QSC DSP-4 User manual

1
DSP-4
Digital Signal Processor
Amplifier Accessory Hardware Manual
*TD-000103-00*
TD-000103-00
Rev.B

2
EXPLANATION OF GRAPHICAL SYMBOLS
The lightning flash with arrowhead symbol,
within an equilateral triangle, is intended to
alert the user to the presence of uninsulated
“dangerous voltage” within the product’s en-
closure that may be of sufficient magnitude to
constitute a risk of electric shock to humans.
The exclamation point within an equilateral
triangle is intended to alert the users to the
presence of important operating and mainte-
nance (servicing) instructions in the litera-
ture accompanying the product.
CAUTION: To reduce the risk of electric shock, do not
remove the cover. No user-serviceable parts inside. Refer
servicing to qualified service personnel.
WARNING: To prevent fire or electric shock, do not expose
this equipment to rain or moisture.
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
Federal Communications Commission (FCC)
Information
NOTE: This equipment has been tested and found to comply with the
limits for a Class B digital device, pursuant to Part 15 of the FCC Rules.
These limits are designed to provide reasonable protection against
harmful interference in a residential installation. This equipment gener-
ates, uses, and can radiate radio frequency energy and, if not installed
andusedinaccordancewiththeinstructions,maycauseharmfulinterfer-
ence to radio communications. However, there is no guarantee that
interference will not occur in a particular installation. If this equipment
does cause harmful interference to radio or television reception, which
can by determined by turning the equipment off and on, the user is
encouraged to try to correct the interference by one or more of the
following measures:
- Reorient or relocate the receiving antenna.
- Increase the separation between the equipment and the receiver.
- Connect the equipment into an outlet on a circuit different from that to
which the receiver is connected.
- Consult the dealer or an experienced radio/TV technician for help.
SAFEGUARDS
Electrical energy can perform many useful
functions. This unit has been engineered
and manufactured to assure your personal
safety. Improper use can result in potential
electrical shock or fire hazards. In order not
to defeat the safeguards, observe the fol-
lowing instructions for its installation, use
and servicing.
•Maximumoperating ambienttemperature
is 50° C.
•Never restrict the airflow through the
device’s fan or vents.
•When installing equipment into a rack,
distribute the units evenly. Otherwise haz-
ardous conditions may be created by an
uneven weight distribution.
•Connect the unit only to a properly rated
supply circuit.
•Reliable Earthing (Grounding) of rack-
mounted equipment should be maintained.
IMPORTANT SAFETY INFORMATION: PLEASE REVIEW!
WARNING!
While QSC has endeavored to develop and produce the most dependable and robust Digital Signal Processor (DSP) audio product for your
use, due to the unlimited and potentially destructive (to the sound system) configurations that may be applied to the DSP by the user, QSC
cannot be held responsible for damages resulting from any deviation or failure by the user to strictly follow the recommendations set forth
in the owner’s manual for the integration of the DSP-4 and Signal Manager software with your sound system.
Allrisksattendanttointegrationofuser-configurableDSPproductswithyoursoundsystemareassumedbyyou.WhileQSCstrivestosupply
the highest quality technical solutions for Digital Signal Processing, in no event will QSC or its suppliers be held liable for any damages,
consequential, incidental, or otherwise, including any claims for lost profits and/or savings resulting from any attempted integration of the
DSP-4 and Signal Manager software which does not strictly adhere to the manual’s recommendations.

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TABLE OF CONTENTS
Warnings, Explanation of Graphical Symbols, and FCC Statement..............................................................2
INTRODUCTION Overview...........................................................................4
Connector & Indicator Descriptions, Illustrations.................5
Functions and Features..........................................................7
Block Diagram..........................................................................................8
INSTALLATION Unpacking..................................................................................................9
What is Included, What else May be Needed.....................................9
Signal Manager Software Installation........................................10
Mounting to QSC DataPort Equipped Amplifiers...............................11
Mounting to the Accessory Remote Mounting Bracket......................12
Connecting to the DataPort of the DSP-4..............................................13
Connecting XLR Audio Inputs and Outputs......................................14
Connecting to RS-232 Port........................................................................15
Connection to Accessory External DC Power Supply.................16
Daisy-chaining the DSP-4 Outputs.........................................................17
USE General Guidelines for Freely Configurable DSP....................................18
Special Information About Saving DSP-4 Configurations.....19
SPECIFICATIONS.........................................................................................................................................20
ARCHITECT’S & ENGINEER’S SPECIFICATION.....................................................................................22
APPENDIX DataPort Pinout.........................................................................................23
RS-232 Pinout ............................................................................................24
XLR Connector Pinout ...............................................................24
Application Information...............................................................25
QSC INFORMATION Maintenance, Warranty & QSC Contact Information................................26
© Copyright 2002, QSC Audio Products, Inc.
QSC® is a registered trademark of QSC Audio Products, Inc., Costa Mesa, CA
“QSC” and the QSC logo are registered with the U.S. Patent and Trademark Office

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INTRODUCTION- Overview
The DSP-4 is a digital signal processor ( DSP ) accessory for
audio power amplifiers. It is designed to reduce the need for
external signal processing while increasing overall system
reliability through distributed intelligence. It is intended prima-
rily for QSC’s CX, DCA, and Powerlight2 series amplifiers and
mounts directly to the rear panel of the 2-RU, 2-channel models
of these amplifiers (pre-August, 1999 date-code of the CX, DCA
and Powerlight2, and all ISA models will require use of an
external power supply). Use of the DSP-4 with Powerlight
models requires remote mounting, external power supply and
useof aspecialinterconnectcable(PL6.0/9.0only).Refertothe
Appendix for application information. The DSP-4 can also be
usedwithamplifiersthatdonothaveaQSCDataPort(olderQSC
models, non-QSC models) with a reduced feature set and
remote mounting/external power.
The signal processing capabilities include Compressors,
Limiters, multiple Parametric Filters, High- and Low-Pass Fil-
ters, Shelf Filters, Muting, Attenuation, Multiple Delays, Polar-
ity Reversal, and Audio Routing. A new feature of the DSP-4 is
amplifier output Power Limiting (QSC DataPort amplifiers only).
Analog-to-digital and digital-to-analog converters are 24-bit
resolution and 48 kHz. sampling rate. Post-processor audio
outputs aredaisy-chainable for connection to additional ampli-
fiers. Input sensitivity and output level is software selectable.
Dynamic range is greater than 106 dB. Inputs are balanced and
the post-DSP outputs are pseudo balanced.
Physically, the DSP-4 is a small module that “piggybacks”
onto the back panel of the specified QSC amplifiers. It connects
directly to the DataPort on the back panel and is secured with
supplied hardware. When used with other amplifiers, the DSP-
4 is mounted remotely on a rack-mount accessory bracket
providing a solid mounting platform. There are two LED’s; blue
to indicate power status and green to indicate input signal
presence.
Connections include an RS-232 port and a DataPort pass-
throughconnectorforusewithQSCDataPortproducts.Fornon-
DataPort applications, two XLR audio inputs and two XLR
outputs(post-DSP)areprovided.Thereisapowerreceptaclefor
use with amplifiers that do not provide DataPort power or with
non-QSC amplifiers.
Control of the DSP-4 is accomplished with the supplied QSC
Signal Manager software and an RS-232 connection between
the module and PC. The Signal Manager software provides an
easy-to-use graphical user interface where DSP “objects” are
placed onto a palette and connected. This interface allows for
almost infinite configuration possibilities. Once the DSP-4 has
been set up as desired and the configuration saved to the DSP-
4, connection to the PC is no longer required. This feature
allows essentially tamper-proof amplifier DSP setup. Further
changes can be implemented in the field by simply connecting
a PC and loading the new setup into the DSP-4.
Operation over an Ethernet network can be accomplished using
QSC’s QSControl platform. Please refer to the software docu-
mentation (software Help file and Readme.txt file) for sup-
ported feature-set and operation information.
FromallofusatQSCAudio,thankyouforyourpurchase.Besure
to check our website at http://www.qscaudio.com for the
latest software and firmware updates as well as sample DSP
configurations.
Overview of the DSP-4

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INTRODUCTION- Connector & Indicator Descriptions
RS-232: DB-9 female jack. Use
for serial cable connection be-
tween the DSP-4 and the com-
puter.Connectionisrequiredonly
forsetupandreal-timecontrolof
themodule.Connection need not
be maintained for use.
Front Panel
CH 1 INPUT, CH 2 INPUT: balanced female
XLR’s. If not using the DataPort for inputs, these
arewhereyouconnecttheline-levelaudioinputs
to the DSP-4.
They are electronically balanced with an input
impedance of 8.3k Ohms. If used in an unbal-
anced configuration, the input impedance is 3.7k
Ohms. Input sensitivity is software selectable.
EXTERNAL POWER:
2.5mmbarrelconnector-
Center (+), Outer(-), 15
VDC,300mA.Use if your
amplifier does not sup-
ply the required operat-
ing voltage from its
DataPort.
CH 1 OUTPUT, CH 2 OUTPUT: pseudo-bal-
anced male XLR’s. These outputs provide post-
DSP (processed) signal from the DSP-4 for down-
stream devices (amplifiers, monitoring busses,
daisy-chaining the processed signal to a second
amplifier).Whenusingwith non-DataPort ampli-
fiers, these outputs should be connected to your
amplifier’s input connectors.
DATAPORT: This is the “in-
put”DataPort. Ifusingwith QSC
DataPort products that supply
audio inputs or provide ampli-
fier control & monitoring, this
is where they are connected. If
using this DataPort for audio
inputs, do not apply input sig-
nal to the XLR inputs.
SIGNALindicator-:This green
LED illuminates when the
DSP-4 detects an input signal
oneither channel. Dualbright-
ness levels indicate signal
level. At -40dB fs, it will light
dimly; at -20dB fs it will light
brightly.
ChassisLance - Usethislance
tosecureaccessory power cord
(if used) with a wire tie.
POWER indicator: This blue
LEDilluminateswhenthemod-
ulehaspower properly applied.

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INTRODUCTION- Connector & Indicator Descriptions
Rear Panel
Overall
DATAPORT (unlabeled): This is the “output”
DataPort.
If the DSP-4 is directly mounted on a 2-RU, 2
channel QSC DataPort equipped amplifier, this
connector plugs into the amplifier’s DataPort con-
nector.
If used with 3-RU, 4- or 8-channel QSC DataPort
equipped amplifiers, the DSP-4 module will need
to be remotely mounted and a male-female
DataPort cable used to interconnect the amp &
module.
If used with a non-DataPort amp (QSC or other),
this connector will not be used.

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INTRODUCTION- Functions & Features
DSP-4 Hardware Features
High- and Low-Pass Crossover
Selectable responses:
Butterworth (6,12,18 or 24 dB/octave slope)
Bessel (6,12,18 or 24 dB/octave slope)
Linkwitz-Riley (12 or 24 dB/octave slope)
Graphical response curve provided in software
Adjustable frequency & slope
Ability to bypass all EQ with a single mouse click
Ability to add or delete EQ
Assignable anywhere in signal chain
High- and Low-Pass Shelf Filter
Adjustable corner frequency
Adjustable Q factor
Adjustable gain
Graphical response curve provided in software
Ability to bypass all EQ with a single mouse click
Ability to add or delete EQ
Assignable anywhere in signal chain
Output Power Limiter (QSC DataPort Amps)
Select QSC amplifier model for tailored results
Graphical response curve provided in software
Ability to quickly bypass limiter with a single mouse click
Directly monitors amplifier output voltages and currents
Multiple Delays
910 millisecond maximum (sum of all delay objects)
20.83 microsecond increments
Entry can be in seconds, feet or meters
Assignable anywhere in signal chain.
Parametric EQ
Adjustable frequency
Adjustable gain
Adjustable Q factor
Ability to bypass all EQ with a single mouse click
Ability to add or delete EQ
Graphical response curve provided in software
Assignable anywhere in the signal chain
Signal Compressor
Adjustable attack and release times
Adjustable Gain
Adjustable threshold
Adjustable compression ratio
Graphical response curve provided in software
Assignable anywhere in the signal chain
Signal Level Meter (peak or RMS response)
Signal Attenuation (mute or bypass)
Output Gain up to +12 dB
2 to 1 Mixer
Signal Splitter
External Contact Closure Sensing
Pink & White Noise Generator
Variable Frequency Tone Generator
Clip & Protect Indication
Signal Polarity Reversal
The full set of features is available on QSC DataPort equipped amplifiers connected to the DSP module via the DataPort connector
(direct-connect or remote-mount with DPX-2 cable). “V2” DataPorts and non-QSC amplifiers do not support Output Power Limiting.
“V2” DataPort amplifiers and non-QSC amplifiers do not support Output Power Limiting.

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INTRODUCTION- Block Diagram and Details
Input Stage- Inputs are electronically balanced and RF filtered. The input sensitivity is software-selectable and any large
signals are prevented from destroying the A-to-D by a diode.
Output Stage- The output is buffered and then filtered to remove high-frequency sampling artifacts. Output sensitivity is
software-selectable and available from both sets of outputs simultaneously.
Data Acquisition- The data acquisition A-to-D samples the output voltage and current of both amplifier channels. This
data is used for amplifier output power limiting. Amplifier clip and protect-mode status data is also sampled. Power, protect/
clip indication, and output power limiting is not possible on non-DataPort amplifiers or “V2” DataPort amplifiers.
Contact Closure Trigger Input- Pin 9 of the RS-232 can be used as a trigger input for operating software “objects”,
such as “Switched Gain”. It’s TTL compatible: pulling this pin to ground through a maximum impedance of 1.3k ohms forces a
general I/O pin of the DSP to a logic-low condition. The Signal Manager software can use this “event” to change gain
settings or Preset mode. Refer to the Signal Manager software Help file for available applications of the Contact Closure
Trigger Input.
Power Supply- The DSP module is normally provided power through its DataPort connection from the amplifier. If you are
using an older amplifier or an amplifier that does not have a DataPort, an external power jack is provided on the DSP module.
If external power is required, use QSC’s DPX-1 accessory power supply.
This portion of the introduction provides some of the technical details of the DSP-4.

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Unpacking
It is recommended that you keep the original packing material for reuse in the rare event that service be required for your DSP-4. If service
is required, and the original packing material is not available, insure that the DSP-4 is adequately protected for shipment (strong box of
appropriate size , sufficient packing material).
What is included in the carton:
Item Description Quantity
1- DSP-4 Digital Signal Processor 1
2- #4-40 machine screw, 1.88” long 2
3- #8-32 machine screw, 0.312” long 1
4- Hardware Manual (this document) 1
5- Signal Manager Software CD disk 1
INSTALLATION- Unpacking and What Else You’ll Need
What else will I need?
1- 200 MHz. Pentium PC (minimum) with CD-ROM, 32 MB or more RAM, 10 MB or more hard drive space available, an available COM (RS-
232) port capable of 38.4k baud, Windows 98, Windows 2000, Windows XP, or NT4.0 with service pack 6a or later, SVGA display at 800
x 600 minimum resolution (1024 x 768 recommended).
2-An RS-232 cable (9-pin serial data cable). This cable attaches your PC to the DSP module. It should be a male-to-female type and no longer
than 25 feet.
Other accessories that may be required (depending on application)-
DPX-1 External Power Supply-
The DPX-1 is used in applications
where the amplifier’s DataPort
does not supply operating voltage
to the DSP-4 module. This includes
non-DataPort amplifiers and
certain models of QSC DataPort
equipped amplifiers (see Appendix
for details).
DPX-2 DataPort Cable
(module to amplifier)- This
cable is a 6 foot long male-female
DataPort cable used for connect-
ing the DSP-4 module to a
DataPort equipped amplifier.
DPC-X DataPort Cable
(module to CM16a)- This cable
is a custom length male-male
DataPort cable used for connecting
the DSP-4 module to a QSC
amplifier network monitor, such as
the CM16a. Length can be
specified from 1 to 10 feet, replace
“X” suffix with length in feet.
DPX-4 Mounting Bracket-
The DPX-4 holds up to 4 DSP-4 (or
DSP-3) modules in a highly-
adjustable 19-inch rackmount
configuration. Main bracket comes
with right angle module support
brackets and adjustable rack
mounting ears for optimum
flexibility.

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INSTALLATION- Software Installation
Software Installation-
1. Insert the CD labeled QSC Signal Manager into your CD drive (typically drive “D:”). If your
computerhasAUTORUNenabled,the installation utility will start automatically.Ifitdoesnot,
then proceed to step 2, below. Otherwise, proceed to step 3.
2. Run D:\Setup.exe (replace “D” with your CD drive’s designation if necessary) and follow the
instructions displayed.
3. When the installation is complete, you will be presented with a screen that prompts you
to view the “Readme” file. Please take time to read this- it contains important information on
how to use the software.
4. After installation, you will have an icon on your desktop labeled “Signal Manager”. Use this
icon to start the application.
5. Using the main menu bar at the top of the window, choose the “Help” item and read the
software help section. The Help system includes the most up-to-date information for
“paperless” reference. Also, visit QSC on the internet at http://www.qscaudio.com for
DSP-4 updates.
6. IMPORTANT! The DSP-4 is shipped with all of its presets configured to pass full-range
audio signals through both channels. THIS MAY NOT BE APPROPRIATE FOR YOUR
SETUP!Be sure to configureanynecessarycrossovers , filters, etc.priortoapplying
audio signals to the inputs. Damage to equipment may result if these recommenda-
tions are not followed.
In order to use your DSP-4 module, you will need to install the QSC Audio Signal Manager software on your PC. The
module is configured to pass full range audio unattenuated from input-to-output as shipped from the factory. You must
use the software to configure the module as desired.
After the software has been installed and the DSP-4 module has been properly mounted and connected to the amplifier,
connect the RS-232 cable from your PC’s COM port to the DSP-4 module’s RS-232 connector. Then apply power to the
DSP-4 (turn on the amplifier or plug in the accessory external power supply). Turn on your PC and start the Signal
Manager software by clicking (or double clicking) on its icon. Refer to the software’s Help system for instructions on
creating and applying configurations to the DSP-4.
Do not run your amplifier “wide open” (maximum gain) while making real-time
adjustments to the DSP-4’s setup. The nature of the communication path between
the PC and DSP-4 is inherently more complex than direct physical controls of an
equivalent analog processing device. Unpredictable results may occur due to failure of the
PC or the communications port. Under such circumstances, damage to your speakers is
possible if the amplifier gain is set for high power levels. Use the minimum useful gain
settings while making system adjustments.

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INSTALLATION- Mounting on Amplifier (QSC CX, DCA, Powerlight2)
The DSP-4 module mounts directly to the rear of QSC’s 2-channel, 2RU, DataPort equipped amplifiers. All
other models require the module to be mounted on an accessory bracket (refer to next page).
1- Configure the amplifier: •All filters off
•Clip limiter setting does not matter
•Mode set as required (stereo, bridge mono, parallel)
2- Align the DataPort plug on the back of the DSP-4 with the DataPort jack on the back of the
amplifier and gently push the module to seat the connector.
3- Install the two #4-40 screws to secure the left side of the module to the amplifier. These
two long screws pass through the module and thread into the inserts on the DataPort (HD15)
jack. (see below). Use a #1-size phillips driver; be sure not to overtighten.
4- Install the #8-32 screw (0.312 inch long) to secure the right side of the DSP-4 to the amplifier
(see below).
If you have an amplifier that supports “direct” mounting, you need to:
Be sure to secure the DSP-4
using all three mounting
screws. The “backside”
DataPort connector can be
easily damaged if the mod-
ule is twisted and there are
no supporting screws to
properly secure it to the
chassis.

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INSTALLATION- Remote mounting (4-ch., 8-ch. Powerlight & non QSC amp’s)
If you have an amplifier that requires “remote” mounting, you need to:
Be sure to secure the DSP-4 using all mounting
screws. This will ensure reliable mechanical
and electrical performance.
The DSP-4 module requires “remote” mounting when used with the 4- and 8-channel CX, 4-channel DCA,
Powerlight, and non-QSC amplifiers.
1- Obtain the Accessory Remote Mounting Bracket.
2- Attach the right angle bracket to the module (see illustration, below).
3- Mount the module/bracket assembly on the main bracket.
4- Secure the adjustable rack ears (included in bracket kit) to the main bracket.
5- Mount the completed assembly in your equipment rack.
6- Connect inputs, outputs, DataPorts, and external power as required.
Powerlight6.0and Powerlight 9.0 ampli-
fiers require that pin #9 be removed from
theremotemountinginterconnectcable.
Amplifier damage may result from use of
cable that has pin #9 connections
present.

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INSTALLATION- DataPort Connections
When using the DSP-4 module with QSC’s amplifier network monitors, the audio input to the module can be delivered
through the DataPort along with amplifier control and monitoring signals. This is the normal application of the DataPort.
Connection from the module to the amplifier network monitor is made using a DPC-X male-male QSC DataPort cable.
Alternatively, the DataPort connection can be used ONLY for control and monitoring, while the audio is input via the XLR
inputs. If using the DSP-4 in this manner, do not apply audio via the DataPort as it will be mixed with the XLR audio input
signals.
The DSP-4’s DataPort output (rear panel DataPort) connects directly to QSC’s 2-channel, 2RU, DataPort equipped
amplifiers when mounting the module on the rear of the amplifier. For all other QSC DataPort equipped amplifiers, the
module is mounted on an accessory bracket and module-to-amplifier connection is made with a DPX-2 male-female
QSC DataPort cable. These connections are shown on the previous page.
Do not use computer VGA cables as they are not correctly constructed for use with the DSP-4.
QSCDataPortcablesmaybeobtainedthrough your QSC distributor or by calling QSC’s Technical Services Department.
1- Orient the DataPort connector with the DataPort jack.
2- Firmly insert the connector into the jack.
3- Tighten the connector’s retaining screws to ensure proper contact is made. Do not overtighten.
If you are using the DataPort for audio input and/or control and monitoring, you need to:

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INSTALLATION- XLR Connections
The DSP-4 can be used with non-DataPort equipment by utilizing the XLR connections. The accessory power
supply, DPX-1, is required for all non-DataPort applications.
Inputs- The audio input can be from one of two sources; the front-panel DataPort or the XLR input connectors. Do not use both sets of
inputs at the same time! Inputs are electronically balanced with an impedance of 8.3k ohms (balanced) or 3.7k ohms (unbalanced).
Input sensitivity is software-selectable from 1.5 to 18 volts (rms) full-scale. Shield terminals connect to the chassis. Use balanced
connections for the lowest possible noise levels and to minimize the possibility of hum-inducing ground loops.
Outputs- The DSP-4’s post-processor audio is output to the rear-panel DataPort AND the XLR output connectors. The outputs are
electronically balanced with an impedance of 600 ohms. Output level is software-selectable from 4 or 6 Vrms. The XLR out’s can
be used for daisy-chaining the processed audio to additional amplifiers, even when connected to a DataPort-equipped amplifier
via the rear-panel DataPort. The maximum number of QSC amplifiers that can be connected to the DSP-4’s outputs (including the
output DataPort) is five. This ensures THD stays below 0.1%. The effect on output level signal strength is about -3 dB when five
QSC amplifiers are daisy chained. An additional +12 dB of output gain is available in software (OUT1 and OUT2 blocks).
If making your own
cables, please refer to
the Appendix for
proper pinout of the
XLR connectors.
Pinouts are provided
for balanced and un-
balanced configura-
tions.

15
INSTALLATION- RS-232 Connection
RS-232 PORT Connection-
1- Plug the 9-pin serial cable into the connector labeled RS-232 . Cable length should be 25 feet
or less. Orient the DB-9 plug correctly, insert the plug fully into the RS-232 port and finger-tighten
the retaining screws.
2- Plug the other end of the serial cable into an available COM port on your PC. Tighten the
retaining screws.
RS-232 connection to the DSP-4 module is required for “setting up” a configuration. After being setup and the
proper operation verified, the RS-232 connection is no longer needed. However, for “real time” adjustments,
the RS-232 connection to the computer must be maintained.
DSP-4 setup and programming takes place via the RS-232 port. Any time setup changes are required to the DSP-4, it must be connected
to its host computer through the RS-232 port. If “real-time” control of the DSP-4 is required, the RS-232 port connection must be maintained.
If “real-time” control is not required, then the DSP-4 can be setup first and then disconnected from the PC.
The RS-232 connection does not have to be maintained for the DSP-4 to operate.
Setup & programming can also be done via Ethernet network communication when using QSC’s QSControl products. Refer
to QSControl documentation for detailed information.

16
Connection to accessory external power supply (DPX-1)
Connection to an improper voltage source can cause immediate
damage to the DSP-4!
QSC offers the DPX-1 accessory
external power supply for applica-
tions with non-QSC amplifiers or with
QSC Powerlight models that do not
provide the required operating
voltage.
When using the external power source, we recommend that the
DSP-4bepowered-upbefore the amplifier in order toinsuretrouble-
free start-up. This will avoid audio “thumps & bumps”.
INSTALLATION- DPX-1 Accessory Power Supply
Whenthe module is used with QSC amplifiers thatdo not provide+15 VDCthrough theirDataPort connection
ORisusedwithnon-DataPortamplifiers,power must be supplied to the DSP-4 from an external power supply.
All non-QSC amplifier applications require use of the DPX-1 accessory external supply. Contact QSC’s
Technical Services Department or your QSC representative for more information. Any damage to the DSP-
4 caused by connection to a non-QSC external power supply is not covered under the warranty. Use of the
DPX-1 with QSC amplifiers that do provide +15VDC through the DataPort will not harm the DSP-4, although
it is not necessary.
To connect the DPX-1 to the DSP-4
module, plug the DPX-1 power
connecter into the DSP-4’s External
Power jack. Then plug the DPX-1
into the AC outlet. After the DSP-4
module has been powered up, the
amplifier may be turned on.

17
INSTALLATION- Daisy Chaining
Daisy chaining the DSP-4 outputs to additional amplifiers
The DSP-4 has two XLR audio outputs, one for each channel. These outputs may be used for daisy-chaining
the post-DSP signal to other amplifiers or for monitoring purposes. The XLR outputs may be used for daisy-
chaining even when the DataPorts are used for input/output. Do not use Output Power Limiting when
daisy chaining.
To daisy-chain the DSP output, connect the output jacks of the DSP-4 to the input jacks of the
next amplifier.
Then connect the paralleled signal from the first amplifier to the second amplifier, and so
on, up to a maximum of five amplifiers (including the output DataPort if connected to an amplifier). Make sure
that all interconnecting cables are balanced and connected properly.

18
The reason:
The Signal Manager software works in conjunction with the DSP-4 module to create specific signal processing algorithms for filters, delays,
limiters, and the like. The algorithms are displayed on the computer screen as ”configuration files”, with graphical representations of each
function and parameters. The user creates a signal chain, “wiring” together blocks of functions as needed for each particular audio channel
or channels.
IMPORTANT! Please read before operating the DSP-4 with your audio system.
The DSP-4 is a professional level DSP product that allows the user to produce virtually unlimited signal
processorvariations and configurations. Because of theinfiniteconfigurationpossibilities of digital signal
processing and the DSP-4, it is possible to create configurations that may result in unwanted signals or
uncontrollable output
SignalManagerhasnowayofknowingiftheDSPconfigurationyou have designed will produce the results
you intend. You can create signal loops in your configuration that may oscillate and could damage your
sound system if you apply such configurations to the DSP-4. When applying an untested configuration or
whendesigningorexperimentingwiththeDSP-4, it is a very good idea to turn down the amplifier’s physical
gain controls. That way, you won’t damage your speakers or create very loud sounds if you apply a
configuration that doesn’t do what you thought it would.
As a general rule, DO NOT CREATE SIGNAL LOOPS! Do not mix the output of a DSP object back into its
own input! There is nothing useful to achieve by doing that, you will only create an oscillator that could
damage you speakers. Also, USE THE SINE AND NOISE GENERATOR OBJECTS WITH GREAT CAUTION!
These objects produce signals that can harm your speakers. Turn down the gain. If you don’t hear a signal
whenyouthinkyoushould,DONOTINCREASETHEGAIN!!! Ifthesignalisn’taudibleatlowerlevels,there
is something else wrong. Turning up the gain to full exposes you and your system to the possibility that
some loose connection somewhere will suddenly send a full-amplitude signal through your sound system.
Like all freely configurable signal processing tools, the DSP-4 will do what the configuration you design
tells it to do. This may not be what you expect it to do, so use caution.
The DSP-4 is configured (programmed) by using the included Signal Manager software. The software must be installed
on your PC and the PC must be connected to the DSP-4 using a 9-pin serial cable and an available COM port. Once
programmed, the module can operate without any connection to the computer. Any time changes are needed to the
DSP’s configuration, the RS-232 connection must be active (cable connected). Software operating instructions are
provided in the form of an in-depth Help file in the Signal Manager software.
USE- General Guidelines for Freely Configurable DSP
The computer which is used to create the DSP-4 signal flow configurations, and subsequently
save them to disk, should be the same computer used to modify and adjust the DSP-4 settings
in the future. Naturally, this might not always be the case. At the least, a copy of the DSP-4
configuration(s) should be saved to floppy disk, so the configuration files can be transferred to
whatever computer(s) might be used to adjust or modify the DSP-4 module settings in the future.
Special Information About Saving DSP-4 Configurations

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• The last applied configuration that is “running” in the DSP-4 when it is turned off becomes the active
configuration once the power is reapplied on to the DSP-4. This ensures that the system “comes up” just
as it was left the last time it was powered down.
• Do not run your amplifier “wide open” (maximum gain) while making real-time adjustments to the DSP-
4’ssetup.The nature of the communication pathbetween thePC andDSP-4 is inherentlymore complexthan
direct physical controls of an equivalent analog processing device. Unpredictable results may occur due
to failure of the PC or the communications channel. Under such circumstances, damage to your speakers
is possible if the amplifier gain is set for high power levels. Use the minimum useful gain settings while
making system adjustments.
Overall Notes and Warnings
USE- Special Information About Saving DSP-4 Configurations
Special Information About Saving DSP-4 Configurations (continued)
When you build a DSP-4 configuration from scratch (or load one from disk) and perform an “Apply to DSP” operation, the information
downloaded into the DSP-4 module is NOT the graphical representation of what is displayed on the screen. The downloaded information
consists of the compiled algorithm coefficients of the functions, i.e. “just the math”. If building a new configuration from scratch, when you
apply it to the DSP-4 you will also be prompted to save it to disk as a Configuration file (*.cfg). The path for this Configuration file is then
associated with the compiled information that is applied to the DSP-4. A previously saved (to disk) configuration file may also be applied
to the DSP-4, and that particular file path is associated with the algorithms now loaded in the DSP-4.
When you connect a DSP-4 to a computer, the Signal Manager software first attempts to locate and display the configuration file that has
beenassociatedwiththealgorithm coefficients currently running in the DSP-4, to correlate “what you hear”with“whatyousee”. Thiswould
allow you to further adjust a delay or a filter parameter, for instance. If the correct file is located, based on the associated path name, the
graphical configuration is displayed. If the file is not found (the file has been renamed, moved, deleted, or you are not using the same
computer on which the DSP-4 was originally configured) the computer will display a message asking if you would like to browse for a
configuration.
Answering YES will open the Browse window. Once a configuration is selected, it is displayed on the screen, but not applied to the DSP-
4. Answering NO will merely display a blank workspace to the screen with no configuration loaded. At this point, what is displayed is NOT
what is currently running in the DSP-4 memory.
When the proper configuration file is displayed on the screen, go to the
Configuration->Edit menu (Ctrl-E), followed by an Apply to DSP
command(Ctrl-D).Thiswilldownloadthecurrentlydisplayed configuration back into the DSP-4 (overwriting itself), allowing synchronization
of what is displayed with what is running in the DSP-4. At this point, you may adjust parameters or modify settings as usual.

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AUDIO PERFORMANCE
Audio converters 24-bit resolution, 48 kHz sampling rate
Frequency response at 3 dB below full scale input voltage 20 Hz–10 kHz ±0.3 dB (XLR outputs)
20 Hz–20 kHz ±0.7 dB (XLR outputs)
20 Hz–20 kHz±0.2 dB (DataPort outputs)
Distortion <0.01% typical THD+N @ +4 dBu out, 20 Hz–20 kHz
Delay (throughput) 1.5 millisecond
Dynamic range >104dB min., unweighted, 1.5V input sensitivity
>106dB min., unweighted, all other input sensitivities
>107dB min., A-weighted, 1.5V input sensitivity
>109dB min., A-weighted, all other input sensitivities
Crosstalk better than 62dB down, 20 Hz–20 kHz, all sensitivities
better than 85dB down, 1 kHz bandpass, all sensitivities
Common-mode Rejection 50dB min.
Polarity In-phase or inverted
Mute >90 dB attenuation
INPUTS
Program inputs 2 via XLR female or DataPort
Type Electronically balanced
Grounding All shield terminals connected to chassis
Input sensitivity 1.5, 4.0, 9.0 or 18.0 Vrms (full scale input level)
6, 14.5, 21.5 or 27.5 dBu
3.5, 12.0, 19.0 or 25.0 dBv
Impedance 8.6 K Ohm balanced input
4.3 K Ohm unbalanced input
OUTPUTS
Program Outputs 2 via XLR male or DataPort
Type Pseudo balanced
Grounding All shield terminals connected to chassis
Outpu Level, pad* out (pad in) 6 (4) Vrms , full scale input level
*pad is software selectable 18 (14.5) dBu
15.5 (12) dBv
Impedance 600 ohms typical
Note: Specifications are subject to change without notice.
SPECIFICATIONS