Marshall Electronics
AR-AM4-BG
Analog Audio Monitor
Operating Instructions
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Contents
Product Overview ...............................................................................................................................5
Features ...............................................................................................................................................5
Installation and Initial Setup ..............................................................................................................5
Unpacking ........................................................................................................................................................ 5
Audio Monitor Mounting .............................................................................................................................. 5
Quick Start Guide................................................................................................................................6
Functional Block Diagram..................................................................................................................6
Front Panel Features ..........................................................................................................................7
Stereo Loudspeakers ..................................................................................................................................................................... 7
Power LED....................................................................................................................................................................................... 7
Headphone Jack ............................................................................................................................................................................. 7
Headphone Volume ........................................................................................................................................................................ 7
Input Select ..................................................................................................................................................................................... 7
Master Volume ................................................................................................................................................................................ 7
Balance ............................................................................................................................................................................................ 7
USB Port .......................................................................................................................................................................................... 7
Mute Button..................................................................................................................................................................................... 7
Phase LED ....................................................................................................................................................................................... 7
LED Bargraph Level Meter ............................................................................................................................................................. 7
Rear Panel Features ...........................................................................................................................8
Power Input ..................................................................................................................................................................................... 8
RS-485 Port ..................................................................................................................................................................................... 8
Audio Output ................................................................................................................................................................................... 8
Audio Inputs.................................................................................................................................................................................... 8
Basic Operation ..................................................................................................................................9
Overview........................................................................................................................................................... 9
Volume Control ............................................................................................................................................................................... 9
Channel Select ................................................................................................................................................................................ 9
Balance Control .............................................................................................................................................................................. 9
Headphone Output.......................................................................................................................................................................... 9
Mute Button..................................................................................................................................................................................... 9
Specifications....................................................................................................................................10
Input / Output ................................................................................................................................................ 11
Warranty ............................................................................................................................................12
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Product Overview
The AR-AM4-BG is a 4-channel stereo analog audio monitoring system with DSP and Peak Meters. It features stereo
loudspeakers in a compact 1RU form factor, with analog amplification and digital processing. A front panel bi-color phase
indicator displays the phase relationship between the left and right channels. At only 6.0" deep, the AR-AM4-BG can be
installed in many shallow rack cases or placed on any level surface. This unit is enhanced with four pairs of balanced XLR
inputs, along with a balanced XLR output for interfacing to downstream equipment. Controls include separate headphone
and speaker volume with master balance and a front panel MUTE button. The unit's dual 10-segment bar graph meters
provide the ability to visually monitor the audio source. A powerful DSP-controlled EQ (coupled with a limiting compressor)
provides unparalleled, pristine sound and speaker protection.
Features
■ Selectable Inputs
Choose between 4 independent sets of stereo inputs.
■ Superior Audio Quality
Stereo Loud Speakers provide superior audio quality in a compact 1RU form factor.
■ Digital Processing
Digital signal processing provides speaker protection.
■ Stereo Headphone Output
¼” stereo headphone jack located on front panel.
■ LED Bargraph Metering
Tri Color LED Display of selected audio levels in stereo.
■ Audio Phase Indicator
Single LED to indicate 180 Degree phase errors.
Installation and Initial Setup
Unpacking
Carefully unpack the AR-AM4-BG audio monitor and verify that the following items are included:
• AR-AM4-BG Audio Monitor
• Power Supply with 4-Pin XLR Connector (24VDC)
• AC Power Cable
• Operating Instructions
Inspect the unit for any physical damage that may have occurred during shipping. Should there be any damage,
immediately contact Marshall Electronics at (800) 800-6608. If you are not located within the continental United States,
call +1 (310) 333-0606.
Audio Monitor Installation
The AR-AM4-BG audio monitor can be installed in an EIA-standard 19-inch rack. At only 6” inches deep, the AR-AM4-BG
can also be installed in many shallow racks cases. Alternately, the AR-AM4-BG audio monitor can be placed on any level
surface. For optimum sound quality, the audio monitor should be installed at ear level.
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Quick Start Guide
1. Connect an Audio Source
Connect an audio source to any of the 4 pairs of rear panel input connectors. We recommend the use of the
Balanced XLR female connectors using a balanced audio signal with a nominal level of +4dBu.
2. Power On the Audio Monitor
Supply power to the audio monitor by connecting the included power supply to an AC power source (100-240 V @
50/60 Hz) and connecting the power supply’s 4-pin XLR connector to the back of the audio monitor. The Power LED
on the front panel will illuminate green.
3. Select Input Channel
Use the Input Select controls to choose one of the four inputs.
4. Adjust the Volume and Balance
Use the Volume and Balance controls to adjust the sound level and stereo balance.
Functional Block Diagram
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Front Panel Features
Stereo Loudspeakers
The stereo loudspeakers are controlled by the Master
Volume Control. The sound from the selected source
will be heard.
Power Indication LED
The power LED will illuminate green when power is
supplied to the audio monitor.
Headphone Output
The headphone output accepts stereo headphones
with a 1/4" TRS connector. When headphone plug is
inserted, MUTE is activated and sound to the
speakers is cut.
Headphone Volume Control
The headphone volume control affects only the stereo
headphone jack.
Input Select
Rotate knob to switch between input channels 1
through 4. This selects the input source for both the
speakers and headphone jack.
Master Volume Control
The master volume control affects only the stereo
speakers.
Balance Control
The balance control adjusts the relative level of each
left and right input to the speakers and headphones.
USB Port
For factory and future use only at this time.
Mute Button
Press to silence the speakers. The LED will light to
indicate MUTE. (Headphone jack remains active)
Phase LED
Will indicate the wiring polarity of incoming audio
comparing left to right. GREEN color indicates
Left+Right is IN Phase. RED indicates a 180 Degree
Phase Error between Left and Right of the selected
input.
LED Bargraph Level Meter
Dual 10-segment LED display of selected audio
source.
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Rear Panel Features
Power Input Connector
Use only the included power supply to power the AR-AM4-BG audio monitor.
RS-485 Ports
For future functions and firmware upgrades.
Audio Outputs
XLR- 3pin male connector. Balanced audio out is same level as XLR audio input. This is an active output from the
selected Audio Input. If power is removed from the unit, there will be no signal on these connectors.
Audio Inputs
XLR - 3pin female connector. Balanced audio in. Pin 1= ground, Pin 2= Signal +, Pin 3= Signal -
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Basic Operation
Overview
Basic operation of the AR-AM4-BG Audio Monitor involves connecting audio sources, and monitoring through the stereo
speakers.
The user can choose between listening to the amplified internal speakers, or headphones. Audio volume can be adjusted
from front panel controls.
There are four (4) separate stereo input channels. One can be selected at any time from the front panel.
Controls
■ Volume Control
The VOLUME control affects only the stereo speakers.
■ Channel Select
The Channel Select controls which of the four inputs is selected to the speakers, headphones and rear XLR Outputs.
■ Balance Control
The BALANCE control adjusts the relative levels of the LEFT and RIGHT channels of the input, affecting both the
stereo speakers and headphone output.
■ Headphone Output
The headphone output accepts standard stereo headphones with a 1/4" TRS connector. Headphones with a 1/8”
(3.5mm) mini-plug connector may be used with an adapter. NOTE: The stereo speakers are muted when a connector
is plugged into the headphone output. Headphones are not included with this unit.
■ MUTE Button
The MUTE button cuts the signal to the internal speakers. The LED will light to indicate the MUTE condition.
Sound to the headphone jack is not affected.
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Specifications
AR-AM4-BG Audio Monitor
■ ACOUSTIC
Speaker Power Output:
Peak Acoustic Output:
Headphone Power Output:
Left/Right RMS @ 4Ω: 3W RMS, 5W Peak
99 dB SPL @ .1m
150 mW
■ ELECTRICAL
Power Consumption:
Voltage Requirement:
Included Power Supply
AC Input:
DC Output:
40W
24VDC
100V-240V, 1.0A, 50-60Hz
24VDC, 1.65A,
■ MECHANICAL
Dimensions (w x h x d):
Rack Height:
Weight:
10
19.0” x 1.75” x 6.0”
1 RU
4.55 lbs. (2 kg)
Specifications (continued)
Input / Output
■ ANALOG STEREO INPUT (x 4)
XLR 3-pin Female +4dBu nominal level (balanced differential)
■ ANALOG STEREO OUTPUT (Selected)
Outputs:
Reference:
2 x Analog (Balanced XLR)
Active balanced from selected Audio Input
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Warranty
Marshall Electronics warranties to the first consumer that this AR-AM4-BG Audio Monitor will, under normal use, be free
from defects in workmanship and materials, when received in its original container, for a period of one year from the
purchase date. This warranty is extended to the first consumer only, and proof of purchase is necessary to honor the
warranty. If there is no proof of purchase provided with a warranty claim, Marshall Electronics reserves the right not to
honor the warranty set forth above. Therefore, labor and parts may be charged to the consumer. This warranty does not
apply to the product exterior or cosmetics. Misuse, abnormal handling, alterations or modifications in design or
construction void this warranty. No sales personnel of the seller or any other person is authorized to make any warranties
other than those described above, or to extend the duration of any warranties on behalf of Marshall Electronics, beyond
the time period described above. Due to constant effort to improve products and product features, specifications may
change without notice.
Marshall Electronics, Inc.
1910 East Maple Ave.
El Segundo, CA 90245
Tel: (800) 800-6608 / (310) 333-0606 • Fax: 310-333-0688
www.LCDRacks.com • sales@lcdracks.com
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2010-0629