P. 1
- AUDIOL AB EQ-2231
EQ-2231
2 x 31-Band Graphic Equalizer
USER MANUAL
P. 2
AUDIOLAB EQ-2231 -
EQ-2231
2 x 31-Band Graphic Equalizer
EQ-2231 is a 2 x 31 band graphic equalizer that
features a 4 LED bar graph indicator for monitoring
gain reduction and output levels. The unit also has
a noise reduction, limiter and 40Hz low cut button.
The unit ships with ¼” and XLR connectors.
Specications
Inputs
• Connectors: XLR/TRS ¼” & barrier terminal
strip
• Type: Electronically balanced/unbalanced,RF
ltered
• Impedance: 40KOhm (Balanced) & 20KOhm
(Unbalanced)
• Max Input Level: >+21dBu,balanced or unbalanced
• CMRR: >40dB, typically >55dB at 1KHz
Outputs
• Connectors: XLR/TRS ¼” & barrier terminal
strip
• Type: Electronically balanced/unbalanced,RF
ltered
• Impedance: 120KOhm (Balanced) & 60KOhm
(Unbalanced)
• Max Output Level:
• - >+21dBu,balanced/unbalanced into 2KOhm
or greater
• - >+18dBm,balanced/unbalanced (into 600Ohm)
System Performance
• Bandwidth: 20Hz to 20KHz, +0.5/-1dB
• Frequency Response: <10Hz to>50KHz,+0.5/3dB
• Noise Reduction In: (+/-6 and +/-15dB range):
• Signal-to-Noise: >100dB,unweighted,ref:+4dBu,22KHz measurement bandwidth
• Dynamic Range: >118dB,unweighted
• Noise Reduction Out: (+/-6dB range):
• Signal-to-Noise: >94dB,unweighted,ref:+4dBu,22KHz measurement bandwidthDynamic
Range: >112dB,unweighted
• Noise Reduction Out: (+/-15dB range):
• Signal-to-Noise: >90dB,unweighted,ref:+4dBu,22KHz measurement bandwidth
• Dynamic Range: >108dB,unweighted
• THD+Noise:
• - <0.04%,0.02%typical at +4dBu,1KHz
• - <0.5%, at 1KHz with 15dB gain reduction
• Interchannel Crosstalk: <-80dB,20Hz to
20KHz (2215/2231)
• Noise Reduction: Up to 20dB of dynamic
broadband noise reduction
Function Switches
• EQ BYPASS: Bypasses the graphic equalizer
section in the signal path
• LOW CUT(recessed): Activates the 40Hz 18dB/
octave Bessel high-pass lter
• RANGE(recessed): Selects either +/-6dB or +/15dB slider boost/cut range
Indicators
• Output Level: 4-LED bar graph
(Green,Green,Yellow,Red) at-10,0,+10,and
+18dBu
• Gain Reduction: 4-LED bar graph (all Red) at
0,3,6,and 10dB
1. OVERVIEW
English version
P. 3
- AUDIOL AB EQ-2231
English version
2. IMPORTANT SAFETY INSTRUCTIONS
CAUTION: Risk of electric shock do not
open.
WARNING: To reduce the risk of re
or electric shock do not expose this
equipment to rain or moisture.
The symbols shown above are internationally
accepted symbols that warn of potential hazards
with electrical products. The lightning ash with
arruwpoint in an equilateral triangle means that
there are dangerous voltages present within the
unit. The exclamation paint in an equilateral triangle indicates that it is necessary for the user to
refer to the owner s manual.
These symbols warn that there are no user serviceable parts inside the unit. Do not open the
unit. Do not attempt to service the unit yourself.
Refer all servicing to qualied personnel. Opening
the chassis for any reason will void the manufacturers warranty. Do not get the unit wet. If liquid
is spilled on the unit, shut it o immediately and
take it to a dealer for service. Disconnect the unit
during storms to prevent damage.
Safety instructions
Notice for customers if your unit is equipped
with a power cord.
WARNING: This appliance must be earthed.
The cares in the mains lead are coloured in ac-
Physical
• Dimensions: 134x483x201 mm. / 5.25x19x7.9 in.
• Weight: 4.8 Kg. / 10.6 Lbs.
cordance with the fallowing code:
• GREEN and YELLOW - Earth
• BLUE - Neutral
• BROWN - Live
As colours of the cores in the mains lead of this
appliance may not correspond with the coloured
markings identifying the terminals in your plug,
proceed as follows:
• The cure which is coloured green and yellow
must he connected to the terminal in the
plug marked with the letter E, or with the
earth symbol, or coloured pen, or green and
yellow. a The care which is coloured blue
must be connected to the terminal marked N
or coloured black.
• The core which is coloured brawn must
he connected to the terminal marked L or
coloured red.
This equipment may require the use of a dierent line cord, attachment plug, or both, depending on the available power source at installation.
If the attachment plug needs to be changed,
refer servicing to qualied service personnel
who should refer to the table below. The green/
yellow wire shall he conned- directly to the units
chassis.
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AUDIOLAB EQ-2231 -
English version
WARNING: If the ground is defeated, certain
fault conditions in the unit or in the system to
which is con¬nected an resui in full line voltage between chassis and earth ground. Severe
injury or death can then result 'd the chassis
and earth ground are touched simuftaneously.
Warning for your protection
Read these instructions:
• Keep these instructions
• Heed all warnings
• Follow all instructions
• Do not use this apparatus near water
• Clean only w i a dry cloth.
• Do not block any of the ventilation openings.
install in accordance with the manufacnrer s
instructions.
• Do not install near any heat sources such
as radiators, heat registers, stoves, or other
apparatus (including ampliers) that produce
heat.
• Only use attachments/accessories specied
by the manufacturer.
• Unplug this apparatus during lightning storms
or when unused for long periods of time.
• Do not defeat the safety purpose of the polarized or grounding-type plug. A polarized plug
has two blades with one wider than the other.
A grounding type plug has two blades and
a third grounding prong. The wide blade or
third prong are provided for your safety. If the
provided plug does not t your outlet, consult
an electrician for replacement of the obsolete
outlet.
• Protect the power cord from being walked on
or pinched particularly at plus, convenience
receptacles, and the point where they exit
from the apparatus.
• Use only with the cart stand, tripod hncket,
or table specied by the manufacture, or
sold with the apparatus. When a cart is used,
use caution when moving the cart/apparatus
combination to avoid injury from tip-over.
• Refer all servicing to to qualied service
personnel. Servicing is required when the
apparatus has been damaged in any way,
such as power-supply cord or plug is damaged, liquid has been spilled or objects have
fallen into the apparatus, the apparatus has
been exposed to rain or moisture, does not
operate normally, or has been dropped.
Power on/o switch: For products provided
with a power switch, the power switch DOES
NOT break the connection from the mains.
Mains disconnect: The plug shall remain readily
apenhle. For rack-mount or installation
where plug is not accessible, an all-pole mains
switch with a contact separation of at least 3
mm in each pole shall he incorporated into the
electrical installation of the rack or building.
For units equipped with externally accessible
fuse receptacle: Replace fuse with
same type and rating only.
Multiple-input voltage: This equipment may
require the use of a dierent line cons, attach
ment plug, or both, depending an the available
power source at installation. Connect this equip
ment only to the power source indicated on the
equipment rear panel. To reduce the risk of
re or electric shack, refer servicing to qualied
service personnel or equivalent.
This Equipment is intended for rack mount use
only.
CONDUCTOR WIRE COLOR
Normal Alt
L Live Brown Black
N Neutral Blue White
E Earth gnd Green/yel Green
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- AUDIOL AB EQ-2231
English version
3. OPERATING CONTROLS
Input Gain Control: This control sets the signal
level to the equalizer. It is capable of -12dB to
+12dB of gain. Its eect is apparent by viewing the
OUTPUT LEVEL BAR GRAPH.
EQ Bypass: This switch removes the graphic
equalizer section from the signal path. ( See Block
diagram on Page 8.) The BYPASS switch does not,
however, aect the INPUT GAIN, or LOW CUT
lters.
EQ Bypass LED: This red LED lights when the EQ
is in bypass mode. Note that bypass mode only
eects the graphic equalizer section of the 20 Series EQs. The INPUT GAIN and LOW CUT controls
remain unaected when the EQ is bypassed.
Boost/Cut Range Selection Switch and LEDs: This
switch selects which of the two boost/cut ranges
the equalizer will use, either ±6dB or ±15dB. The
red LED lights when the ±15dB range is selected,
and the yellow LED lights when the ±6dB range
is selected. Note that the BOOST/CUT switch is
slightly recessed. This is to prevent accidental
activation of the switch, possibly causing damage
to other sound system components.
Output Level Bar Graph: These four LEDs indicate output level of the equalizer. The red LED is
3dB below clip-ping and is marked as +18dBu. It
monitors the level at the output of the equalizer
after all other process ing, including the limiter.
Clip LED: This LED lights whenever any internal
signal level reaches 3dB below clipping which
may occur when any of the following happen: 1)
the input signal is "hotter" than +22dBu, 2) excessive gain is applied by the input gain control,
or 3) excessive boost is applied using the frequency sliders.
Gain Reduction Meter: These four LEDs indicate the amount of gain reduction being induced
by the setting of the PeakPlus' LIMITER THRESHOLD control as the signal level from the graphic
EQ section exceeds this limiter threshold setting.
PeakPlus' Limiter Threshold Control: This control engages the PeakPlus'M limiter. It sets the
threshold level at which -:1 gain reduction will
begin to occur. Its design is borrowed from the
patent-pending PeakStopPlus'M Limiter found
on the popular compressor/limiters. It is capable of a range of OdBu through "OFF" (+24dBu).
When the threshold control is set to "OFF", the
limiter is eectively disabled, and no gain reduction will occur.
P. 6
AUDIOLAB EQ-2231 -
English version
EQ Type III Noise Reduction Switch: The switch
engages the EQ Type III Noise Reduction circuit
within the EQ.
EQ Type III Noise Reduction LED: The yellow LED
lights when the EQ Type III Noise Reduction circuit
is activated via the NOISE REDUCTION Switch.
Frequency Band Slider Controls: Each one of
these slider potentiometers will boost or cut at
its noted frequency by ±6dB or ±15dB, depending upon the position of the BOOST/CUT RANGE
switch. When all the sliders are in the center
detented position the output of the equalizer is
at. The frequency band centers of the 2231 are
marked at 1/3rd of an octave intervals on ISO
standard spacings.
Low Cut Enable Switch: The LOW-CUT switch
inserts or removes the 18dB/octave 40Hz Bessel
low-cut lter from the signal path. When the
LOW-CUT switch is pushed in, the LOW-CUT lter
is IN the audio path.
4. CONNECTING THE EQ TO YOUR SYSTEM
The EQ-2231 Equalizers have balanced inputs and
outputs that can be used with any balanced or
unbalanced linelevel device. For more specic information about cabling possibilities, please refer
to the section entitled
To connect the equalizer to your sound system
refer to the following steps:
• Turn o all equipment before making connections.
• Mount equalizer in a standard-width rack.
Install the EQ-2231 in a rack with the rack
screws provided. It can be mounted above or
below anything that does not generate excessive heat. Ambient temperatures should
not exceed 113° F (45°C) when equipment is
in use. Although the unit's chassis is shielded
against radio frequency and electromagnetic
interference, extremely high elds of RF and
EMI should be avoided.
• Make audio connections via XLR, barrier
strip, or 114" TRS jacks (according to appli-
cation needs) All three types of connectors
for the inputs and outputs can be used for
balanced or unbalanced connections. The
use of more than one connector at a time for
the inputs could unbalance balanced lines,
cause phase cancellation, short a conductor
to ground, or cause damage to other equipment connected to the equalizer. More than
one output may be used simultaneously as
long as the combined parallel load is greater
than 60052.
• Select the operating range with the
BOOST/CUT RANGE SELECTION switch
Note: Be sure to reduce audio levels at the pow-
er ampliers when changing the setting of this
switch as it may generate an audible transient.
• Apply power to the equalizer Connect the
AC power cord to the AC power receptacle
on the back of the equalizer. Route the AC
power cord to a convenient power outlet
away from audio lines. The unit may be
P. 7
- AUDIOL AB EQ-2231
English version
5. REAR PANEL DESCRIPTIONS
Power Switch: Switches the power on and o.
Always make audio connections with the power
switch in the OFF position.
Input Connectors: Three types of input connectors are provided for input connections: female
locking XLR type connectors, 1/4" tip-ring-sleeve
phone jack connectors, and a barrier strip. The
maximum input level that the equalizer can accept
is +22dBu (ref: 0.775Vrms).
Output Connectors: Three types of output connectors are provided for output connections: male
XLR type connectors, 1/4" tip-ring-sleeve phone
jack connectors and a barrier strip.
turned on and o from the rear panel power
switch or a master equipment power switch.
Since the EQ Series Equalizers consume a relatively small amount of power, the units may be
left on continuously.
Chassis Ground Lift Strap: By removing the
jumper connecting the two screws on the barrier
strip, the chassis ground is separated from the
circuit ground of the equalizer. This is sometimes
necessary to prevent "ground loops" in a sound
system. When lifting the ground strap, you must
make a connection from the circuit ground ( )
terminal to some other ground point in your audio system in order for the equalizer to function
properly.
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