Monoprice 31028 User manual

6 Zone Home Audio Multizone 12-channel Amplifier
P/N 31028
User's Manual

2
CONTENTS
SAFETY WARNINGS AND GUIDELINES.......................................................................................................................................4
INTRODUCTION................................................................................................................................................................................................5
FEATURES..............................................................................................................................................................................................................6
CUSTOMER SERVICE....................................................................................................................................................................................6
PACKAGE CONTENTS................................................................................................................................................................................. 7
PRODUCT OVERVIEW................................................................................................................................................................................. 7
Front Panel..................................................................................................................................................................................................... 7
Rear Panel.......................................................................................................................................................................................................8
IR Remote Control..................................................................................................................................................................................11
SAMPLE CONNECTION DIAGRAM ................................................................................................................................................12
CONSTANT VOLTAGE VS LOW IMPEDANCE SPEAKER SYSTEMS .................................................................... 13
WIRE GAUGES.................................................................................................................................................................................................14
LINE CONNECTIONS...................................................................................................................................................................................15
Line In...............................................................................................................................................................................................................15
Bus Audio......................................................................................................................................................................................................15
SPEAKER CONNECTIONS.......................................................................................................................................................................16
4Ω/8Ω Stereo...........................................................................................................................................................................................16
Bridged 8Ω Mono.................................................................................................................................................................................. 17
Constant Voltage 70V/100V Stereo......................................................................................................................................18
TRIGGER CONNECTIONS........................................................................................................................................................................19
Line/Bus Trigger In................................................................................................................................................................................19
Master Control In...................................................................................................................................................................................19
Master Control Out.............................................................................................................................................................................20
Mute In...........................................................................................................................................................................................................20

3
Status Out ...................................................................................................................................................................................................20
RS-232 CONNECTION................................................................................................................................................................................21
RS-232 COMMANDS..................................................................................................................................................................................21
RS-232 Commands...............................................................................................................................................................................22
RS-232 Queries ........................................................................................................................................................................................24
Zone Status................................................................................................................................................................................................24
Volume Level............................................................................................................................................................................................25
Bass/Treble Level..................................................................................................................................................................................26
Balance Setting....................................................................................................................................................................................... 27
TECHNICAL SUPPORT.............................................................................................................................................................................. 27
SPECIFICATIONS...........................................................................................................................................................................................28
REGULATORY COMPLIANCE.............................................................................................................................................................29
Notice for FCC .........................................................................................................................................................................................29
Notice for Industry Canada..........................................................................................................................................................29

4
SAFETY WARNINGS AND GUIDELINES
Please read this entire manual before using this device, paying extra attention to these
safety warnings and guidelines. Please keep this manual in a safe place for future reference.
This device is intended for indoor use only.
Do not expose this device to water or moisture of any kind. Do not place drinks or
other containers with moisture on or near the device. If moisture does get in or on
the device, immediately unplug it from the power outlet and allow it to fully dry
before reapplying power.
Do not touch the device, the power cord, or any other connected cables with wet
hands.
This device uses a grounded power cord and requires a ground connection for safe
operation. Ensure that the power source has a proper ground connection. Do not
modify the plug or use a "cheater" plug to bypass the ground connection.
Do not expose this device to excessively high temperatures. Do not place it in, on,
or near heat sources, such as a fireplace, stove, radiator, etc. Do not leave it in direct
sunlight.
This device ventilates excessive heat through the slots and openings in the case. Do
not block or cover these openings. Ensure that the device is in an open area where
it can get sufficient airflow to keep from overheating.
Prior to operation, check the unit and power cord for physical damage. Do not use if
physical damage has occurred.
Take care to prevent damage to the power cord. Do not allow it to become
crimped, pinched, walked on, or become tangled with other cords. Ensure that the
power cord does not present a tripping hazard.
Never unplug the unit by pulling on the power cord. Always grasp the connector
head or adapter body.
Ensure that power is turned off and disconnected before making any electrical
connections.

5
Disconnect the unit from the power source when replacing the fuse. Replace the
fuse only with the same type.
Clean using a soft, dry cloth only. Do not use chemical cleaners, solvents, or
detergents. For stubborn deposits, moisten the cloth with warm water.
This device has no user serviceable parts. Do not attempt to open, service, or
modify this device.
INTRODUCTION
Thank you for purchasing this 6-Zone Home Audio Multizone 12-channel Amplifier! This
amplifier is a 12-channel audio distribution amp that can be configured for six stereo 4-8
ohm zones, six stereo 70/100V constant voltage zones, or three high powered 8-ohm
bridged zones. It supports any combination of stereo, bridged, and constant voltage zones.
Each zone can be controlled using the included IR remote control or RS-232 computer
control. The RS-232 section is bi-directional, with an easy to configure command structure.
It can be configured to automatically send zone status updates or respond to queries to
confirm zone status and settings.
It has an Audio Bus IN, which can be manually selected using the remote control, RS-232
commands, or a voltage trigger. The voltage trigger will switch the zone to use the Audio
Bus IN as long as there is voltage present on the zone Line / Bus Trigger IN. When the
voltage is removed, the zone automatically switches back to the zone Line IN, making it
ideal for global paging across an entire facility.
Additionally, each zone has a Mute Trigger IN, which mutes zone audio when voltage is
present. Each zone also has a +12 VDC Status or Control OUT, which can be used to activate
a zone specific voltage controlled device or otherwise indicate zone ON/OFF status. Audio
is rounded out with a built-in -20dB audio limiter for each zone, designed to prevent
incidental peaks from becoming irrevocable problems.
Finally, each zone features a Remote Bypass switch, which allows or blocks IR and RS-232
control for those zones that you want to set and not mess with again. You can select 110-
120 VAC or 220-240 VAC input voltage, allowing the amp to be used anywhere there is AC
voltage. It is rack mountable, with removable rack ears for shelf mounting.

6
FEATURES
Each zone can independently select a zone-specific stereo audio source or the
global unbalanced stereo Audio Bus IN
Each zone can be independently configured for stereo 4Ω/8Ω mode, high powered
bridged 8Ω mode, or 70V/100V constant voltage mode for total flexibility
All zones are independently controllable using the included IR remote control, RS-
232 control, and voltage trigger lines
Each zone has a built-in -20dB Audio Limiter
Each zone has an independent mute trigger input
Each zone has an individual Status Output that corresponds to the zone's ON/OFF
status
Front panel Zone ON and Zone Overload LED indicators for each zone
Master global Control In and Control Out
Detachable screw-terminal connectors for Zone IR IN, Zone Mute, Zone Status OUT,
and Zone Speaker Outputs
Global optical S/PDIF and analog stereo 3.5mm audio inputs for the global Audio
Bus IN/OUT
Rack mountable in a standard 19" equipment rack (2U height)
Selectable 110-120 VAC, 60Hz or 220-240 VAC, 50Hz power input
CUSTOMER SERVICE
The Monoprice Customer Service department is dedicated to ensuring that your ordering,
purchasing, and delivery experience is second to none. If you have any problem with your
order, please give us an opportunity to make it right. You can contact a Monoprice
Customer Service representative through the Live Chat link on our website
www.monoprice.com during normal business hours (Mon-Fri: 5am-7pm PT, Sat-Sun: 9am-
6pm PT) or via email at [email protected]

7
PACKAGE CONTENTS
Please take an inventory of the package contents to ensure you have all the items listed
below. If anything is missing or damaged, please contact Monoprice Customer Service for a
replacement.
1x Amplifier
1x IR remote control
1x IR transmitter
1x AC power cord
1x User's manual
PRODUCT OVERVIEW
Front Panel
1. ZONE POWER LEDs: Six LEDs illuminate solid green when a stereo zone is ON and is
off when the zone is OFF.
2. PEAK OUTPUT LEDs: Six LEDs illuminate red when the amplifier is within 5% of the
maximum volume setting. To be safe, back off the volume a bit when this LED
illuminates to prevent damage to the amplifier or speakers.
3. RACK EARS: Two rack ears for mounting the amplifier in a standard 19" equipment
rack (2U height). If rack mounting, leave one empty rack space above and below to
allow for ventilation. The rack ears can be removed for shelf mounting, as desired.

8
Rear Panel
1. 70V/100V HIGH VOLTAGE SPEAKER OUTPUT: Slide switch for selecting 70V or 100V
for all zones configured for constant voltage output. The U.S. National Electrical
Code prohibits the use of 100V constant voltage systems for installations in the
United States.
2. OPTICAL IN: S/PDIF digital optical audio input for BUS AUDIO. When OPTICAL IN is
used, 3.5mm BUS AUDIO IN (3) cannot be used and vice versa. The optical audio
signal is converted to analog and is distributed to the BUS AUDIO OUT (4) and to
each zone.
3. BUS AUDIO IN: 3.5mm TRS unbalanced stereo input jack for BUS AUDIO. When BUS
AUDIO IN is used, OPTICAL IN (2) cannot be used and vice versa. The analog signal is
distributed to the BUS AUDIO OUT (4) and to each zone.
4. BUS AUDIO OUT: 3.5mm TRS unbalanced stereo output jack for delivering BUS
AUDIO to another 6-zone amplifier, powered speakers, or other line level input
device.
5. SPEAKER OUTPUT: Removable screw-terminal plug for connecting the speaker
output(s). Each plug has six connections for different speaker output configurations,
as detailed below. Note that failure to adhere to the warnings in the notes below
can result in permanent damage to the amplifier and/or the speakers.
Bridge 8Ω: Use the indicated terminals (2 and 5) to connect a single 8-ohm
speaker for bridged mono operation (100W@8Ω). WARNING! When using the

9
Bridge 8Ω terminals, the 8Ω/4Ω-70V/100V switch (6) MUST be in the OUT
position and the Stereo-Bridged switch (11) MUST be in the IN (Bridged) position.
4/8Ω: Use the indicated terminals (2 and 3, 4 and 5) to connect a pair of 4-ohm
or 8-ohm speakers (30W@8Ω or 50W@4Ω). WARNING! When using the 4/8Ω
terminals, the 8Ω/4Ω-70V/100V switch (6) MUST be in the OUT position and the
Stereo-Bridged switch (11) MUST also be in the OUT (Stereo) position.
70/100V: Use the indicated terminals (1 and 3, 4 and 6) to connect a pair of
constant voltage speakers (30W@70V/100V). WARNING! When using the
70/100V terminals, the 8Ω/4Ω-70V/100V switch (6) MUST be in the IN position,
the Stereo-Bridged switch (11) MUST also be in the OUT (Stereo) position, and
the 70V/100V HIGH VOLTAGE SPEAKER OUTPUT switch (1) must be set to the
proper voltage.
6. 8Ω/4Ω-70V/100V: Push button switch to select passive (8Ω/4Ω) or constant
voltage (70V/100V) operation. 8Ω/4Ω operation is selected when the switch is in
the OUT position and 70V/100V operation is selected when the switch is in the IN
position.
7. IR IN/MUTE/STATUS: Connect the included IR transmitter to the IR IN and GND
terminals to allow for zone IR control using the included IR remote control. Connect
a +3 ~ +30 VDC@1mA control voltage to the MUTE and GND terminals to mute the
local zone. Connect a trigger enabled device to the STATUS and GND terminals to
provide a +12 VDC@1mA Status OUT signal to trigger the zone specific device.
8. LINE/BUS TRIGGER IN: 3.5mm jack for connecting a +3 ~ +30 VDC@1mA control
voltage to determine the zone's audio source. When there is no voltage present, the
zone uses its LINE IN RCA jacks (10) for the audio source. When a +3 ~ +30
VDC@1mA signal is present, the zone uses BUS AUDIO (2 or 3) for the audio source.
9. LIMITER: Push button switch to determine whether the built-in -20dB Audio Limiter
is used on not. The Audio Limiter is ON when the switch in the IN position and is
OFF when the switch is in the OUT position.
10. LINE IN: Two RCA jacks for connecting a line level stereo audio source.
11. STEREO/BRIDGED: Push button switch to determine whether the zone is set for
Bridged or Stereo operation. The zone is set for Stereo operation when the switch is

10
in the OUT position and is set for Bridged operation when the switch is in the IN
position.
12. VOLTAGE SELECT: Slide switch for setting the input AC voltage level to nominal
120V or 240V operation. The switch is set to the 120V position at the factory and the
appropriate fuse is installed. If you change to 240V operation, the fuse must also be
changed to the appropriate type.
13. MASTER CONTROL IN: 3.5mm jack for connecting a +3 ~ +30 VDC@1mA control
voltage to turn the amplifier ON. When voltage is applied, the amplifier powers ON
and when no voltage is present, the amplifier powers OFF. Note that the POWER
ON/OFF switch (16) must be set to the OFF position when using this feature.
14. POWER IN: Three-conductor IEC 60320 C14 panel connector for connecting the
included AC power cord or an alternate power cord (not included) if operating the
amplifier in a country that doesn't use NEMA power plugs.
15. MASTER CONTROL OUT: 3.5mm jack for connecting a trigger voltage controlled
device that is intended to be automatically turned on or off depending on the
amplifier's status. Whenever any zone is ON, the MASTER CONTROL OUT jack will
output +11.5 VDC@1mA ~ +10 VDC@5mA. When all zones are OFF, the output is 0
VDC.
16. POWER ON/OFF: Rocker switch to turn the amplifier on or off. Note that when the
switch is set to the OFF position, the MASTER CONTROL IN (14) trigger can be used
to turn the amplifier on or off.
17. FUSE: Fuse holder for the system fuse. If the VOLTAGE SELECT (12) is changed, the
fuse must also be changed. The proper fuse for nominal 120 VAC operating is T10AL,
250V, while the proper fuse for nominal 240 VAC operation is T5AL, 250V.
18. REMOTE BYPASS: A six position DIP switch that determines whether the zone can
respond to IR remote control and RS-232 control inputs or not. When set to the OFF
position, the zone can respond to IR and RS-232 control signals. When set to the ON
position, the zone will not respond to IR and RS-232 control signals.
19. RS232: Female DB9 jack for connecting an automation system or other controller for
bi-directional communications with and control of the amplifier.

11
IR Remote Control
1. Mute: Press the Mute button to turn zone audio
muting on or off.
2. Source: Press the Source buttons to select Bus or Line
for the zone audio source.
3. Treble: Press the Treble buttons to increase or
decrease the zone treble response.
4. Balance L: Press the Balance L button to increase the
zone volume level of the left channel relative to that
of the right channel. Note that an RS-232 command is
required to reset the zone balance to center.
5. Volume: Press the Volume buttons to increase or
decrease the overall zone volume level.
6. Balance R: Press the Balance R button to increase the
zone volume level of the right channel relative to that
of the left channel. Note that an RS-232 command is
required to reset the zone balance to center.
7. Bass: Press the Bass buttons to increase or decrease the zone bass response.
8. Power: Press the Power button to turn the zone on or off.
9. IR LED: The high-power IR LED on the front of the remote control transmits infrared
control signals whenever a button is pressed.

12
SAMPLE CONNECTION DIAGRAM

13
CONSTANT VOLTAGE VS LOW IMPEDANCE SPEAKER
SYSTEMS
A constant voltage speaker system differs from a traditional low impedance (e.g., 8-ohm)
speaker system in that it uses a step-up transformer at the audio source to raise the
voltage and lower the current on the transmission line. At the speaker end, a step-down
transformer converts the signal back to a normal speaker level voltage. This reduces power
loss during transmission, which allows for the use of longer speaker wire runs using smaller
gauge wire.
Additionally, a constant voltage speaker system allows for the use of multiple speakers on
each channel, without the need for complicated impedance calculations and
configurations. In a constant voltage system, all speakers on a given channel are connected
in parallel and the complicated impedance calculations are replaced by simple wattage
calculations.
For example, if you want to connect two speakers per channel in a traditional 8-ohm
speaker system, you must either connect them in series, which results in an overall 16-ohm
impedance, or in parallel, which results in an overall 4-ohm impedance. In the first case, the
16-ohms impedance effectively halves the output power of your amplifier, resulting in
lower overall volume levels. In the latter case, the 4-ohms impedance means that your
amplifier will have to work harder and must be rated as stable at 4 ohms. Adding a third
speaker to the mix would complicate it further, producing either a 24-ohm or 2.67-ohm
overall impedance. Note that very few amplifiers are stable under 2-ohm loads, so that is
usually not an option.
On the other hand, with a constant voltage system, you consider first the RMS output
wattage of the amplifier. This should be reduced by 20% to compensate for insertion loss.
Each individual speaker on a given channel is set to a value such that the total does not
exceed the rated power, less 20%. You do not need to worry about making the total as
close as possible to the limit; just ensure that the total does not exceed the limit. For
example, with this 30-watt amplifier, the total load from speakers should not exceed 24
watts.
If all speakers are set to the same wattage value, they will all have the same volume level.
If one speaker is set to a higher wattage value, it will be louder than the others, while a

14
speaker set to a smaller value will be quieter than the others. This allows you to
compensate for the environment in which the speaker is placed. For example, a speaker
placed outside would need to be louder than a speaker placed in a small room.
WIRE GAUGES
The following tables show the maximum speaker wire lengths using different gauge wires
for both 4Ω/8Ω and 70V/100V installations.
4Ω/8Ω Installations
Maximum Wire Length
Wire Gauge
150 ft. (46m)
16 AWG
400 ft. (122m)
14 AWG
1000 ft. (305m)
12 AWG
70V/100V Installations
Maximum Wire Length
Wire Gauge
350 ft. (106m)
24 AWG
550 ft. (167m)
22 AWG
900 ft. (274m)
20 AWG
1400 ft. (426m)
18 AWG
2300 ft. (701m)
16 AWG

15
LINE CONNECTIONS
Line In
Each zone has its own dedicated stereo LINE IN using two RCA jacks. Use a stereo RCA
audio cable (not included) to connect the LINE OUT of an audio source device (e.g., CD
player, FM tuner, etc.) to the individual zone LINE IN, as shown in the diagram below.
Bus Audio
The amplifier also features a stereo analog BUS
AUDIO IN (3), a digital S/PDIF OPTICAL IN (2),
and an analog BUS AUDIO OUT (4). The audio
on BUS AUDIO IN overrides the zone's LINE IN
(10) audio whenever a +3 ~ +30 VDC trigger
voltage is applied to LINE BUS TRIGGER IN (8).
BUS AUDIO IN (3) is a 3.5mm stereo analog
input. Use a stereo 3.5mm to RCA or 3.5mm to
3.5mm audio cable (not included) to connect
to a stereo line level or headphone level
source. Alternatively, use a digital optical
S/PDIF cable (not included) to connect the BUS
AUDIO OPTICAL IN (2) to the optical S/PDIF
output of an audio source device.
BUS AUDIO OUT (4) is a 3.5mm analog stereo
audio output that can be used to connect to
the input of another amplifier or audio processor. BUS AUDIO OUT (4) is a copy of BUS

16
AUDIO IN (3) or a digital-to-analog converted version of the OPTICAL IN (2) signal. Use a
3.5mm to RCA or 3.5mm to 3.5mm stereo audio cable (not included) to connect BUS AUDIO
OUT (4) to the line input of another audio device.
SPEAKER CONNECTIONS
Each of the six zones on this amplifier support three different kinds of speaker
connections: passive stereo 4Ω/8Ω speakers, passive bridged monophonic 8Ω speaker,
and stereo 70V/100V constant voltage speakers.
4Ω/8Ω Stereo
The basic speaker connection for each zone uses a pair of 4-ohm passive speakers
designed to handle up to 50 watts each or a pair of 8-ohm passive speakers designed to
handle up to 30 watts each.
Connect the speakers to
the 4/8Ω terminals (2 and
3, 4 and 5), then ensure
that the 8Ω/4Ω-70V/100V
switch (6) is in the 8Ω/4Ω
(OUT) position and that
the Stereo/Bridged
switch (11) is in the Stereo
(OUT) position.

17
Bridged 8Ω Mono
Another option is to configure the zone to bridge the stereo outputs to a single
monophonic audio output with approximately double the power of the stereo outputs. In
this configuration, each zone only connects to a single 8-ohm speaker designed to handle
up to 100 watts of power.
Connect the speaker to the Bridge 8Ω terminals (2 and 5), then ensure that the 8Ω/4Ω-
70V/100V switch (6) is in the 8Ω/4Ω (OUT) position and that the Stereo/Bridged switch (11)
is in the Bridged (IN) position.
Note that the only way to get a stereo output using Bridged 8Ω mode by using two zones
and splitting the left channel input to one zone and the right channel input to the other, as
shown in the image below.

18
Constant Voltage 70V/100V Stereo
The third speaker option is to use a pair of constant voltage speaker arrays. Each array can
consist of almost any number of speakers. When an array uses multiple speakers, they must
all be wired in parallel and the wattage settings of each must not exceed 24 watts (30
watts x 80%).
Connect the two speaker arrays to the 70/100V terminals (1 and 3, 4 and 6), then ensure
that the 8Ω/4Ω-70V/100V switch (6) is in the 70V/100V (IN) position and the
Stereo/Bridged switch (11) in the Stereo (OUT) position. For installations in the United
States, the 70V/100V switch (1) must be set to the 70V (left) position, while installations in
other countries can be set to either the 70V (left) or the 100V (right) position, as desired.

19
TRIGGER CONNECTIONS
This amplifier features several trigger inputs and outputs. The trigger inputs activate when
a +3 ~ +30 VDC@1mA voltage is applied, while the trigger outputs deliver ether +11.5
VDC@1mA ~ +10 VDC@5mA or +12 VDC. Each trigger output is used for activating another
trigger-enabled devices, such as a motorized projection screen.
Line/Bus Trigger In
Each zone has a Line/Bus Trigger In, which is a 3.5mm TS plug.
Normally, the zone outputs the audio signal on the zone's LINE IN
(10) RCA audio inputs, but outputs BUS AUDIO when a +3 ~ +30
VDC@1mA voltage is applied.
Master Control In
The amplifier has a single Master Control In (13), which is used to
turn the amplifier on or off. To use the Master Control In (13)
trigger input, place the POWER switch (16) in the OFF position,
then whenever a +3 ~ +30 VDC@1mA voltage is applied, the
amplifier will power on. When the voltage is removed, the
amplifier will power off.

20
Master Control Out
The amplifier features a single Master Control Out (15), which
outputs a +11.5 VDC@1mA ~ +10 VDC@5mA voltage for triggering
another trigger-enabled device. The voltage is applied whenever
the amplifier is powered on and delivers 0 VDC when the amplifier
is powered off.
Mute In
Each zone features a MUTE IN (7), which accepts a +3 ~ +30
VDC@1mA trigger voltage to mute the audio in that zone. When
voltage is present, the zone is muted. When voltage is not present,
audio will play as normal. Connect a two conductor wire from an
audio mute trigger source to the GND and MUTE terminals.
Status Out
Each zone has a STATUS OUT (7) connection, which provides +12
VDC whenever the zone is active to trigger external trigger
controlled devices, such as a motorized projection screen. Connect
a two conductor wire from the GND and STATUS terminals to an
external trigger controlled device.