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User’s Guide
for the
LS1-131
LS2-215
LS3-231
Constant Q Graphic Equalizers
Crate Pro Audio’s Live Sound Graphic Equalizers feature constant Q circuits which, unlike inferior broad band EQs, let
you boost or cut only the frequencies you choose. Combined with a switchable equalization range, these EQs allow greater
system control and accuracy whether using them for house coloration, feedback control, or speaker correction.
In order to achieve the highest level of performance from your equalizer, p
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LS1-131/LS2-215/LS3-231 Constant Q Graphic Equalizers Congratulations on the purchase of your new Crate Pro Audio Live Sound Graphic Equalizer. These outstanding devices have been designed with the audio professional in mind, providing the degree of accuracy and level of qual- ity you demand. Their ease of use and straight-forward design lend them to use by novices as well. This owner’s guide is designed to acquaint you with the workings of these equalizers and how they may be used in your sound
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LS1-131/LS2-215/LS3-231 Constant Q Graphic Equalizers 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
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LS1-131/LS2-215/LS3-231 Constant Q Graphic Equalizers 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). Figure 2: Q vs. Ringing: 1kHz TONE BURST 1kHz TONE BURST INPUT SIGNAL INPUT SIGNAL START START INPUT SIGNAL STOP INPUT SIGNAL STOP All three equalizers have a flat phase response (see Figure 3 below) for accurate sou
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LS1-131/LS2-215/LS3-231 Constant Q Graphic Equalizers The LS1-131/LS3-231 both feature variable Low Cut and High Cut controls. The low cut control is not only useful for subsonic filtering, but provides a wider range of control for low frequency “ringing” in some sub-woofer systems and controls “wind” noises in microphones. This filter is extremely useful in using amplifi- er power more efficiently. This is accomplished by eliminating inaudible subsonic frequencies below 30Hz from reaching the
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LS1-131/LS2-215/LS3-231 Constant Q Graphic Equalizers The LS1-131/LS3-231 Front and Rear Panels: NOTE: The LS1-131 is shown; the LS3-231 is identical, except it has two channels, one over the other, in a 2 rack-space enclosure. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 - POWER: Use this switch to turn the unit on and off. 2 - EQ SLIDERS: Use these slide controls to make adjustments at the standard ISO 1/3-octave frequencies indicated above each slider. Each slider adjusts the signal ±6dB or ±12dB depen
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LS1-131/LS2-215/LS3-231 Constant Q Graphic Equalizers The LS2-215 Front and Rear Panels: 1 2 3 4 5 6 2 4 4 5 6 7 8 8 7 9 10 11 12 1 - POWER: Use this switch to turn the unit on and off. 2 - EQ SLIDERS: Use these slide controls to make adjustments at the standard ISO 2/3-octave frequencies indicated above each slider. Each slider adjusts the signal ±6dB or ±12dB depending on the setting of the RANGE switch (#3). Moving a slider up boosts the signal; moving it down cuts the signal. The center dete
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LS1-131/LS2-215/LS3-231 Constant Q Graphic Equalizers Using an Equalizer: Mixing and equalizing music requires an experienced ear and knowledge of the different tonal characteristics of each instrument. The voice characteristics of some common instruments are compared to a conventional 88-note piano keyboard in figure 5 below. As indicated on the chart, the piano has the widest frequency range among the instruments shown. This makes the comparison easier to understand. For instructional purpose
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LS1-131/LS2-215/LS3-231 Constant Q Graphic Equalizers Upper-Mid Range: (4kHz-8kHz) This region is the “presence” range which can determine whether the mix or instrument is “harsh” and “piercing” or “distant” and “muffled”. This range will also help voices and other instruments cut through a mix when boosted. When high frequency “feedback” occurs, this region is one of the most critical in eliminating it. High Range: (8kHz-20kHz) High end, as it is usually perceived, is actually below 12kHz. Howe
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LS1-131/LS2-215/LS3-231 Constant Q Graphic Equalizers APPLICATIONS: SOME METHODS OF CONNECTION (Continued): Figure 8: In-Line Between a Mixer and Amplifier: MIXER (OR PREAMP) POWER AMPLIFIER EQUALIZER Output signal from BALANCED OUTPUT mixer/preamp jack of equalizer SPEAKER OUTPUT connects to connects to INPUT jack of power amplifier BALANCED INPUT jack of power amplifier connects to INPUT jack of equalizer jack of speaker APPLICATIONS: ROOM EQUALIZATION: Any sound system, whether it is a ho
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LS1-131/LS2-215/LS3-231 Constant Q Graphic Equalizers Figure 9: Fletcher-Munson Equal Loudness Contours: 140 LOUDNESS LEVEL IN PHONS 120 120 200 110 100 100 20 90 80 80 2.0 70 60 60 0.2 50 40 40 0.02 30 20 20 0.002 10 0 0 0.000 20 100 1000 10,000 FREQUENCY IN Hz FEEDBACK CONTROL: Feedback can be a major problem in live sound reproduction. Feedback occurs when an outgoing signal finds its way back into the system via a microphone or a guitar pickup and gets re-amplified. The outgoing signal is t
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LS1-131/LS2-215/LS3-231 Constant Q Graphic Equalizers Technical Specifications Filters LS1-131: 1x31 Constant Q Multiple-feedback 1/3 octave ISO spacing from 20Hz to 20kHz LS2-215: 2x15 Constant Q Multiple-feedback 1/3 octave ISO spacing from 20Hz to 20kHz LS3-231: 2x31 Constant Q Multiple-feedback 1/3 octave ISO spacing from 25Hz to 16kHz Center Frequencies, Hz (±3%) LS1-131/LS2-231: 20, 25, 31.5, 40, 50, 63, 80, 100, 125, 160, 200, 250, 315, 400, 500, 630, 800, 1k, 1.25k, 1.6k, 2k, 2.5k, 3.15
