Page 1
Owner’s Manual
DSP 4x4
www.stewartaudio.com
July 2014
DSP 4x4
USB POWER
OUTPUT 1 OUTPUT 2 OUTPUT 3 OUTPUT 4 INPUT 1 INPUT 2 INPUT 3 INPUT 4
POWER
5V
1234
PHANTOM
POWER
RS232
TX
RX
- + - + - + - + - + - + - + - +
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Important Safety Instructions
Before using your Stewart Audio Inc. Product, please read this Owner’s Manual carefully to ensure optimum trouble-free performance.
WARNING: TO REDUCE THE RISK OF ELECTRICAL SHOCK, DO NOT EX-
POSE THIS AMPLIFIER TO RAIN OR MOISTURE. DANGEROUS HIGH
VOLTAGES ARE PRESENT INSIDE THE ENCLOSURE. DO NOT OPEN THE
CABINET. REFER SERVICING TO QUALIFIED PERSONNEL ONLY.
The lighting bolt within arrowhead symbol, within an
equilateral triangle, is intended to alert the user to the
presence of un-insulated “dangerous voltage” within
the product’s enclosure that may be of sufcient magnitude to constitute a risk of electrical shock to person.
The exclamation point within an equilateral triangle, is
intended to alert the user to the presence of important
operating and maintenance (servicing) instruction in the
literature accompanying the appliance.
Important Safety Instruction – Please Read Prior to Product
Installation.
1. Installation should be performed by a trained and licensed professional to
insure safe and lasting operation.
2. All of the safety and operating instructions should be read before the amplier is installed or operated. Retain these instructions for future reference. All instructions should be followed; all warnings on the amplier
and in the operating instructions should be adhered to.
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK,
DO NOT REMOVE COVER (OR BACK). NO USER-
SERVICEABLE PARTS INSIDE. REFER SERVICING TO
QUALIFIED SERVICE PERSONNEL.
3. The unit should be situated so that its location and position does not interfere with its proper ventilation. For example, the unit must not be placed
on a rug, bed, sofa or similar surface that impedes airow across the
chassis. Airow through the ventilation openings should be unobstructed.
4. This unit should not be used near water, for example, near a bathtub, in a
wet basement, near a swimming pool, etc. This unit is intended to be
operated in a controlled indoor environment.
5. Do not place the unit near heat sources such as radiators, heat registers,
stoves, or other appliances that produce heat.
6. The unit should only be connected to 120-240 VAC, 50-60 Hz power supply. Do not defeat the ground or polarization of the power plug.
7. Route power cord and other cables so that they are not likely to be
walked on, tripped over or stressed. Pay particular attention to condition
of cords and cables at plugs and at the point where they exit the amplier. To prevent risk of re or injury, damaged cords and cables should be
replaced immediately.
8. Clean the unit with a clean, damp cloth. Do not use solvents or abrasive
cleaners. Never pour any liquid on the unit.
9. When left unused for a long period of time, the power cord should be
unplugged form the outlet.
10. Damaged units requiring service should be repaired by a qualied service
technician when:
a. The power cord or AC plug has been damaged.
b. Objects have fallen, or liquid has spilled into the unit.
c. The unit has been exposed to rain or other moisture.
d. The unit does not appear to operate normally or exhibits a
marked change in performance.
e. The unit has been dropped or the enclosure
damaged.
11. The user should not attempt to service the unit beyond that described in
the operating instructions. All other servicing should be referred to qualied service personnel.
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Table of Contents
1 Welcome
Congratulations on your purchase of the new Stewart Audio DSP 4x4.
This unit has been designed and built to provide you with years of highquality audio performance and trouble-free operation. If after reading
this manual you should have any questions concerning amplier installation and operation, please contact your Authorized Stewart Dealer, or
you may contact us directly using the contact information provided on
the back of this manual.
1.1 Features
Your Stewart Audio DSP 4x4 is the result of years of experience in the
design and manufacture of quality audio products. As such it provides a
combination of performance and operational benets that simply cannot be found in conventional audio products
4 channels of digital signal processing
Congurable via USB Port (http://www.stewartaudio.com/
DSPCC)
RS–232 connection for remote control
1/3 rack package
Made in the USA
1.2 Using this Manual
In order to obtain maximum performance from your DSP 4x4 please
take time to read this brief owner’s manual and carefully follow the
guidelines for connection and operation.
This manual provides you with the information necessary to safely install and operate your new DSP 4x4 in the most common scenarios. If
you nd yourself requiring additional assistance, please feel free to contact your Authorized Dealer, or you may contact us directly using the
contact information provided on the back of this manual.
Important Safety Instructions ······························································ 2
Table of Contents ················································································ 4
1 Welcome ························································································· 5
1.1 Features ··············································································· 5
1.2 Using this Manual ································································ 5
2 Setup ······························································································· 6
2.1 Setup Precautions ······························································· 6
2.2 Product Installation ····························································· 6
2.3 Input Connections ······························································· 8
2.4 Output Connections ·························································· 12
2.5 RS–232 Connection ··························································· 12
3 Operation ····················································································· 13
3.1 Operation Precautions ······················································· 13
3.2 Controls and Indicators ······················································ 14
3.3 RS–232 Commands ·························································· 16
4 Troubleshooting ·········································································· 17
5 Technical Specications ····························································· 18
6 Warranty Information ·································································· 19
6.1 Warranty Summary ··························································· 19
6.2 Return Procedure ····························································· 19
7 Accessories ·················································································· 22
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2 Setup
2.1 Setup Precautions
CAUTION: Before installing your unit, make sure that you
have read the Important Safety Precautions at the beginning of this manual.
2.2 Product Installation
The DSP 4x4 incorporates a number of different mounting options in
order to t your installation needs.
2.2.1 Pole-Mounting
The DSP 4x4 has mount holes on the top of the unit which can be
used with the AV-Pole bracket available from Stewart Audio.
Part Number: AV-Pole
2.2.2 Universal-Mount Installation
The DSP 4x4 also has a universal bracket available which allows the
unit to be mounted against a wall or under a table. Two screws are
included in the kit which will afx the bracket to the top of the unit.
Once this is done, two holes are available for mounting the unit where
desired.
CAUTION: Use only the screws provided in mounting
brackets to the unit. Do not over tighten.
Part Number: AV-Bracket
DSP 4x4
USB POWER
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2.2.3 Product Dimensions
2.3 Input Connections
Your DSP4x4 is provided with a 3-pin Phoenix connector for each input.
This connector will accept both balanced or unbalanced connections,
however some modications must be made for an unbalanced connection. See the next two sections for instructions on connecting the DSP
4x4 to its input source.
2.3.1 Balanced Connections
When using a balanced input source and connector, you must ensure
that the hot, cold, and ground pins of the connector are matched up to
the +, -, and ground pins of the DSP 4x4’s Phoenix connector respectively. Diagrams have been provided for standard XLR and TRS connectors. Please refer to the manual of your input source in case it does
not follow the standard pin-out. Caution: Incorrect wiring may re-
sult in damage to equipment.
1.72in
4.3cm
Side
DSP 4x4
USB POWER
1.72in
4.3cm
6.2in
15.7cm
4.0in
10.3cm
Female XLR
Input Connector
-
+
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2.3.2 Unbalanced Input Connections
When using an unbalanced input source and connector, a jumper must
be added between the negative (-) terminals and the ground terminals.
Once this has been done, the unbalanced source can be connected to
the positive (+) and ground terminals. Please refer to the manual of
your input source in case it does not follow the standard pin-out. For
your convenience, pre-wired connectors are available for purchase, see
the next page for details.
NOTE: A jumper is required for connecting an unbalanced
input.
Pre-wired unbalanced connectors are available for purchase from Stewart Audio. The summing adapters will properly sum a stereo source for
use with the mono input on the rear of the DSP 4x4 without causing
sound cancellation. Part numbers are found below the diagrams.
2.3.3 Phantom Power
The DSP 4x4 is designed with software-selectable 24VDC phantom
power on all 4 channels capable of supplying 25mA per channel. This
power level is sufcient to operate most condenser microphones in a
typical DSP 4x4 application.
Phantom power can be switched on/off via the Input Block of the
Stewart Audio Control Center Software (http://www.stewartaudio.com/
DSPCC) or using RS–232 commands documented in Section 3.3.
When phantom power is being supplied on a channel, the appropriate
LED indicator on the rear of the DSP 4x4 will illuminate.
CAUTION: Microphones or other input devices which do
not require phantom power can be permanently damaged
by the application of phantom power. Stewart Audio will
not be held responsible for damage to these devices.
ADPT-RCA
Mono
Female RCA
ADPT-SUMRCA
Stereo
Female RCA
ADPT-SUM35
Stereo
Female 3.5mm
Male RCA
Input Connector
Ground
(Shield)
+
A jumper has been added between the
negative (
-
) terminals and ground
Ground
(Shield)
-
+
Input Connector
A jumper has been added between the
negative (
-
) terminals and ground
+
Ground
(Shield)
Ground
(Shield)
R
-
+
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3 Operation
3.1 Operating Precautions
1. Before use, your DSP 4x4 must be congured to customize its operation, including input and output wiring hookup. Improper wiring
can result in damage to equipment or potentially harm to the operator. Consult Section 2 for setup instructions.
2. Tampering with the circuitry, or making unauthorized changes is
not only dangerous but may also violate local regulations.
3. Use care when making connections between the unit and the input
or output equipment.
NOTE: Stewart Audio will not be held responsible for
damage to your DSP 4x4 or connected equipment if the
instructions in this manual are not followed.
NOTE: For additional operating precautions, please refer
to “Important Safety Instructions” located on Page 2.
2.4 Output Connections
Your DSP 4x4 is provided with a 3-pin Phoenix connector for each output. This connector offers a balanced output to interface with the input
of another device.
Connection methods for balanced and unbalanced outputs are identical
as the methods for inputs as referenced in Section 2.3.
2.5 RS–232 Connection
Your DSP 4x4 can be controlled using the RS–232 connection on the
rear of the device. For the available RS–232 commands, see Section
3.3.
All communications should be performed at 9600 baud, 8 bits, 1
stop bit, no parity, and no ow control.
TX
RX
1
2
3
4
5
6
7
8
9
DB9 Female
(Rear)
NOTE - TX and RX
labelings are relative to the
Stewart Audio Device
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3.2.1 Controls
The DSP 4x4 is congured entirely via USB programming (http://
www.stewartaudio.com/DSPCC). An RS–232 connection allows re-
mote control of select functions (see section 3.3). There is no power
switch so the unit will remain on continuously when plugged in. Due to
the inherently low power consumption design, there is no need for a
sleep mode.
3.2.2 Indicators
The DSP 4x4 has 2 sets of LEDs to indicate power, and phantom power.
The green power LED on the front of the device will illuminate whenever the unit is plugged in.
The green phantom power LED’s will illuminate when 24VDC phantom
power is being applied to a channel. This is switched via the DSP Control Center Software. For more information, please reference the DSP
Control Center Software manual (http://www.stewartaudio.com/
DSPCC).
3.2 Controls and Indicators
DSP 4x4
USB POWER
OUTPUT 1 OUTPUT 2 OUTPUT 3 OUTPUT 4 INPUT 1 INPUT 2 INPUT 3 INPUT 4
POWER
5V
1234
PHANTOM
POWER
RS232
TX
RX
- + - + - + - + - + - + - + - +
1
1
2
3 4
5
6
7
1
USB 2.0 Connector
2
Power LED
3
Power Connector - 3.5mm
4
Output Connections - 3.5mm
5
Input Connections - 3.5mm
6
Phantom Power Indicator
7
RS232 Connector - 3.5mm
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4 Troubleshooting
Problem: No power LED indicator
Procedure: Ensure that only the provided 5VDC 2A power supply has
been used and that it is connected to a live power outlet supplying 100240VAC.
Problem: No RS–232 communication
Procedure: Ensure that the connections are done as specied in Section 2.5. Check that the communication is at 9600 baud. Shorten the
cable lengths to see if it affects the communication
Problem: No output on individual channel
Procedure: Refer to the DSP Control Center Software manual (http://
www.stewartaudio.com/DSPCC) for instructions on using live mode to
meter the signal in the DSP signal path. If a condenser microphone is in
use, ensure phantom power is being supplied. Check input connections
(see Section 2.8). Check that the volume on the audio source is at a
sufcient level.
Command Name and Description
Hex Command
TRIM
Changes trim by AMOUNT1 on CHAN2
0x12 AMOUNT1 CHAN2 0x03
VOLUME_DISCRETE
Sets CHAN
2
volume to VOL
3
0x12 0x06 CHAN2 VOL3 0x03
VOLUME_STATUS
Return CHAN
2
volume in the format:
0x06 VOL
3
0x0A
0x12 0x07 CHAN2 0x03
FORCE_MUTE_ON
Turn mute off for CHAN
2
0x12 0x08 CHAN2 0x03
FORCE_MUTE_OFF
Turn mute on for CHAN
2
0x12 0x09 CHAN2 0x03
MUTE_TOGGLE
Toggle mute on CHAN
2
0x12 0x10 CHAN2 0x03
MUTE_STATUS
Return CHAN
2
mute status in the format:
0x06 MUTE5
3
0x0A
0x12 0x11 CHAN2 0x03
CHANGE_PRESET
Change to PRESET
0x12 0x12 PRESET3 0x03
FIRMWARE_VERSION
Returns the current version in the format:
0x02 0xXX 0xYY 0x03
(XX = Version, YY = Revision)
0x12 0x13 0x13 0x03
3.3 RS–232 Commands
1
The AMOUNT is as follows:
0x01 = Up 10%, 0x02 = Up 5%,
0x04 = Down 10%, 0x05 = Down 5%,
2
The CHAN is as follows:
0x00 = all channels, 0x01 = CH1, 0x02=CH2, etc..
3
The VOLUME is in the range 0-100 expressed in hexadecimal. This
equates to a range of
0x00 - 0x64
4
The PRESET is zero-based in the range 0x00 - 0x09
5
The MUTE is in the format 0x00 = Unmuted, 0x01 = Muted
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5 Technical Specications
Frequency Response
20Hz—20kHz ±0.2dB
THD+N
<0.007%
Signal-to-Noise Ratio
>120dB at 0dB gain
Unweighted Crosstalk
<-95dB
Input Sensitivity
-24dB to +0dB
Input Impedance (Balanced/
Unbalanced/Phantom)
20k Ω, 10k Ω, 2.4k Ω
Phantom Power
24VDC @ 25mA Software Controlled
D/A Conversion
24-bit, 48kHz
Current Draw
400mA @ 5VDC
Input Connectors
3.5 Euro Block
Output Connectors
3.5 Euro Block
LED Indicators
Power, Phantom Power
Controls
USB (Programming), RS–232
(Operation)
Serial Control Port
Bidirectional RS–232
Baud Rate & Protocol
9600 baud, 8 bits, 1 stop bit, no parity, no ow control
USB Control Port
Front panel female mini USB-B
USB Standards
USB 2.0 Low Speed
Dimensions
1.7" (4.3cm) H x 6.2" (15.7cm) W x
4.0" (10.3cm) D
Weight
0.6lbs (0.3kg)
Regulatory
CE
Environmental
RoHS
Warranty
3 years
Program Control
Stewart Audio DSP Control Center
Power Supply Input
External in-line 5VDC (Universal Input
AC/DC Supply Included)
Construction
Aluminum Chassis
Mounting
Universal Bracket, Pole-Mountable
Cooling
Convection-Cooling
6 Warranty Information
6.1 Warranty Summary
All Stewart Audio ampliers and accessories, unless excluded in this
summary, are covered by a 3-year limited warranty on parts and labor
from the data of purchase. In order to be eligible for warranty repairs,
the ampliers and accessories must have been purchased through an
authorized Stewart Audio dealer and submitted by the original purchaser. This warranty is only valid in the country in which the amplier was
purchased.
6.1.1 Eligibility Requirements.
Stewart Audio warrants against all malfunctions which come as a result
of component or manufacturer defect. The amplier is also covered
from all failures which arise during the warranty period (3 years from
date of purchase) that are not a result of misuse. The following actions
will void your warranty:
The power cord or AC plug has been damaged through misuse.
The amplier has been exposed to moisture or extreme tempera-
tures.
The amplier has been dropped, items have been dropped on the
amplier, or the enclosure has been damaged.
The amplier has been opened by the operator.
The amplier was improperly packaged when sending to the fac-
tory for repair, resulting in damage.
Any of the precautions or instructions found in this manual were
not followed.
Damages resulting to the amplier which are not covered under this
warranty can be factory-repaired at cost to the customer. Use the contact information below to initiate the repair process.
6.2 Return Procedure
This section includes the return procedures which must be followed in
order to prevent processing delay or cost to the customer. Please read
the entire section before contacting Stewart Audio for returns.
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6.2.1 Return Authorization Number
All returns to the factory for service must be accompanied by a Return
Authorization (RA) number. One can be obtained by contacting Stewart
Audio at (209) 588-8111 or via e-mail at support@stewartaudio.com.
NOTE: Any defective products received without an RA number
will be returned to sender at their expense.
If Stewart Audio is unable to contact the sender in 14 days, the merchandise will be considered scrap and may be disposed of.
6.2.2 Shipment Instructions
If Stewart Audio requests that you ship the defective product back to
their service center, please refer to the guide below. To ensure prompt
warranty service, be sure to follow all instructions.
1. Return Authorization (RA) is required for product being sent to the
factory for service.
2. See packing instructions in Section 6.2.3.
3. Ship the defective product using a method which provides for order tracking or order conrmation. The service center is located at
the following address:
Stewart Audio
14397 Cuesta Court Suite D1
Sonora, CA 95370
4. Use a bold black marker and write the RA number on three sides
of the box.
5. Record the RMA number for future reference. The RA number can
be used to check the repair status.
6.2.3 Packaging Instructions
Should Stewart Audio request that you ship your product to their service center, these instructions must be followed in order to ensure safe
delivery. If they are not followed, Stewart Audio assumes no responsibility for damaged goods and/or accessories that are sent with your
unit.
6.2.3 Packaging Instructions (cont.)
1. Please write the RA number on three sides of the box. Include the
Stewart Audio RA number inside the box and a brief description of
the problem.
2. You will be advised during the RA process what accessories
should be included with the amplier (Power supplies, connectors,
cords, etc.). This is dependent on the failure assessment.
3. When shipping your amplier, it is important that it has adequate
protection. We recommend you use the original packing material
when returning the product for repair. If you do not have the original box, see number 4.
4. If you provide your own shipping pack, the minimum recommended requirements for materials are as follows:
a. 275 P.S.I. burst test, Double-Wall carton that allows for 2-
inch solid Styrofoam on all six sides of unit or 3 inches of
plastic bubble wrap on all six sides of unit.
b. Securely seal the package with an adequate carton sealing
tape.
c. Do not use light boxes or “peanuts”.
NOTE: Damage caused by poor packaging will not be covered
under warranty.
6.2.4 Payment of Non-Warranty Repairs
Payment for non-warranty repairs must be submitted to Stewart Audio
before the product will be returned to the customer.
Page 12
7 Accessories
The following accessories are available from Stewart Audio for your
amplier.
All part numbers shown are Stewart Audio Part Numbers.
To purchase these accessories or to see the full
Stewart Audio product lineup, visit us at:
www.stewartaudio.com
Mounting Brackets
AV-POLE Pole-mount bracket for AV Series ampliers
AV-BRACKET Universal mounting bracket for AV Series ampliers
Connection Adapters
ADPT-RCA Mono Female RCA to male Euroblock.
ADPT-SUMRCA Stereo Female RCA to male Euroblock.
ADPT-SUM35 Stereo Female 3.5mm to male Euroblock
WP-RVC-B Wallplate with 10k potentiometer and knob for re-
mote volume control (Black)
WP-RVC-A Wallplate with 10k potentiometer and knob for re-
mote volume control (Aluminum)
Wall Plates
22
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