QSC DSP-4 Owners manual

DSP-4

Digital Signal Processor
Amplifer Accessory Hardware Manual

*TD-000103-00*

TD-000103-00 rev.C

IMPORTANT SAFETY PRECAUTIONS & EXPLANATION OF 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 enclosure 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 user to the presence of impor­tant operating and maintenance (servicing) instructions in this manual.

CAUTION: To reduce the risk of electric shock, do not remove the cover. No user-serviceable parts inside.
Refer servicing to qualified service personnel.

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 following instructions for its installation, use and servicing.

•Maximum operating ambient temperature 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 hazardous 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 maintined.

•To prevent fire or electric shock, do not expose this equipment to rain or moisture.

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.
All risks attendant to integration of user-configurable DSP products with your sound system are assumed by you.
While QSC strives to supply 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.

FCC INTERFERENCE STATEMENT
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 generates, uses, and can radiate radio
frequency energy and if not installed and used in accordance to the instructions, may cause harmful inter­ference 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 be determined by switching 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 or TV technician for help.

© Copyright 2002, 2004 QSC Audio Products, Inc. QSC® is a registered trademark of QSC Audio Products, Inc. “QSC” and the QSC logo are registered

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with the U.S. Patent and Trademark Office. All trademarks are the property of their respective owners.

Introduction

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 pri­marily 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 use of a special interconnect cable
(PL6.0/9.0 only). Refer to the Appendix for application infor­mation. The DSP-4 can also be used with amplifiers that do
not have a QSC DataPort (older QSC 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 Low­Pass Filters, Shelf Filters, Muting, Attenuation, Multiple
Delays, Polarity 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-to­analog converters are 24-bit resolution and 48 kHz. sam­pling rate. Post-processor audio outputs are daisy-chain­able for connection to additional amplifiers. 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.

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 pass­through connector for use with QSC DataPort products . For
non-DataPort applications, two XLR audio inputs and two
XLR outputs (post-DSP) are provided. There is a power
receptacle for 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 tamper­proof amplifier DSP set up. 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 documentation (software Help file and Readme.txt
file) for supported feature-set and operation information.

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

From all of us at QSC Audio, thank you for your purchase. Be
sure to check our website at http://www.qscaudio.com
for the latest software and firmware updates as well as
sample DSP configurations.

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Connector and Indicator Descriptions

CH 1 INPUT, CH 2 INPUT: balanced female XLR’s.

If not using the DataPort for inputs, these are where
you connect the line-level audio inputs to the DSP-4.

They are electronically balanced with an input
impedance of 8.3k Ohms. If used in an unbalanced
configuration, the input impedance is 3.7k Ohms.
Input sensitivity is software
selectable.

SIGNAL indicator: This
green LED illuminates when
the DSP-4 detects an input
signal on either channel.
Dual brightness levels indi­cate signal level. At -40dB
fs, it will light dimly; at ­20dB fs it will light brightly.

RS-232: DB-9 female jack.
Use for serial cable connec­tion between the DSP-4 and
the computer. Connection is
required only for setup and
real-time control of the
module. Connection need
not be maintained for use.

CH 1 OUTPUT, CH 2 OUTPUT: pseudo-balanced male
XLR’s. These outputs provide post-DSP (processed) signal
from the DSP-4 for downstream devices (amplifiers, mon­itoring busses, daisy-chaining the processed signal to a
second amplifier). When using with non-DataPort amplifi­ers, these outputs should be connected to your amplifier’s
input connectors.

EXTERNAL POWER:

2.5mm barrel connector­Center (+), Outer(-), 15
VDC, 300 mA. Use if your
amplifier does not supply
the required operating volt­age from its DataPort.

DATAPORT: This is the
“input” DataPort. If using
with QSC DataPort prod­ucts that supply audio
inputs or provide amplifier
control & monitoring, this
is where they are con­nected. If using this
DataPort for audio inputs,
do not apply input signal to
the XLR inputs.

POWER indicator: This
blue LED illuminates when
the module has power
properly applied.

Chassis Lance: Use
this lance to secure
accessory power cord
(if used) with a wire tie.

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 con­nector.

If used with 3-RU, 4-, or 8­channel QSC DataPort
equipped amplifiers, the DSP­4 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 con-

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nector will not be used.

Introduction - Functions and Features

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.

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

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.

Signal Polarity Reversal

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Introduction- Block Diagram

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 software­selectable 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.

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Installation-

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
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

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 upon application)

DPX-2 DataPort Cable (module to amplifier)- This cable is a 6 foot long male-female DataPort cable used for connecting the DSP-4

module to a DataPort equipped amplifier.

Description Quantity

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-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-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.

Software Installation

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.

1. Insert the CD labeled QSC Signal Manager into your CD drive (typically drive “D:”). If your computer has AUTORUN enabled, the
installation utility will start automatically. If it does not, 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.

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Software Installation (continued)

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 configure any necessary crossovers , filters, etc. prior to
applying audio signals to the inputs. Damage to equipment may result if these recommendations are not followed.

7. 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.

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).

If you have an amplifier that supports “direct” mounting, you need to:

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).

Be sure to secure the DSP-4 using
all three mounting screws. The
“backside” DataPort connector can
be easily damaged if the module is
twisted and there are no supporting
screws to properly secure it to the
chassis.

Ensure all mounting screws are
installed.

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