dbx 131, 215, 231 User manual

User Manual
2-Series
GraphicEqualizers
131
215
231
®

2
WARNINGFORYOURPROTECTION
PLEASEREADTHEFOLLOWING:
KEEPTHESEINSTRUCTIONS
HEEDALLWARNINGS
FOLLOWALLINSTRUCTIONS
DONOTUSETHISAPPARATUS NEAR WATER
CLEANONLYWITHADRYCLOTH.
DO NOT BLOCK ANY OF THE VENTILATION OPENINGS. INSTALL IN ACCORDANCE WITH
THEMANUFACTURER’SINSTRUCTIONS.
DO NOT INSTALL NEAR ANY HEAT SOURCES SUCH AS RADIATORS, HEAT REGISTERS,
STOVES,OROTHERAPPARATUS (INCLUDING AMPLIFIERS) THATPRODUCEHEAT.
ONLYUSEATTACHMENTS/ACCESSORIES SPECIFIED BY THE MANUFACTURER.
UNPLUG THIS APPARATUS DURING LIGHTNING STORMS OR WHEN UNUSED FOR LONG
PERIODSOFTIME.
Do not defeat the safety purpose of the polarized or grounding-type plug. A polar-
izedplug has two blades withone wider than the other. Agrounding type plug has
two blades and a third grounding prong. The wide blade or third prong are pro-
videdforyoursafety. If the providedplugdoesnotfityouroutlet,consultanelec-
tricianforreplacementoftheobsoleteoutlet.
Protectthepowercordfrombeingwalkedonorpinchedparticularlyatplugs,con-
veniencereceptacles,andthepointwheretheyexitfromtheapparatus.
Useonlywiththe cartstand,tripodbracket,ortable specifiedbythemanufacture,
or sold with the apparatus. When a cart is used, use caution when moving the
cart/apparatuscombinationtoavoidinjuryfromtip-over.
Refer all servicing to to qualified service personnel. Servicing is required when
theapparatushasbeen damagedinanyway,suchaspower-supplycordorplug is
damaged,liquidhasbeenspilledorobjectshavefallenintotheapparatus,theappa-
ratushasbeenexposedtorainormoisture,doesnotoperatenormally,orhasbeen
dropped.
POWERON/OFFSWITCH:ThePowerswitchusedinthispieceofequipmentDOESNOT
breaktheconnectionfromthemains.
MAINS DISCONNECT: The plug shall remain readily operable. 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 be incorporated into the electrical
installationoftherackorbuilding.
FORUNITSEQUIPPEDWITHEXTERNALLYACCESSIBLEFUSERECEPTACLE: Replacefuse
withsametypeandratingonly.
MULTIPLE-INPUT VOLTAGE: This equipment may require the use of a different line
cord, attachment plug, or both, depending on the available power source at instal-
lation.Connectthisequipmentonly to the power source indicated on the equipment
rearpanel.Toreducethe riskoffireor electricshock,referservicing toqualified
servicepersonnelorequivalent.
ThisEquipmentisintendedforrackmountuseonly.
SAFETY INSTRUCTIONS
NOTICE FOR CUSTOMERS IF YOUR UNIT IS EQUIPPED
WITHA POWER CORD.
WARNING: THIS APPLIANCE MUST BE EARTHED.
The cores in the mains lead are coloured in accordance with
the following code:
GREEN andYELLOW - 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 ter-
minals in your plug,proceed as follows:
•The core which is coloured green and yellow must be
connected to the terminal in the plug marked with the
letter E,or with the earth symbol, or coloured green,or
green and yellow.
•The core which is coloured blue must be connected to
the terminal marked N or coloured black.
•The core which is coloured brown must be connected to
the terminal marked L or coloured red.
This equipment may require the use of a different 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 qualified service personnel who
should refer to the table below. The green/yellow wire shall be
connected directly to the units chassis.
WARNING:If the ground is defeated,certain fault conditions in
the unit or in the system to which it is connected can result in
full line voltage between chassis and earth ground. Severe injury
or death can then result if the chassis and earth ground are
touched simultaneously.
LIVE
ENEUTRAL EARTH GND
CONDUCTOR
L
NBROWN BLUE
GREEN/YEL
BLACK
Normal Alt
WIRE COLOR
WHITE
GREEN
The symbols shown above are internationally accepted
symbols that warn of potential hazards with electrical
products. The lightning flash with arrowpoint in an equi-
lateral triangle means that there are dangerous voltages
present within the unit. The exclamation point in an equi-
lateral 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
qualified personnel. Opening the chassis for any reason
will void the manufacturer’s warranty. Do not get the unit
wet. If liquid is spilled on the unit, shut it off immediately
and take it to a dealer for service. Disconnect the unit
during storms to prevent damage.
CAUTION
ATTENTION: RISQUE DE CHOC ELECTRIQUE - NE PAS OUVRIR
WARNING: TO REDUCE THE RISK OF FIRE OR ELECTRIC
SHOCK DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE
RISK OF ELECTRIC SHOCK
DO NOT OPEN
IMPORTANT SAFETY INSTRUCTIONS

3
U.K. MAINS PLUG WARNING
A molded mains plug that has been cut off from the cord is unsafe.
Discard the mains plug at a suitable disposal facility. NEVER UNDER
ANY CIRCUMSTANCES SHOULD YOU INSERT A DAMAGED OR CUT
MAINS PLUG INTO A 13 AMP POWER SOCKET. Do not use the
mains plug without the fuse cover in place. Replacement fuse covers
can be obtained from your local retailer. Replacement fuses are 13
amps and MUST be ASTA approved
to BS1362.
LITHIUM BATTERY
WARNING
CAUTION!
This product may contain a lithium battery.There is dan-
ger of explosion if the battery is incorrectly replaced.
Replace only with an Eveready CR 2032 or equivalent.
Make sure the battery is installed with the correct polari-
ty.Discard used batteries according to manufacturer’s
instructions.
ADVARSEL!
Lithiumbatteri - Eksplosjonsfare.Ved utskifting benyttes
kun batteri som anbefalt av apparatfabrikanten. Brukt bat-
teri returneres apparatleverandøren.
ADVARSEL!
Lithiumbatteri - Eksplosionsfare ved fejlagtig håndtering.
Udskiftning må kun ske med batteri av samme fabrikat og
type. Levér det brugte batteri tilbage til leverandøren.
VAROITUS!
Paristo voi räjähtää,jos se on virheellisesti asennettu.
Vaihda paristo ainoastaan laitevalmistajan suosittelemaan
tyyppin.Hävitä käytetty paristo valmistajan ohjeiden
mukaisesti.
VARNING!
Explosionsfara vid felaktigt batteribyte.Använd samma bat-
terityp eller en ekvivalent typ som rekommenderas av
apparattillverkaren. Kassera använt batteri enligt fabrikan-
tens instruktion.
IMPORTANT SAFETY INSTRUCTIONS
ELECTROMAGNETIC
COMPATIBILITY
This unit conforms to the Product
Specifications noted on the Declaration
of Conformity. Operation is subject to
the following two conditions:
• this device may not cause harmful
interference, and
• this device must accept any interfer-
ence received, including interference
that may cause undesired operation.
Operation of this unit within significant
electromagnetic fields should be avoided.
• use only shielded interconnecting
cables.
DECLARATION OF
CONFORMITY
Manufacturer’s Name: dbx Professional Products
Manufacturer’s Address: 8760 S. Sandy Parkway
Sandy,Utah 84070, USA
declares that the product:
Product name: dbx 131,215 and 231
Note: Product name may be suffixed
by the EU.
Product option: None
conforms to the following Product Specifications:
Safety: IEC 60065 (1998)
EMC: EN 55013 (1990)
EN 55020 (1991)
Supplementary Information:
The product herewith complies with the requirements
of the LowVoltage Directive 72/23/EEC and the EMC
Directive 89/336/EEC as amended by Directive
93/68/EEC.
Vice-President of Engineering
8760 S.Sandy Parkway
Sandy,Utah 84070, USA
Date:April 19,2002
European Contact: Your local dbx Sales and
Service Office or
Harman Music Group
8760 South Sandy Parkway
Sandy,Utah 84070 USA
Ph:[phone]
Fax:[phone]

4
User Manual 2-Series
Table of Contents
Safety Info...............................................................3
Service Contact Info...............................................4
Warranty..................................................................5
Introduction and Features......................................6
Operating Controls.................................................7
Connecting the EQ to your system.......................8
Rear Panel Descriptions.........................................8
Installation Considerations.....................................9
Operation and Applications Notes........................9
Specifications ........................................................10
Service Info
If you require technical support, contact dbx Customer Service. Be prepared to
accurately describe the problem. Know the serial number of your unit - this is
printed on a sticker attached to the top panel. If you have not already taken the
time to fill out your warranty registration card and send it in, please do so now.
Before you return a product to the factory for service, we recommend you refer to
the manual. Make sure you have correctly followed installation steps and opera-
tion procedures. If you are still unable to solve a problem, contact our Customer
Service Department at [phone] for consultation. If you need to return a
product to the factory for service, you MUST contact Customer Service to obtain a
Return Authorization Number.
No returned products will be accepted at the factory without a Return
Authorization Number.
Please refer to the Warranty information on the following page, which extends to
the first end-user. After expiration of the warranty, a reasonable charge will be
made for parts, labor, and packing if you choose to use the factory service facility.
In all cases, you are responsible for transportation charges to the factory. dbx will
pay return shipping if the unit is still under warranty.
Use the original packing material if it is available. Mark the package with the
name of the shipper and with these words in red: DELICATE INSTRUMENT, FRAG-
ILE! Insure the package properly. Ship prepaid, not collect. Do not ship parcel
post.

5
User Manual
2-Series
Warranty
This warranty is valid only for the original purchaser and only in the United States.
1. The warranty registration card that accompanies this product must be mailed
within 30 days after purchase date to validate this warranty. Proof-of-purchase is
considered to be the burden of the consumer.
2. dbx warrants this product, when bought and used solely within the U.S., to be
free from defects in materials and workmanship under normal use and service.
3. dbx liability under this warranty is limited to repairing or, at our discretion,
replacing defective materials that show evidence of defect, provided the product
is returned to dbx WITH RETURN AUTHORIZATION from the factory, where all
parts and labor will be covered up to a period of 2 years. A Return
Authorization number must be obtained from dbx by telephone. The company
shall not be liable for any consequential damage as a result of the product's use
in any circuit or assembly.
4. dbx reserves the right to make changes in design or make additions to or
improvements upon this product without incurring any obligation to install the
same additions or improvements on products previously manufactured.
5. The foregoing is in lieu of all other warranties, expressed or implied, and dbx
neither assumes nor authorizes any person to assume on its behalf any obligation
or liability in connection with the sale of this product. In no event shall dbx or its
dealers be liable for special or consequential damages or from any delay in the
performance of this warranty due to causes beyond their control.

6
User Manual 2-Series
Congratulations on your purchase of a dbx 2-Series Graphic Equalizer. The 2-Series
represents a major step forward in the performance of entry-level graphic equalizers.
From their amazing 10Hz to 50kHz frequency response, to its 108dB dynamic range,
internal torodial transformer, the 2-Series offer out of this world specifications with a
down to earth price point. Sure to find a home in the studio, on tour and with
installed sound venues, the 2-Series is destined to take its rightful place in the lineage
of great dbx®signal processors that are the Professional’s Choice™. With such afford-
able quality, there’s no longer any excuse for compromising your sound. The 2-Series
Equalizers include the following features:
• (131) One 31-band, 1/3-octave Constant Q frequency bands
(215) Two 15-band, 2/3-octave Constant Q frequency bands
(231) Two 31-band, 1/3-octave Constant Q frequency bands
• Switchable boost/cut ranges of ±6 or ±12 dB
• 12 dB per octave 50Hz low-cut filter
• Front-panel bypass switch
• ±12 dB input gain range
• 4-segment LED ladders for monitoring output levels
• XLR and TRS Inputs and Outputs
• Internal Toroidal Transformer
• Frequency Response of <10Hz to >50kHz
• Dynamic range of greater than 108dB
INSPECTION
Verify that the equalizer’s package contains the following:
• Equalizer unit matching serial number marked on package
• AC power cord
• Operation Manual
• Registration Card
• Four rack mount screws and washers
If any of these items are missing please contact dbx customer service at the number
provided on the back cover of this manual.

7
User Manual
2-Series
Operating Controls
Front Panels
Input Gain Control: This control sets the signal level to the equalizer. It is capable of -
12dB to +12dB of gain. Its effect is apparent by viewing the OUTPUTLEVEL BAR GRAPH.
EQ Bypass: This switch removes the graphic equalizer section from the signal path.
The BYPASS switch does not, however, affect the INPUT GAIN, or LOW CUT filters.
EQ Bypass LED: This red LED lights when the EQ is in bypass mode. Note that
bypass mode only effects the graphic equalizer section of the 2 Series EQs. The
INPUT GAIN and and LOW CUT controls remain unaffected 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 ±12dB. The red LED lights
when the ±12dB range is selected.
Output Level Bar Graph: These four LEDs indicate output level of the equalizer.
The red LED is 3dB below clipping and is marked as +18dBu. It monitors the level at
the output of the equalizer after all other processing.
Clip LED: This LED lights whenever any internal signal level reaches 3dB below clip-
ping which may occur when any of the following happen: 1) the input signal is “hot-
ter” than +22dBu, 2) excessive gain is applied by the input gain control, or 3) exces-
sive boost is applied using the frequency sliders.
Frequency Band Slider Controls: Each one of these slider potentiometers will boost
or cut at its noted frequency by ±6dB or ±12dB, 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 flat. The frequency band centers of the 131 and 231 are
marked at 1/3rd of an octave intervals on ISO standard spacings, while the frequency
band centers of the 215 are marked at 2/3rds of an octave intervals on ISO standard
spacings.
Low Cut Enable Switch: The LOW-CUT switch inserts or removes the 12dB/octave
50Hz low-cut filter from the signal path. When the LOW-CUT switch is pushed in, the
LOW-CUT filter is IN the audio path.
131- Single Channel 31 Band Graphic EQ
215- Dual Channel 15 Band Graphic EQ
231- Dual Channel 31 Band Graphic EQ

8
User Manual 2-Series
CONNECTING THE EQTOYOUR SYSTEM
The 2-Series Equalizers have balanced inputs and impedance balanced outputs that
can be used with any balanced or unbalanced line-level device.
To connect the equalizer to your sound system refer to the following steps:
•Turn off all equipment before making connections.
• Mount equalizer in a standard-width rack.
Install the EQ in a rack with the rack screws provided. It can be mounted
above or below anything that does not generate excessive heat. Ambient tem-
peratures should not exceed 113° F (45°C) when equipment is in use. Although
the unit’s chassis is shielded against radio frequency and electromagnetic inter-
ference, extremely high fields of RF and EMI should be avoided.
• Make audio connections via XLR or 1/4"TRS jacks (according to applica-
tion needs).
Both 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 2kΩ.
• Select the operating range with the BOOST/CUT RANGE SELECTION
switch.
Note: Be sure to reduce audio levels at the power amplifiers 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 turned on and off from the rear panel power
switch or a master equipment power switch (231 only). Since the 2-Series
Equalizers consume a relatively small amount of power, the units may be left
on continuously.
REAR PANEL DESCRIPTIONS
Rear Panels
131- Single Channel 31 Band Graphic EQ
215- Dual Channel 15 Band Graphic EQ

9
User Manual
2-Series
Power Switch (231 only): Switches the power on and off. Always make audio con-
nections with the power switch in the OFF position.
Power Cord Receptacle: Connects AC power to the equalizer.
Output Connectors: Two types of output connectors are provided for output con-
nections: male XLR type connectors, and 1/4" tip-ring-sleeve phone jack connectors.
Input Connectors: Two types of input connectors are provided for input connec-
tions: female locking XLR type connectors, and 1/4" tip-ring-sleeve phone jack con-
nectors. The maximum input level that the equalizer can accept is +22dBu (ref:
0.775Vrms).
INSTALLATION CONSIDERATIONS
Hookups and Cabling: The 2-Series Equalizers are designed for nominal +4dBu lev-
els. The equalizers can be used with either balanced or unbalanced sources, and the
outputs can be used with either balanced or unbalanced loads, provided the proper
cabling is used.
A balanced line is defined as two-conductor shielded cable with the two center con-
ductors carrying the same signal but of opposite polarity when referenced to ground.
An unbalanced line is generally a single-conductor shielded cable with the center
conductor carrying the signal and the shield at ground potential.
Input Cable Configurations: The equalizer has an input impedance of 40kΩbal-
anced and 20kΩunbalanced. This makes the 2-Series Equalizers’ audio inputs suit-
able for use with virtually any low source impedance (under 2kΩ).
Output Cable Configurations: The equalizer’s output is capable of driving a 2kΩ
load to +18dBu. For maximum hum rejection with a balanced source, avoid common
grounding at the equalizer’s inputs and outputs. Most balanced (3-conductor) cables
have the shield connected at both ends. This can result in ground loops which cause
hum. If hum persists try disconnecting the shield on one or more of the cables in the
system, preferably at the input of a device, not at the output.
OPERATION AND APPLICATION NOTES
The dbx 2-Series Graphic Equalizers are useful audio signal processing tools in situa-
tions where precise frequency control is required across the audible frequency spec-
trum.
When used with an audio spectrum analyzer the EQs can tune any acoustical envi-
ronment -- from the studio to the concert hall -- to stop ringing, increase clarity, and
flatten the overall frequency response of the environment. A real-time spectrum ana-
lyzer or other types of audio environment analyzers are very useful in determining
the amount of equalization needed.
231- Dual Channel 31 Band Graphic EQ

10
User Manual 2-Series
Insert the graphic equalizer between the signal source (usually a mixer) and the
power amplifiers (or the crossover if there is one). Adjust the level and equalization as
required to yield the desired system response.
For optimum signal-to-noise response, the gain structure of the sound system must be
properly set up. Each component of the sound system should be set at its nominal
operating level, starting with the first element in the system, usually a mixing console.
Each element should be run at its nominal operating level in order to take advantage
of the maximum signal-to-noise properties of that element. Loudspeaker amplifiers, as
the last element in the chain, should be set only as loud as necessary, in order to
avoid inducing unnecessary noise into the system.
SPECIFICATIONS
Inputs
Connectors: 1/4" TRS, female XLR (pin 2 hot)
Type: Electronically balanced/unbalanced, RF filtered
Impedance: Balanced 40kΩ, unbalanced 20kΩ
Max Input Level: >+21dBu balanced or unbalanced
CMRR: >40dB, typically >55dB at 1kHz
Outputs
Connectors: 1/4" TRS, male XLR (pin 2 hot)
Type: Impedance-balanced/unbalanced, RF filtered
Impedance: Balanced 100Ω, unbalanced 50Ω
Max Output Level: >+21dBu balanced/unbalanced into 2kΩor greater
>+18dBm balanced/unbalanced (into 600Ω)
System Performance
Bandwidth: 20Hz to 20kHz, +0.5/-1dB
Frequency Response: <10Hz to >50kHz, +0.5/-3dB
Dynamic Range: 108db
Signal-to-Noise: 90db
THD+Noise: <0.004%
Interchannel Crosstalk: <-80dB, 20Hz to 20kHz
Function Switches
EQ Bypass: Bypasses the graphic equalizer section in the sig-
nal path
Low Cut: Activates the 50Hz 12dB/octave high-pass filter
Range: Selects either +/- 6dB or +/- 12dB slider boost/cut
range
Power Supply
Operating Voltage: 100VAC 50/60Hz, 120VAC 60Hz, 230VAC 50/60Hz
Power Consumption: 12W (231=15W)
Mains Connection: IEC receptacle
Physical Dimensions
231: Size: 3.5"Hx19"Wx6"D Weight: 6 lbs
215: Size: 1.75"Hx19"Wx6"D Weight: 4.7 lbs
131: Size: 1.75"Hx19"Wx6"D Weight: 4.7 lbs
Note: Specifications subject to change.

User Manual
2-Series
Notes:

8760 South Sandy Parkway • Sandy, Utah 84070
Phone: [phone] • Fax [phone]
Int’l Fax: [phone]
E-mail us at: [e-mail] or visit us on
the web at:
www.dbxpro.com • www.driverack.com
www.blueseries.com
A Harman International Company
18-1333V-A Printed in China
®
The Professional’s Choice In Signal Processing