Electro-Voice EQ-131 User manual

Description
The Electro-Voice EQ-131 is a boost and cut
1/3-octave graphic equalizer whose primary
use is for tuning the overall frequency re-
sponseofasoundreinforcementsystem,both
toincreasegain-before-feedbackandto com-
pensate for the deficiencies in the acoustic
environment and the sound system.
Features
The variable-Q active filter sets used in the
EQ-131 allow effective equalization with
few problematic side effects. As Figure 1 il-
lustrates, the filter characteristics vary with
the amount of boost or cut used. At low con-
trol settings, the filter Q is very wide. As the
control is boosted or cut, the filter Q nar-
rows so that there is minimum interaction
between adjacent frequency bands. The fil-
ter response is designed to affect a 1/3-octave
range. Many graphic equalizer designs have
filters in which the Q, or sharpness of the
filter, varies depending on the amount of
boost or cut used. In most cases, the Q is
very low when small corrections are set and
the affected frequency range goes beyond
even the adjacent filter controls. In these
designs, when a large amount of boost or cut
is used, the filter skirt spreads out and influ-
ences a larger frequency range so that adja-
cent controls must be readjusted.
Each of the 31 1/3-octave filters provides 12
dB of boost or cut at ISO frequencies 20
through 20,000 Hz. The faders have a posi-
tive detent in the center, flat-response posi-
tion.
The gain control also has a center detent at
unity gain. It should be adjusted so that the
adjacent peak LED rarely or never lights.
This will help achieve maximum possible
signal-to-noise ratio.
The infrasonic low-cut filter, with a 43-Hz
corner frequency and a slope of 18 dB per
octave, is engaged by the front-panel Lo-Cut
switch. For most applications, the filter
should be engaged. Most professional
speaker systems have little output below 45
Hz.Atbest, driving them in this rangewastes
amplifier power, and can result in excessive,
ultra-low-frequency cone motion which dis-
torts the output in the reproduced frequency
range and, most seriously, could damage the
speakerfrom excessive cone motion or “bot-
toming.”
The range select switch allows selection of
either 6 or 12 dB of boost and cut. The 6-dB
range will allow more control selectivity
while the 12-dB range allows for greater
range of adjustment.
The EQ-131 has a IEC connector to allow
compatibilitywith ac connections anywhere.
The integral fuseholder also doubles as the
voltage selector to allow for operation any-
where in the world.
Architects’ and
Engineers’ Specifications
The equalizer shall have 31 filters centered
at the ISO standard 1/3-octave frequencies
between 20 and 20,000 Hz. The filters shall
provide either 6 or 12 dB of boost or cut and
be set by 22.5-mm linear controls. The front
panel shall have the following controls: a
gain control that is continuously variable
from -12 dB to +12 dB from unity gain; a
high-pass filter with a slope of 18 dB per
octave and a corner frequency of 43 Hz; a
range switch to select either 6 or 12 dB of
boostor cut from the filters; anEQ-on switch
to put the filters in the signal path and an on/
off switch.
The rear panel shall have the input and out-
put connectors, a ground-lift switch and a
IEC connector with an integral fuse holder
that allows voltage selection by the way it is
inserted.
The input and output of the equalizer shall
beaccessiblevia3-pinXLR-typeand1/4-inch
EQ-131
Mono One-Third Octave
Graphic Equalizer
• 31 1/3-octave filters for effective
sound system equalization
• Switchable infrasonic filter and
ground-lift
• Selectable (6 or 12 dB) range of
boost/cut
• Active-balanced 3-pin XLR-type
and TRS 1/4-inch inputs
• Space saving single rack space
chassis with internal power
supply with IEC connector

EQ-131/Graphic Equalizer
EQ-131/Graphic Equalizer
2
TRS phone jacks located on the rear of the
unit. The input shall be actively balanced.
The output shall be balanced on the 3-pin
XLR-type plug.
The equalizer shall meet or exceed the fol-
lowing performance specifications: fre-
quency response at unity gain, …1 dB 20 -
20,000Hz;totalharmonicdistortionlessthan
0.01%,20 - 20,000 Hzat 0 dBu; anoise level
of less than -97 dBu; gain of ±6 dB or ±12
dB; balanced-input impedance of 44,000
ohms; output impedance of 120 ohms; a
maximum input level of +20 dBu at unity
gain; a maximum output level of 20 dBu into
loads greater than or equal to 600 ohms.
The equalizer shall operate on 120 V / 240
V ac, 50/60 Hz, and consume less than 18
watts. The unit shall be operable over the
temperaturerangeas high as 50 degrees Cen-
tigrade or 122 degrees Fahrenheit. The chas-
sis shall be steel with a gray front panel and
black top, bottom, sides and back with white
nomenclature. The chassis shall occupy one
rackspacein a standard 19-inch rack (height:
1.73 inches; depth: 9.24 inches; width: 19
inches). The weight shall be 7 lbs. (3.4 kg).
The equalizer shall have a three-year parts
and labor warranty. The equalizer shall be
the Electro-Voice EQ-131.
Limited Warranty
Electro-Voice products are guaranteed
against malfunction due to defects in mate-
rials or workmanship for a specified period,
as noted in the individual product-line
statement(s)below,or in the individual prod-
uct data sheet or owner’s manual, beginning
with the date of original purchase. If such
malfunction occurs during the specified pe-
riod, the product will be repaired or replaced
(at our option) without charge. The product
will be returned to the customer prepaid. Ex-
clusions and Limitations: The Limited
Warranty does not apply to: (a) exterior fin-
ish or appearance; (b) certain specific items
described in the individual product-line
statement(s)below,or in the individual prod-
uct data sheet or owner’s manual; (c) mal-
function resulting from use or operation of
the product other than as specified in the
product data sheet or owner’s manual; (d)
malfunction resulting from misuse or abuse
of the product; or (e) malfunction occurring
at any time after repairs have been made to
the product by anyone other than Electro-
Voice Service or any of its authorized ser-
vice representatives. Obtaining Warranty
Service: To obtain warranty service, a cus-
tomer must deliver the product, prepaid, to
Electro-Voice Service or any of its autho-
rized service representatives together with
proof of purchase of the product in the form
of a bill of sale or receipted invoice. A list of
authorized service representatives is avail-
able from Electro-Voice Service at 600 Cecil
Street, Buchanan, MI 49107 (800/234-6831
or FAX [phone]). Incidental and
Consequential Damages Excluded: Prod-
uct repair or replacement and return to the
customer are the only remedies provided to
the customer. Electro-Voice shall not be li-
ablefor any incidental or consequential dam-
ages including, without limitation, injury to
persons or property or loss of use. Some
states do not allow the exclusion or limita-
tion of incidental or consequential damages
so the above limitation or exclusion may not
apply to you. Other Rights: This warranty
gives you specific legal rights, and you may
also have other rights which vary from state
to state. Electro-Voice Electronicsareguar-
anteed against malfunction due to defects in
materials or workmanship for a period of
three (3) years from the date of original pur-
chase. Additional details are included in the
Uniform Limited Warranty statement.
For warranty repair or service informa-
tion, contact the service repair department
at: 616/695-6831 or 800/685-2606.
Fortechnical assistance, contact Technical
Support at 800/234-6831 or 616/695-6831,
M-F, 8:00 a.m. to 5:00 p.m. Eastern Stan-
dard Time.
Specifications subject to change without
notice.

EQ-131/Graphic Equalizer
EQ-131/Graphic Equalizer
3
FIGURE 1 — Filter Characteristics at
1,000 Hz (±12 dB) FIGURE 2 — ±12 dB control settings
FIGURE 3 — Lo-Cut filter roll-off
characteristics FIGURE 4 — EQ on, 12 dB range,
ground switch “grounded”

EQ-131/Graphic Equalizer
EQ-131/Graphic Equalizer
4
ELECTRONICS–Graphic Equalizer Part Number 532249— 9937
600 Cecil Street, Buchanan, MI 49107
616/695-6831, 616/695-1304 Fax
©EVI Audio 1999 • Litho in U.S.A.
Operating Environment:
Up to 50° C (122° F)
Power Requirements:
110 or 220 V ac, 50/60 Hz, 18 watts
Overall Dimensions (see Figure 1):
44 mm (1.73 in.) high;
483 mm (19.0 in.) wide;
235 mm (9.24 in.) deep
Net Weight:
3.4 kg (11.5 lb)
Input Specifications
Type:
Electronically balanced
Impedance,
Unbalanced:
22,000 ohms
Balanced:
44,000 ohms
Maximum Input Level at Unity Gain:
+20 dBu (7.75 V rms)
Connectors,
Type:
Parallel female 3-pin XLR-type
and 1/4-in. phone jack TRS, balanced
or unbalanced
XLR-typeConnector Format (IECStan-
dard 268):
Pin 1 shield;
Pin 2 high;
Pin 3 low
General Specifications
Conditions:
1. 0dBu = 0.775 volts rms.
2. 120 volt ac line input voltage
maintained for all tests unless noted.
Frequency Response at Unity Gain,
High-Pass Filter Disengaged:
20 Hz - 20,000 Hz … 1 dB
TotalHarmonicDistortion at UnityGain,
20 - 20,000 Hz, 0 dBu Output:
<0.01%
Noise at Unity Gain:
>97 dBM A-weighted
Front-Panel Controls:
31 center-detent boost/cut slide
controls; level control with center
detent; low-cut select switch; range
select switch; EQ-on switch
LED Indicators:
Peak output level; 6- or 12-dB range
and EQ on
Chassis Construction:
Painted steel
Colors:
Gray front panel with white
nomenclature;blacktop,sides,rear and
bottom.
Mounting:
Standard 19-in. rack, 1.73 in. high,
9.24 in. deep behind mount
Supplied Accessories:
Power cord; one package of mounting
screws;onepackage of rubber feet; one
decal and fuse for 230 V ac operation;
owner’s manual and service
information.
Output Specifications
Type:
Electronically balanced XLR-type
Unbalanced 1/4-inch
Impedance,
Balanced:
120 ohms
Unbalanced:
60 ohms
Maximum Output Level:
+20 dBu
Filter Specifications
Type:
Variable Q active filter set
Center Frequencies (31 bands on ISO
one-third-octave centers):
20, 25, 32, 40, 50, 63, 80, 100, 125,
160, 200, 250, 315, 400, 500, 630, 800,
1,000, 1,250, 1,600, 2,000, 2,500,
3,150, 4,000, 5,000, 6,300, 8,000,
10,000, 12,500, 16,000 and 20,000 Hz
Maximum Boost/Cut
12 dB
Infrasonic Low-Cut Filter,
Corner Frequency (3 dB down):
43 Hz
Slope:
18 dB per octave