User Guide

Sound System Design Reference Manual
System Equalization and Power
Response of Loudspeakers
It is customary to equalize all professional
sound reinforcement systems for two reasons:
overall response shaping and control of feedback.
The overall response may be made smoother for a
more natural effect through the use of broadband
equalization and through the proper choice of drive
components themselves. Where high system gain is
required, narrow-band notch filters may successfully
remove the tendency of the system to “ring” at
certain frequencies. We will examine the
requirements of broad-band equalization first.
6-17
A sound system is equalized by feeding pink
noise (equal power per octave) into the system and
adjusting the system’s response to fit a preferred
contour at some point in the middle of the house. This
procedure is shown in Figure 6-17A. The response
contour most often used today is shown at B .
At the point in the house where the
measurement is made, the reverberant field
predominates, and what we are shaping with the
equalizer is actually the power response of the
loudspeaker as influenced by boundary absorption in
the room. If the loudspeaker’s power response is
smooth to begin with, then all is well. However, if, as
in some older designs, the system’s power response
is irregular, then equalization will usually make things
worse, as shown in Figure 6-18.
Figure 6-17. Sound system equalization procedure
Figure6-18. System equalization