Studio Technologies Model 544D User manual

50729-0123, Issue Preliminary 1
Copyright © 2023 by Studio Technologies, Inc., all rights reserved
studio-tech.com
User Guide
Issue Preliminary 1, January 2023
This User Guide is applicable for serial numbers
M544D-00151 and later with Application Firmware 1.0 and later
and STcontroller application version 3.10.00 and later.
Model 544D
Audio Interface

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Model 544D User Guide Issue Preliminary 1, January 2023
Studio Technologies, Inc. Page 3
Model 544D
AUDIO INTERFACE
Table of Contents
Revision History ................................................................................................................................ 4
Introduction........................................................................................................................................ 5
Getting Started .................................................................................................................................. 9
Dante Conguration .......................................................................................................................... 13
Model 544D Conguration................................................................................................................. 15
Operation........................................................................................................................................... 20
Technical Notes................................................................................................................................. 22
Specications .................................................................................................................................... 26
Appendix A–STcontroller Default Conguration Values..................................................................... 28
Appendix B–Graphical Description of the Installation Kit for Panel-Cutout or Surface-Mounting
Use (Order Code RMBK-10) ............................................................................................................. 29
Appendix C–Graphical Description of Left- or Right-Side Rack-Mount Installation Kit for
One “1/2- Rack” Unit (Order Code RMBK-11)................................................................................... 30
Appendix D–Graphical Description of Rack-Mount Installation Kit for Two “1/2- Rack” Units
(Order Code RMBK-12)..................................................................................................................... 31
Appendix E–Graphical Description of Center Rack-Mount Installation Kit for One “1/2- Rack”
Unit (Order Code RMBK-13) ............................................................................................................. 32
Appendix F–Interfacing with RTS
®
Matrix Intercom Systems............................................................ 33
Appendix G–Interfacing with Riedel
®
Artist™ Matrix Intercom Systems ........................................... 34
Appendix H–Interfacing with Clear-Com
®
Matrix Intercom Systems ................................................. 35

Issue Preliminary 1, January 2023 Model 544D User Guide
Page 4 Studio Technologies, Inc.
Model 544D
AUDIO INTERFACE
Revision History
Issue Preliminary 1, January 2023:
•Initial preliminary release.

Model 544D User Guide Issue Preliminary 1, January 2023
Studio Technologies, Inc. Page 5
Model 544D
AUDIO INTERFACE
Introduction
The Model 544D Audio Interface provides a simple yet
high-performance means of interfacing two channels
of analog line-level audio to and from applications that
utilize Dante
®
audio-over-Ethernet media network-
ing technology. Two Model 544D units can provide
one-to-one signal paths, two in each direction, over
a standard local area network (LAN). A Model 544D
can work on its own to allow Dante-enabled products
to interface with analog input and output signals. In
addition, the unit supports transport of status signals
or contact closures between Model 544D units and
other compatible products. There are two general-
purpose inputs (GPI) and two general-purpose out-
puts (GPO) on each Model 544D. The Model 544D
can also provide a tone generator function. This allows
sine-wave signals at a frequency of 1 kHz, 18 kHz, or
20 kHz to be output by way of the analog line-level
and Dante digital interface channels.
The Model 544D is a fully professional product that
offers the audio quality, features, and reliability
required by 24-hour, on-air, and commercial appli-
cations. The two line-level analog audio inputs use
standard 3-pin female XLR connectors for easy inter-
facing with balanced and unbalanced sources. The
input audio signals are converted to 24-bit digital and
then transported via the Dante interface. Two digital
audio signals arrive into the Model 544D via the Dante
interface and are then converted to analog. Two 3-pin
male XLR connectors on the Model 544D’s back panel
provide balanced analog line-level outputs.
The Model 544D can serve as an analog-to-Dante
bridge, linking analog audio interfaces found on
devices such as matrix intercom systems, broadcast
routers, and audio consoles to and from the Dante
domain. An Ethernet connection is all that’s required
to make the Model 544D part of a sophisticated,
networked audio system. Dante audio-over-Ethernet
has found wide acceptance as an audio “backbone”
due to its ease of use, high performance, strong
interoperability, and wide adoption by a large number
of equipment manufacturers. The Model 544D is a
general-purpose “tool” that helps to expand Dante’s
capabilities to facilities and equipment that primarily
supports signals in the analog domain.
Audio data is sent to the Model 544D using the Dante
audio-over-Ethernet media networking technology.
Audio signals with a sample rate of 44.1 or 48 kHz
and a bit depth of up to 24 are supported. The two
line-level input channels are converted to digital and
then routed to transmitter (output) channels on the
Dante interface. Two transmitter (output) channels
from an associated Dante-enabled device can be
assigned to the Model 544D’s receiver (input) chan-
nels using the Dante Controller application. These are
then converted into analog outputs.
Careful attention to circuit design and component
selection ensures that excellent audio quality is main-
tained. Extensive ltering helps prevent damage or
less-than-optimal performance should DC voltage,
ESD (“static”), or strong RF signals be present on the
associated analog signals.
Figure 1. Model 544D Audio Interface front and back views

Issue Preliminary 1, January 2023 Model 544D User Guide
Page 6 Studio Technologies, Inc.
Model 544D
AUDIO INTERFACE
The STcontroller software application is used to
congure the Model 544D’s wide range of operating
parameters. These include the nominal signal levels
and which sources are utilized for the analog and
Dante digital channels. Versions of STcontroller are
available that are compatible with the Windows
®
and
macOS
®
operating systems. They are available, free
of charge, from the Studio Technologies’ website.
Using STcontroller, the nominal audio levels of the line
input and line output functions can be independently
selected. In this way, compatibility with SMPTE
®
, EBU,
and “semi-pro” nominal signal levels is supported.
Audio level meters provide conrmation of system per-
formance during setup and operation. Two general-
purpose input (GPI) and two general-purpose output
(GPO) functions allow support for installer-selected
applications, including party-line intercom call-light
functions. LED indicators provide a direct indication
of the status of the GPI and GPO functions.
The Model 544D can be powered by power-over-
Ethernet (PoE) or an external source of 12 volts DC.
Standard connectors are used for the analog line
inputs and analog line outputs, Ethernet, GPI, GPO,
and DC power interconnections. The Model 544D’s
enclosure has a “1/2-rack” 1U form factor and weighs
less than two pounds, making it well suited for use
in portable applications. Alternately, using one of the
optional rack-mount front panels, one or two Model
544D units can be mounted in a single space (1U) of
a standard 19-inch rack enclosure.
Applications
The most basic application for Model 544D is for trans-
porting analog audio signals to and from one location
to another using the data transport resources of a
local area network — there’s really no simper means
to getting high-quality audio from “point A to point B”
and back. With standard connectors and PoE power,
setup can be completed in just a few minutes. This
makes Model 544D units e󰀨ective in both xed and
portable applications.
The Model 544D can also nd use when an applica-
tion already supports Dante. For example, ports on a
matrix intercom system that directly supports Dante,
such as the RTS
®
ODIN
®
or ADAM
®
with OMNEO
®
,
can be routed to a Model 544D’s Dante transmitter
(output) and receiver (input) channels. The Model
544D will then provide two analog line inputs and two
analog line outputs for use in a variety of applications.
These can include interfacing with audio inputs and
outputs associated with audio consoles, providing
talent cueing (IFB) feeds, and interfacing with the
audio outputs of aerial camera systems.
The GPI and GPO functions allow Model 544D units to
transport contact closures using high-frequency audio
tones that are embedded as part of the unit’s audio
channels. Two independent contact closures can be
“repeated” across a network using Dante audio paths.
Provided for installer-specied applications, having
the ability to transport contact closures over signicant
distances can be a unique and valuable resource.
The Model 544D’s tone generator capability enables
the unit to create 1 kHz, 18 kHz, and 20 kHz sine-
wave analog and Dante digital audio signals. The
ability to generate precision 1 kHz sine-wave tones
is intended for general-purpose audio use. The
18 kHz tone is provided as a resource when sup-
porting remote-production (REMI) applications that
use the Studio Technologies’ Model 5422A Dante
Intercom Audio Engine. This 18 kHz tone can be used
by a matrix intercom system to facilitate creation of
voice-with-tone interruptible foldback (IFB) signals.
When routed to Model 5422A interrupt inputs, these
specialized IFB interrupt signals will allow creation of
excellent talent cueing channels.
The 20 kHz tone option is provided for use in appli-
cations where generation of a party-line call signal is
desired. For example, the 20 kHz tone can be con-
nected to a matrix intercom system which would be
congured such that a button press will cause 20 kHz
to be sent out an intercom channel. This can serve as
a “trigger” signal for visual or audible alerting devices,
such as the Studio Technologies’ Model 391 Dante
Alerting Unit.
Line Inputs
The Model 544D provides two analog line-level input
channels. Two STcontroller configuration choices
allow the nominal levels of each input to be +4 dBu,
–2 dBu, or –10 dBu. When congured for +4 dBu the
unit will be compatible with SMPTE applications where
the nominal digital signal level is –20 dBFS. The
–2 dBu conguration choice allows the line inputs to
be optimized for EBU applications where the nominal
digital signal level is –18 dBFS. The –10 dBu cong-
uration is provided for “semi-pro” applications where

Model 544D User Guide Issue Preliminary 1, January 2023
Studio Technologies, Inc. Page 7
Model 544D
AUDIO INTERFACE
sources are typically unbalanced (single-ended).
Using this selection, an analog signal with a level of
–10 dBu will result in a Dante digital output signal with
a level of –20 dBFS.
The electronically balanced (di󰀨erential) input circuits
are capacitor-coupled and ESD (static) protected for
reliable operation in a variety of applications. They
are also protected from damage should a moderate
DC voltage be accidentally connected. Sources can
include analog I/O cards on matrix intercom systems,
audio consoles, wireless microphone receivers, and
broadcast routers.
Line Outputs
The Model 544D provides two analog line-level output
channels. As with the line inputs, STcontroller choic-
es allow the audio source for each line output to be
selected. Choices include the Dante receiver (input)
channels, the line inputs, and three sine-wave tone
sources. The nominal level of the line outputs can
be selected in STcontroller to be +4, –2, or –10 dBu.
This allows compatibility in applications where SMPTE
(+4 dBu = –20 dBFS) or EBU (0 dBu = –18 dBFS)
standards may apply. The –10 dBu setting can be use-
ful for “semi-pro” applications where a lower nominal
level is necessary. The line outputs are electronically
balanced, capacitor-coupled and ESD (static) pro-
tected. The outputs are compatible with virtually all
balanced and unbalanced inputs with an impedance
of 2 k ohms or greater.
Pro Audio Quality
The Model 544D’s audio circuitry was designed in
the spirit of professional audio equipment rather
than that found in typical broadcast or commercial
audio gear. High-performance components are used
throughout, providing low-distortion, low-noise, and
high headroom. Care was taken so that signal integrity
is maintained in both the analog and digital domains.
Audio Meters and Status LEDs
The Model 544D provides four 5-segment LED
meters. The meters, located on the unit’s front panel,
display the level of the audio signals associated with
the two line inputs and two line outputs. At the time
of installation and setup the meters are invaluable in
helping to conrm correct operation. During normal
operation the meters o󰀨er a real-time conrmation of
the unit’s audio signal levels, helping to ensure that
optimal audio quality is maintained. Additional LED
indicators are provided on the front panel, o󰀨ering
status indications of the incoming power, GPI, and
GPO functions.
GPI and GPO Capability
The Model 544D allows the sending and receiving
of status signals using high-frequency audio tones
that are transported within the Dante audio channels.
When two Model 544D units are interconnected
using an Ethernet network and Dante, two status
signals can be transported in each direction. The
GPI (general-purpose input) functions are compatible
with contact closures provided by equipment such as
matrix intercom systems, video/audio routers, or tally
systems. During operation, a closure on one Model
544D GPI will result in the closing (shorting) of a solid-
state relay contact associated with the GPO on a
second Model 544D unit. To assist in implementing
specialized GPI and GPO applications a source of
low-current DC power is also provided.
The GPI and GPO functions can be especially useful
in party-line intercom applications where call-light
signals are utilized. Contact closures on matrix
intercom systems can be “repeated” by Model 544D
units that are located anywhere on the same local
area network (LAN). The Model 544D is also directly
compatible with the call-light signal support provided
by the Studio Technologies’ Model 545DC and Model
545DR Intercom Interface units. With a Model 544D
appropriately interconnected with a matrix intercom
system full call-light support can be provided to and
from RTS and Clear-Com
®
party-line intercom circuits.
Tone Generator Mode
For special applications, the Model 544D can be
configured to serve as an audio tone generator.
Instead of functioning as an interface device, the
Model 544D will generate low-distortion, frequency-
accurate, sine-wave audio signals. STcontroller con-
guration choices allow the frequency of the tones to
be 1 kHz, 18 kHz, or 20 kHz. The tone signals are
available as line-level analog and Dante digital audio
outputs. When selected to output a tone, the level on
a analog line output will follow the congured nominal
level. Using STcontroller, the choices are +4 dBu,
–2 dBu, and –10 dBu. The tone level on the Dan-
te transmitter (output) channels will be fixed at
–20 dBFS.

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Page 8 Studio Technologies, Inc.
Model 544D
AUDIO INTERFACE
The 1 kHz tone is provided for general-purpose audio
use. This can serve as an audio reference for an entire
audio “plant” or facility to access as needed. Having
a continuous source of 1 kHz sine-wave in analog or
Dante digital formats can be useful for installation,
testing, and troubleshooting applications.
The 18 kHz tone is intended for use with matrix inter-
com systems that are used with the Studio Technolo-
gies’ Model 5422A Dante Intercom Audio Engine. This
tone will be connected to a matrix intercom system
using either analog or Dante inputs. The matrix inter-
com system will be congured such that it will combine
voice audio with the 18 kHz tone to create specialized
IFB interrupt signals. These voice-with-tone signals
will be routed, by way of an audio transport system,
to Model 5422A interrupt inputs associated with tone
operated (TOX) IFB channels. The Model 5422A
will detect the 18 kHz tone and “trigger” the associ-
ated IFB function. In this way, high-performance IFB
functions can be implemented for REMI (remote-
production) applications.
The 20 kHz tone is provided for use in applications
where generation of in-band signals that are compati-
ble with the call function on RTS TW-series party-line
(PL) intercom channels is desired. One example
would be for the 20 kHz tone to be connected to an
analog or Dante receiver (input) channel on a matrix
intercom system. The intercom system would be con-
gured such that a button press on an intercom “key”
panel would cause 20 kHz to be sent out an intercom
channel. This would then serve as a call “trigger” for
devices such as a Studio Technologies’ Model 391
Dante Alerting Unit. Another interesting example
would be for the 20 kHz tone to be used to serve as
an activation signal for contact closures. Using Dante
subscriptions (routes), the intercom channel from the
matrix interface would be connected to additional
Model 544D units. When those units receive the
20 kHz tone signal they would enable their associated
GPO contact closures.
Ethernet Data, PoE, and DC Power
Source
The Model 544D connects to a local area data net-
work (LAN) using a standard 100 Mb/s twisted-pair
Ethernet interface. The physical interconnection is
made by way of a Neutrik etherCON RJ45 jack. While
compatible with standard RJ45 plugs, an etherCON
jack allows a ruggedized and locking interconnection
for harsh or high-reliability environments. The Model
544D’s operating power can be provided by way of
the Ethernet interface using the Power-over-Ethernet
(PoE) standard. This allows fast and e󰀩cient intercon-
nection with the associated data network. To support
PoE power management, the Model 544D’s PoE
interface reports to the power sourcing equipment
(PSE) that it is a class 1 (very low power) device. The
unit can also be powered using an external source
of 12 volts DC. For redundancy, both power sources
can be connected simultaneously. Three LEDs on the
unit’s back panel display the status of the network
connection, Dante interface, and PoE power source.
Two LEDs on the unit’s front panel provide a real-time
indication of the connected power sources.
Simple Installation
The Model 544D uses standard connectors to allow
fast and convenient interconnections. An Ethernet
signal is connected using a Neutrik etherCON RJ45
jack. If Power-over-Ethernet (PoE) is available opera-
tion will commence immediately. An external 12 volts
DC power source can also be connected by way of a
4-pin female XLR connector. Analog line-level input
and output connections are made using 3-pin male
and female XLR connectors. GPI, GPO, and auxil-
iary DC connections are made using a 9-pin female
D-subminiature (DE-9F) connector. The Model 544D
is housed in a rugged yet lightweight aluminum en-
closure that is designed to be “eld tough.” It can be
used as a standalone portable unit, supporting what’s
known in the broadcast world as “throw-down” appli-
cations. Rack-mounting option kits are available that
allow one or two Model 544D units to be mounted in
one space (1U) of a standard 19-inch rack enclosure.
Future Capabilities and Firmware
Updating
The Model 544D was designed so that its capabili-
ties and performance can easily be enhanced in the
future. A USB receptacle, located on the unit’s back
panel, allows the application rmware (embedded
software) to be updated using a USB ash drive. To
implement its Dante interface the Model 544D uses
the UltimoX2™ integrated circuit from Audinate. The
rmware in this integrated circuit can be updated via
the Ethernet connection helping to ensure that its
capabilities remain up to date.

Model 544D User Guide Issue Preliminary 1, January 2023
Studio Technologies, Inc. Page 9
Model 544D
AUDIO INTERFACE
Getting Started
In this section, a location will be selected for the Model
544D. If desired, an optional installation kit will be
used to mount one or two units into a panel cutout, at
surface, or equipment rack. Signal interconnections
will be made using the unit’s back-panel connectors.
An Ethernet data connection, which typically includes
Power-over-Ethernet (PoE) capability, will be made
using a cable-mounted etherCON plug or a stan-
dard RJ45 patch cord. A 4-pin XLR connector allows
connection of an optional 12 volts DC power source.
Connections to analog line-level input and output
signals will be made using 3-pin male and female
XLR connectors. Some applications may utilize the
GPI and GPO functions which are accessible using
a 9-pin female D-subminiature (DE-9F) connector.
What’s Included
Included in the shipping carton are a Model 544D
Audio Interface and instructions on how to obtain an
electronic copy of this guide. An optional installation kit
allows a Model 544D to be mounted in a rectangular
opening in a tabletop or attached to a at surface. If
one or two Model 544D units are going to be mounted
in a 19-inch equipment rack then having another of
the optional rack-mount installation kits is required.
If an installation kit was purchased it would typically
have been shipped in a separate carton. As a device
that can be powered by Power-over-Ethernet (PoE)
or an external source of 12 volts DC, no power source
is included. (A compatible power supply, the Studio
Technologies’ PS-DC-02, is available as an option.)
Locating the Model 544D
Where to locate a Model 544D will depend on
being able to access the associated analog line
input, analog line output, and, if utilized, GPI and
GPO functions. The Model 544D is shipped as a
self-contained “throwdown” unit suitable for portable
use or placement in a semi-permanent location. In-
stalled on the bottom of the chassis are screw-a󰀩xed
“bump on” protectors (also known as rubber “feet”).
These are useful if the unit is going to be placed on a
surface where scratching of either the Model 544D’s
enclosure or the surface material could take place.
However, if applicable the feet can be removed when
installation in a panel cutout, onto a at surface, or in
a rack enclosure is going to be performed.
Once the unit’s physical location has been established
its assumed that the twisted-pair Ethernet cabling will
be within 100-meters (325-feet) of the Ethernet port
on an associated network switch. If this is not the
case, then the overall length limit can be overcome by
using a ber-optic interconnection between the Model
544D’s-related-Ethernet switch and another Ethernet
switch that’s part of the application’s local-area-
network (LAN). With a ber interconnect there’s no
reason why a Dante-supporting LAN can’t be distrib-
uted over many miles or kilometers.
Mounting Options
Panel Cutout or Surface Mounting One
Model 544D Unit
Installation kit RMBK-10 allows one Model 544D to
be mounted in a panel cutout or onto a at surface.
The kit contains two standard-length brackets and
four 6-32 thread-pitch Phillips-head machine screws.
Refer to Appendix B for a visual explanation.
Get ready to install the kit by rst removing the four
machine screws and associated bump on protectors
from the bottom of the Model 544D’s chassis. They
are removed using a #1 Phillips screwdriver. Store the
four machine screws and four bump on protectors for
possible later use.
To prepare the unit to mount in a cutout or other
opening in a panel, use a #2 Phillips screwdriver
and two 6-32 machine screws to attach one of the
standard-length brackets onto the left side (when
viewed from the front) of the Model 544D’s enclosure.
Orient the standard-length bracket such that its front is
parallel to the Model 544D’s front panel. The screws
will mate with the threaded fasteners that can be seen
on the side of the Model 544D’s enclosure, near the
front of the unit. Using two additional 6-32 machine
screws, attach the other standard-length bracket onto
the right side of the Model 544D’s enclosure.
Once the two standard-length brackets have been
installed the Model 544D will be ready to be mount-
ed into an opening. Secure the unit into the top left
and right edges of the opening using two mounting
screws per side.
To prepare the unit to be mounted onto a at surface
simply requires the standard-length brackets be
attached to the Model 544D at 90 degrees from how
they are mounted for use in a panel cutout. Use a

Issue Preliminary 1, January 2023 Model 544D User Guide
Page 10 Studio Technologies, Inc.
Model 544D
AUDIO INTERFACE
#2 Phillips screwdriver and two 6-32 machine screws
to attach one of the standard-length brackets onto the
left side (when viewed from the front) of the enclosure.
Orient the bracket such that its front is parallel with
the top surface of the Model 544D’s enclosure. The
screws will mate with the threaded fasteners that can
be seen on the side of the Model 544D’s enclosure,
near the front of the unit. Following the same orienta-
tion, use two additional 6-32 machine screws to attach
the other standard-length bracket onto the right side
of the Model 544D’s enclosure.
Once the two standard-length brackets have been
installed the Model 544D will be ready to be mounted
onto a at surface. Secure the unit to the surface using
two mounting screws per side.
Left- or Right-Side Rack Mounting One
Model 544D Unit
Installation kit RMBK-11 allows one Model 544D to be
mounted in the left or right side of one space (1U) of a
standard 19-inch rack enclosure. The kit contains one
standard-length bracket, one long-length bracket, and
four 6-32 thread-pitch Phillips-head machine screws.
Refer to Appendix C for a visual explanation.
Get ready to install the kit by removing the four ma-
chine screws and associated bump on protectors
from the bottom of the Model 544D’s chassis. They
are removed using a #1 Phillips screwdriver. Store the
four machine screws and four bump on protectors for
possible later use.
To prepare the unit to mount in the left side of a rack
enclosure, use a #2 Phillips screwdriver and two 6-32
machine screws to attach the standard-length bracket
onto the left side (when viewed from the front) of the
enclosure. The screws will mate with the threaded
fasteners that can be seen on the side of the Model
544D’s enclosure, near the front of the unit. Using
two additional 6-32 machine screws, attach the long-
length bracket onto the right side of the Model 544D’s
enclosure.
To prepare the unit to mount in the right side of a
rack enclosure, use a #2 Phillips screwdriver and
two 6-32 machine screws to attach the long-length
bracket onto the left side of the enclosure. Using
two additional 6-32 machine screws, attach the
standard-length bracket onto the right side of the
Model 544D’s enclosure.
Once the standard-length and long-length brackets
have been installed the Model 544D will be ready
to be mounted into the designated equipment rack.
One space (1U or 1.75 vertical inches) in a standard
19-inch equipment rack is required. Secure the unit
into the equipment rack using two mounting screws
per side.
Rack-Mounting Two Model 544D Units
Installation kit RMBK-12 is used to allow two Model
544D units to be mounted in one space (1U) of a
standard 19-inch equipment rack. The kit can also
be used to mount one Model 544D and one other
Studio Technologies’ product that is compatible with
the RMBK-12, such as the Model 545DR Intercom
Interface or the Model 5421 Dante Intercom Audio
Engine. The RMBK-12 installation kit contains two
standard-length brackets, two joiner plates, eight 6-32
thread-pitch Phillips-head machine screws, and two
2-56 thread-pitch Torx™ T7 thread-forming machine
screws. Refer to Appendix D for a visual explanation.
Get ready to install the kit by removing the four ma-
chine screws and associated bump on protectors from
the bottom of each chassis. They are removed using
a #1 Phillips screwdriver. Store the eight machine
screws and eight bump on protectors for possible
later use.
With assistance from a #2 Phillips screwdriver, use
two of the 6-32 machine screws to attach one of the
standard-length brackets onto the left side (when
viewed from the front) of one of the Model 544D units.
The screws will mate with the threaded fasteners that
can be seen on the side of the Model 544D’s enclo-
sure, near the front of the unit. Using two more of the
6-32 machine screws, attach one of the joiner plates
onto the right side of that same Model 544D unit.
Again using two of the 6-32 machine screws, attach
the second standard-length bracket onto the right side
of the second Model 544D or another compatible unit.
Using the nal two 6-32 machine screws, attach the
second joiner plate onto the left side of the second
Model 544D or other compatible unit with an orien-
tation of 180 degrees from the way in which the rst
plate was installed.
To complete the assembly, “join” the units together
by sliding each joiner plate through the other. The
grooves in each joiner plate will carefully align with

Model 544D User Guide Issue Preliminary 1, January 2023
Studio Technologies, Inc. Page 11
Model 544D
AUDIO INTERFACE
each other and form a relatively tight bond. Line up
the two units so that the front panels form a common
plane. With the aid of a Torx T7 screwdriver, use the
two 2-56 Torx machine screws to secure the two
joiner plates together. The screws should t snugly
into the small openings formed by the mating of the
two joiner plates.
The 2-unit assembly is now ready to be mounted
into the designated equipment rack. One space (1U
or 1.75 vertical inches) in a standard 19-inch equip-
ment rack is required. Secure the assembly into the
equipment rack using two mounting screws per side.
Center Rack Mounting One Model 544D
Unit
Installation kit RMBK-13 allows one Model 544D
to be mounted in the center of one space (1U) of a
standard 19-inch rack enclosure. The kit contains two
medium-length brackets and four 6-32 thread-pitch
Phillips-head machine screws. Refer to Appendix E
for a visual explanation.
Get ready to install the kit by removing the four ma-
chine screws and associated bump on protectors
from the bottom of the Model 544D’s chassis. They
are removed using a #1 Phillips screwdriver. Store the
four machine screws and four bump on protectors for
possible later use.
To prepare the unit to mount in the center of a rack
enclosure, use a #2 Phillips screwdriver and two 6-32
machine screws to attach one of the medium-length
brackets onto the left side (when viewed from the
front) of the enclosure. The screws will mate with the
threaded fasteners that can be seen on the side of
the Model 544D’s enclosure, near the front of the unit.
Using two additional 6-32 machine screws, attach the
other medium-length bracket onto the right side of the
Model 544D’s enclosure.
Once the two medium-length brackets have been
installed the Model 544D will be ready to be mounted
into the designated equipment rack. One space (1U or
1.75 vertical inches) in a standard 19-inch equipment
rack is required. Secure the unit into the equipment
rack using two mounting screws per side.
Ethernet Connection with PoE
An Ethernet connection that supports 100BASE-TX
(100 Mb/s over twisted-pair) is required for Model
544D operation. A 10BASE-T connection is not
su󰀩cient; a 1000BASE-T (GigE) connection is not
supported unless it can automatically “fall back” to
100BASE-TX operation. An Ethernet connection that
supports Power-over-Ethernet (PoE) is preferred as it
will also provide operating power for the Model 544D.
To support Ethernet switches that include PoE power
management capability the Model 544D will enumer-
ate itself as a PoE class 1 device.
A 100BASE-TX Ethernet connection is made by way
of a Neutrik etherCON RJ45 jack that is located on the
back panel of the Model 544D. This allows connection
by way of a cable-mounted etherCON plug or a stan-
dard RJ45 patch cord. A crossover cable will never
be required as the Model 544D’s Ethernet interface
supports auto MDI/MDI-X. Per the Ethernet standard,
the Ethernet Switch-to-Ethernet Device length limita-
tion for twisted-pair cabling is 100-meters (325-feet).
External 12 Volt DC Input
An external source of 12 volts DC can be connected
to the Model 544D by way of a 4-pin male XLR con-
nector which is located on the back panel. While the
requirement for the external source is nominally 12
volts, correct operation will take place with any source
that has a range of 10 to 18 volts DC. The Model
544D requires 300 milliamperes maximum at 12 volts
DC for correct operation. The DC source should be
terminated to a 4-pin female XLR connector with
pin 1 negative (–) and pin 4 positive (+). Purchased as
an option, the compatible PS-DC-02 power supply is
available from Studio Technologies. Its AC mains input
allows connection of a 100-240 volts, 50/60 Hz source
and its 12 volt DC, 1.5 amperes maximum output is
terminated on a 4-pin female connector.
As previously discussed, an Ethernet connection that
provides Power-over-Ethernet (PoE) can serve as the
Model 544D’s power source. Alternately, an external
12 volts DC source can be connected. For redundan-
cy, both PoE and an external 12 volts DC source can
be connected at the same time. If both PoE and an
external 12 volts DC source are connected, power will
be drawn only from the PoE supply. If the PoE source
becomes inoperative the 12 volts DC source will pro-
vide the Model 544D’s power with no interruption in
operation. (Of course, if both PoE and Ethernet data
support are lost that is a very di󰀨erent situation!)

Issue Preliminary 1, January 2023 Model 544D User Guide
Page 12 Studio Technologies, Inc.
Model 544D
AUDIO INTERFACE
Line Inputs
The Model 544D provides two analog line-level
inputs that are intended for connection to balanced
or unbalanced signal sources associated with profes-
sional audio and video equipment. It’s expected that
the nominal level of the analog sources will either be
+4 dBu for SMPTE
®
applications, 0 or –2 dBu for EBU
applications, or –10 dBu for “semi pro” applications.
(Refer to a later section of this guide for analog line
input nominal level conguration.) Commonly used
sources could include analog I/O ports on broadcast
matrix intercom systems, audio consoles, video
storage and playback systems, wireless microphone
receivers, and audio testing equipment. The circuitry
associated with the line inputs is analog, electronically
balanced, capacitor coupled, with a nominal imped-
ance of 20 k ohms.
Two 3-pin female XLR connectors, located on the
Model 544D’s back panel, are used for interfacing
with the source signals. Prepare 3-pin male XLR
mating connectors such that pin 2 is signal high (+),
pin 3 is signal low (–), and pin 1 is common/shield. It’s
also probable that unbalanced sources will interface
correctly. With an unbalanced source begin by con-
necting signal high (+) to pin 2 and signal low/shield
(–) to both pins 1 and 3. If this results in hum or noise,
next try connecting signal high (+) to pin 2 and signal
low/shield (–) only to pin 3; leave pin 1 unconnected
(“oating”).
Line Outputs
The Model 544D provides two analog line-level out-
puts. These analog outputs are designed for general-
purpose use which could include connecting to analog
inputs on devices including matrix intercom systems,
transmitters associated with wireless in-ear monitors,
audio consoles, or amplied speakers. The circuitry
associated with the line outputs is analog, capacitor-
coupled, and has a nominal source impedance of 200
ohms. They will perform optimally when driving loads
of 2 k (2000) ohms or greater. The nominal level of
the line outputs is congurable to be either +4 dBu,
–2 dBu, or –10 dBU, corresponding to the needs of
SMPTE, EBU, or “semi-pro” applications. (Refer to a
later section of this guide for analog line output level
conguration.)
Two 3-pin male XLR connectors, located on the Model
544D’s back panel, are provided for interfacing the
line outputs with associated equipment. Prepare 3-pin
female XLR mating connectors such that pin 3 is
signal high (+), pin 2 is signal low (–), and pin 1 is
common/shield. To connect to an unbalanced load
use pin 2 as signal high (+) and pin 1 as low/shield;
do not connect anything to pin 3. Do not short pin 3
to pin 1 on a line output connector as it will stress the
output circuitry.
General-Purpose Inputs (GPI)
The Model 544D provides two general-purpose
input functions that are referred to as GPI 1 and
GPI 2. These functions allow transport of the status
of relay contacts or open-collector logic signals. The
Model 544D’s GPI inputs use logic circuitry “pulled
up” to 3.3 volts DC by way of resistors, which are
active whenever they are brought to their logic low
state. While the GPI input circuitry is protected from
over-current and static discharge (ESD), care should
be taken to minimize the chance that “nasty” signals
can reach them.
The GPI inputs are active only when held in their low
state; they can’t be congured to change state (“latch”)
in response to a logic pulse or momentary closure.
Pins on a 9-pin female D-subminiature connector
(DE-9F) are used for interfacing with the GPI inputs
and system common connections. This connector is
located on the Model 544D’s back panel. A GPI is
only active when its corresponding pin is connected
to system common. GPI 1 is accessible on pin 3 and
GPI 2 on pin 4. System common is available on pins
8 and 9. Refer to Figure 2 for connection details.
General-Purpose Outputs (GPO)
The Model 544D provides two general-purpose output
functions that are referred to as GPO 1 and GPO 2.
These functions provide contact closures that respond
to trigger signals transported over the Dante input
(receiver) audio paths. The trigger signals are in the
form of high-frequency audio tones (typically 18 or
20 kHz) that travel along with the normal audio sig-
nals (“in band” audio). The GPO functions can also
change state in response to user activation using the
“virtual” on/o󰀨 buttons accessible via the STcontroller
application. The normally-open (not shorted) contact
closures are isolated from system common. They are
implemented using solid-state relay contacts which
are intended to control low-voltage/low-current DC
functions. The contacts are rated for use at up to

Model 544D User Guide Issue Preliminary 1, January 2023
Studio Technologies, Inc. Page 13
Model 544D
AUDIO INTERFACE
60 volts DC or AC with a maximum current of 400
milliamperes. They are not intended for direct connec-
tion to AC mains (high-voltage AC signals.).
Pins on a 9-pin female D-subminiature connector
(DE-9F), located on the Model 544D’s back panel,
allow interfacing with the GPO connections. Two
connections are provided for each GPO, pins 1 and
6 for GPO 1 and pins 2 and 7 for GPO 2. Refer to
Figure 2 for connection details.
Auxiliary DC Output
A source of low-voltage, low-current DC is available to
support special applications that use the GPO func-
tions. The auxiliary DC output is referenced to system
common and can supply nominal 12 volts DC at a
maximum current of 25 milliamperes. During normal
operation the auxiliary DC output can range from 10
to 18 volts DC if an external power source is con-
nected to the Model 544D and is providing operating
power. The auxiliary DC output is accessible by way
of pin 5 of the 9-pin female D-subminiature (DE-9F)
connector that’s located on the Model 544D’s back
panel. System common is provided on pins 8 and 9.
Refer to Figure 2 for connection details.
The exact use of the auxiliary DC output will depend
on the needs of the specific applications and the
capabilities of the installer. The auxiliary DC output
can, for example, be connected in series with a
GPO’s contact and used to directly light a status LED,
enable an optical coupler, or provide a “GPO active”
voltage output. Be careful to limit the load placed on
the auxiliary output. Its circuitry will limit the current
to approximately 25 milliamperes but keeping it from
reaching that maximum value is a good idea.
Dante Conguration
To integrate the Model 544D into an application
requires that a number of Dante-related parameters
be congured. These conguration settings will be
stored in non-volatile memory within the Model 544D’s
Dante interface circuitry. Conguration will typically
be done using the Dante Controller software appli-
cation which is available for download free of charge
at audinate.com. Versions of Dante Controller are
available to support the Windows and macOS per-
sonal computer operating systems. The Model 544D
uses the UltimoX2 2-input/2-output integrated circuit
to implement its Dante interface. The Model 544D’s
Dante interface is compatible with AES67 as well
as the Dante Domain Manager™ (DDM) software
application.
Audio Routing
Two Dante transmitter (output) channels on associ-
ated equipment should be routed (subscribed) to the
Model 544D’s two Dante receiver (input) channels.
The Model 544D’s two transmitter (output) channels
should be routed (subscribed) to two Dante receiv-
er (input) channels on associated equipment. This
achieves audio interconnection of the Model 544D’s
two input and two output channels with the Dante
network and associated Dante device or devices. This
will support the transport of human-understandable
audio signals and/or tones associated with the GPI/
GPO functions.
Within Dante Controller, a “subscription” is the term
used for routing a transmitter channel or a ow (a
group of up to four output channels) to a receiver
channel or a ow (a group of up to four input chan-
nels). The number of transmitter ows associated with
an UltimoX2 integrated circuit is limited to two. These
can either be unicast, multicast, or a combination
of the two. If the Model 544D’s transmitter (output)
channels need to be routed using more than two ows
it’s possible that an intermediary device, such as the
Figure 2. GPI, GPO, and Auxiliary DC Output
connections
Pin Function
1 GPO 1-A
2 GPO 2-A
3 GPI 1
4 GPI 2
5 Aux DC Out
6 GPO 1-B
7 GPO 2-B
8 COM
9 COM
Note:
Connector type on Model 44D is a 9-pin female
D-subminiature (DE-9F). Installer must provide a
9-pin male D-subminiature (DE-9M). Connector uses
4-40 threaded inserts for locking with mating plug.

Issue Preliminary 1, January 2023 Model 544D User Guide
Page 14 Studio Technologies, Inc.
Model 544D
AUDIO INTERFACE
Studio Technologies’ Model 5422A Dante Intercom
Audio Engine, can be used to “repeat” the signals.
Model 544D units will be commonly utilized in one of
two congurations: “point-to-point” or in association
with other Dante-enabled equipment. The rst cong-
uration will utilize two Model 544D units that “work”
together to link two physical locations. At each location
there would typically be balanced or unbalanced an-
alog audio (4-wire) signals. Alternately, or in addition
to, there could be connections made to the unit’s GPI
and GPO functions. The two Model 544D units would
operate “point-to-point,” interconnecting the send and
receive analog audio signals, and possible GPI/GPO
signals, by way of the associated Ethernet network.
To implement this application is very simple. The two
transmitter (output) channels on each unit would be
routed (subscribed) to the two receiver (input) chan-
nels on the other unit.
The other typical application will have one Model 544D
connected to existing analog audio circuits and/or
GPI/GPO functions. The unit’s Dante audio channels
would be routed (subscribed) to the Dante transmitter
(output) and receiver (input) channels on associated
Dante-enabled equipment. An example of this equip-
ment could be the RTS ADAM matrix intercom system
that provides Dante interconnection capability using
its OMNEO interface card. The audio channels on the
Model 544D would be routed (subscribed) to and from
audio channels on the OMNEO card. Other equipment
that supports Dante, such as audio consoles or audio
interfaces (Dante-to-MADI, Dante-to-SDI, etc.), can
have their audio channels routed (subscribed) to and
from a Model 544D.
Device and Channel Names
The Model 544D has a default Dante device name
of ST-M544D- followed by a unique su󰀩x. The suf-
x identies the specic Model 544D that is being
configured. The suffix’s actual alpha and numeric
characters relate to the MAC (media access control)
address of the Ultimo integrated circuit that’s present
in the specic Model 544D. The two Dante receiver
(input) channels have the default names of Ch1 and
Ch2. The two Dante transmitter (output) channels also
have the default names of Ch1 and Ch2. Using Dante
Controller these names can be revised as appropriate
for the specic application.
Device Conguration
The Model 544D supports audio sample rates of 44.1
and 48 kHz with no pull-up/pull-down values avail-
able. The audio encoding is xed for PCM 24. Device
Latency and Clocking can be adjusted if required but
the default value is typically correct.
Network Conguration – IP
Address
By default, the Model 544D’s Dante IP address and
related network parameters will be determined auto-
matically using DHCP or, if not available, the link-local
network protocol. If desired, Dante Controller allows
the IP address and related network parameters to be
manually set to a xed (static) conguration.
AES67 Conguration – AES67
Mode
The Model 544D can be congured for AES67 oper-
ation. This requires that the AES67 Mode be set for
Enabled. By default, AES67 mode is set for Disabled.
Note that in the AES67 mode the Dante transmitter
(output) channels will function in multicast; unicast is
not supported.
Model 544D Clocking Source
While technically the Model 544D can serve as a
Leader clock for a Dante network (as can all Dante-
enabled devices) in virtually all cases the unit will be
congured to receive “sync” from another device. As
such, the check box for Preferred Leader associated
with the Model 544D would not want to be enabled.

Model 544D User Guide Issue Preliminary 1, January 2023
Studio Technologies, Inc. Page 15
Model 544D
AUDIO INTERFACE
Model 544D Conguration
The STcontroller software application is used to congure a number of Model 544D operating functions. No DIP
switch settings or other local actions are used to congure the unit. This makes it imperative that STcontroller
be available for convenient use on a personal computer that’s connected to the related LAN.
Installing STcontroller
STcontroller is available free of charge on the Studio Technologies’ website (studio-tech.com). Versions are
available that are compatible with personal computers running selected versions of the Windows and macOS
operating systems. If required, download and install STcontroller onto a designated personal computer. This
personal computer must be on the same local area network (LAN) and subnet as the one or more Model 544D
units that are to be congured. Immediately after starting STcontroller the application will locate all the Studio
Technologies’ devices that it can control. The Model 544D units that can be congured will appear in the de-
vice list. Use the Identify command to allow easy recognition of a specic Model 544D unit. Double-clicking
on a device name will cause the associated conguration menu to appear. Review the current conguration
and make any changes that are desired. Conguration changes made using STcontroller will be immediately
reected in the unit’s operation; no Model 544D reboot is required. As an indication that a conguration change
has been made the two LEDs associated with input power, labeled DC and PoE, on the Model 544D’s front
panel will ash in a distinctive pattern.
General Menu Page
The following conguration selections are available in the General menu selections tab.
Source Conguration – Dante Transmitter
Ch 1
Choices are Analog Line Input Ch 1, Analog Line
Input Ch 2, Dante Receiver Ch 1, Dante Receiver
Ch 2, 1 kHz Tone, 18 kHz Tone, and 20 kHz Tone.
This conguration choice determines the audio source
that is utilized by Dante transmitter (output) channel 1.
There are seven choices allowing a variety of applica-
tions to be supported.

Issue Preliminary 1, January 2023 Model 544D User Guide
Page 16 Studio Technologies, Inc.
Model 544D
AUDIO INTERFACE
Analog Line Input Ch 1: If this choice is selected,
the analog source connected to the XLR connector
associated with analog line input channel 1 will be
routed to Dante transmitter (output) channel 1. This
will be the typical setting for most applications.
Analog Line Input Ch 2: If this choice is selected,
the analog source connected to the XLR connector
associated with analog line input channel 2 will be
routed to Dante transmitter (output) channel 1.
Dante Receiver Ch 1: When this choice is selected,
the audio source associated with Dante receiver
(input) channel 1 will be routed to Dante transmitter
(output) channel 1. This is in essence a Dante digital
“loop-back” function which can be useful for testing
purposes.
Dante Receiver Ch 2: When this choice is selected,
the audio source associated with Dante receiver
(input) channel 2 will be routed to Dante transmitter
(output) channel 1. This is in essence a type of Dante
digital “loop-back” function which can be useful for
testing purposes. But be careful, audio associated
with Dante receiver (input) 2 will be output by way of
Dante transmitter (output) channel 1!
1 kHz Tone: If this choice is selected, a digitally gen-
erated source of 1 kHz sine-wave tone will be routed
to Dante transmitter (output) channel 1. The output
level will be –20 dBFS.
18 kHz Tone: If this choice is selected, a digitally
generated source of 18 kHz sine-wave tone will be
routed to Dante transmitter (output) channel 1. The
output level will be –20 dBFS.
20 kHz Tone: If this choice is selected, a digitally
generated source of 20 kHz sine-wave tone will be
routed to Dante transmitter (output) channel 1. The
output level will be –20 dBFS.
Source Conguration – Dante Transmitter
Ch 2
Choices are Analog Line Input Ch 1, Analog Line
Input Ch 2, Dante Receiver Ch 1, Dante Receiver
Ch 2, 1 kHz Tone, 18 kHz Tone, and 20 kHz Tone.
This conguration choice determines the audio source
that is utilized by Dante transmitter (output) channel 2.
The available choices and associated actions are very
similar to that of Dante transmitter (output) channel 1.
Refer to the previous paragraphs for details.
Source Conguration – Analog Line
Output Ch 1
Choices are Analog Line Input Ch 1, Analog Line
Input Ch 2, Dante Receiver Ch 1, Dante Receiver
Ch 2, 1 kHz Tone, 18 kHz Tone, and 20 kHz Tone.
This conguration choice determines the audio source
that is utilized by analog output channel 1.
Analog Line Input Ch 1: If this choice is selected, the
audio signal connected to the XLR connector associ-
ated with analog line input channel 1 will be routed to
analog line output channel 1. This is an analog “loop-
back” function that is provided for testing purposes.
Analog Line Input Ch 2: If this choice is selected, the
analog signal connected to the XLR connector associ-
ated with analog line input channel 2 will be routed to
analog line output channel 1. This is a form of analog
“loop-back” that is provided for testing purposes. But
be careful with this selection! Analog line input 2 will
be output by way of analog line output 1.
Dante Receiver Ch 1: If this is selected, the audio
source associated with Dante receiver (input) channel
1 will be routed to analog line output channel 1. This
will be the typical setting for most applications.
Dante Receiver Ch 2: If this choice is selected, the
audio source associated with Dante receiver (input)
channel 2 will be routed to analog line output channel
1. Be careful with this setting! It’s kind of a “channel
cross.”
1 kHz Tone: When selected, a digitally generated
source of 1 kHz sine-wave tone will be routed to
analog line output channel 1. This is provided for
general-purpose use. The level will be the selected
nominal for the analog line outputs.
18 kHz Tone: If this choice is selected, a digitally
generated source of 18 kHz sine-wave tone will be
routed to analog line output channel 1. The level will
be the selected nominal for the analog line outputs.
20 kHz Tone: If this choice is selected, a digitally
generated source of 20 kHz sine-wave tone will be
routed to analog line output channel 1. The level will
be the selected nominal for the analog line outputs.

Model 544D User Guide Issue Preliminary 1, January 2023
Studio Technologies, Inc. Page 17
Model 544D
AUDIO INTERFACE
Source Conguration – Analog Line
Output Ch 2
Choices are Analog Line Input Ch 1, Analog Line
Input Ch 2, Dante Receiver Ch 1, Dante Receiver
Ch 2, 1 kHz Tone, 18 kHz Tone, and 20 kHz Tone.
This conguration choice determines the audio source
that is utilized by analog line output channel 2. The
actions of the configuration choices are the same
as those available for analog line output channel 1.
Details were provided in the previous paragraphs.
Nominal Levels – Analog Line Inputs
Choices are +4 dBu, –2 dBu, and –10 dBu.
This configuration choice determines the nominal
level of the two analog line inputs. This equates to the
signal level required to cause a Dante signal level of
–20 dBu to be created on a Dante transmitter (output)
channel. The conguration choice should be selected
so as to best match the nominal level of the sources
that are being connected to the Model 544D’s line
input XLR connectors.
The choice of +4 dBu would be compatible with most
North American (SMPTE
®
-standard) applications
where +4 dBu analog will equate to –20 dBFS digi-
tal. The choice of –2 dBu is intended for compatibly
with signals that may be present in Europe (EBU-
standard). In this case, an analog signal source with
a level of 0 dBu will cause a digital output signal at a
level –18 dBFS. The –10 dBu choice is provided for
applications where semi-professional unbalanced
sources are connected. They will typically have a
much lower nominal signal level.
Nominal Levels – Analog Line Outputs
Choices are +4 dBu, –2 dBu, and –10 dBu.
This configuration choice determines the nominal
level of the Model 544D’s two analog line outputs.
The nominal level should be selected to best match
the needs of inputs on equipment that will be utilizing
these analog signal sources. The output level choices
are all referenced to the designated signal source
being a Dante receiver (input) with a level of –20 dBu.
When congured for +4 dBu the analog line outputs
are configured such that a Dante input (receiver)
channel with a signal level of –20 dBFS will result in
an analog output signal having a level of +4 dBu. This
conguration would allow compatibility with SMPTE
digital-to-analog level-relationship standards. When
selected for –2 dBu, a Dante input (receiver) with
a signal level of –18 dBFS will result in an analog
output signal having a level of 0 dBu. This relationship
would make the analog line outputs compliant with
EBU standards. The –10 dBu selection is provided
for applications where the analog line outputs might
need a lower or “semi-pro” signal level. A signal
on a Dante input (receiver) channel with a level of
–20 dBu would result in an analog output level
of –10 dBu.

Issue Preliminary 1, January 2023 Model 544D User Guide
Page 18 Studio Technologies, Inc.
Model 544D
AUDIO INTERFACE
GPO Menu Page
The following conguration selections are available in the GPO menu selections tab.
high-frequency tone (nominally 18 kHz or above) that
is present in the audio channel (“in-band”) will be used
as a control signal. GPO 1 will be active when a signal
that meets the requirements for level and frequency is
present on Dante receiver (input) channel 1.
Note that when this choice is selected, the high-
frequency content on analog output channel 1 will
be limited to nominally 10 kHz. This prevents a
high-frequency tone present in Dante receiver
(input) channel 1 that’s serving as a TOX signal from
being output in analog output channel 1. This ltering
function is accomplished by way of low-pass ltering
sections within the digital domain.
TOX – Dante Receiver Ch 2: This choice allows a
high frequency signal that is present in Dante receiver
(input) channel 2 to control the state of GPO 2. The
acronym TOX has traditionally meant “Tone Operated
Relay.” In the case of the Model 544D, it means that a
high-frequency tone (nominally 18 kHz or above) that
is present in the audio channel (“in-band”) will be used
as a control signal. GPO 2 will be active when a signal
that meets the requirements for level and frequency
is present in Dante receiver (input) channel 2.
Source Conguration – GPO 1
Choices are STcontroller On/O Button,
TOX – Dante Receiver Ch 1, and
TOX – Dante Receiver Ch 2.
The state (active or inactive) of GPO 1 can be con-
trolled by the conguration selected from among three
available sources.
STcontroller On/O󰀨 Button: When this choice is
selected, the state of GPO 1 will be controlled by the
virtual “button” that’s present in the On/O󰀨 Buttons
click or keyboard key the GPO 1 On/O󰀨 button icon
will cause the state of GPO 1 to change. This function
can be useful during installation and conguration of
the Model 544D and related signals. It can also be
used as a means for an STcontroller user to control
the state of GPO 1.
TOX – Dante Receiver Ch 1: This choice allows a
high frequency signal that is present in Dante receiver
(input) channel 1 to control the state of GPO 1. The
acronym TOX has traditionally meant “Tone Operated
Relay.” In the case of the Model 544D, it means that a

Model 544D User Guide Issue Preliminary 1, January 2023
Studio Technologies, Inc. Page 19
Model 544D
AUDIO INTERFACE
Note that when this choice is selected, the high-
frequency content on analog output channel 2 will
be limited to nominally 10 kHz. This prevents a high-
frequency tone present in Dante receiver (input) chan-
nel 2 that’s serving as a TOX signal from being output
in analog output channel 2. This ltering function is
accomplishing by way of low-pass ltering sections
within the digital domain.
Source Conguration – GPO 2
Choices are STcontroller On/O Button,
TOX – Dante Receiver Ch 1, and
TOX – Dante Receiver Ch 2.
The state (active or inactive) of GPO 2 can be con-
trolled by the conguration selected from among the
three available sources. The functionality of the three
choices has previously been discussed for GPO 1.
On/O󰀨 Buttons
On the GPO page there is a section called On/O󰀨
Buttons which provides two software-implemented
(virtual) pushbutton switches. These allow manual
control of the state of the two GPO outputs when their
respective source conguration has been selected for
STcontroller On/O󰀨 Button. If this conguration choice
has not been selected, the associated On/O󰀨 button
will be “grayed out” and not available for use.
On/O󰀨 Buttons – GPO 1: This can be pressed, using
a mouse click or keyboard key, to change the state
of GPO 1 from inactive-to-active or active-to-inactive.
This can prove useful during installation and testing of
the Model 544D’s GPO functions. It can also be used
to manually control the state of GPO 1.
On/O󰀨 Buttons – GPO 2: This can be pressed, using
a mouse click or keyboard key, to change the state
of GPO 2 from inactive-to-active or active-to-inactive.
It can nd value during installation and testing of the
Model 544D’s GPO functions. It can also be used to
manually control the state of GPO 2.

Issue Preliminary 1, January 2023 Model 544D User Guide
Page 20 Studio Technologies, Inc.
Model 544D
AUDIO INTERFACE
Operation
At this point, the Model 544D should have its Ethernet,
line input, line output, and GPI/GPO connections im-
plemented as desired for the application. Depending
on the capabilities of the connected Ethernet signal,
an external source of nominal 12 volts DC power may
have also been connected. Using the Dante Controller
software application, the two Dante receiver (input)
channels and two Dante transmitter (output) channels
should have been routed as desired. Normal operation
of the Model 544D should now be occurring.
The Model 544D is designed for continuous operation
with no adjustments required. Maintaining the correct
signal levels coming into the line inputs and the Dante
receiver (input) channels is important. This will ensure
that proper signal levels are presented to the Model
544D’s circuitry and associated equipment, leading
to optimal audio performance. The audio level meters
and GPO status LEDs will provide assistance in con-
rming that correct operation is taking place.
Initial Operation
The Model 544D will begin its initial functioning a
few seconds after its power source is connected. As
previously discussed, the unit’s power source can be
provided by Power-over-Ethernet (PoE) or an exter-
nal source of 12 volts DC. If both are connected, the
PoE source will power the unit. Should PoE power
subsequently no longer be available, uninterrupted
operation will continue using the external 12 volts
DC source. (This will probably prove to be a “hollow”
victory since a loss of PoE will probably also mean a
loss of the required Ethernet data connection!)
Upon Model 544D power up, the status LEDs will
light in various ways. The Dante and Ethernet status
LEDs, located on the back panel, will light in various
ways. On the front panel the input power, GPI and
GPO status, and audio level meter LEDs will light in
a test sequence. Once the sequence has completed
the two columns of level meter LEDs associated with
the line outputs will momentarily display the version
number of the unit’s application rmware (embedded
software). Details on how to “read” the version number
are provided in the Technical Notes section.
The Model 544D will now begin normal operation. The
way in which the back-panel LINK/ACT, SYS, and
SYNC LEDs light will depend on the characteristics of
the connected Ethernet signal and the conguration
of the unit’s Dante interface. Details will be covered in
the next paragraph. The user is presented on the front
panel with two input power status LEDs, two GPI sta-
tus LEDs, two GPO status LEDs, and four 5-segment
LED audio level meters. These resources are simple
to understand and should prove to be useful as will
be highlighted in the following paragraphs.
Power Status LEDs
Two power status LEDs are located on the left side
of the Model 544D’s front panel. When an Ethernet
connection with power-over-Ethernet (PoE) has been
connected the PoE LED will light. When an external
source of nominal 12 volts DC is connected the DC
LED will light. If both LEDs are lit then the Model 544D
is being powered by the PoE connection.
Ethernet and Dante Status LEDs
Three status LEDs are located below the etherCON
RJ45 jack on the Model 544D’s back panel. The
LINK/ACT LED will light green whenever an active
data connection to a 100 Mb/s Ethernet network has
been established. It will ash on and o󰀨 in response
to data packet activity. The SYS and SYNC LEDs
display the operating status of the Dante interface
and associated audio-over-Ethernet network. The
SYS LED will light red upon Model 544D power up
to indicate that the Dante interface is not ready. After
a short interval, it will light green to indicate that it is
ready to pass audio data with another Dante device.
The SYNC LED will light red when the Model 544D
is not synchronized with a Dante network. It will light
solid green when the Model 544D is fully synchronized
with a Dante network and an external clock source
(timing reference) is being received. It will slowly ash
green if this specic Model 544D is serving as the
Leader clock for the Dante network. While technically
possible, typically a Model 544D should not server as
the Leader clock for a Dante application!
How to Identify a Specic Model
544D
Functions within the Dante Controller and STcontroller
software applications allow specic Model 544D units
to be identied. Each application provides an “eye-
ball” icon that when clicked will activate the Identify
function. When the Identify command is activated the
associated software application will send a command