Crucial subtle refinements of frequency response are for the first time possible, allowing for an unequaled clarity of sound reproduction. The advantages of the Constant-Q design go far beyond yielding a more accurate picture they provide a degree of adjustment never before possible. Gone is the misleading picture formed by conventional designs: if a single slider is boosted 3 dB then only that 1/3-octave frequency band is being affected, unlike other equalizers where the real picture is over one octave wide. Finally, equalizers are available that are accurately 'graphic' in the picture formed by their slider positions. The new Constant-Q graphic equalizer circuit topology allows true 1/3-octave bandwidth control at all slider positions.

For true 'graphic' operation, and real control of a system's frequency response, this was an unacceptable design.

At all modest boost/cut positions the filter bandwidths exceeded one octave. Namely, that the bandwidth of the filters was a function of the slider position only at the extreme boost/cut positions were the filter bandwidths truly 1/3-octave wide. In 1982, Rane pioneered a new type of graphic equalizer called a Constant-Q Graphic Equalizer to solve one of the most annoying problems that plagued all previous 1/3-octave designs. Without equalizers the system is left without nearly enough controls to turn to try and correct for room difficulties, speaker anomalies, and individual performer preferences. They are an essential tool that every sound person keeps in their bag of tricks for establishing high quality sound.

Constant-Q Graphic Equalizers Dennis Bohn, Rane RaneNotes 101 & 117 combined written 1982 & 1987 last revised 11/05 Introductionįew would argue the necessity of equalizers for quality sound reinforcement systems.

Iso standard equalizer frequencies