Crate Amplifiers LS2-215, LS1-131, LS3-231 User Manual

User’s Guide

for the

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, please read this owners guide prior to its use.

“Thank You” from

LS1-131

LS3-231

LS2-215

LS1-131/LS2-215/LS3-231

Constant Q Graphic Equalizers

CAUTION

RISK OF ELECTRIC SHOCK

DO NOT OPEN

CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK,

DO NOT REMOVE COVER.

NO USER-SERVICEABLE PARTS INSIDE.

REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.

ATTENTION

RISQUE D'ELECTROCUTION

NE PAS OUVRIR

ATTENTION: POUR REDUIRE D'ELECTROCUTION NE PAS

ENLEVER LE COUVERCLE. AUCUNE PIECE INTERNE N'EST REPRABLE

PAR L'UTILISATEUR. POUR TOUTE REPARATION, S'ADRESSER A UN

TECHNICIEN QUALIFIE.

VORSICHT

ELEKTRISCHE SCHLAGGEFAHR

NICHT OFFENEN

VORSICHT: ZUR MINIMIERUNG ELEKTRISCHER SCHLAGGEFAHR NICHT

DEN DECKEL ABENHMEN. INTERNE TEILE KONNEN NICHT VOM

BENUTZER GEWARTET WERDEN. DIE WARTUNG IS QUALIFIZIERTEM

WARTUNGSPERSONAL ZU UBERLASSEN.

THIS EQUIPMENT HAS BEEN DESIGNED AND ENGINEERED TO PROVIDE SAFE AND RELIABLE OPERATION. IN ORDER TO PROLONG THE LIFE OF THE UNIT AND PREVENT ACCIDENTALDAMAGES OR INJURY, PLEASE FOLLOW THESE PRECAUTIONARY GUIDELINES:

CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT OPEN CHASSIS; DO NOT DEFEAT OR REMOVE THE GROUND PIN OF THE POWER CORD; CONNECT ONLY TO A PROPERLYGROUNDED AC POWER OUTLET.

WARNING: TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE. CAUTION: NO USER-SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.

"IT IS NECESSARY FOR THE USER TO REFER TO THE INSTRUCTION MANUAL" "REFERREZ-VOUS AU MANUAL D'UTILISATION" "UNBEDINGT IN DER BEDIENUNGSANLEITUNG NACHSCHLAGEN"

EXPLANATION OF GRAPHICAL SYMBOLS:

"DANGEROUS VOLTAGE" "DANGER HAUTE TENSION" "GEFAHLICHE SPANNUNG"

Table of Contents:

An Introduction to Equalizers........................................................3

The LS1-131/LS3-231 Front and Rear Panels ................................6

The LS2-215 Front and Rear Panels ..............................................7

Using an Equalizer........................................................................8

Applications:

Some Methods of Connection ...........................................9

Room Equalization ..........................................................10

Fletcher-Munson Equal Loudness Contours .....................10

Feedback Control ............................................................11

Creative or Enhancement Equalization ............................11

Technical Specifications .....................................back cover

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 quality 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 system and should be read through before using them.

LS1-131/LS2-215/LS3-231

Constant Q Graphic Equalizers

Figure 1: Constant Q Response:

200 500 1k 2k 5k

Amplitude (dB)

Frequency (Hz)

Inferior broad band filters: width of filter changes with amplitude.

200 500 1k 2k 5k

Amplitude (dB)

Frequency (Hz)

= lower frequency

= center frequency

= higher frequency

Constant "Q" filters: width of filter does not change with amplitude.

1k 2k

= lower frequency

= center frequency

= higher frequency

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).

These filters have a relatively low “Q” thus preventing “ringing”. Ringing occurs when a filter instantaneously 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.

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

-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

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