SoundPals™
DAC-24 User Guide
Stereo D-to-A converter
Printing History
SoundPals™ DAC-24 D-to-A converter
Rev. N/C
JANUARY 2015
Printed in U.S.A.
Part Number 08-2044-00
The information contained in this guide is subject to change without notice or obligation.
Copyrights and Trademarks
© 2015
Contents of this publication may not be reproduced in any form without the written permission of RJM & Associates.
Reproduction or reverse engineering of copyrighted software is prohibited.
FCC Compliance
This equipment has been tested and found to comply with the limits for a Class A digital device pursuant to Part 15
of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the
equipment is operated in a commercial environment. This equipment generates, uses, and can radiate radio
frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful
interference to radio communications. Operation of this equipment in a residential area is likely to cause harmful
interference in which case the user will be required to correct the interference at your own expense.
Warranty Statement
RJM & Associates, LLC warrants that the equipment it manufactures is free from defects in workmanship and
materials and meets applicable published specifications. Equipment that has been operated within published ratings
and has not been subjected to abuse or modification, and which fails because of such defects, will be replaced or
repaired at the Company’s discretion if it is returned, freight prepaid, to RJM within three years of receipt.
This warranty supersedes all other Warranties, express or implied. RJM & Associates is not liable for any
consequential damages.
Company Address
RJM & Associates, LLC
175 Joerschke Drive
Suite A
Grass Valley, CA 95945
530-205-3437
info@rjmandassociates.com
Table of Contents
Table of Contents ii
Introduction 1
What are SoundPals? .............................................................................................................. 1
Documentation Conventions .................................................................................................... 1
Signals and Values .................................................................................................................. 1
Warnings .................................................................................................................................. 1
Unpacking and Inspection ....................................................................................................... 2
Power Supply Note .................................................................................................................. 2
DAC-24 3
About the DAC-24 .................................................................................................................... 3
DAC-24 Installation .................................................................................................................. 4
Connecting Power ............................................................................................................. 4
Connecting Inputs ............................................................................................................. 4
Connecting Outputs........................................................................................................... 5
DAC-24 Operation ................................................................................................................... 5
DAC-24 Interconnection .......................................................................................................... 6
Basic - Monitoring Digital Signals ...................................................................................... 6
Basic - Inserting Analog Equipment .................................................................................. 6
Advanced - Simultaneous Multi-Format Outputs .............................................................. 7
DAC-24 Internal Jumpers ........................................................................................................ 8
DAC-24 Troubleshooting ......................................................................................................... 8
DAC-24 Specifications ............................................................................................................. 9
Audio Specifications .......................................................................................................... 9
Environmental Specifications and Dimensions ................................................................. 9
Inside the Module ........................................................................................... 10
In This Section ....................................................................................................................... 10
Before You Begin ................................................................................................................... 10
Opening the Module .............................................................................................................. 10
Closing the Module ................................................................................................................ 10
External Power ................................................................................................ 11
About Power Supplies ........................................................................................................... 11
CE Compliance ...................................................................................................................... 11
Portable Power Sources ........................................................................................................ 11
Power Supply Specifications ................................................................................................. 11
Power Supply Sources .......................................................................................................... 12
ii • Table of Contents DAC-24 User Guide
Page
1
Introduction
What are SoundPals?
Each RJM & Associates SoundPals module is essentially a digital audio building block that can
be used independently, or interconnected to perform more advanced mixing and audio
processing functions.
SoundPals can be used in both standalone and system configurations:
• In a “standalone” configuration, each SoundPals module is designed to perform a specific
audio processing function such as ADAT-to-Analog conversion. In this way, each module
functions as a perfect low-cost adjunct to larger mixing consoles (such as the GrahamPatten D/ESAM series) — for single-purpose processing tasks.
• In a “system” configuration, SoundPals can be linked to form more comprehensive digital
audio tools. For field recording, studio applications, and workstation applications,
SoundPals can be used to seamlessly perform functions that would otherwise require
extensive peripheral gear. Best of all, SoundPals “systems” can be re-configured quickly
and easily — to suit your changing audio production requirements.
All SoundPals modules are extremely compact, rugged, and identical in size for ease of
installation, interconnection, and use. In addition, SoundPals support AES3id. This allows
longer, more robust AES signal distribution using standard coaxial cable. Error free distances of
1000 feet can be attained using inexpensive coaxial cables.
Documentation Conventions
The following documentation conventions are used in this guide:
• Buttons, knobs, connectors, and switches are indicated in bold-faced capital letters. For
example:
Adjust the left GAIN TRIM to …
• Primary sections are listed in bold text, with a line above:
Primary Section
• Secondary sections are listed in bold text, with no line:
Secondary Section
Signals and Values
Note the following important information regarding audio signal level:
• 0 dBu = 0.778 Vrms
• AES3 = Balanced output with 2 channels of digital audio (left and right)
• AES3id = Unbalanced output with 2 channels of digital audio (left and right)
Warnings
Please observe the following important warnings:
• Heed all warnings on the unit and in the instructions.
• Do not use this product in or near water.
• Route power cords and other cables so that they are not likely to be damaged.
Disconnect power before cleaning. Do not use liquid or aerosol cleaners; use only a
damp cloth.
DAC-24 User Guide
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2
Unpacking and Inspection
When you receive your SoundPals modules, inspect the cartons for signs of damage. Contact
your dealer and the shipper immediately if you suspect any damage has occurred during
shipping. Check the contents of each box to be sure that all parts are included. If any items are
missing, contact your dealer immediately.
Power Supply Note
SoundPals are delivered with a power connector only. A separate power supply must be
obtained. RJM & Associates offers several power solutions for both domestic and international
customers. Refer to “External Power” for detailed power specifications for users who wish to
configure their own power source, rather than purchase one from RJM.
DAC-24 User Guide
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3
DAC-24
About the DAC-24
The RJM & Associates SoundPals DAC-24 is a stereo, 24-bit, AES digital-to-analog converter.
The unit offers the following features:
• Stereo headphone monitoring with level control
• 24-bit D/A converter
• Automatic detection and de-emphasis
• LED indicators for emphasis and valid AES input
• Separate analog output level adjustments
(-10 to +4 dBu at -20 dBFS)
• Terminating or bridging input
• Optional rack mounting tray (1 RU)
• Compact size, rugged construction
The DAC-24 takes one AES input (on an XLR or BNC connector) and converts it to two analog
outputs (on XLR connectors).
The figure below illustrates the DAC-24’s front panel:
DAC-24
1 2
VOLUME L R
GAIN
3
4
EMPH
ERR
7
+6V
DAC-24
8
65
1) Stereo Headphone Connector — accepts standard low-impedance TRS stereo
headphones.
2) Headphone Gain Control — adjusts stereo headphone volume. The control does not
affect analog output levels.
3) Left Analog Output Gain Trim — the L GAIN trim sets the analog line level for the left
channel output.
4) Right Analog Output Gain Trim — the R GAIN trim sets the analog line level for the
right channel output.
5) Emphasis Detection LED — the EMPH LED lights when the channel status bits of the
AES input signal indicates that pre-emphasis has been applied to the signal. If the
sampling frequency is within 4% of 48 KHz, 44.1 KHz or 32 KHz, de-emphasis correction
is automatically applied.
6) AES Input Error LED — the ERR LED lights when no signal is applied to the AES input,
or when the signal is not valid. A non-valid signal exhibits errors such as format
violations, bit errors, low level, or incorrect frequency.
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4
7) Power Connector — accepts the power jack from the 6 VDC power supply. Refer to
Do not connect both AES inputs at the same time.
“External Power” for more information regarding external power.
8) Power LED — the large green LED below the power jack lights when power is applied.
The figure below illustrates the DAC-24’s rear panel:
1 2 3 4
MADE IN THE USA
AES IN RIGHT OUT LEFT OUT
1) AES Balanced Input — the AES IN XLR connector accepts a balanced AES input
signal.
2) AES Unbalanced Input — the AES IN BNC connector accepts an unbalanced AES
input signal.
NOTE: Do not connect both AES inputs at the same time.
3) Right Channel Analog Output — provides decoded right channel output at analog line
level, adjustable via R GAIN on the front panel.
4) Left Channel Analog Output — provides decoded left channel output at analog line
level, adjustable via L GAIN on the front panel.
DAC-24 Installation
This section provides instructions for connecting power, AES inputs, and analog outputs.
Connecting Power
Plug a 6 VDC power supply into the appropriate voltage outlet for your specific country, and
connect the end of the cord into the DAC-24 jack marked +6V. Secure the locking ring finger
tight. The green LED below the jack lights when power is applied.
Connecting Inputs
Connect a digital input signal, between 30 KHz and 50 KHz sampling frequency, to one of the two
inputs marked AES IN. The ERR LED on the front panel will light until a valid input signal is
applied.
NOTE
The inputs are normally terminated internally with 110 Ω (AES3) and 75 Ω (AES3id). When you
need to loop an input signal to several SoundPals, the signal must be terminated only once, and
always at the last unit in the chain. Refer to the “DAC-24 Internal Jumpers” section for
information on changing the input termination.
DAC-24 User Guide
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5
Connecting Outputs
Connect the analog audio outputs from the LEFT OUT and RIGHT OUT connectors to the inputs
of the desired analog destination device. Please note:
• Balanced outputs are taken from pins 2 (+) and 3 (-) with pin 1 and the shell grounded.
• Unbalanced outputs are taken from pin 2 with pin 1 and the shell grounded.
CAUTION Do not connect pin 3 to the low (grounded) side of an unbalanced load.
See the “DAC-24 Operation” section below for instructions on adjusting level for conditions other
than 4 dBu reference with 20 dB headroom.
DAC-24 Operation
This section provides instructions for using the gain controls, aligning outputs, and adjusting the
headphone monitor.
Using the Gain Controls
For setting left and right output levels, each output has its own level adjustment on the front
panel. Outputs are factory-set for +4 dBu at -20 dBFS. Other levels can be set by using the
following alignment procedure:
To align the left and right analog outputs:
1. Connect a reference digital tone generator to the DAC-24’s AES IN connector.
2. Connect analog VU meters to the LEFT OUT and RIGHT OUT connectors.
3. Turn on the digital reference tone, and while metering the analog output levels, adjust the
associated L and R trimmers for the desired output level.
Using the Headphone Monitor
The analog outputs may be monitored with a pair of stereo headphones plugged into the
headphone jack. Best results are obtained with a headphone impedance of 20-50 Ω. Use the
associated stereo VOLUME control to set a comfortable listening level.
DAC-24 User Guide
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6
DAC-24 Interconnection
This section provides basic and advanced interconnection diagrams.
• Basic — Monitoring Digital Signals
In this basic application, connect the DAC to an AES patch panel. You can then quickly
monitor the signal on any circuit, using either headphones or VU meters.
AES Jackfield
Analog VU Meters
Stereo
Headphones
AES In
AES In
Right Out
Left Out
SoundPals DAC-24
PWR
R Trim
L Trim
Volume
Headphones
• Basic — Inserting Analog Equipment
In this application, an analog ATR is seamlessly inserted in a digital stream, using both
the DAC and ADC together.
Analog
ATR
AES
Output
AES
Input
AES In
AES In
Right Out
Left Out
SoundPals DAC-24
PWR
R Trim
L Trim
Volume
Headphones
AES Out
AES Ref
Right In
Left In
SoundPals ADC-24
PWR
AES Out
R Trim
L Trim
DAC-24 User Guide
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7
Advanced — Simultaneous Multi-Format Outputs
In this application, SoundPals are combined in a sub-mix configuration. A CD player
feeds a DFADE for level control, and then a DMIX. Dual mics are converted to digital,
routed to a DFADE for level control, and then to a DMIX. One DMIX output provides a
digital feed, while the other is converted to analog using a DAC. Thus the mix is
available in both analog and digital formats simultaneously.
CD Player
PWR
Analog
Microphones
AES In
AES Out
SoundPals DFADE-2
Control
Mode
R Trim
L Trim
AES Out
AES Ref
Right In
Left In
SoundPals DMIC-24
PWR
AES Out
Sensitivity
AES In
AES Out
SoundPals DFADE-2
PWR
Control
Mode
R Trim
L Trim
Stereo
Headphones
AES In 1
AES In 2
AES In 3
AES In 4
SoundPals DMIX-41
PWR
Control
AES Out
AES In
AES In
Right Out
Left Out
SoundPals DAC-24
PWR
R Trim
L Trim
Volume
Headphones
Analog Out (L)
Analog Out (R)
Digital Out
DAC-24 User Guide
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8
DAC-24 Internal Jumpers
•
This section provides information about the DAC-24’s internal jumpers and adjustments.
NOTE For detailed instructions on opening and closing the DAC-24, see
“Inside the Module.”
The figure below shows the DAC-24’s internal jumper locations:
Input
Termination
Jumper
• To change the AES input from terminating to bridging, remove jumper J1.
J1
J3
DAC
04-0223-
DAC-24 Troubleshooting
The table below lists several DAC-24 problems, and provides a variety of “checklist” procedures
designed to solve them.
Problem Procedure
No signal at any
analog output.
No audio on XLR
outputs.
No audio on
headphone output.
Emphasis on input is
not corrected.
NOTE Please contact the RJM factory if the problem still exists after completing the
above procedures.
•
Is power applied? Check the power LED and power supply.
•
Is a valid AES input signal connected? Check ERR LED off.
Is the input signal silent? Check the signal source.
•
Are the outputs connected correctly? Check + to pin 2, to pin 3
(balanced) or hot to pin 2, ground to pin 1/shell, pin 3 open
(unbalanced).
•
Is the volume control turned up?
•
Is the phone jack connected correctly? Check left hot to tip, right hot
to ring, ground to sleeve.
•
Does AES channel status indicate emphasis? Check EMPH LED on.
•
Is the sampling frequency within 4% of 48 KHz, 44.1 KHz or 32 KHz?
•
Does the emphasis use 50/15 µs time constants?
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9
DAC-24 Specifications
This section provides audio and environmental specifications.
Audio Specifications
Parameter Specification
Digital input
Sample Rate 30 KHz - 50 KHz
Impedance
Level range -5 dBu to 12 dBu at -20 dBFS
Maximum output -87dB THD+N
+24 dBu (bridging load)
-20 dBFS @ +4dB -98 dB THD+N
Frequency response
Crosstalk
Dynamic range 100 dB
Impedance
Frequency response
Dynamic range 91 dB
Terminated (110 Ω AES3, 75 Ω AES3id)
Analog Outputs
30 Ω
+22 dBu (600 Ω load)
+
0/-0.2 dB, 20 Hz - 20 KHz
<
-84 dB, 20 Hz - 10 KHz
Headphone Output
20 Ω
+
0/-0.2 dB, 50 Hz - 20 KHz
Options
RT-2, 1RU rack tray for mounting up to 3 units
Power supplies:
•
PSU-1, 90-260V 50/60Hz in-line power supply with detachable IEC power cord
NOTE
• All specifications listed above subject to change without notice.
• All parameters listed above specified at 48 KHz sampling frequency.
Environmental Specifications and Dimensions
Parameter Specification
Dimensions
(less connectors)
Power 375 mA @ 6 Vdc
Operating Temp.
Operating Humidity 10 – 90% RH non-condensing
DAC-24 User Guide
5.2W x 1.62H x 6.625D
13.2 x 4.1 x 16.8 cm
10 – 50 °C
Page
10
Inside the Module
In This Section
This section provides instructions for opening and closing the SoundPals DAC-24 module to gain
access to the internal circuit board.
NOTE The internal circuit board should only be removed from the module if you want to set
the termination jumper.
Before You Begin
Check the following items before opening the module and attempting to remove the internal
circuit board:
If required, remove the SoundPals module from the rack tray.
Disconnect the power supply from the front of the product.
Disconnect all input and output cables.
Perform the remaining steps only in a static free environment. Make sure that you and
the product are both grounded.
The following tools are required:
• #2 Philips screwdriver
Opening the Module
Use the following steps to open the DAC-24 SoundPals module:
1. On the rear panel, remove the four Phillips screws from the four corners of the module.
2. On the rear panel, remove all Philips XLR mounting screws from the module.
3. On the rear panel remove the BNC nut and associated lock washer.
4. Remove the rear panel.
5. On the front panel, remove four Phillip screws from the four corners of the module.
6. Pulling the front panel, carefully draw the internal circuit board and front panel assembly
from the housing.
CAUTION Keep the case horizontal so that the BNC bushing stays with the connectors.
7. Set the housing and all mounting hardware in a safe place.
Closing the Module
Use the following steps to close the DAC-24 SoundPals module:
1. Ensure that product label is on the bottom.
2. Carefully slide the internal circuit board and front panel assembly through the housing.
Keep the case horizontal so that the BNC bushing stays with the connectors.
3. Replace, but do not tighten, the four Phillips screws in the front corners of the SoundPals
module.
4. Replace the rear panel.
5. Replace, but do not tighten, the four Phillips screws in the rear corners of the SoundPals
module.
6. Tighten the four front plate corner screws making sure that the plate is aligned with the
housing. Repeat with the four rear plate corner screws.
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7. Replace all Philips XLR mounting screws at the rear of the SoundPals module.
8. Replace the BNC nut and associated lock washer at the rear of the SoundPals module.
CAUTION Do not over tighten the screws.
External Power
About Power Supplies
An external power supply conforming to the specifications listed in the following “Power Supply
Specifications” section must be used to guarantee that published SoundPals performance
figures are met. Any power supply meeting these specifications will supply adequate power for a
single SoundPals module. Although the specification is written for power supplies running from
AC line inputs, DC (battery) sources may be used if they meet all of the listed requirements.
CE Compliance
For CE compliance, the power supply that you use must comply with the following requirements:
• Low Voltage Directive 73/23/EEC
• EMC Directive 89/336/EEC
• EMC Directive 93/68/EEC
• The connector locking ring must be tight.
Portable Power Sources
For portable SoundPals power sources, sealed lead-acid, nickel cadmium or alkaline primary
batteries may be used. However, the maximum voltage must not exceed 8.6 volts, and a
minimum of 5.6 volts is required for normal operation. Maximum current drain will be 400mA.
Power Supply Specifications
The following specifications must be met over all anticipated operating conditions including AC
power line range, temperature range, etc.
Parameter Specification
Output voltage 5.6 V minimum (measured at trough of ripple) at 400 mA constant current.
8.6 V maximum (measured at peak of ripple) at 262 mA constant current.
Ripple voltage 2 V p-p at 700 mA constant current.
Connector Switchcraft 761K with center positive, sleeve negative.
400 mV p-p at 700 mA constant current with external 2200 µF capacitor.
DAC-24 User Guide
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Power Supply Sources
In addition to the RJM-supplied universal power supply, the following power supplies meet the
SoundPals requirements:
Company Model Note
Stancor STA-4860 120V AC, 60 Hz
Stancor STAF-0797F 220V AC, 50 Hz with European wall plug (CE compliant).
Elpac MI2007
95-250V AC, 47-63 Hz with IEC inlet (line cord required). Will power up to six
units (CE compliant).
DAC-24 User Guide
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