AiRocks Pro ARX-900 User manual

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AIROCKS PRO ARX-900 USER GUIDE V1.0
AiRocks Pro
ARX-900
Digital Wireless Audio Repeater
User Guide
V1.0
March 28, 2015

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AIROCKS PRO ARX-900 USER GUIDE V1.0
1CONTENTS
2 AiRocks Pro Overview ........................................................................................................................... 4
2.1 Traditional Wireless Audio............................................................................................................ 5
2.2 The AiRocks Pro Repeater............................................................................................................. 5
2.3 The AiRocks Pro Network.............................................................................................................. 5
2.4 Network Overview ........................................................................................................................ 7
2.4.1 Unmanaged Network............................................................................................................ 7
2.4.2 Managed Network ................................................................................................................ 7
2.5 Equipment Overview and Features .............................................................................................. 8
2.5.1 AiRocks Pro ARX-900 Wireless Audio Repeater.................................................................... 9
2.5.2 Key Features of the AiRocks Pro System............................................................................. 10
2.5.3 AiRocks Pro ARX-900-BOB Breakout Box ............................................................................ 12
3 AiRocks ARX-900 Configuration and Operation..................................................................................13
3.1 Front Panel Configuration and Display .......................................................................................13
3.1.1 Top Level Menu................................................................................................................... 13
3.1.2 System Configuration Functions ......................................................................................... 13
3.1.3 Master Mode configuration functions................................................................................ 14
3.1.4 Relay Mode configuration functions................................................................................... 15
3.1.5 Relay Antenna Diversity...................................................................................................... 15
3.2 Audio Input and Output Configurations .....................................................................................17
3.2.1 Stereo vs Mono ................................................................................................................... 17
3.2.2 Audio Input Configurations (Master unit)........................................................................... 18
3.2.3 Audio Output Connector Configurations (Relay units) ....................................................... 19
4 Equipment Installation and Operation ............................................................................................... 22
4.1 Installing the ARX-900 Master and Relay Units ..........................................................................22
4.1.1 Installing the Master Unit ................................................................................................... 22
4.1.2 Installing Relay Units...........................................................................................................24
4.1.3 Environmental Considerations............................................................................................ 25
5 Network Management System ...........................................................................................................26
5.1 NMS Overview ............................................................................................................................ 26
5.2 GUIDs and Registration............................................................................................................... 26
5.3 Network Security ........................................................................................................................28

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AIROCKS PRO ARX-900 USER GUIDE V1.0
5.3.1 Open Networks ................................................................................................................... 28
5.3.2 Secure Networks ................................................................................................................. 28
5.4 Master Mode Operation .............................................................................................................29
5.4.1 Master Mode Screen........................................................................................................... 29
5.4.2 Relay Monitor Window .......................................................................................................34
5.5 Spectrum Analyzer Mode Screen................................................................................................ 39
5.6 Relay Mode Screen ..................................................................................................................... 40
5.7 System Setup Screen................................................................................................................... 40
5.8 Installing the Network Management System Application ..........................................................42
5.9 Deploying and Managing a Network...........................................................................................44
5.9.1 Node Registration ............................................................................................................... 44
5.9.2 Channel Selection Mode .....................................................................................................44
5.9.3 Frequency Scan ................................................................................................................... 44
5.9.4 Mounting Position............................................................................................................... 44
5.9.5 Deployment Sequence........................................................................................................44
5.9.6 ALO and RSA........................................................................................................................ 45
5.9.7 DC Power............................................................................................................................. 45
6 System Specifications..........................................................................................................................46
8 FCC Statements................................................................................................................................... 48
8.1 Class A Devices:........................................................................................................................... 48
8.2 RF Exposure and Safety Information ..........................................................................................48
9 Industry Canada Specific Statements: ................................................................................................ 48

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AIROCKS PRO ARX-900 USER GUIDE V1.0
Introduction
2AIROCKS PRO OVERVIEW
AiRocks Pro is a revolutionary new digital wireless audio system designed to provide significantly
extended coverage area and ultra-reliable audio distribution for pro-audio sound reinforcement
applications. AiRocks Pro is typically used in large indoor or outdoor venues to distribute audio from a
main mixer board to multiple powered speakers distributed over a wide area. Based on a novel
“repeater” or “transceiver” multi-hop audio technology, AiRocks Pro can be used to go around
obstacles, such as buildings, trees, or other obstructions, or to dramatically extend the coverage area
compared to traditional wireless audio products.
Figure 1 AiRocks Pro ARX-900

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AIROCKS PRO ARX-900 USER GUIDE V1.0
2.1 TRADITIONAL WIRELESS AUDIO
Traditional wireless audio equipment consists of a “transmitter” and a “receiver” which send analog
audio from point A to point B. This type of network is called a “point-to-point” network. Most wireless
microphones, wireless in-ear devices, and wireless instrument equipment are point-to-point products.
Some newer wireless audio products provide the ability to send a signal from a single transmitter to
multiple receivers. This type of network is called “point-to-multipoint” and can be effective if all
receivers are within the transmission range of the transmitter. However, since the FCC limits the amount
of power that each transmitter can radiate, the effective range of this type of system is somewhat
limited.
Also, some of these newer devices include what are called “transceivers”. These devices give a single
unit the ability to be manually configured as EITHER a transmitter OR receiver, but not both
simultaneously.
2.2 THE AIROCKS PRO REPEATER
AiRocks Pro is the world’s first digital wireless audio “repeater”. Each AiRocks Pro unit includes BOTH a
transmitter AND a receiver operating simultaneously in the same unit. A signal that is received by an
AiRocks Pro unit is immediately re-transmitted on a different frequency to other AiRocks Pro units
within its transmission range. When AiRocks Pro units are positioned in a “line” (linear fashion) they
form what is called a “multi-hop” wireless audio network. The range of this type of network is
theoretically “unlimited”, however, practical considerations (such as path obstructions and interference)
can limit the actual size of the achievable coverage area.
2.3 THE AIROCKS PRO NETWORK
An AiRocks Pro network consists of a single Master and one or more Relay units. A network can be as
simple as a single Master and one Relay:

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AIROCKS PRO ARX-900 USER GUIDE V1.0
Or the network can consist of one Master and up to 100 Relay units operating in a multi-hop
configuration:
Each AiRocks Pro unit can be configured to operate either as the
network “Master” unit or as a “Relay” unit (all AiRocks Pro units are
identical and include the same hardware and software). The number
of Relay units is limited by both the practical considerations
mentioned above, as well as network “polling” when using the
AiRocks Pro Network Management System (NMS) discussed below.
In an AiRocks Pro network, each AiRocks Pro Relay unit receives an
audio transmission from a single “upstream” unit, and then re-
transmits that same signal to one or more downstream units. Thus,
each AiRocks Pro unit creates its own point-to-multipoint sub-network. The input to each sub-network is
the signal received by the single uplink AiRocks Pro unit. Therefore, an AiRocks Pro network is a group of
one or more sub networks all of which emanate from a single network Master. Networks can be as
simple as one Master unit and one Relay unit in a point-to-point configuration, or as complex as
hundreds of units with multiple “branches” and “sub-networks”.
If there is a failure of one of the upstream AiRocks Pro units, the downstream units automatically begin
scanning for any other AiRocks Pro transmission within range. If an acceptable signal is found, it then
becomes the input signal for that sub-network, or any newly created sub-networks. Thus an automatic
switchover is accomplished without the need for manual intervention.
An AiRocks Pro network creates an extensive “cloud” of ultra-reliable wireless audio for both small and
large venue sound reinforcement applications. AiRocks Pro operates in the license-free 900 MHz
frequency band and includes fully automatic channel scanning and selection with automatic link
monitoring and optimization, so there is no need for complex frequency coordination or
intermodulation calculations.
AiRocks Pro units are designed to be very simple to install. When initially powered up, an AiRocks Pro
unit enters the Relay operating mode (unless it was previously configured as a Master unit) and begins
scanning for an upstream signal. When a signal is found, the unit begins sending the received analog
audio out to the connected speaker via an XLR connector. It (optionally) also begins relaying the digital
wireless signal, on a different frequency, to any downstream units within range. Front panel controls

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AIROCKS PRO ARX-900 USER GUIDE V1.0
allow the installer to manually configure operating parameters, as well as monitor several key functions
such as received signal level, and audio level and activity.
2.4 NETWORK OVERVIEW
An AiRocks Pro network can operate in one of two modes: Managed or Unmanaged.
2.4.1 Unmanaged Network
An unmanaged network is simply an AiRocks Pro network that does not use the Network Management
System. If the user wishes to merely deploy one or more Relay units in a small network, this can be done
by simply plugging the units in and turning on the power. The AiRocks Pro units function fully
automatically and autonomously. Front panel controls give the user full control of configuration
parameters and monitor functions.
2.4.2 Managed Network
A managed network is one that employs the AiRocks Pro Network Management System (NMS)
application. Use of the NMS is strictly optional, but highly recommended since it can give valuable
information for configuring the network for optimum performance in the presence of interference,
range, or obstruction limitations of the venue. The NMS gives a graphical view of everything that is
happening in the network and can help quickly diagnose problems that arise during an event.
Note: The ARX-900 USB interface uses a standard HID driver which is built into the PC’s operating
system. Therefore, no custom USB drivers need to be installed. When the ARX-900 is first attached to a
USB port, the operating system installs a HID driver for that port. This OS installation process can take
up to 30 seconds. Be patient while this process takes place. It will only occur when the ARX-900 is first
connected to the USB port.

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AIROCKS PRO ARX-900 USER GUIDE V1.0
2.5 EQUIPMENT OVERVIEW AND FEATURES
The AiRocks Pro system consists of the ARX-900 Wireless Audio Repeater and an optional ARX-900-BOB
“breakout box”. The BOB is essentially an extender for the IO ports on the ARX-900 as well as a remote
AC or DC power injector. Below is a diagram of the typical Master configuration using a Breakout Box.
Figure 2 - Typical Master Location Setup

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AIROCKS PRO ARX-900 USER GUIDE V1.0
2.5.1 AiRocks Pro ARX-900 Wireless Audio Repeater
The ARX-900 is enclosed in a weather resistant outdoor enclosure and includes a sealed pushbutton
front panel interface with an LCD display. The user can configure the unit from either the front panel, via
the USB port of the BOB, or over the air by using the Network Management System.
Figure 3 - AiRocks Pro ARX-900 Wireless Audio Repeater
Audio Out
Audio In
To/From
BOB
AC Power

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AIROCKS PRO ARX-900 USER GUIDE V1.0
2.5.2 Key Features of the AiRocks Pro System
The AiRocks Pro system is the most feature-rich pro-audio wireless system on the market. These
powerful features give the user a broad array of tools for managing the system in every the most
challenging venues.
2.5.2.1 Multi-Hop Transceiver Architecture
The AiRocks system is the world’s first “multi-hop transceiver” architecture targeting the pro-audio
market. As mentioned earlier, traditional wireless audio systems include separate, inflexible transmitters
and receivers with a transmit range limited by their FCC allowable transmit power. The AiRocks
transceiver architecture gives vastly superior range and coverage of large outdoor venues by virtue of its
“multi-hop” transmission technology.
2.5.2.2 Automatic Link Optimization (ALO)
The AiRocks system includes a novel feature called Automatic Link Optimization (ALO) which
continuously monitors the quality of the link between units (Master->Relay or Relay->Relay) and
automatically selects a new transmission channel if the interference level is too high. If the Packet Error
Rate (PER) of a link exceeds a user-settable limit, the downlink unit will temporarily go off-line, perform
a scan of the local interference environment, determine which of the local channels contains the least
interference, sort the channels by best-to-worst, then send the sorted list of channels to its current
uplink node. If ALO is enabled in the uplink node, the uplink unit will change it transmit channel to one
of the most desirable channel in the list received from the down link node. Thus, if interference appears
after the initial installation has taken place, the links continue to self-optimize to avoid any new or
transient local interference. The entire ALO scan and optimization takes approximately 2 seconds during
which the audio output from the unit is muted.
2.5.2.3 Powerful Network Management System
The AiRocks system includes a powerful Network Management System (NMS) which gives the user a
broad array of tools for monitoring and controlling the network. NMS is built into every ARX-900 unit
and provides a two-way control channel the gives the user a window into the detailed performance of
any remote unit from one central location. Critical functions such as Receive Signal Strength Indicator
(RSSI or receive signal level), Packet Error Rate (PER), Remote Spectrum Analysis (RSA), Audio Level,
Audio Delay, can all be monitored AND controlled from the NMS GUI screen.
2.5.2.4 Network Security
The AiRocks Pro system implements network security through the use of Globally Unique IDs (GUID),
which are similar to MAC addresses in Ethernet network equipment. If the GUID has not been registered
in the NMS database, the unit will not be granted access to the network audio or control information.
2.5.2.5 Automatic or Manual Channel Selection
The AiRocks system is easily deployed by virtue of its automatic transmit and receive channel selection
functions. In the Automatic Channel Selection mode the unit will automatically scan for an uplink
AiRocks transmission. If found the unit will begin receiving the signal and immediately scan its local RF
spectrum for the most desirable downstream channel. Once found, the Relay unit will begin sending the
signal it has received from its uplink source to any downstream units within range. For venues with very
closely spaced AiRocks units (due to speaker placement) a Manual Channel Selection mode is available
which gives the user full control over selection of TX and RX channels.

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AIROCKS PRO ARX-900 USER GUIDE V1.0
2.5.2.6 Remote Spectrum Analyzer (RSA)
The AiRocks Pro system includes a Remote Spectrum Analyzer function that allows the user the scan the
local RF environment of any remote unit and plot results of the scan on a Spectrum Analyzer graph in
the NMS Relay Monitor Window. Thus, the network operator can keep track of any potential
interference at any remote Relay location.
2.5.2.7 Flash Memory Storage of Configuration Settings
All critical user configuration settings are store in flash memory so that when power is lost and restored,
the last set configuration is re-established.
2.5.2.8 Weather Resistant Enclosure
The AiRocks Pro is housed in a sturdy aluminum weather resistant enclosure that is designed to
withstand rain and dust encountered in the most hostile outdoor venues.

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AIROCKS PRO ARX-900 USER GUIDE V1.0
2.5.3 AiRocks Pro ARX-900-BOB Breakout Box
The ARX-900-BOB is an optional remote connector interface that duplicates audio interfaces, AC power
connection, and USB interface of the ARX-900 repeater. The BOB also includes a DC (battery) power
input connector to facilitate field deployment when AC power may not yet be available. The BOB allows
the ARX-900 to be place up to 100 feet away (i.e. on a pole to raise it above any obstructions in a venue
to provide better line-of-site to other nodes). The interconnection between the ARX-900 and the BOB is
a standard 8-conductor Ethernet cable. The main I/O connector is a Neutrik Ethercon (NE8FDV) which
can accommodate standard RJ45 terminations or the Neutrik NE8MC Cable Connector Carrier, which
provides a rugged termination for harsh environments.
Figure 4 - ARX-900-BOB Breakout Box

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AIROCKS PRO ARX-900 USER GUIDE V1.0
3AIROCKS ARX-900 CONFIGURATION AND OPERATION
The AiRocks ARX-900 Wireless Audio Repeater includes numerous features and operating modes which
are described in this section.
3.1 FRONT PANEL CONFIGURATION AND DISPLAY
The ARX-900 can be configured from the front panel by using the 5-key navigation switch. The resulting
modes and settings are displayed on the LCD. Below is a summary of the front panel menu functions.
3.1.1 Top Level Menu
Master
Select Master Mode
Relay
Select Relay Mode
System
Select System Configurations Functions
This top-level menu allows the operator to configure the unit to Master or Relay operating mode, or to
select System Configuration Functions.
3.1.2 System Configuration Functions
System Configuration
Channel Select Mode
Auto
Manual
MSP Firmware Version
DSP Firmware Version
Physical ID (PID)
Startup Screen (Default)
Receive Signal Monitor
Audio Level Monitor
Net ID Monitor
PID Monitor
3.1.2.1 Channel Select Mode
Channel Select Mode allows the user to select either fully automatic transmit and receive channel
selection, or manual channel selection. It is important to keep in mind that several automatic functions
will be disabled when Manual Channel Select mode is selected (i.e. Automatic Link Optimization,
automatic channel scanning for an uplink transmission, and automatic selection of optimum downlink
TX frequency). However, Manual channel selection may be helpful in difficult RF environments.
3.1.2.2 MSP Firmware Version
Displays the currently installed version of the MSP (microprocessor) firmware.

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AIROCKS PRO ARX-900 USER GUIDE V1.0
3.1.2.3 DSP Firmware Version
Displays the currently installed version of the DSP firmware.
3.1.2.4 Physical ID
Allows the user to assign a “physical ID” (PID) to an ARX-900 unit. The PID will show up on a spectrum
analyzer graph so that one can uniquely identify the transmission of the specific PID when the NMS is
not used in the network. When the NMS is used, the Net ID of the unit appears on the spectrum
analyzer graph.
3.1.2.5 Startup Screen
The display defaults to the selected screen after power up and after key pad timeout. The factory
default screen is Receive Signal level.
3.1.3 Master Mode configuration functions
Master Mode
Master Transmit Channel
Master Transmit Power
Master Receive Channel (monitor)
Master Audio Gain
3.1.3.1 Master Transmit Channel
Displays and controls the current downstream transmit channel. In Auto Channel Select Mode the
transmit channel is automatically selected when the unit scans for an available channel with the least
local interference during power up. In Manual Channel Select Mode the transmit channel is selected by
the user. Note: If you are unable to change the Transmit Channel, the system is in Manual Channel Select
Mode.
3.1.3.2 Master Transmit Power
Displays the current transmit power. Power can be adjusted from ~0dbm to ~+20dbm. It is
recommended to keep the power at its maximum level (+20dbm).
3.1.3.3 Master Receive Channel
Displays the current receive uplink control channel (UCC). The receive channel is automatically selected
when the unit scans for an available channel with the least local interference during power up.

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AIROCKS PRO ARX-900 USER GUIDE V1.0
3.1.4 Relay Mode configuration functions
Relay Mode
Relay RX Channel
Relay RX Signal
Relay RX Ant Diversity
Relay TX Enable
Relay TX Channel
Relay TX Power
Relay Audio Level Monitor
Relay Audio Gain
Relay Audio Delay
Relay Audio Channel Output
Relay Net ID
3.1.4.1 Relay Receive Channel
Displays and controls the current receive channel. In Auto Channel Select Mode the receive channel is
automatically selected when the unit scans for and finds a transmission from an uplink unit. In Manual
Channel Select Mode the receive channel is selected by the user.
3.1.4.2 Relay Receive Signal Level (factory default screen)
If the unit has found a signal, this function displays the current receive signal level. The receive signal
display range is approximately -95dbm to 0dbm. It is desirable to keep this signal level greater than one
bar (-70dbm). This is the factory default screen that appears after power up.
3.1.5 Relay Antenna Diversity
Antenna diversity is helpful when using the standard dipole antennas. This allows the receiver to select
the stronger of the two received signals automatically. When using a single, high-gain directional
antenna, diversity should be disabled since the antenna will be connected only to Antenna Port #1
(right-hand side of unit).
3.1.5.1 Relay Transmit Enable
Displays and controls the current setting for the TX Enable function. This function can be used to disable
the “transceiver” functionality of the ARX-900 so that the unit is “receive only”. Keep this function in
mind when troubleshooting what appears to be a non-functioning unit. The unit will not “relay” a
signal to downstream units if TX is disabled.
3.1.5.2 Relay Transmit Channel
Displays and controls the current setting for the downstream transmit channel. In Auto Channel Select
Mode the transmit channel is automatically selected when the unit scans for an available transmit
channel with the least local interference during power up. In Manual Channel Select Mode the transmit
channel is selected by the user.

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AIROCKS PRO ARX-900 USER GUIDE V1.0
3.1.5.3 Relay Transmit Power
Displays the current transmit power. Power can be adjusted from ~0dbm to ~+20dbm. It is
recommended to keep the power at its maximum level (+20dbm) unless two units are placed very near
each other.
3.1.5.4 Relay Audio Signal Monitor
Displays the average audio signal level received by the unit. It is desirable to keep the audio signal in the
middle of the display during normal operation since this will give the best dynamic range of the Digital-
to-Analog Converter (DAC) in the receiver. The audio level can be manually controlled at the input of the
Master unit and by the Relay Audio Gain function (below).
3.1.5.5 Relay Audio Gain
Displays the controls the audio gain in the receiver’s audio path. The settings range from -15db to
+20db. The factory default setting is 0db gain.
3.1.5.6 Relay Audio Delay
The ARX-900 can add delay into the audio path to help compensate for speaker placement in a large
venue. Up to 500mSec of delay per hop (Relay location) can be added. The delay can be applied either in
a “cumulative” fashion (the delay of each hop is added to the relayed signal), or “non-cumulative”
fashion (the delay is added only to the local node but not to the relayed signal). This gives the user a
great deal of latitude in tuning the delay within the venue.
3.1.5.7 Relay Audio Output Channel Configuration
This function gives the user control of the audio output channel configuration (see the Audio Output
Configuration section). The selectable configurations include Left+Right, Left Channel only, and Right
Channel only.
The latter two configurations are useful for feeding balanced Left channel or Right channel stereo delay
stacks. These signals are balanced and use XLR Pins 2 & 3.
The Left+Right configuration will output the Left channel on XLR Pin2 (Tip/Hot) and the Right channel on
XLR Pin3 (Ring/Cold). XLR Pin 3 is Ground
3.1.5.8 Relay Network ID
When used in a Managed Network, this function displays the Network ID that has been assigned by the
Network Managements System. In Unmanaged mode the Network ID is 0. Also, the Master network ID is
always 0.

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AIROCKS PRO ARX-900 USER GUIDE V1.0
3.2 AUDIO INPUT AND OUTPUT CONFIGURATIONS
As a convenience to the user, the ARX-900 can accommodate several different audio input and output
configurations. Each of the configurations can be selected electronically (no hardware jumpers) and can
accommodate balanced mono and stereo audio input and output signals. This is accomplished internally
by the use of switched audio connections as shown below. These audio configurations are selectable via
the front panel or via the NMS. The NMS gives the user the ability to switch configurations remotely
over the air.
Since the ARX-900 can only operate in one mode at a time (Master or Relay), the Audio Input connector
and Audio Output connector share the same audio path (Audio+ and Audio-) and are therefore
connected in parallel.
3.2.1 Stereo vs Mono
The ARX-900 transmit two independent audio channels over the air. The Master will always transmit XLR
Pin 2 (Tip/Hot) on one channel, and XLR Pin 3 (Ring/Cold) on the other channel. This allows the user to
apply (at the Master XLR) either balanced mono or unbalanced stereo to Pins 2 &3. The remote Relay
can be configured by the user to output either balanced mono audio, unbalanced stereo (Left and
Right), balanced Left channel only, or balanced Right channel only. The table below summarizes these
configurations.
Left & Right Left Right
XLR Pin Balanced Mono Balanced Mono N/A N/A
Pin 1 Ground Ground
Pin 2 Audio +, Tip, Hot Audio +, Tip, Hot
Pin 3 Audio -, Ring, Cold Audio -, Ring, Cold
XLR Pin Unbalanced Stereo Unbalanced Stereo Left & Right Balanced Left Channel Only Balanced Right Channel Only
Pin 1 Ground Ground Ground Ground
Pin 2 Left Channel, Tip, Hot Left Channel, Tip, Hot Left Channel +, Tip, Hot Right Channel +, Tip, Hot
Pin 3 Right Channel, Ring, Cold Right Channel, Ring, Cold Left Channel -, Ring, Cold Right Channel -, Ring, Cold
Audio Out at Relay
Source Audio at Master XLR
Relay Output Audio Selector Button

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AIROCKS PRO ARX-900 USER GUIDE V1.0
3.2.2 Audio Input Configurations (Master unit)
3.2.2.1 Balanced Mono Audio Input Connector Configuration (factory default)
The Balanced Mono audio input configuration is shown below. In this mode the audio input signal clips
at +8.2dbu (~1.9Vrms, 2.8Vpk).
Figure 5 Balanced Mono Audio Configuration
3.2.2.2 Unbalanced Stereo Audio Input Connector Configuration
The ARX-900 transmits two independent audio channels over the air. This allow the Master to send
unbalanced stereo channels on XLR Pins 2 & 3 (Pin 1 is a common ground for both channels). The Relay
unit can select either the Left or Right channel and output this signal as a balanced audio output signal
(Left or Right balanced output). Or the Relay can be configured send the Left channel out on Pin 1, and
the Right channel out on Pin 2 with Pin 1 being a common ground for both channels. In this mode the
audio input signal clips at +2.2dbu (~.98Vrms, 1.4Vpk).
Figure 6 Unbalanced Stereo Audio Input Connector Configuration

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AIROCKS PRO ARX-900 USER GUIDE V1.0
3.2.3 Audio Output Connector Configurations (Relay units)
3.2.3.1 Balanced Mono Audio Output Connector Configuration (factory default)
When the Relay audio output configuration is set to L&R, the audio output on Pin 2 is the signal applied
to the Master XLR Pin 2 (Audio +, Tip, Hot), and the output on Pin 3 is the signal applied to the Master
XLR Pin 3 (Audio-, Ring, Cold). If balanced mono audio is applied to the Master XLR input connector, the
Relay audio output selector button should be left in L&R so that both Tip and Ring signals are applied to
the output XLR connector.
The Balanced Mono audio output connector configuration is shown below. In this mode the audio
output signal clips at +8.2dbu (~2Vrms, 2.8Vpk).
Figure 7 Balanced Mono Audio Output Connector Configuration
3.2.3.2 Stereo Audio Output Connector Configuration
3.2.3.2.1 Unbalanced Stereo Output (Left and Right Channels)
If unbalanced stereo is applied to the Master XLR input connector, and the Relay audio output is set to
L&R, the audio output on Pin 2 is the signal applied to the Master XLR Pin 2 (Left channel audio), and the
output on Pin 3 is the signal applied to the Master XLR Pin 3 (Right channel audio).

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AIROCKS PRO ARX-900 USER GUIDE V1.0
In this mode the audio output signal of each channel clips at +2.2dbu (~1Vrms, 1.4Vpk). The Stereo
Audio Output Connector configuration is shown below.
Figure 8 Unbalanced Stereo Audio Output Connector Configuration
3.2.3.2.2 Balanced Stereo Output (Left Channel Only)
When using AiRocks Pro for stereo delay stacks it is desirable to feed a balanced Left channel signal to
one stack, and a balanced Right channel signal to the other stack. When the Relay audio output
configuration is set to “Left”, the Left channel audio signal is output as a balanced single channel on Pins
2 & 3 of the Relay XLR output connector. This configuration is shown below.
Figure 9 Balanced Stereo Output (Left)
3.2.3.2.3 Balanced Stereo Output (Right Channel Only)
When the Relay audio output configuration is set to “Right”, the Right channel audio signal is output as a
balanced single channel on Pins 2 & 3 of the Relay XLR output connector. This configuration is shown
below.