Three Band Equalizer - part 2

In addition to bass and treble controls, you may find 'mid' controls, such as the 3-band equalizers commonly found on mixers. As you may guess, this affects frequencies 'in between' the highs and lows. This is often referred to as a peaking or band pass filter. Again, it generally does not attempt to isolate certain frequencies, but rather boost or cut a small portion of the audio spectrum without affects the other frequency bands. This type of filter generally does not have a defined cutoff frequency, but is instead defined by two other characteristics. The frequency at which the peaking filter is at its maximum (or when cutting the signal, the minimum) gain is called the center frequency. The other important characteristic is the bandwidth which basically means how wide the peaking filter is (how wide of a frequency range it affects). Generally you are only able to adjust the boost or cut, and the center frequency and bandwidth are fixed.