalizers. A 'peaking EQ' is used to raise or lower frequency ranges around a bell-shaped central point. A 'parametric EQ' is a peaking EQ with controls to adjust the 'Gain', the bandwidth (Q) and the center frequency. If the controls for the bandwidth are not given, then the bandwidth is fixed by the manufacturers, these are called quasi or semi-parametric EQ. Pass filters attenuate high frequencies and stop lower frequencies at a certain point, it's defined by its slope, or decibels/octave. 'Shelving EQ' attenuate a vast range of frequencies, but only to certain levels. A 'low-shelving EQ' will change low frequencies, while 'high-shelving EQ' will change the level of the higher frequencies. The most common type of equalizers is the graphic EQ which consist of a range of band-pass filters, with their independent gain control. These bands cover a range from around 20Hz to 20kHz, also the range of hearing of a human. The 4-band equalizers have bands at 20Hz, 200Hz, 2kHz and 20kHz. The EQ used for studio recordings and live performances have as many as 31 bands. Equalizers are used to make certain that no frequency bands have a round trip gain greater than 1, since these cause feedback. They are used in sound studios and live performances to make sure that the microphones and instruments sound clear and crisp. DJs also use EQ while mixing music. Popular graphic and parametric EQ brands are Alesis, Rane, Power Acoustik, Pyle, Audio Source and Technics.