Nexus Unite U74 User manual

Unite U74 Audio Amplifier
User Guide
Unite Audio
Nexus Audio Video Pty Ltd
15-19 Villas Road
Dandenong South,
Victoria, Australia 3175

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Table of Contents
Introduction ............................................................................................................................... 3
Installation ................................................................................................................................. 3
Equipment.................................................................................................................................. 3
Amplifier Front-Panel Features................................................................................................... 3
Amplifier Rear-Panel Features .................................................................................................... 4
Web Interface............................................................................................................................. 5
Amplifier Configuration .............................................................................................................. 6
Settings ...................................................................................................................................... 9
Amplifier Use............................................................................................................................ 14
Rear Panel Layout..................................................................................................................... 17
Specifications ........................................................................................................................... 18
Document Revision
Details
dd/mm/yy Inits
Rev A
Initial Release.
12/04/21 DJA

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Introduction
This document provides a user’s guide for the Unite U74 amplifier. The U74 is part of
the Unite family of Commercial and Domestic amplifiers.
In this guide the term Zone refers to a particular location serviced by one of the amplifier
outputs. Each Zone may be stereo or Mono. Zones can be single-ended or connected
for Bridge-Tied Load (BTL).
The term Source refers to a particular signal source connected to the amplifier inputs.
Example sources are CD players, solid-state sources such as memory sticks, Internet
streaming sources, microphones and so on.
Installation
The simplest configuration of the U74 is with mono (Inputs 1 and 2) and stereo (Inputs
3, 4 and 5) analog signal Inputs and stereo Speaker outputs.
An S/PDIF digital audio signal may also be connected to Input 6.
Equipment
•Model U74 Amplifier
•Loudspeakers
•Signal sources
•Internet connection
•Web browser (Chrome, Firefox, Edge, Vivaldi etc.)
•Interconnect cables
Amplifier Front-Panel Features
The U74 amplifier can be controlled from the front panel. There are four multi-function
rotary controls to adjust Source and Volume configuration for each Zone.
The U74 amplifier indicates its operational condition with three LED indicators on the
right-hand side and a full-colour screen on the left-hand side.
LED indicators
The U74 LED indicators show the power/boot status, network connection status and
alert status.
Display
The U74 display shows the Source selected for each Zone and the volume setting for
each Zone. The display also shows the IP address the amplifier and ID.

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Controls
The U74 features 4 rotary/push controls (encoders) for user control over basic
operation.
This includes setting:
•Volume of Zone
•Source for Zone
•Set Power
•Controls Off
Amplifier Rear-Panel Features
All the connectors for the U74 amplifier are on the rear panel. This includes Power,
internet, hardware controls, signal Source inputs and Zone speaker outputs.
Basic Connections
Make sure the amplifier mains switch is in the Off (O) position before making any
connections.
•Connect mains power to the mains input socket.
•Connect Source signal sources to the Inputs as required.
•Connect Zone speakers to the Speaker Outputs as required.
•Connect the amplifier to the internet via a patch cable to the LAN socket.
If hardware controls such as Mute and PTT are not required, there is no need to make
any connections to these inputs.

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Power-up
Check connections and move the power switch to the ON (I) position.
The front panel power LED will flash while the amplifier boots up, acquires and IP
address and loads its last-set configuration.
When this process has completed the power LED will remain ON steady and the Display
will light up and indicate the current Zone Source and volume settings.
Web Interface
The U74 amplifier can be configured and controlled via its web interface.
There are 2 levels of access: User and Manager. Manager access is required for
Configuration and Control while User only allows Zone volume control.
Login
Record the IP address of the amplifier as shown on the front panel display.
Option1: Enter the following address into your Web browser (most browsers):
http://unite.local
Option2: If the browser does not connect using option1 method then enter the IP
address into your Web browser in the following format:
http://aaa.bbb.ccc.ddd
Where aaa.bbb.ccc.ddd is the address noted from the front panel display.
Option1 or Option2 will take you to the login page of the amplifier.
Mono Mic or
Line Inputs 1
and 2
Stereo Line
Inputs 3 to 5
Digital
Input 6
Speaker
Outputs
1 to 4
Mute and
PTT inputs
1 and 2
USB
Input
LAN

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In this case the amplifier’s IP address is 192.168.0.3. (Individual address ranges will
vary.)
For basic User access enter the word “user” for the user and “uunite2020” for the
password.
For full access enter Manager credentials. Please request this information from your
sales contact.
Amplifier Configuration
The U74 amplifier needs to be configured via web browser prior to use in a new
installation. Manager credentials are required for this process. The parameters that
need to be set include the following:
Sources:
•Input gain setting (Sources 1 and 2)
•Volume settings - Volume Limit, Volume and Balance
•Equalisation settings –High, HighMid, Mid, LowMid, and Low
•Unite Bass
The amplifier also can also have its Zone type configured and Zones and Sources can be
renamed for convenience to suit the physical layout and signal sources.
Configuration
Upon successful login the amplifier will display its Zone configuration web page as
shown in the image example below.

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There is a separate page for each Zone. The individual Zones are selected via the
UP/DOWN arrows in the ZONE selection box:
The name of each Zone will be displayed. Note that the Zone names can be changed to
suit a particular installation. The defaults are Zone1, Zone2 … Zone4 (Zone6 for 6-Zone
variants).
The ON icon next to the Zone name MUST be ON (Blue) for the Zone to be enabled and
active. If the Zone is not enabled the ON icon will be greyed-out as shown below:
To select a particular Source for a given Zone, select it directly from the SOURCE
selection boxes. Note that the Source names can be changed to suit a particular
installation. The defaults are Source1, Source2 … Source7.

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In the example shown above, Source 1 has been selected.
For the selected Source, the Amplitude settings need to be configured. This includes the
Volume that is also able to be set via the front panel controls.
In a similar manner, the Equalisation for the Zone may be configured:

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Settings
The Settings page shows the current Source/Zone crosspoint configuration of the
amplifier. This setting is only required if the amplifier zones and speaker setup is
changed during installation.
The Connected Device will show the MAC of the target device. This can be verified from
the front display panel with the last 4 digits of the ID field.
Click the Read button to show the amplifier’s current Zone Configuration:

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Make any required Zone configuration changes and then click the Apply button to
implement these changes and store these settings. The Apply button will only become
active for valid configurations.
Output Configurations
The U74 amplifier can be configured in a variety of mono or stereo Single-Ended or
mono or stereo Bridge-Tied-Load formats. It is also possible to mix zone modes.
Mono
In basic mono configuration, each speaker output is an independent mono signal and
each connects to a separate speaker.
The zone configuration for this mode is:
Volume and Tone controls are independent for all 8 zones.
The speaker wiring for this mode is as follows:
4Ω
1, 3,
5, 7
2, 4,
6, 8
4Ω

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Stereo
In this configuration Left and Right source signals are treated as a stereo pair and
separate Left and Right speakers are used.
The zone configuration for this is:
The speaker wiring for this mode is:
4Ω
Left
1, 3
Right
2, 4
4Ω

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Mono BTL
In this configuration Left and Right source signals are downmixed to mono and a single
8Ω speaker is used.
The zone configuration for this is:
The negative (-) speaker terminals must be left unconnected.
The speaker wiring for this mode is as follows:
8Ω
Left
+
Right

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Stereo BTL
In this configuration Left and Right source signals are routed as mono BTL signals and
single 8Ω speaker are used for each pair.
The zone configuration for this is:
The negative (-) speaker terminals must be left unconnected.
The speaker wiring for this mode is as follows:
8Ω
Left
8Ω
Right

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Amplifier Use
Once configuration is complete, the amplifier may be controlled via web interface in
either Manager or User modes and by the front panel controls.
Web Interface
With User-level access, only the volume, zone enable, and source controls are available:
The User cannot change other settings. These settings need to be configured by a
Manager.
Front Panel Status and Control
The U74 has a 2.5 inch full-colour status display and four rotary/push controls for user
control over basic operation.
This includes setting:
•Volume of Zone
•Source for Zone
•Set Power
•Controls Off
Each press of a control knob will change which of the above is being controlled. The
active mode cycles around with each control knob push as shown overleaf:

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Zone
Volume
Controls
Off
Each
Push
Zone
Source
Zone
Power
Set Volume
Set volume is the default screen and control following power-up. Each front panel
control has direct control over its respective zone.
Rotate the controls clockwise to increase the Zone’s volume, counterclockwise to
decrease.
Zone Source
Push any control once to advance from the Set Volume mode to Set Source mode.
Rotate the controls to select the active Source for each Zone.

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Set Power
Use this function to disable Zones, muting them and powering them down.
Each Zone can be individually powered-down. Rotate the Zone’s control clockwise to
activate, counterclockwise to power-down.
Control Off
This function disables all controls to prevent accidental adjustment.
Press any control again to re-activate.

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Rear Panel Layout
The diagram below shows the rear panel layout of the U74 amplifier.
Mono Mic or
Line Inputs 1
and 2
Stereo Line
Inputs 3 to 5
Digital
Input 6
Speaker
Outputs
1 to 4
Mute and
PTT inputs
1 and 2
USB
Input
LAN
Power
Switch
Fuse
IEC Mains
Input Socket
ID Switch

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Specifications
Unless otherwise specified, Ta=25C, Supplied by U74 @ 230Vac mains voltage.
Mains Supply Voltage
100 to 240Vac
Mains Absolute
Minimum/Maximum Supply
Voltage
85 to 264Vac
Mains Frequency
45 to 65Hz
Maximum Mains Power Input
400W
Mains Socket
IEC-style
Mains Supply Transients
6kV common mode
Maximum Power Consumption
320W
Standby Power
115Vac: 4.2W
230Vac: 7.8W
Fuse Rating
T3AL Time-Lag
115Vac: 5A
230Vac: 3A
Ambient Temperature
0 to 50C
Maximum Humidity
85% Non-Condensing
Maximum Altitude
2,000m
Cooling
Fan forced, thermostatic control
USB
5Vdc, 0.5A
Output power @ 0.1%THD+N
20Hz < f < 20kHz (single Zone)
RL = 8Ω BTL: 160W
RL = 4ΩSE: 80W
Zones
4 x Stereo or BTL Mono
Sources
•2 x Mic/Line –XLR or ¼” plug
•3 x Stereo –RCA
•1 x S/PDIF –RCA
•1 x USB
Dimensions
Stand Alone: 96.5 x 438 x 327.5 (H x W x D)
Rack Mount: 87.6 x 481.8 (2RU) x 304 (H x W x D)
Weight
TBA
Rack Mount
Optional RM kit, SA as standard.
Display
63.5mm (2.5”) diagonal full-colour display
•240 x 320 Dot Matrix

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•36.72 x 48.96 (W x H) Active Display Area
Status Indication
3 x Status LEDs:
•Power/boot status
•Network connection status
•Alert status.
Control
4 x rotary/push encoders
Mic input Phantom Power
12, 24 or 48Vdc