Constant Q Vs. Variable Q - Alesis DEQ224 Reference Manual

3
Basics of Equalization

Constant Q vs. Variable Q

What makes the DEQ224 unique?
At their inception, graphic equalizers relied solely on a form of
equalization known as "Variable Q." The DEQ224, on the other
hand, is what is known as a "Constant Q" equalizer. This method
of equalization is a relatively recent development in the history of
sound reinforcement and recording technology. As you will see
illustrated in the charts in this section, the Constant Q method
allows for a higher degree of control over the sound being
processed because of its significantly greater accuracy.
Before we go any further, it's time for some definitions:
Q
Variable Q
Constant Q
It may help to define these terms visually as well.
In the following illustration, we see the three basic terms that
govern the operation of a single band. The vertical bar of the
graph represents decibels of cut/boost, and the horizontal bar
represents frequency in Hz. The dotted line leading to the center
of the curve indicates the frequency at which this band is set. You
can see that in this example, Q covers a range of frequencies from
about 200 Hz to about 5 KHz.
44
The range of frequencies affected by a
band
A process in which the range of
frequencies affected by a band changes as the
amount of gain is cut/boosted
A process in which the range of
Frequencies affected by a band stays the
same as the amount of gain is
cut/boosted