HR AMP-4840 User manual

User’s Manual
AMP-4840
40 Watt Audio Amplifier
with RS-232 and IR Control
UMA1272 Rev B
Order toll-free in the U.S. 800-959-6439
FREE technical support: 714-641-6607 or [email protected]m
Hall Research, 1163 Warner Ave. Tustin, CA 92780
www.hallresearch.com
CUSTOMER
SUPPORT
INFORMATION

d
40 Watt Audio Am
p
lifier with RS-232
© Copyright 2018 Hall Research, Inc.
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Table of Contents
1.0 Introduction ................................................................................. 4
Features .................................................................................................4
2.0 Package Contents ........................................................................4
3.0 Connectors, Indicators, and Controls......................................5
3.1 Input Panel .................................................................................5
3.2 Output Panel...............................................................................6
3.3 Top Panel.................................................................................... 7
4.0 RS-232 Serial Control of Amplifier ..........................................7
5.0 Troubleshooting.......................................................................... 9
6.0 Specifications...............................................................................9
FCC Notice
This device complies with Part 15 of the FCC Rules. Operation is subject to the following
conditions:
1. This device may not cause harmful interference.
2. This device must accept any interference even if it causes undesired operation.
This equipment has been desinged to comply with the limits for a Class A digital device,
pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable
protection against harmful interference when the equipment is operated in a
commercial environment. This equipment generates, uses, and can radiate radio
frequency energy, and if it is not installed and used in accordance with the instruction
manual, it may cause harmful interference to radio communications. Operation of this
equipment in a residential area is likely to cause harmful interference, in which case the
user will be required to correct the interference at his own expense.

AMP-4840
4© Copyright 2018 Hall Research, Inc.
1.0 Introduction
The AMP-4840 is a compact, economical and energy efficient (Class D) mono /
stereo audio amplifier with 3 inputs (2 line in and 1 balanced microphone).
Versatile design is compatible with dynamic, condenser or wireless
microphones with fully adjustable control options including RS-232, IR, and
front panel buttons. Functions include bridge connection, dual-mono, EQ
control, and microphone mixer.
The AMP-4840 is a perfect for classrooms, meeting rooms, boardrooms, sports
bars, and more.
Features
•Drives: 2x 20w @ 4 Ω or 2x 10w @ 8 Ω or 1x 40w @ 8 Ω in bridge mode
•Two stereo audio inputs, switchable by button, IR remote & RS-232
•Volume / Bass / Treble controllable by buttons, IR remote & RS-232
•MIC port supports balanced or unbalanced signals
•3.5mm jack line audio output with controllable volume
•Mono mix switch for summing left and right channels for driving mono
outputs
•Microphone input can be mixed with line input and each can be
controlled separately
•MIC input supports 48V phantom power, dynamic MIC and wireless MIC
•Auto noise squelch. Detects audio on inputs and mutes the output when
there is no input
•Does not have fans
2.0 Package Contents
(1x) AMP-4840 device itself
(1x) AC Adapter (24 VDC) Power supply
(1x) User’s Manual
Optional Accessories (sold separately)
IR Remote with IR Detector Cable

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40 Watt Audio Am
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lifier with RS-232
© Copyright 2018 Hall Research, Inc. 5
3.0 Connectors, Indicators, and Controls
3.1 Input Panel
The input panel is shown above. There are two audio inputs that are mixed
together they are the Mic In and Line In. The speaker output audio is a mix of
these two inputs. You can control the level of each used in the composite output
from the top panel as described below.
Within the Line input group, there are two inputs labeled A and B. Only one can
be active at a time based on the selection made from the top panel.
The microphone input is a balanced 3 terminal detachable screw-type
connector. There is a 3-position slide-switch next to the screw terminal to select
the type/level of the Microphone input signal as described below:
•Phantom: Use this position for microphones requiring phantom power
such as condenser Mics. Typical input level for this mode is (-48 dBV, -
45 dBu) or around 4 mv rms sine wave.
•Dynamic: This position is used for dynamic microphones with low-level
outputs. Typical input level for this mode is (-60 dBV, -58 dBu) or
around 1 mv rms sine wave.
•Wireless: This position is for Mics that output full consumer line level
outputs, such as wireless microphone receive outputs.
The External Control group includes a screw terminal for RS-232 (please see
related section below), and IR jack for connection of optional IR detector cable.
The Speaker Mode is a 3-position slide switch that functions as described
below:
•Stereo: This position is used for connecting two 8 Ω or 4 Ω speakers.
The Left and Right channel audio separations are intact and you will
get stereo output sound.

AMP-4840
6© Copyright 2018 Hall Research, Inc.
•Mono: This position is also used for connecting two speakers, but the
amplifier mixes the Left and Right audio so the sound from both
speakers is identical. Use this position if you want the same mono
sound from all speakers. In a large classroom, it may make sense to use
this mode so all students get the same sound regardless of how close
they are sitting to each speaker.
•Bridge: This position is used to drive 40 watts into a single 8 Ω speaker.
3.2 Output Panel
Power input jack is used to connect the supplied 24 V adapter. There is a Red
LED indicator to show power status.
There are two outputs, Line (L/R) and Speaker screw terminal. The L/R outputs
standard consumer line-level (variable) audio. When connecting two speakers
connect them as shown for Stereo/Mono settings.
When connecting a single 8 Ω speaker (40 w), use the outer two (+) terminals as
shown. Make sure to set the Speaker Mode slide switch to Bridge position
NOTE In Stereo or Mono modes, you can connect more than two speakers.
For example, you can connect two 8 Ω speakers in parallel to each
side, or two 4 Ω speakers in series to each side.
Example showing four 8 Ω speakers

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40 Watt Audio Am
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lifier with RS-232
© Copyright 2018 Hall Research, Inc. 7
3.3 Top Panel
The SEL INPUT button and A/B LED indicators is to select which line input you
are using, RCA inputs or 3.5mm. Remember, the selected input gets mixed with
microphone input. If you are not using microphone input, reduce its volume to
zero so you don’t have the added noise from the microphone amp in the output.
The ADJ button is used to select which parameter to adjust, then use the Up and
Down arrow bottons to make the adjustment.
This button is for Muting the audio
4.0 RS-232 Serial Control of Amplifier
RS232 communication protocol:
Baud rate: 9600
Data bit: 8 - Stop bit: 1 - Parity: none
Valid commands are listed in the table below

AMP-4840
8© Copyright 2018 Hall Research, Inc.
Do not append carriage returns.
Commands are terminated with “.” or “%”
Command Description Response
1A1. Switching the audio to input 1 A: 1 -> 1
2A1. Switching the audio to input 2 A: 2 -> 1
0A0. Mute Audio of MIC and Line out Mute
1A0. Mute audio of MIC Mute MIC
2A0. Mute audio of line out Mute LIN
0A1. Unmute Audio Unmute
3A0. Switch on squelch Gate On
4A0. Switch off squelch Gate Of
f
600% Checking the working status A: 1 -> 1
Volume: 30
Bass: 00
Treble: 00
601% MIC volume up Volume of MIC: 51
602% MIC volume down Volume of MIC: 51
603% Line volume up Volume of LINE: 51
604% Line volume down Volume of LINE: 51
605% Bass level up Bass of LINE: 04
606% Bass level down Bass of LINE: 04
607% Treble level up Treble of LINE: 04
608% Treble level down Treble of LINE: 04
609% Initiate Factory Restore Init O
K
5[xx]% Direct set MIC volume
[xx] range: 00 to 60
Volume of MIC: 50
(factory default)
7[xx]% Direct set LINE volume
[xx] range: 00 to 60
Volume of LINE: 50
(factory default)
8[xx]% Direct set the bass level
[xx] range: 00 to 08
Bass of LINE: 04
(factory default)
9[xx]% Direct set the treble level
[xx] range: 00 to 08
Treble of LINE: 04
(factory default)

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40 Watt Audio Am
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lifier with RS-232
© Copyright 2018 Hall Research, Inc. 9
5.0 Troubleshooting
If you are experiencing problems getting the amplifier to work properly, please
use the following troubleshooting suggestions.
•Cycle Power on the device
•Issue RS-232 Factory Restore command
•Check wiring and speaker impedances used
If you determine that your amp is malfunctioning, do not attempt to repair the
unit instead, contact Hall Research Technical Support at 714-641-6607. To
return the unit to Hall Research you must first get a Return Authorization
(RMA) number. Package the unit carefully, if returning. We recommend that you
use the original container.
6.0 Specifications
Audio
Rated Output 2 x 20 w @ 4 Ω
2 x 10 w @ 8 Ω
Gain
1 x 40 w @ 8 Ω - in bridge mode
32 dB
Frequency Range 20 Hz to 20 KHz
Signal/Noise Ratio 80 dB (at max output)
Total Harmonic Distortion 1% (1 KHz), 0.3% (20 KHz) -- at nominal levels
Input Impedance >10 Kohm
Output Impedance 3.5mm Loop Out: 50 Ω
Speaker out: 4 Ω ~ 8 Ω - Amplified
Stereo Channel Separation >75 dB from 20 Hz to 20 KHz
CMRR >70 dB from 20 Hz to 20 KHz
Temperature
Operating 0 °C to 40 °C (32 °F to 104 °F)
Humidity 20 to 90% non-condensing
Power
Max Consumption 40 watts
Idle Consumption 4 watts
General
Power Supply Input: 100 VAC to 240 VAC, 47-63 Hz
Output 24 VDC / 5 A
Dimensions H x W x D = 38 x 96 x 87 (mm) or 1.5 x 3.78 x 3.43 (inch)
Weight Device: 0.3 kg (0.66 lbs)
Shipping: 0.98 kg (2.16 lbs)
Certifications Unit: CE, FCC, RoHS
Power Supply: cULus
Specifications are subject to change without notice

AMP-4840
10 © Copyright 2018 Hall Research, Inc.