Monoprice 31027 User manual

Unity 450-watt Bridgeable Power Amp
P/N 31027
User's Manual

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CONTENTS
SAFETY WARNINGS AND GUIDELINES.......................................................................................................................................3
INTRODUCTION................................................................................................................................................................................................4
FEATURES..............................................................................................................................................................................................................4
CUSTOMER SERVICE....................................................................................................................................................................................5
PACKAGE CONTENTS.................................................................................................................................................................................5
PRODUCT OVERVIEW.................................................................................................................................................................................6
Front Panel.....................................................................................................................................................................................................6
Rear Panel.......................................................................................................................................................................................................6
THERMAL PROTECTION ............................................................................................................................................................................ 7
SHORT CIRCUIT PROTECTION.............................................................................................................................................................. 7
MOUNTING OPTIONS ................................................................................................................................................................................. 7
Stand-Alone Setup................................................................................................................................................................................. 7
Single Rack-Mount Setup.................................................................................................................................................................8
Dual Rack-Mount Setup.....................................................................................................................................................................8
STEREO INSTALLATION.............................................................................................................................................................................9
MONO BRIDGED INSTALLATION.....................................................................................................................................................11
TECHNICAL SUPPORT...............................................................................................................................................................................12
SPECIFICATIONS............................................................................................................................................................................................ 13
REGULATORY COMPLIANCE..............................................................................................................................................................14
Notice for FCC ..........................................................................................................................................................................................14
Notice for Industry Canada...........................................................................................................................................................14

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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.

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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 Unity 450-Watt Bridgeable Power Amp! This 2-channel class
D power amplifier features a stereo speaker output, with support for 4-ohm and 8-ohm
speakers. It can deliver 150 watts per channel into 8-ohm loads or 225 watts per channel
into 4-ohm loads. Additionally, the output can be bridged to provide 450 watts to a single
8-ohm speaker.
FEATURES
Class-D amplifier providing 150 watts/channel (RMS) into 8 ohm loads or 225
watts/channel into 4-ohm loads
Bridgeable output provides 450 watts into a single 8-ohm load
4-pole detachable speaker screw connector (Phoenix connector) with support for
up to 12 AWG speaker wire
Built-in thermal and short circuit protection circuits
Includes rack-mount ears

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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]
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 450-watt stereo power amplifier
1x AC power cord (NEMA 5-15 to IEC 60320 C13)
2x Short rack-mount ears
1x Long rack-mount ear
1x Bridge plate
6x Button head screws
4x Countersunk screws
4x Rubber feet
1x User's manual

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PRODUCT OVERVIEW
Front Panel
1. POWER: Press the switch to turn the amplifier on or off.
2. STATUS: The LED illuminates green during normal operation or red when in standby
mode. Note that after 5 minutes with no audio input, the amplifier will
automatically go into standby mode.
3. VOLUME: Turn the knob to increase or decrease the volume level.
Rear Panel
1. INPUT: 3.5mm TRS and stereo RCA inputs. Note that if both inputs are used, the two
inputs will be mixed.
2. MODE: Use the switch to set the amplifier for stereo or bridged mono operation.
3. SPEAKER: Phoenix connector for connecting one or two speakers.
4. AC VOLTAGE SELECTOR: Use the switch to select 115 or 230 VAC power input.
5. AC IN: Grounded AC power input connector.

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THERMAL PROTECTION
The amplifier monitors its temperature and will activate the thermal protection circuit if
the temperature exceeds a safe limit. This can occur if the amp has been operated at high
volumes for an extended period of time, if it has inadequate ventilation, or if the speaker
load is below the minimum impedance of 4 ohms. The amp will shut down when the
Thermal Protection circuit engages. You must turn off the amp's power switch and wait
until the amp cools down, then power the amp back on.
SHORT CIRCUIT PROTECTION
If the amplifier detects a short circuit on one or both speaker outputs, the output will be
disabled. If this occurs, turn off the amplifier and check the speakers and speaker wires for
a short circuit.
MOUNTING OPTIONS
This amplifier can be placed stand-alone on a flat surface, such as a table or shelf, or can be
installed into a standard 19" equipment rack, either by itself or side-by-side with a second
Unity power amp.
Stand-Alone Setup
To use the amplifier in a stand-alone installation, locate the included sheet with four
rubber feet. Peel each rubber foot from the sheet and attach them to the bottom of the
amp at each of the four corners. This will both protect your mounting surface from
scratches and will prevent any incidental noise from vibration.

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Single Rack-Mount Setup
Perform the following steps to install a single amplifier into a 19" equipment rack.
1. Using three of the button head screws, attach one short rack-mount ear to one side
of the amplifier, with the flat side flush with the front panel.
2. Using the remaining three button head screws, attach the long rack-mount ear to
the other side of the amplifier, with the long flat side flush with the front panel. It
does not matter which side of the amp has the short rack-mount ear and which side
has the long one.
3. Using rack-mount screws (not included), secure the two rack-mount ears to the rack
mount.
Dual Rack-Mount Setup
Perform the following steps to install two amplifiers side-by-side into a 19" equipment rack.
1. Turn the amplifiers over and place them side by side.
2. Place the bridge plate over the junction of the two amps with the beveled holes
visible, then attach it to the two amps using the four countersunk screws.
3. Turn the amps over so they are right-side up, then attach one short rack-mount ear
to the exposed side of each amp using three button head screws.

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4. Using rack-mount screws (not included), secure the two rack-mount ears to the rack
mount.
STEREO INSTALLATION
1. Ensure that all equipment to be connected is powered off and unplugged from its
power source prior to making any electrical or audio connections.
2. Place or mount the amplifier in its intended location.
3. Using a 1/8" flat head screwdriver, loosen the four screws on the SPEAKER Phoenix
connector to open the speaker wire clamps.
4. Using a two-conductor speaker wire (not included), insert the negative lead into the
L- connector, then tighten the screw to lock it in place. Give the wire a gentle tug to
ensure it is securely attached to the connector. Repeat for the positive lead and the
L+ connector.
5. Connect the negative lead of the speaker wire to the negative input on your left
channel speaker, then connect to the positive lead to the positive input.
6. Using a second two-conductor speaker wire, repeat steps 4 and 5 for the R- and R+
connectors, and the right channel speaker.
7. Using a stereo RCA cable (not included), plug the left and right plugs into the Land
Rconnectors on the INPUT, then plug the other end into the analog stereo outputs

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on your preamplifier, television, or other audio source device. Alternatively, using a
3.5mm TRS audio cable, plug one end into the 3.5mm INPUT, then plug the other
end into the stereo output of your audio source device (e.g., smartphone). Note that
if both inputs are used, the two inputs will be mixed.
8. Turn the VOLUME knob fully counterclockwise to the minimum position.
9. Ensure that the POWER switch is in the OFF position.
10. Ensure that the MODE switch is in the STEREO position.
11. Ensure that the AC INPUT SELECTOR switch is set to the position that most closely
matches the AC power level in your area.
12. Plug the C13 connector on the included AC power cord into the C14 AC IN
connector, then plug the other end into a nearby AC power outlet. The STATUS LED
will illuminate red to indicate that the amplifier is in standby mode.
13. Depress the POWER switch to turn the amplifier ON. The STATUS LED will change
from red to green.
14. Plug in and power on your audio source device, then start audio playback.
15. Slowly turn the VOLUME control clockwise until the volume is at a comfortable
level. Enjoy!

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MONO BRIDGED INSTALLATION
Rather than driving two 8-ohm or 4-ohm speakers in stereo mode, the amplifier can be
configured to bridge the two channels to provide 450 watts of power into a single 8-ohm
load. Note that only 8-ohm loads can be used when using Mono Bridged mode.
1. Ensure that all equipment to be connected is powered off and unplugged from its
power source prior to making any electrical or audio connections.
2. Place or mount the amplifier in its intended location.
3. Using a 1/8" flat head screwdriver, loosen the R- and L+ screws on the SPEAKER
Phoenix connector to open the speaker wire clamps.
4. Using a two-conductor speaker wire (not included), insert the negative lead into the
R- connector, then tighten the screw to lock it in place. Give the wire a gentle tug
to ensure it is securely attached to the connector. Repeat for the positive lead and
the L+ connector.
5. Connect the negative lead of the speaker wire to the negative input on your
speaker, then connect to the positive lead to the positive input.
6. Using a single conductor RCA cable (not included), plug one end into the L
connector on the INPUT connector, then plug the other end into one of the analog
stereo outputs on your preamplifier, television, or other audio source device.
Alternatively, using a 3.5mm TRS audio cable, plug one end into the 3.5mm INPUT
connector. Note that if both inputs are used, the two inputs will be mixed.
7. Turn the VOLUME knob fully counterclockwise to the minimum position.
8. Ensure that the POWER switch is in the OFF position.
9. Ensure that the MODE switch is in the BRIDGE MONO position.
10. Ensure that the AC INPUT SELECTOR switch is set to the position that most closely
matches the AC power level in your area.
11. Plug the C13 connector on the included AC power cord into the C14 AC IN
connector, then plug the other end into a nearby AC power outlet. The STATUS LED
will illuminate red to indicate that the amplifier is in standby mode.

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12. Press the POWER switch to turn the amplifier ON. The STATUS LED will change from
red to green.
13. Plug in and power on your audio source device, then start audio playback.
14. Slowly turn the VOLUME knob clockwise until the volume level is at a comfortable
level.
TECHNICAL SUPPORT
Monoprice is pleased to provide free, live, online technical support to assist you with any
questions you may have about installation, setup, troubleshooting, or product
recommendations. If you ever need assistance with your new product, please come online
to talk to one of our friendly and knowledgeable Tech Support Associates. Technical
support is available through the online chat button on our website www.monoprice.com
during regular business hours, 7 days a week. You can also get assistance through email by
sending a message to [e-mail]

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SPECIFICATIONS
Model
31027
Audio Inputs
Stereo analog RCA and 3.5mm TRS line inputs
Output Power
150 watts/channel into 8 ohms or
225 watts/channel into 4 ohms or
450 watts into a single 8-ohm load
Minimum Output Impedance
4 ohms in stereo mode
8 ohms in mono bridged mode
Total Harmonic Distortion
< 1% @ 150 watts into 8 ohms
Signal-to-Noise Ratio
> 90dB(A)
Frequency Response
20Hz ~ 20kHz +0/-2dB @ 8 ohms
Input Sensitivity
700mV
Protection Circuits
Thermal and short circuit
Input Power
115 or 230 VAC, 50/60 Hz
Dimensions
8.4" x 9.8" x 1.7" (214 x 250 x 44 mm)
Weight
3.6 lbs. (1.65 kg)

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REGULATORY COMPLIANCE
Notice for FCC
This device complies with Part 15 of the FCC rules. Operation is subject to the following two
conditions: (1) this device may not cause harmful interference, and (2) this device must accept any
interference received, including interference that may cause undesired operation.
Modifying the equipment without Monoprice’s authorization may result in the equipment no
longer complying with FCC requirements for Class B digital devices. In that event, your right to use
the equipment may be limited by FCC regulations, and you may be required to correct any
interference to radio or television communications at your own expense.
This equipment has been tested and found to comply with the limits for a Class B digital device,
pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection
against harmful interference in a residential installation. This equipment generates, uses and can
radiate radio frequency energy and, if not installed and used in accordance with the instructions,
may cause harmful interference to radio communications. However, there is no guarantee that
interference will not occur in a particular installation. If this equipment does cause harmful
interference to radio or television reception, which can be determined by turning the equipment
off and on, the user is encouraged to try to correct the interference by one or more of the
following measures:
Reorient or relocate the receiving antenna.
Increase the separation between the equipment and receiver.
Connect the equipment into an outlet on a circuit different from that to which the receiver
is connected.
Consult the dealer or an experienced radio/TV technician for help.
Notice for Industry Canada
This Class B digital apparatus complies with Canadian ICES-003.
Cet appareil numérique de la classe B est conforme à la norme NMB-003 du Canada.