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LS1-131/LS2-215/LS3-231
Constant Q Graphic Equalizers
Figure 1: Constant Q Response:
0
200 500 1k 2k 5k
200 500 1k 2k 5k
Amplitude (dB)
Frequency (Hz)
Inferior broad band filters:
width of filter changes with
amplitude.
0
200 500 1k 2k 5k
200 500 1k 2k 5k
Amplitude (dB)
Frequency (Hz)
ƒ
L
ƒ
L
= lower frequency
ƒ
C
= center frequency
ƒ
H
= higher frequency
Constant "Q" filters: width
of filter does not change
with amplitude.
ƒ
H
ƒ
C
1k 2k
ƒ
L
ƒ
L
= lower frequency
ƒ
C
= center frequency
ƒ
H
= higher frequency
ƒ
H
ƒ
C
ƒ
L
ƒ
H
An Introduction to Equalizers:
The Crate Pro Audio Live Sound Graphic Equalizers are available in two mounting configurations: a 1-3/4”
single rack space (LS1-131/LS2-215) and a 3-1/2” double rack space (LS3-231). These equalizers are a perfect
addition to any professional sound system, particularly the Crate Pro Audio systems.
The Crate Pro Audio LS1-131/LS2-215/LS3-231 equalizers offer precision control of the audio spectrum.
Some features of these equalizers include:
• Balanced and unbalanced inputs and outputs
• Constant “Q” bandpass filter sets for precision control
• Two control ranges for greater accuracy
• Hardwire switchable bypass from input jacks to output jacks for total elimination of the
equalizer from the system
• Peak LEDs to obtain optimal signal levels
• High signal-to-noise ratio (greater than 94dB) and a wide frequency response (20Hz to
20kHz)
• Flat phase response for accurate reproduction and stereo imaging
• Very low THD (less than 0.01%)
• Maximum input level of +22dBm
• Variable low cut and high cut controls (LS1-131/LS3-231 only)
• Built in power supply
The LS1-131 and LS3-231 provide 31 bands of equalization at standard ISO center frequencies, 1/3
octave apart. They cover the entire audio spectrum from 20Hz to 20kHz. This allows precision control and
fine tuning of your audio system. (The LS3-231 offers two channels of 31 band equalizers.) The LS2-215
provides two channels of 15 band equalization at standard ISO center frequencies, 2/3 octave apart from
25Hz to 16kHz.
All of the new Crate Pro Audio Live Sound Equalizers incorporate constant “Q” multiple-feedback
bandpass filter sets for high resolution with minimal interaction between bands (see Figure 1 below).