Studio Technologies 348 User manual

Copyright © 2021 by Studio Technologies, Inc., all rights reserved
studio-tech.com
User Guide
Issue 5, May 2021
This User Guide is applicable for serial numbers
M348-00251 and later with Main Firmware version 2.01 and later
and STcontroller application version 3.03.00 and later.
50291-0521 Issue 5
Model 348 Intercom Station

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Model 348 User Guide Issue 5, May 2021
Studio Technologies, Inc. Page 3
MODEL 348
INTERCOM STATION
Table of Contents
Revision History ...................................................................... 4
Introduction ............................................................................... 5
Getting Started ......................................................................... 8
Dante Configuration ................................................................ 11
Model 348 Configuration ......................................................... 13
Operation ................................................................................. 21
Technical Notes ....................................................................... 31
Specifications .......................................................................... 36
Appendix A–STcontroller Default Configuration Values ........... 38
Appendix B–3-Pin Header Connector Details .......................... 39

Issue 5, May 2021 Model 348 User Guide
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MODEL 348
INTERCOM STATION
Revision History
Issue 5, May 2021:
• Documents that support is now included for two remote control inputs.
• Documents that a Dante receiver (input) channel can be used as a microphone input source.
(In conjunction with this, Dante receiver (input) channel 16 renamed from “IFB Pgm 8” to
“Aux In.”)
• Documents new Talk with Quindar Tones button mode.
• Miscellaneous corrections and improvements.
Issue 4, April 2021:
• Documents that unit now enumerates itself as a class 3 PoE device.
Issue 3, February 2021:
• Clarifies the Microphone Input – Source function in STcontroller.
Issue 2, August 2020:
• Corrects errors in Issue 1.
Issue 1, January 2020:
• Initial release of complete document.

Model 348 User Guide Issue 5, May 2021
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MODEL 348
INTERCOM STATION
Introduction
The Model 348 Intercom Station provides
eight independent talk and listen channels
that are compatible with Dante® audio-over-
Ethernet networks. The desktop unit is de-
signed to serve as an audio control center for
production and support personnel in numer-
ous applications including on-air television
sports and news broadcasting, live events,
theater, industrial, aerospace, and corporate
AV. The Model 348’s channels can be part of
virtual “party-lines” created with other compat-
ible devices or be used directly in point-to-
point intercom implementations. The range of
resources makes it simple to use the Model
348 locally, or as part of a REMI or “At-Home”
geographically diverse implementation. In
addition to intercom applications, the unit
can create multiple independent IFB (talent
cue) channels. Other applications may benefit
from the Model 348 user’s ability to easily cre-
ate monitor mixes from the eight input audio
channels. This makes the unit a viable choice
for listen-only scenarios.
Over a standard IP network, multiple Model
348 units can be used in party-line (PL) in-
tercom applications with help from external
Dante-enabled audio devices such as the
Studio Technologies’ Model 5421 or Model
5422A Dante Intercom Audio Engine. Model
348 units can also be used “point-to-point”
or interfaced with Dante-compatible matrix
intercom systems. The Model 348 includes
two Neutrik etherCON RJ45 jacks which allow
interfacing with single or redundant Dante
Ethernet networks. The primary network con-
nection can provide power to the unit using
standard Power-over-Ethernet (PoE). It can
also be powered using a 12 volts DC source
that is connected using a broadcast-standard
4-pin XLR connector.
The Model 348 supports connection of a
broadcast- or intercom-style headset that use
a dynamic or electret (DC powered) micro-
phone. The unit provides both a 5-pin female
XLR and a 3.5 mm TRRS connector allow-
ing for a traditional “pro” or a contemporary
gaming headset to be utilized. In addition,
the Studio Technologies’ GME-3-12 electret
gooseneck microphone can be directly con-
nected using the 1/4-inch jack located on the
top of the unit’s enclosure. A low-noise micro-
phone preamplifier and associated voltage-
controlled-amplifier (VCA) dynamics controller
(compressor) ensures excellent headset and
gooseneck microphone audio quality while
minimizing the chance of signal overload.
Figure 1. Model 348 Intercom Station front and back views

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MODEL 348
INTERCOM STATION
A Dante receiver (input) channel can also be
used as the talk audio source. This was specif-
ically included to allow two Model 348 units to
“work” together to support more than eight talk
channels. A pushbutton switch allows users
to directly select the active talk audio source.
Choices include the headset mic, the goose-
neck mic, or the Dante Aux In receiver (input)
channel.
All Model 348 operating features are config-
ured using the STcontroller software applica-
tion. An extensive set of parameters allows
the unit’s functions to be tailored to meet the
needs of many applications. STcontroller is
available, free of charge, from the Studio
Technologies’ website. Versions are available
that are compatible with the Windows® and
macOS® operating systems. STcontroller is a
fast and simple means of configuring, revising,
saving, and loading a unit’s operating param-
eters.
The Model 348’s front panel includes eight
rotary controls (“encoders”) which are used
to adjust the level of the eight Dante monitor
input signal sources. Using RGB (red-green-
blue) LEDs, the knob of each encoder is illu-
minated and can display if a channel is muted,
indicate if a signal is present on the associ-
ated audio input, and light when an in-band
(20 kHz tone) call signal is detected. The user
can monitor the Dante audio inputs by means
of a headset, a built-in speaker, or two Dante
transmitter (output) channels. Two additional
rotary encoders are used to control the overall
audio level and on or off (mute) status of the
signals being sent to the headset and speaker
outputs. A modern class-D amplifier integrated
circuit drives the speaker efficiently while pre-
serving audio fidelity.
Extensive configuration choices allow the
operation of the eight pushbutton switches and
associated output channels to be optimized
to meet the needs of an extensive range of
specialized applications. They can be inde-
pendently configured for talk (intercom), IFB
(talent cue), call signal (20 kHz tone), and
other related actions. The buttons can also be
configured to provide an “all-call” action asso-
ciated with the talk and IFB functions.
A special button configuration mode supports
the generation of talk channels that include
Quindar Tones. These are short-duration
“intro” and “outro” audio signals that were
traditionally used in space programs to control
the on and off status of transmitters. In recent
years these tones have taken on the function
of providing an audible indication of when
Capsule Communicator (CapCom) transmis-
sions are taking place. These ubiquitous
“beeps” have become synonymous with
ground-to-astronaut communications.
For performance confirmation an integrated
sidetone function allows audio coming from the
active talk audio source to be returned to the
headset output. An audible alert, using the in-
ternal speaker, can be generated in response
to a call signal. Provision has been made such
that a technician can “customize” the Model
348’s hardware. Option kits, purchased sepa-
rately, can be added to support additional func-
tions. These include adding two remote control
inputs which can be configured to mimic the
action of talk buttons.
The Model 348’s compact enclosure has over-
all dimensions of 6.5 inches wide (16.5 cm),
2.5 inches high (6.4 cm), and 4.6 inches deep
(11.7 cm). Weighing 1.8 pounds (0.8 kg), the
enclosure is made of steel to provide some
“heft” to minimize the chance of inadvertent
movement. The Model 348’s main application
firmware can be updated using the USB port
on the back of the unit; the Dante firmware can
be updated via an Ethernet connection.

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MODEL 348
INTERCOM STATION
Ethernet Data and PoE
The Model 348 connects to one or two local
area networks (LANs) by way of two twisted-
pair Ethernet interfaces. The 1000BASE-T
Gigabit Ethernet (GigE) interconnections are
made by way of Neutrik® etherCON RJ45
jacks. While compatible with standard RJ45
plugs, etherCON allows a ruggedized and
locking interconnection for harsh or high-
reliability environments. The two Ethernet
interfaces can be configured, using the Dante
Controller software applications, to serve in
Switched or Redundant modes.
The Model 348’s operating power can be
provided by way of the Primary-PoE Ethernet
interface using the 802.3af Power-over-
Ethernet (PoE) standard. PoE allows fast
and efficient interconnection with the associ-
ated data network. Alternately, an external
source of nominal 12 volts DC can be con-
nected to power the unit. If both are connect-
ed then PoE will be the active power source.
Dante Audio-over-Ethernet
Audio data is sent to and received from the
Model 348 using the Dante audio-over-Eth-
ernet media networking technology. As a
Dante-compliant device, the Model 348’s 11
Dante transmitter (output) audio channels and
16 Dante receiver (input) audio channels can
be assigned (routed or “subscribed”) using
the Dante Controller software application.
The Dante transmitter and receiver channels
support 32 Dante flows, 16 in each direction.
The digital audio’s bit depth is up to 32 with a
sample rate of 48 kHz. Bi-color LEDs, located
on the unit’s back panel, provide status indi-
cations of the Ethernet network and Dante
interface performance.
The Model 348 is compliant with the AES67
interoperability standard. In addition, the unit
is compatible with Audinate’s® Dante Domain
Manager™ (DDM) software application.
Audio Quality
The Model 348’s audio performance is com-
pletely “pro.” A low-noise, wide dynamic-range
microphone preamplifier and associated
voltage-controlled-amplifier (VCA) dynamics
controller (compressor) ensure that headset
and gooseneck microphone audio quality is
preserved and minimizes the chance of signal
overload. The output of the microphone pre-
amp and compressor is routed to an ana-
log-to-digital conversion (ADC) section that
supports sampling rates of 48 kHz. A Dante
receiver (input) channel can be used as an
alternate talk source.The selected talk audio
signal routes through a 32-bit microprocessor
and on to the Dante interface section where
it is packetized and prepared for transport
over Ethernet. A total of 11 Dante transmit-
ter (output) channels are provided: one each
associated with the unit’s eight channels, two
monitor output channels, and one hot mic
output channel.
Audio input signals arrive via 16 Dante re-
ceiver (input) channels and pass into the
Model 348’s 32-bit microprocessor. Eight
input channels are associated with the moni-
tor section while the other eight inputs are
used as program sources for the IFB (talent
cue) functions. One of the latter input sources
can also serve as a talk audio source. All
channel routing, headphone and monitor level
control, IFB creation, and sidetone functional-
ity is performed within the digital domain. This
provides flexibility, allows precise level con-
trol, and eliminates the need for analog audio
signals from having to pass through electro-
mechanical level controls. The audio signals
destined for the headphone and speaker
outputs are sent to high-performance digital-
to-analog converter circuitry and then on to
robust driver circuitry.

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MODEL 348
INTERCOM STATION
Future Capabilities and
Firmware Updating
The Model 348 was designed so that its ca-
pabilities and performance can be easily en-
hanced in the future. A USB connector, located
on the unit’s back panel, allows the application
firmware (embedded software) to be updated
using a USB flash drive. The Model 348 uses
the Broadway™ integrated circuit from Audi-
nate to implement its Dante interface. The firm-
ware in this integrated circuit can be updated
via an Ethernet connection, helping to ensure
that its capabilities remain up to date.
Getting Started
What’s Included
Included in the shipping carton are a Model
348 Announcer’s Console and instructions on
how to obtain an electronic copy of this guide.
As a device that can be Power-over-Ethernet
(PoE) powered, no external power source is
provided. This is because in most applications
an Ethernet switch with PoE capability will be
utilized. It’s also possible to connect an exter-
nal source of 12 volts DC to power the Model
348. If this is the case then a power supply
would need to be provided separately.
Connections
In this section signal interconnections will be
made using the connectors located on the
back of the Model 348’s enclosure. In addition,
many applications will utilize the Studio
Technologies’ GME-3-12 gooseneck micro-
phone which will be attached via the 1/4-inch
jack located on the top surface of the unit.
One or two Ethernet connections will be
made using either standard RJ45 patch
cables or etherCON protected RJ45 plugs.
The Ethernet data connection associated
with the Primary-PoE RJ45 jack is compatible
with Power-over-Ethernet (PoE). If desired, an
Ethernet connection made to the Secondary
Ethernet receptacle can provide access to a
Redundant Dante network. Or it can be utilized
as an active “loop through” connection associ-
ated with the Primary Ethernet connection. If
PoE is not going to be utilized, or a redundant
source of power is desired, a source of 12 volts
DC can be connected by way of a 4-conductor
XLR connector.
A dual-channel or single-channel (dual- or
single-ear) headset can be connected using
a cable-mounted 5-pin male XLR connector.
Alternately, a “computer” headset with a
3.5 mm 4-conductor TRRS plug can be used.
An electret gooseneck microphone that has
an integrated 1/4-inch plug can be connected.
For special applications, the Model 348’s inter-
nal circuit boards contain 3-pin “header” con-
nectors that allow access to several functions.
In addition, there’s one spare connector loca-
tion on the Model 348’s back panel. A techni-
cian can add a connector and wire it to the
headers such that application-specific needs
can be supported. For example, two contact
closures can be interfaced to the Model 348’s
circuitry allowing external switches to activate
two of the button functions. Refer to the Tech-
nical Notes section of this guide for details.
One or Two Ethernet Connections
One 1000BASE-T Gigabit Ethernet (GigE)
connection is required for Model 348 operation.
If available and connected to the Primary-PoE
RJ45 jack, this connection can provide both
the Ethernet data interface and power for the
Model 348’s circuitry. A 100BASE-TX (100
Mb/s) connection may be adequate but not
optimal. A 10BASE-T (10 Mb/s) connection is
not sufficient.
A second 1000BASE-T Gigabit Ethernet
(GigE) connection can be made if Redundant
Dante is desired. The Model 348’s network

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MODEL 348
INTERCOM STATION
configuration must be set for Redundant for
this functionality to be active. PoE is not sup-
ported on the Secondary Ethernet connection.
The Secondary Ethernet interface can also
be used as a “loop through” connection such
as would be provided by an Ethernet switch.
This requires that the Model 348’s network
configuration be set for Switched. Using the
secondary port in this mode for applications
other than troubleshooting is not recommend-
ed. It will function reliably but “daisy chaining”
Ethernet signals can limit flexibility and pres-
ent a failure point.
The Ethernet connections are made by way
of two Neutrik etherCON protected RJ45
jacks that are located on the back of the Mod-
el 348’s enclosure. These allow connection
by way of cable-mounted etherCON connec-
tors or standard RJ45 plugs. The Model 348’s
Ethernet interfaces support auto MDI/MDI-X
so that crossover cables are not required.
The Model 348’s Primary Ethernet connec-
tion enumerates itself as a class 3 device. As
such, a PoE power-sourcing-equipment (PSE)
port could be required to supply up to 12.94
watts of power.
External 12 Volts DC Input
An external source of 12 volts DC can be
connected to the Model 348 by way of the
4-pin male XLR connector which is located on
the back panel. While the requirement for the
external source is nominally 12 volts, correct
operation will take place over a 10 to 18 volt
range. The Model 348 requires a maximum
of 600 milliamperes (0.6 amperes) 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 (+).
If an external power source is required, the
PS-DC-02 power supply, available as an
option from Studio Technologies, is directly
compatible with the Model 348. Its AC mains
input allows connection to 100-240 volts,
50/60 Hz with an output of 12 volts DC,
1.5 amperes maximum. Its DC output is termi-
nated on a 4-pin female XLR connector.
As previously discussed in this guide, an
Ethernet connection that provides power-over-
Ethernet (PoE) can serve as the Model 348’s
power source. Alternately, an external 12 volts
DC source can be connected. For redundancy,
both PoE and the external source can be con-
nected 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 provide the Model 348’s
power. No interruption in operation will occur
during a power source transition.
Headset Connections
The Model 348 allows two different types of
headsets to be connected. A 5-pin female XLR
connector, located on the Model 348’s back
panel, allows connection of a standard broad-
cast- or intercom-style communications head-
set. A 3.5 mm 4-conductor TRRS jack, also
located on the back panel, allows a computer
gaming headset to be directly connected. The
Model 348’s two headset connectors are elec-
trically wired in parallel. As such, only one type
of headset should be connected at one time.
Headset A
The Model 348 provides a 5-pin female XLR
connector that interfaces with the microphone
and headphone connections of a single- or
dual-ear intercom or broadcast-style headset.
The connector is labeled Headset A. Refer
to Figure 2 for connection details. The micro-
phone input connections are compatible with
most unbalanced dynamic or electret (low-
voltage DC-powered) microphones. A bal-
anced dynamic microphone should, in most
cases, also function correctly if its signal
– (low) is connected to Model 348’s mic in
–/shield connection. No support is provided

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MODEL 348
INTERCOM STATION
for microphones that require P12 or P48 phan-
tom power.
To allow users of stereo (dual-earpiece or
“double-muff”) headsets to hear a monaural
version of the two headphone output chan-
nels does not require special wiring of the
5-pin male XLR mating connector. The head-
set’s left headphone channel should always
be wired to pin 4 and the right headphone
channel to pin 5. Configuration choices us-
ing the STcontroller software application, as
discussed later in this guide, can be used to
create the desired monaural output. It’s impor-
tant not to connect together (short) pins 4 and
5 of the headset’s connector as damage to the
Model 348’s output circuitry could result.
A monaural (single-earpiece or “single-muff”)
headset should be wired such that its head-
phone is wired only to pin 4; pin 5 should be
remain unused. Configuration choices, pro-
vided in STcontroller, can be used to create
a monaural output.
It’s possible that some Beyerdynamic headset
interconnecting cable assemblies will termi-
nate its earpiece’s left and right connections
opposite from what the Model 348 and other
broadcast equipment require. These cables
may terminate the left earpiece to pin 5 of the
5-pin male XLR connector and the right ear-
piece to pin 4. If this condition is present it will
require reversing or “flipping” the two wires in a
headset’s connector such that the left earpiece
connects to pin 4 and the right earpiece to pin 5.
If a separate microphone and pair of stereo or
monaural headphones need to be connected
an adapter cable assembly must be fabricated.
It would consist of a 5-pin male XLR connector
wired to both a 3-pin female XLR connector for
the microphone and a 3-conductor 1/4-inch or
3.5 mm TRS jack for the headphones. In this
scenario the microphone would, in most cases,
be a dynamic type as the Model 348 provides
only low-voltage DC electret power. Phantom-
powered (P12 or P48) microphones would
not be compatible. Most hand-held or “stick”
microphones are dynamic and should function
correctly.
Headset B
The Model 348 also allows direct connection
of gaming headsets that are ubiquitous in the
personal computer world. The 3.5 mm 4-
conductor TRRS jack, labeled Headset B, is
compatible with the CTIA™/AHJ configuration
standard which has the headphone left chan-
nel on the tip connection, the headphone right
channel on the ring 1 connection, common on
the ring 2 connection, and the microphone on
the sleeve connection.
Compatible headsets are readily available,
typically described as personal computer or
gaming headsets. The microphones used in
these headsets are electret type which require
a low-voltage DC source for operation. The
Model 348 is able to provide this power and
requires only that the appropriate setting in the
STcontroller software application be selected.
Refer to Figure 3 for a detailed description of
the compatible TRRS plug.
Gooseneck Microphone
A threaded combination bushing/3-conductor
1/4-inch jack is incorporated into the top panel
of the Model 348. This allows direct connection
Figure 2. Headset A connection pinout chart