Filter
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These filters have a relatively low “Q” thus preventing “ringing”. Ringing occurs when a filter instantaneous-
ly receives an input signal and hangs on to the signal for a period of time after it has stopped (see Figure 2
below).
All three equalizers have a flat phase response (see Figure 3 below) for accurate sound reproduction
with no coloration to your speaker system. This maintains pure stereo imaging without the “comb filter”
effect. As your ear passes across the stereo plane of your system, the comb filter effect sounds like “peaks”
and “nulls” in the response which can change the imaging dramatically.
4
LS1-131/LS2-215/LS3-231
Constant Q Graphic Equalizers
Figure 2: Q vs. Ringing:
1kHz TONE BURST
INPUT SIGNAL
STOP
INPUT SIGNAL
START
1kHz TONE BURST
INPUT SIGNAL
STOP
INPUT SIGNAL
START
Figure 3: Phase Response:
PHASE (Degrees)
180
150
120
90
60
30
0
-30
-60
-90
-120
-150
-180
10 20 50 100 200 500 1k 2k 5k 10k 20k
FREQUENCY (Hz)
Smooth, flat phase
response of the
Crate Pro Audio
equalizers
Example of an extremely
bad phase response,
typical of some "other"
equalizers