Meyer Sound Laboratories, Inc.
2832 San Pablo Avenue
Berkeley, CA 94702
Operating Instructions
CP-10S
Complementary
Phase
Parametric
Equalizer
Example of
Complementary Phase
Equalization
Effective equalization of loud-
speaker/room resonances re-
quires exact and opposite match-
ing with anti-resonance circuitry.
An example is shown here of the
correction of a response curve
aberration caused by reflection
from a single surface adjacent to
a loudspeaker under test (half-
space loading). All measurements
have been made with Meyer
Sound’s SIM
®
System II.
Figure 1
The test loudspeaker is first
measured in near-free space
conditions (on a stand approxi-
mately six feet off the ground,
away from all other reflecting
surfaces). The upper window
displays the amplitude re-
sponse, and the lower the
phase response. Frequency
resolution is third-octave. The
loudspeaker exhibits very flat
response in both amplitude and
phase.
Figure 2
This display shows the impulse
response (amplitude vs time) of
the test loudspeaker under the
same near-free field conditions.
The upper window is a ±560
msec span, and the lower
window shows the same data
zoomed to a ±56 msec span.
The loudspeaker exhibits a
very controlled and coherent
impulse response.
Figure 3
The loudspeaker is now placed
with its back against a wall,
again at approximately six feet
off the ground. This frequency
response measurement illus-
trates the low-frequency (below
500 Hz) aberrations that half-
space loading typically causes.
Disruptions appear in both the
amplitude and the phase trace.
