Studio Technologies 5130 User manual

Copyright © 2013 by Studio Technologies, Inc., all rights reserved
www.studio-tech.com
50177-0713, Issue 5
User Guide
Issue 5, July 2013
This User Guide is applicable for serial numbers
M5130-00301and later
Model 5130
Party-Line Interface Module

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Model 5130 User Guide Issue 5, July 2013
Studio Technologies, Inc. Page 3
Model 5130
Party-Line Interface Module
Table of Contents
Introduction ................................................................... 5
Installation .................................................................... 7
Configuration ................................................................ 9
Operation ...................................................................... 10
Technical Notes ............................................................ 12
Specifications ............................................................... 18
Appendix A—Model 5130 Front Panel and
Printed Circuit Board (PCB) Dimensions ...................... 19
Appendix B–Interconnection Details ............................. 20

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Model 5130
Party-Line Interface Module
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Model 5130 User Guide Issue 5, July 2013
Studio Technologies, Inc. Page 5
Model 5130
Party-Line Interface Module
Introduction
The Model 5130 Party-Line Interface Mod-
ule is a compact, self-contained unit for
use in custom broadcast, live-performance,
and general party-line intercom applica-
tions. The module provides a high-quality
2-channel party-line to analog line level
(“4-wire”) audio signal interface in an easy
to use yet technically sophisticated pack-
age. The module’s basic functions include
two channels of 2-wire-to-4-wire conver-
sion with auto-null capability, input and
output level metering, a +28 volt DC party-
line power source with two channels of 200
ohm intercom audio termination, and DC
output control and status monitoring. Party-
line beltpack user devices can be directly
connected. Two analog inputs and two
analog outputs interface the Model 5130
with a variety of external audio transport,
matrix intercom, and infrastructure equip-
ment. Module operation requires only an
externally-provided source of 12 volts DC.
Advanced features include remote control
and monitoring capability when installed
with remote access modules available from
Studio Technologies.
Applications for the Model 5130 include
sports broadcasting booth packages,
remote news gathering “fly packs,” stadium
audio/video interface (I/O) locations, and
government/corporate/performance space/
aerospace test infrastructure projects. The
number of Model 5130 modules used in a
project can vary widely—from one to
dozens. And in each case the performance
will be completely “pro” with audio quality,
reliability, and installation flexibility match-
ing that of larger-scale products. Typical
applications will find the Model 5130’s 4-
wire audio inputs and outputs being inter-
faced with fiber-optic transport modules,
matrix intercom systems, and audio/video
routers.
The Model 5130 provides a full-featured
2-channel interface which includes two
2-wire-to-4-wire hybrid circuits with auto-
matic nulling capability. The analog hybrid
circuitry provides excellent audio quality
and high return-loss. Audio level meters
provide confirmation of system perfor-
mance during setup and operation. The
Model 5130’s party-line interface is acces-
sible using a 3-pin male XLR connector.
This allows industry-standard party-line
intercom user beltpacks to be directly in-
terfaced. With a maximum output current of
180 milliamperes, up to three of the popu-
lar RTS® BP325 devices can be directly
connected. Devices from Clear-Com® are
also compatible.
Figure 1. Model 5130S Party-Line Interface Module Front and Back Views

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Model 5130
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The 4-wire audio inputs and outputs were
carefully designed for use in permanent
as well as field applications. Filtering on
the inputs minimizes the chance that radio
frequency (RF) energy will interfere with
the audio input sources. Other components
were included to address ESD (“static”)
and DC over-voltage conditions. In addi-
tion, the DC power input is protected from
accidental polarity reversal.
For operation, the Model 5130 only re-
quires connection of analog audio inputs
and outputs, along with an external source
of nominal 12 volts DC. The acceptable
input voltage range is 10 to 18, allowing
a variety of power sources to be utilized.
Power supply circuitry within the Model
5130 creates the voltages required for the
analog and digital circuitry.
Standard connectors are used throughout
the Model 5130. The party-line intercom
interface is accessed using a 3-pin male
XLR connector. The 4-wire audio input
and output connections are made using
5-position, 0.1-inch “header” connectors.
The DC power input and data bus con-
nections use a 4-position, 0.1-inch header.
Low-cost IDC (insulation displacement)
mating connectors allow simple intercon-
nection with the audio input, audio output,
DC input, and RS-485 data signals.
For compliance with international broad-
cast audio level standards two versions of
the Model 5130 are available. The Model
5130S supports SMPTE® audio levels
where the analog audio reference level
is +4 dBu. The Model 5130E supports
applications that require European Broad-
cast Union (EBU) compliance with an
analog audio reference level of 0 dBu.
Model 5130 Party-Line Interface Modules
do not include a mounting enclosure or
chassis. They are intended for mounting
in custom 19-inch rack panels, equipment
boxes, broadcast furniture, “NEMA” I/O
boxes, or other specialized enclosures. It
is expected that integration firms will cre-
ate applications that use Model 5130
modules as part of complete broadcast,
production, corporate, and government
solutions. Sophisticated users will be
able to create “one-off” solutions to solve
unique challenges.
Party-Line Power Source
The party-line intercom power supply cir-
cuitry provides a low-noise, current-limited
source with a nominal 28 volt DC output.
Termination networks provide the required
200 ohm impedance for the audio signals
associated with the two party-line intercom
channels. With these features the Model
5130’s party-line intercom interface is es-
sentially identical to that created by stand-
alone intercom power supplies or powered
master stations.
Logic circuitry contained within the Model
5130 monitors the voltage on pin 2 for a
low-voltage/over-current condition. If de-
tected, the DC output will automatically
enter a protection mode. Once the fault
condition is removed normal operation will
again resume. The pin 2 status LED offers
the user a simple “go/no go” indication for
rapid troubleshooting.
Analog Hybrids with Auto
Nulling
The 2-wire-to-4-wire hybrids provide low
noise, low distortion, good frequency
response, and high return-loss (“nulling”),
even when presented with a wide range

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Model 5130
Party-Line Interface Module
of party-line conditions. Unlike telephone-
line (“POTS”) oriented DSP-based hybrid
circuits, the Model 5130’s analog circuitry
maintains extended frequency response.
With this wide audio bandwidth, natural-
sounding voice signals can be sent to, and
received from, the connected party-line
user devices. This bandwidth also allows
high-frequency “call light” and “mic kill” sig-
nals to pass through to connected 4-wire
equipment.
The Model 5130’s sophisticated auto null-
ing function uses analog circuitry under
microprocessor control to achieve sig-
nificant trans-hybrid loss. This return-loss
“null” is achieved by making a series of
software-directed adjustments to account
for the resistive, inductive, and capacitive
conditions that are present on the con-
nected party-line user devices and associ-
ated cabling. Whenever a user presses the
Model 5130’s auto null button digital cir-
cuitry adjusts the 2-wire-to-4-wire hybrids
to achieve their maximum return-loss for
both interface channels. The nulling pro-
cess is automatic, lasting less than
15 seconds, and only takes place upon
user request. The resulting null parameters
are stored in non-volatile memory.
Audio Inputs and Outputs
Two analog line-level inputs and two out-
puts are associated with the 4-wire portion
of the Model 5130’s circuitry. These are
intended to interconnect with a variety of
devices, including matrix intercom sys-
tems, audio-over-fiber transport systems,
and specialized audio equipment. The
audio input and output circuitry is elec-
tronically balanced and capacitor coupled
to minimize the chance that hum, noise,
or interfacing issues will occur. The two
Model 5130 versions allow compatibility
with equipment that supports SMPTE (+4
dBu) and EBU (0 dBu) analog audio level
standards.
Indicators
The Model 5130 contains four 5-segment
LED level meters. Two meters display the
level of the signals being received from the
party-line channels and two display the
level being sent to the party-line channels.
At the time of installation and setup the
meters are invaluable in helping to confirm
correct operation. During normal operation
the meters offer rapid confirmation of the
audio signals flowing into and out of the
module. Three additional LED indicators
are also provided, offering status indica-
tions of the party-line DC power supply,
auto null, and remote control data func-
tions.
Pro Audio Quality
The Model 5130’s audio circuitry was
designed in the spirit of professional audio
equipment rather than that found in typical
party-line intercom gear. High-performance
components are used throughout, provid-
ing low-distortion, low-noise, and high
headroom. The party-line DC power source
offers a unique level of performance—its
ability to deliver power while maintaining
audio quality is simply unmatched.
Installation
Integration of the Model 5130 into the
selected application is quite simple, only
requiring connecting analog audio inputs
and outputs along with DC power. Some
applications will also require connection
to the RS-485 data bus. The audio signals

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Model 5130
Party-Line Interface Module
have a nominal level of either +4 or
0 dBu, depending on the Model 5130 ver-
sion being installed. The DC power source
is nominal 12 volts with an acceptable
range of 10 to 18 volts. The RS-485 data
bus is a single pair of wires that would inter-
connect the Model 5130, along with other
Model 5100-Series modules, to a remote
access card. After the connections have
been completed, the module can then
be secured into the designated mounting
location.
Audio Inputs
The Model 5130 allows two channels of
analog line-level audio to be connected.
Each signal is associated with one of the
two party-line interface channels. The input
circuitry is electronically balanced and
capacitor coupled. The nominal input level
of Model 5130S (SMPTE) version modules
is +4 dBu with a maximum allowable input
level of +24 dBu. The nominal input level
of Model 5130E (EBU) version modules
is 0 dBu with a maximum allowable level
of +18 dBu.
Connections to the audio inputs are
made using a 5-position header connector
located on the Model 5130’s rear-most
circuit board. For details on appropriate
mating connectors refer to Appendix B
located at the end of this document.
For connecting to balanced sources the
signal + (high), signal – (low), and common/
shield connections should be used. With
unbalanced sources connect source signal
high to the Model 5130’s signal + (high) and
source signal low to both the signal – (low)
and common/shield connections. Refer to
Figure 2 for details.
Audio Outputs
Associated with each of the Model 5130’s
two party-line interface channels is a bal-
anced (differential), line-level analog audio
output. The circuitry is electronically bal-
anced and capacitor coupled. The nominal
output level of a Model 5130S (SMPTE)
version module is +4 dBu with a maximum
output level of +24 dBu. The nominal level
of a Model 5130E (EBU) version module is
0 dBu with a maximum level of +18 dBu.
Connections to the audio outputs are
made using a 5-position header connector
located on the Model 5130’s rear-most
circuit board. For details on appropriate
mating connectors refer to Appendix B
located at the end of this document.
For connection to balanced inputs on
related equipment the signal + (high) and
signal – (low) connections should be used.
Pin 1, common/shield, may or may not
need to be connected as dictated by the
specific installation. Refer to Figure 3 for
details.
When interfacing the outputs to unbal-
anced inputs on associated equipment
connect only to the Model 5130’s signal
+ (high) and common/shield. Do not make
any connections to the Model 5130’s
– (low) terminals.
Pin Number Function
1 Common/Shield
2 + CH1
3 – CH1
4 + CH2
5 – CH2
Figure 2. Audio Inputs

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Model 5130
Party-Line Interface Module
DC Input and Data
A 4-position header, located adjacent to
the audio input and output headers, is
used to connect DC power and RS-485
data to the Model 5130. For details on
appropriate mating connectors refer to
Appendix B located at the end of this
document.
A source of nominal 12 volts DC, with an
acceptable range of 10 to 18, is required
for Model 5130 operation. The maximum
current is 800 milliamperes at 12 volts DC.
For remote control operation an RS-485
data bus connection from a compatible
Studio Technologies’ remote access mod-
ule is required. Most applications will only
have the DC power connections imple-
mented so these two pins will typically
remain unconnected. Refer to Figure 4
for details.
Mounting
The Model 5130 is intended for mount-
ing into an installation-specific enclosure
or rack panel. Refer to Appendix A for the
unit’s dimensions and mounting screw
locations. Please contact the factory to
discuss mounting options.
Configuration
RS-485 Address ID
One configuration setting must be per-
formed for applications that implement
remote control of Model 5130 functions. Up
to sixteen Model 5100-Series modules can
“share” an RS-485 data bus but each must
have a unique address ID. Selecting the
device’s address ID involves setting four
DIP switches. Refer to Figure 5 for details.
Figure 5. RS-485 Address ID Settings
Pin Number Function
1 – DC (Common)
2 + DC (10-18 volts)
3 + Data (RS-485)
4 – Data (RS-485)
Figure 4. DC Input/Data
Pin Number Function
1 Common/Shield
2 + CH1
3 – CH1
4 + CH2
5 – CH2
Figure 3. Audio Outputs

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Model 5130
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Operation
The Model 5130 is designed for continu-
ous operation with no internal adjustment,
calibration, or maintenance required.
The auto null function is used whenever
significant changes are made to the num-
ber of user devices or the interface cabling
connected to the party-line interface. It
also should be used if the characteristics
of a connected party-line intercom system
change. Activating the auto null function is
simple, only requiring the pressing of the
auto null pushbutton switch.
Maintaining the correct levels coming from
the 4-wire audio sources is very important.
This will ensure proper signal levels are
presented to party-line users and maintain
optimal audio fidelity. The audio level meters
and pin 2 power LED will assist users in
confirming that correct operation is taking
place. In addition, the under-voltage shut-
down function will help to protect the party-
line intercom power supply should a fault
condition be detected.
Auto Null
The Model 5130 contains circuitry to auto-
matically null the two 2-wire-to-4-wire inter-
faces. Normally this process is performed
at the time of initial Model 5130 user set up
and operation, but there’s no reason why
“auto nulling” can’t be initiated anytime one
desires. The only time that auto null must be
performed is if conditions have changed vis-
à-vis the party-line intercom user devices
and wiring connected to a Model 5130’s
party-line intercom interface connector.
Even a slight change to a party-line inter-
com circuit, such as adding or removing a
section of cable, is sufficient to require that
the auto null process be performed.
A pushbutton switch, located on the Model
5130’s front panel, is used to activate the
auto null process. To initiate auto null re-
quires simply pressing and releasing (“tap-
ping”) the button. An LED provides a visual
indication of the auto null process, flashing
when the auto null process is active. The
sequence takes less than 15 seconds to
complete.
An auto null sequence begins with the mut-
ing of the 4-wire audio input and output sig-
nal paths. This is followed by a short period
of 24 kHz signal that is sent out both the
party-line intercom interface channels. This
will turn off microphones on those connect-
ed user devices that are compatible with
the RTS TW-series “mic kill” protocol. The
actual auto nulling process is performed
next. A series of tones will be sent out the
party-line interface channels. Other Model
5130 circuitry, under software control, will
rapidly perform adjustments to achieve the
best null possible. After the null adjustments
have been made the results are stored in
non-volatile memory. Once the process is
complete the audio input and output paths
are again activated.
If possible, prior to performing an auto null
it’s polite to warn all personnel who are
actively using the connected party-line in-
tercom devices. The tones sent to the party-
line intercom channels during the nulling
process are not excessively loud or obnox-
ious, but most users might want to remove
their headsets during the process. In ad-
dition to warning users, it might be a good
time to ask them to mute any active micro-
phones. While the automatic “mic kill” signal
will apply to many user devices it may not
apply to all. Muting microphones is signifi-
cant as obtaining a “deep” null requires that
no extraneous signals be present on the
party-line circuit.

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Model 5130
Party-Line Interface Module
Auto Null and Operating Mode
There is one situation where pressing the
auto null button will not start the auto null
process. If the Model 5130 has been con-
figured for operating mode 1, a minimal
amount of DC current must be drawn from
the party-line interface to indicate that a
2-wire party-line device has been con-
nected. If this threshold (15 milliamperes)
has not been reached the circuitry, under
firmware control, assumes that nothing has
been connected to the XLR connector as-
sociated with the party-line interface and
the auto null process will not start. (Techni-
cally, if nothing has been connected to the
party-line interface, performing an auto null
sequence would result in an inappropriate
2-wire-to-4-wire converter calibration.) If the
auto null button is pressed and the minimum
DC current level has not been reached the
auto null LED will flash six times and then
stop. This indicates that the button press
was recognized but that the minimum DC
current draw requirement was not met.
If the Model 5130 has been configured for
operating mode 2 the auto null function is
always available. A minimum amount of DC
current is not required to be drawn from the
2-wire party-line interface. This operating
mode was provided for applications where
the 2-wire party-line interface is intercon-
nected to a valid device (or devices) but
DC current is not being drawn. An example
of this would be connecting Studio Tech-
nologies’ Model 200-Series announcer’s or
producer’s consoles which are being locally
powered. (Model 200-Series devices can
be powered by the Model 5130 but in most
cases an external source of 24 volts DC will
be connected.) In this case each Model 200-
Series device would be a completely “valid”
connection to the Model 5130 although no
DC current would be drawn by it.
To view and, if desired, change the operat-
ing mode refer to the Technical Notes
section of this guide.
Level Meters
The four audio level meters on the Model
5130 are calibrated differently from typi-
cal “VU” meter scales. Their “steps” are
labeled in reference to the level of the
signals being sent to, and received from,
the party-line interface. The ballistics of
the meters is also different, being a cross
between VU and peak.
During operation the green “0” LEDs will
light in response to audio levels of –10 dBu
being present on the party-line channels.
When a 5130S (SMPTE level) module has
its “0” LEDs lighting they correspond to
+4 dBu being present on its associated
4-wire audio input or output connections.
In the case of a 5130E (EBU level) module
the audio input and output level would be
0 dBu.
The four green LEDs of each meter in-
dicate that the levels are in the normal
range. The yellow LED lights when a signal
is approximately 6 or more dB above the
nominal (–10 dBu to or from the party-line
channel) level. Optimal signals will result in
the four green LEDs lighting almost solidly
with the yellow LED lighting only on peak
signals.
Party-Line Power Supply
One or more party-line user devices can
be directly connected and powered by the
Model 5130’s party-line interface. The only
restriction on the number of user devices
that can be connected is that the total
current draw must be equal to or less than
180 milliamperes. Broadcast-standard

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Model 5130
Party-Line Interface Module
devices such as the RTS BP325 are di-
rectly compatible and will provide excellent
performance. Up to three of these units
can typically be supported.
For reference, this paragraph provides de-
tails on the signals that are present on the
party-line intercom interface’s 3-pin male
XLR connector. Pin 1 provides common
for power and audio; pin 2 has 28 volts DC
with channel 1 audio; pin 3 has channel 2
audio. The nominal audio output level on
the two channels is –10 dBu, no matter if
the module is a 5130S or a 5130E. The
maximum current draw from pin 2 to pin 1
is 180 milliamperes. The circuitry associ-
ated with pin 3 is protected from damage
should pin 2 (nominal 28 volts DC) be-
come accidentally connected to it.
DC Voltage Monitoring
The pin 2 power LED can be a highly use-
ful “tool” for understanding the status of the
party-line intercom connection. It does this
by proving an indication of the DC voltage
that is present on pin 2 (with respect to pin
1) of the Model 5130’s party-line interface
connector. The Model 5130’s microcon-
troller integrated circuit, under software
control, “watches” to ensure that the DC
voltage present on pin 2 of the party-line
intercom interface is at an acceptable level.
The under-voltage threshold for pin 2 is 24
volts. This is four volts less than the normal
level of 28 volts DC. The LED will “flash” at
a moderate cadence if the voltage on the
interface falls below the acceptable 24 volt
value. This can be caused by a temporary
over-current or short-circuit condition, such
as when interconnecting user devices to
the party-line intercom interface using por-
table cabling.
Fault Condition
If the Model 5130 is in an under-voltage
condition that’s present for a continuous
1-second period it will cause a fault condi-
tion to be recognized. The pin 2 power LED
will indicate this condition by changing from
being continuously lit to flashing. In addition,
the output voltage on the party-line power
supply circuit will automatically shut down
to an essentially off condition. A 5-second
“cool-down” period will then take place, after
which the output voltage will again become
active. As soon as the output is enabled
normal output voltage monitoring will again
take place. A continuous short circuit pre-
sented to the party-line intercom output
will result in a continuous 4-seconds-on,
5-seconds-off error cycle. It’s important to
note that during the 5-second-off period no
voltage monitoring takes places. Removing
the fault condition will not result in the out-
put voltage immediately turning on again;
the 5-second shut-down period must first
elapse.
Technical Notes
Maintaining Correct Input
Signal Levels
The Model 5130’s 4-wire audio inputs and
outputs are designed for compatibility with
either SMPTE (5130S) or EBU (5130E)
audio level standards. Applying signals to
these audio inputs at a significantly lower
level than the intended nominal will re-
duce the signal-to-noise ratio (raising the
perceived noise floor) and can prevent the
connected user devices from operating
optimally. Applying signal levels significantly
higher than nominal will reduce the head-
room and greatly increase the chance of

Model 5130 User Guide Issue 5, July 2013
Studio Technologies, Inc. Page 13
Model 5130
Party-Line Interface Module
reaching audio “clipping.” Obviously, these
cautions are not unique to the Model 5130,
but apply to most audio equipment. The
front-panel level meters provide an easy
means of confirming that a Model 5130
is being presented with the correct audio
levels.
For the Model 5130S the nominal 4-wire
input and output signal levels are +4 dBu.
For the Model 5130E the nominal levels are
0 dBu. For both versions the nominal output
level to the two channels associated with the
party-line interface is –10 dBu. (Of course
pin 2 on the party-line interface connector
has both DC and audio present on it.)
To confirm correct party-line intercom
operation at locations away from where the
Model 5130 is installed, it’s possible to use
the Model 72 Level Meter/Interface, also
available from Studio Technologies. The
Model 72 is a compact, portable device that
plugs directly into a party-line intercom or
IFB circuit and provides two useful functions.
Two 5-segment LED meters display the au-
dio levels present on pins 2 and 3. And two
“dry” line-level audio outputs are provided,
one for each channel. Complete information
on the Model 72 is available on the Studio
Technologies website.
Party-Line Interface Current
Draw
The Model 5130’s party-line output is de-
signed to provide up to 180 milliamperes
of DC current. By design, the power sup-
ply circuit is protected so that an overload
condition, or even a complete short circuit,
should not cause damage. Exceeding 180
milliamperes for more than one second will
cause the auto shut-down mode to become
active. A continuous overload condition will
cause the output voltage to cycle through a
4-seconds-on, 5-seconds-off sequence.
Restoring the output load to be within the
rated 180 milliamperes will allow the party-
line output to again operate normally. In
extreme cases, such as where the Model
5130 is located in an environment with
elevated temperatures, a few minutes may
be required from the time an overload con-
dition is removed to when normal opera-
tion will again take place. Please don’t test
the Model 5130’s ability to sustain frequent
overload or short-circuit conditions! The
long-term reliability of the unit can be
impacted by the stresses caused by these
fault conditions.
The pin 2 power LED makes it simple
to know if an excessive load, or a short
circuit, is being placed on the party-line
output. Technically the LED, under soft-
ware control, provides a direct indication
of the party-line’s DC output voltage. And
the output voltage is directly related to the
amount of current being drawn.
The LED lights steadily when the party-
line DC output voltage is within its normal
range. During normal operation the DC
level on pin 2 of the party-line XLR output
connector will be approximately 28 volts.
The LED will begin to flash on and off if the
level falls below approximately 24 volts DC
for at least one second. This will typically
occur because the current draw is greater
than nominally 180 milliamperes.
There’s really only one piece of advice
when it comes to understanding how
to use the pin 2 power LED: if it flashes
there’s a problem that must be corrected!
The most likely cause will be too many
user devices being connected to the party-
line output connector. It’s also possible that
a wiring problem could cause a partial or
full short circuit between the output XLR’s

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Party-Line Interface Module
pin 1 (common) and pin 2 (power with chan-
nel one audio) pins. Troubleshooting should
prove quick and easy. Begin by disconnect-
ing the party-line user devices. Observe the
pin 2 power LED and see if the problem has
gone away. If not, review the interconnecting
cables and find the fault condition. Within
five seconds of the problem being “cleared”
the pin 2 LED will stop flashing.
Cable Length
There are no “hard and fast” rules defin-
ing the maximum cable length possible
when connecting user devices to the Model
5130’s party-line intercom output. The
maximum cable length is directly related to
the amount of resistance in the connect-
ing cable; the lower the resistance per foot
(or meter), the longer the cable can be.
Although cable capacitance affects high-
frequency performance, resistance is the
limiting factor in most cases. For example, a
contemporary microphone cable is Belden
1172A which has 18 ohms resistance per
conductor per 1000 feet. Since we’re us-
ing two conductors to carry the signal (pins
1 and 2) you’d get 36 ohms per 1000 feet
of cable. By knowing the cable resistance
value, along with the minimum voltage and
maximum load current required by a party-
line intercom user device, a simple “ohms
law” calculation will tell you the maximum
cable length.
Let’s use the example of an RTS BP325
beltpack being connected to the Model
5130’s party-line XLR connector. We’ll
select Belden 1172A as the interconnecting
cable. For correct operation, a BP325 needs
at least 18 volts DC between pins 1 and 2
of its interface connector. And the BP325
has a rated maximum current draw of
approximately 60 milliamperes. The Model
5130 presents a party-line voltage of 28
volts across pins 1 and 2 and can supply a
maximum current of 180 milliamperes. (As
the BP325’s current draw is well within the
Model 5130’s capability, this is not a limiting
factor.) The difference between the voltage
supplied by the Model 5130 (28 volts) and
the voltage required by the BP325 (18 volts)
allows a 10 volt maximum drop over the
interconnecting cable. Using the current
draw and maximum voltage drop figures,
the maximum cable resistance can eas-
ily be calculated: 10 volts divided by 0.060
amperes equals 167 ohms. And finally, with
1172A’s 36 ohms (total) per 1000 feet of
cable, a maximum of approximately 4600
feet (1424 meters) of cable can be used and
still be less than or equal to 167 ohms. Using
this example as a guide, entering the appro-
priate values will allow you to determine the
maximum cable length for your application.
Cabling Issues – Crosstalk
The Model 5130’s party-line interface con-
forms to the broadcast-industry standard
for sending DC power and two channels of
audio over a single pair with shielded audio
cable. This implementation allows standard
portable cables, such as those used for
microphone signals, to interconnect vari-
ous party-line user devices. This method is
undoubtedly convenient and practical, but
is not without limitations. The main audio
quality issue is the possibility of crosstalk
between the two audio channels. This issue
arises due to the capacitance presented by
the two wires that form the twisted pair. The
greater the capacitance presented and the
longer the cable run, the greater the cross-
talk. Is this normally a problem during actual
use? No. But it’s something that should be
noted.

Model 5130 User Guide Issue 5, July 2013
Studio Technologies, Inc. Page 15
Model 5130
Party-Line Interface Module
Figure 6. Detail of front panel showing the level meter LEDs that display
the software version. In this example, the software version is 1.2.
Release Sub-Number
Major Release Number (No LED lit indicates .0)
O 5 .5 O
O 4 .4 O
O 3 .3 O
O 2 .2 
 1 .1 O
Software Version Display
After the Model 5130’s power-up sequence
has completed, some of the unit’s LEDs are
used to automatically display the software
version number. This is useful when work-
ing with factory personnel on application
support and troubleshooting situations. The
five LEDs associated with the channel 1
FROM audio level meter are used to display
the major release number with a range of
1 through 5. The five LEDs associated with
the channel 2 FROM audio level meter are
used to display the release sub-number
which ranges from 0 to 5. (No lit channel 2
LEDs indicates sub-number 0.) The soft-
ware version number will display for ap-
proximately one second after the power-up
sequence has completed but before normal
operation begins. Refer to Figure 6 for a de-
tailed view of the LEDs and the correspond-
ing software version numbering scheme.
Note that while it’s easy to determine
which software version is loaded into
the Model 5130 a trip back to the fac-
tory is required to update it. The 8-bit
microcontroller that provides the unit’s
logic “horsepower” also includes internal
FLASH memory. This non-volatile memory
is used to store the operating software
(“firmware”). Re-programming this memory
requires using a specialized programming
unit. While not outrageous in price, it still
costs in the range of US$500. The pro-
grammer uses a ribbon cable and socket
to interface with a 6-pin “header” on one
of the Model 5130’s printed circuit boards.
And, as you would guess, once connected,
reprogramming takes only a matter of sec-
onds. But unfortunately the programmer
is not something that would be found in a
typical “field shop” or repair facility.

Issue 5, July 2013 Model 5130 User Guide
Page 16 Studio Technologies, Inc.
Model 5130
Party-Line Interface Module
Operating Modes
To allow optimal performance in a variety
of applications the Model 5130 can func-
tion in either of two operating modes.
The difference between the two modes
is somewhat subtle, relating to how the
4-wire audio output muting function re-
sponds to the party-line interface’s DC
output current detection function.
When the Model 5130 has been config-
ured for operating mode 1 the two 4-wire
audio outputs will remain muted unless a
DC current of 15 milliamperes or greater
is actively being supplied by the 2-wire
party-line interface. This 15 milliampere
threshold was selected as being represen-
tative of what the smallest amount of DC
current a typical party-line device would
require. Requiring that a party-line device
be connected (as evidenced by DC cur-
rent being drawn) will minimize the chance
that undesirable audio signals will be sent
to the connected 4-wire equipment. These
undesirable signals would typically consist
of a portion of the 4-wire audio input being
“bounced” back through the Model 5130’s
unterminated 2-wire to 4-wire hybrid circuit.
This condition is especially undesirable
for optimal audio performance with 4-wire
intercom systems.
It might be helpful to clarify why operat-
ing mode 1 can be valuable. When the DC
current drawn from the party-line interface
is less than 15 milliamperes the module
determines that no party-line device, such
as a user beltpack, has been connected.
When no user device is connected it’s
probable that the Model 5130’s two 2-wire
to 4-wire hybrid circuits are not fully nulled.
If the circuits are not fully nulled then the
return loss value will be low and a large
percentage of the signal present on the
4-wire audio input will be “returned.” The
automatic muting of the 4-wire audio out-
puts will prevent this signal from being sent
to connected devices.
When the Model 5130 has been selected
for operating mode 2 the two 4-wire au-
dio outputs are always active. In operat-
ing mode 2 there is no requirement that a
minimum amount of DC current be drawn
from the 2-wire party-line interface. This
mode is provided for atypical but legitimate
applications where devices connected to
the Model 5130’s 2-wire party-line inter-
face do not draw DC current. (Or draw an
amount that’s less than the 15 milliam-
peres threshold.) Such devices might be
powered locally but are still intended to be
connected to party-line interface circuits
that have a –10 dBu (nominal) audio
operating level and a 200 ohm (nominal)
terminating impedance on each channel.
An example of this would be connecting
one of the Studio Technologies’ Model
200-Series of announcer’s or producer’s
consoles which is being locally powered.
(The Model 200-Series device can be pow-
ered by the Model 5130 but in most cases
an external source of 24 volts DC will be
connected.) In this case the Model 200-
Series device would be a completely “valid”
connection to the Model 5130 but no DC
current would be drawn by it. Only by
selecting operating mode 2 would it func-
tion correctly with the Model 5130.
Viewing and Changing the Operating
Mode
A Model 5130’s operating mode can be
viewed and, if desired, changed by way
of a power-up/button-press sequence.
With the Model 5130 in the un-powered
state (no source of 12 volt DC applied),
press and hold the auto null button. Then

Model 5130 User Guide Issue 5, July 2013
Studio Technologies, Inc. Page 17
Model 5130
Party-Line Interface Module
apply power while continuing to press the
button. The module will go through its nor-
mal power-up sequence and upon comple-
tion light one of two LEDs. If the Model
5130 is configured for operating mode 1
the CH1 TO –18 LED will light. If the
module is configured for operating mode 2
the CH1 TO –12 LED will light. Refer to
Figure 7 for details. From the factory
the Model 5130 is typically configured
for operating mode 1.
If the button is released within a few sec-
onds of the LED displaying the operating
mode no change will be made and the
Model 5130 will begin normal operation.
However, if after the operating mode is
displayed, the auto null button remains
pressed for approximately five additional
seconds the mode will automatically
change (“toggle”). For example, if the “–18”
LED indicates that operating mode 1 is the
current configuration, continuing to hold the
auto null button will cause the configuration
to change to operating mode 2. It should
be very clear that a change has occurred
as the LED will change from “–18” to “–12.”
After the change has occurred, releasing
the button will cause the revised configura-
tion to be saved and the Model 5130 will
begin operation under the revised mode.
When described in words this procedure
seems fairly technical. But a couple of
practice sessions will show how simple
it actually is.
Figure 7. Detail of front panel showing opertaing modes
1 and 2.
Operating Mode 1
Operating Mode 2

Issue 5, July 2013 Model 5130 User Guide
Page 18 Studio Technologies, Inc.
Model 5130
Party-Line Interface Module
Specifications
General Audio:
Frequency Response (analog input to party-line
interface):
–3.0 dB @ 80 Hz
–2.5 dB @ 100 Hz
–2.3 dB @ 20 kHz
–3.0 dB @ 24 kHz
Distortion (THD+N, measured at 1 kHz, analog
input to party-line interface):
Party-Line Interface Pin 2: 0.06%
Party-Line Interface Pin 3: 0.02%
Signal-to-Noise Ratio (measured at 1 kHz,
analog input to party-line interface):
Party-Line Interface Pin 2: 60 dB
Party-Line Interface Pin 3: 86 dB
Audio Inputs: 2
Type: analog, electronically balanced, capacitor-
coupled, 20 k ohms
Nominal Level: +4 dBu (Model 5130S), 0 dBu
(Model 5130E)
Maximum Level: +24 dBu
Audio Outputs: 2
Type: analog, electronically balanced, capacitor-
coupled, intended to drive balanced loads of 2 k
ohms or greater
Nominal Level: +4 dBu (Model 5130S), 0 dBu
(Model 5130E)
Maximum Level: +24 dBu into 10 k ohms
Source Impedance: 200 ohms, nominal, differential
Party-Line Intercom Interface:
Type: 2-channel party-line, unbalanced (common
on pin 1, DC modulated with channel 1 audio on
pin 2, channel 2 audio on pin 3)
Compatibility: single- and dual-channel intercom
system such as from RTS® and Clear-Com®
Nominal Audio Level: –10 dBu
Maximum Audio Output Level:
Pin 2: +9 dBu with +23 dBu (Model 5130S) on
audio input
Pin 3: +10 dBu with +24 dBu (Model 5130S) on
audio input
DC Output Voltage (pin 2 to pin 1): 28 volts
nominal
DC Output Current (pin 2 to pin 1): 180 milliam-
peres maximum; requires ≥15 mA current draw for
detection of connected device
Impedance (pin 2 to pin 1; pin 3 to pin 1):
200 ohms, nominal
Hybrids: 2
Topology: 3-section analog circuitry compensates
for resistive, inductive, and capacitive 2-wire party-
line loads
Nulling Method: automatic upon user initiation,
processor implements digital control of analog
circuitry; settings stored in non-volatile memory
Nulling Line Impedance Range: 120 to 240 ohms
Nulling Cable Length Range: 0 to 3500 feet
Trans-Hybrid Loss: >45 dB, typical at 1 kHz
Meters: 4, 5-segment LED, modified VU ballistics
Remote Control Capability: audio level monitoring,
pin 2 DC output status, auto null activation
Connectors:
Party-Line Intercom: 3-pin male XLR
Audio Inputs and Outputs: 2, 5-position male
header. Refer to Appendix B for mating connector
details.
DC Input/Data: 4-position male header. Refer to
Appendix B for mating connector details.
Power Requirement: 12 volts DC nominal, 800 mA
max; acceptable range 10-18 volts DC, 950 mA max
at 10 volts
Dimensions (Overall):
3.75 inches wide (9.5 cm)
1.69 inches high (4.3 cm)
2.30 inches deep (5.8 cm)
Mounting: requires custom implementation;
no mounting method provided. Refer to Appendix A
for details.
Weight: 0.2 pounds (91 g)
Specifications and information contained in this
User Guide subject to change without notice.

Model 5130 User Guide Issue 5, July 2013
Studio Technologies, Inc. Page 19
Model 5130
Party-Line Interface Module
Appendix A–Model 5130 Front Panel and Printed Circuit
Board (PCB) Dimensions

Issue 5, July 2013 Model 5130 User Guide
Page 20 Studio Technologies, Inc.
Model 5130
Party-Line Interface Module
Appendix B–Interconnection Details
The required mating receptacles are from the TE Connectivity (formerly AMP) MTA-100
series of IDC (insulation displacement) connectors. This series was selected because of
its low-cost and wide range of offerings. Separate connectors are offered for compatibility
with 22, 24, 26, and 28 AWG (American Wire Gauge) insulated wire. The connector color
indicates its AWG-compatibility. Unfortunately, with flexibility can come some confusion. The
MTA-100 offers a number of different connectors that will work with the Model 5130’s audio
input, audio output, and DC input/data headers. Before obtaining receptacles it’s important
to determine two things: wire gauge and wiring arrangement.
Audio Inputs and Outputs
• For 22 AWG wire this receptacle (red in color) is recommended:
TE Connectivity (AMP) 3-643813-5
Digi-Key part number A31109-ND (www.digikey.com)
Mouser part number 571-3-643813-5 (www.mouser.com)
• For 24 AWG wire this receptacle (white in color) is recommended:
TE Connectivity (AMP) 3-643814-5
Digi-Key part number A31020-N
Mouser part number 571-3-643814-5
DC Input/Data
• For 22 AWG wire this receptacle (red in color) is recommended:
TE Connectivity (AMP) 3-644540-4
Digi-Key part number A31122-ND
Mouser part number 571-3-644540-4
Tools for Connecting Wires to the Mating Receptacles
For applications where just a few Model 5100-Series modules are going to be installed a
manual IDC termination tool is recommended. While requiring a steady hand to achieve
reliable wire connections to the mating receptacles, the price, at less than US$40, is fairly
reasonable:
• “T Handle” termination hand tool:
TE Connectivity (AMP) 59803-1
Digi-Key part number A9982-ND
Mouser part number 571-598031