ALFAtron ALF-PA2B User manual

www.alfatronelectronics.com
ALFATRON ELECTRONICS GmbH GERMANY
ALF-PA2B

ALF-PA2B
Preface
Read this user manual carefully before using this product. Pictures shown in this
manual are for reference only, different models and specifications are subject to real
product.
This manual is for operation instruction only, not for any maintenance usage. The
functions described in this version are updated as of April 2020. Any changes of
functions and parameters since, will be informed separately. Please refer to the
dealers for the latest details.
FCC Statement
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. It 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 commercial
installation.
Operation of this equipment in a residential area is likely to cause interference, in
which case the user at their own expense will be required to take whatever measures
may be necessary to correct the interference.
Any changes or modifications not expressly approved by the manufacture would void
the user’s authority to operate the equipment.
Do not dispose of this product with the normal household waste at the end of
its life cycle. Return it to a collection point for the recycling of electrical and
electronic devices. This is indicated by the symbol on the product, user
manual or packaging. The materials are reusable according to their
markings. By reusing, recycling or other forms of utilisation of old devices
you make an important contribution to the protection of our environment.
Please contact your local authorities for details about collection points.

ALF-PA2B
SAFETY PRECAUTIONS
To ensure the best performance from the product, please read all instructions carefully
before using the device. Save this manual for further reference.
Unpack the equipment carefully and save the original box and packing material for
possible future shipment.
Follow basic safety precautions to reduce the risk of fire, electrical shock, and injury to
persons.
Do not dismantle the housing or modify the module. It may result in electrical shock or
burn.
Using supplies or parts not meeting the products’ specifications may cause damage,
deterioration, or malfunction.
Refer all servicing to qualified service personnel.
To prevent fire or shock hazards, do not expose the unit to rain, moisture or install this
product near liquid.
Do not put any heavy items on the extension cable in case of extrusion.
Do not remove the housing of the device as opening or removing housing may
expose you to dangerous voltage or other hazards.
Install the device in a place with adequate ventilation to avoid damage caused by
overheating.
Keep the module away from liquids.
Substances spilled into the housing may result in fire, electrical shock, or equipment
damage. If an object or liquid falls or spills onto the housing, unplug the module
immediately.
Do not forcefully twist or pull ends of the optical cable. It can cause a malfunction.
Do not use liquid or aerosol cleaners to clean this unit. Always unplug the power from
the device before cleaning.
Unplug the power cord when left unused for a long period of time.
Information on disposal for scrapped devices: do not burn or mix with general
household waste, please treat as normal electrical waste.

ALF-PA2B
Table of Contents
1. Product Introduction....................................................................................................1
1.1. Features ...........................................................................................................1
1.2. Package List .....................................................................................................2
2. System Connection.....................................................................................................3
2.1. Audio Output.....................................................................................................3
2.1.1. Default Output: 2x20Watt@4Ohm ..........................................................3
2.1.2. Bridge Connection: 1x40Watt@8Ohm....................................................3
2.1.3. Dual-mono Output ..................................................................................4
2.2. Microphone Input..............................................................................................5
2.2.1. 48V Phantom Power Input......................................................................5
2.2.2. MIC Input................................................................................................5
2.2.3. LINE Input...............................................................................................5
3. Panel Control ..............................................................................................................6
3.1. Audio Switching ................................................................................................6
3.2. Volume/EQ controlling ......................................................................................6
4. IR Remote Control (Optional) .....................................................................................7
5. System Diagram .........................................................................................................8
6. RS232 Command .......................................................................................................9
7. Specifications............................................................................................................ 11
8. Troubleshooting & Maintenance ...............................................................................12
9. After-sales Service....................................................................................................13

ALF-PA2B
1
1. Product Introduction
The Alfatron PA2B is a compact-size digital amplifier (Class-D) with 3 inputs, 2 line in
and 1 balanced MIC. Integrated functions include bridge connection, dual-mono, EQ
control, microphone mixer etc.
Excellent in varied applications, including classrooms, small meeting rooms, lecture
halls, bars etc.
1.1. Features
2x20 Watt@4 Ohm as the default amplifier output.
Bridge connection function. User can switch the Mini Digital Amplifier to be
1x40Watt@8Ohm by bridge connection.
Two stereo audio inputs, switchable via buttons, IR remote & RS232.
Volume/Bass/Treble controllable via buttons, IR remote & RS232.
MIC port supports both balanced and unbalanced signal, suppressing the external
noise effectively.
Line audio output at 3.5mm jack, with volume control.
Dual-mono function. User can sum up the stereo audio to two times mono audio.
MIC mixer function. The microphone will be mixed to the line audio output and be
controlled separately.
MIC input supports 48V phantom power, dynamic MIC, and wireless MIC.
Auto noise gate. It keeps detecting the audio and MIC input, will mute the output
when there is no input.
Ultra low inrush current, no need for power sequencing. This allows multiple Mini
Digital Amplifiers to be powered on simultaneously without overloading power
circuits.
Convection cooled; a fan is not required.
Antistatic case design: providing good protection for long-term and stable
performance.

ALF-PA2B
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1.2. Package List
1 x PA2B mini amplifier
2 x Pluggable Terminal Blocks
1 x RS232 Cable
1 x Power Adapter
1 x Power Cord
4 x Plastic Cushions
1 x User Manual
Optional Accessories
IR remote control is available separately for purchasing.
IR receiver is available separately for purchasing.
Note:
Please ensure listed accessories are all included, should it not be, please contact the
dealer.

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2. System Connection
2.1. Audio Output
2.1.1. Default Output: 2x20Watt@4Ohm
The default output of the amplifier is 2x20Watt@4Ohm. Output connection is pictured
below:
2.1.2. Bridge Connection: 1x40Watt@8Ohm
The amplifier has the bridge connection, which would double the output power at
1x40Watt@8Ohm. It will sum up the left and right input channel to be a mono output,
the power is up to 40Watt.
The bridge connection is:

ALF-PA2B
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2.1.3. Dual-mono Output
The amplifier also has the function of double-mono output. It can sum up the left and
right channel to be the mono audio output. In this way, both of the outputs are
outputting the same mono audio.
The connection is:

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2.2. Microphone Input
The microphone input of Mini Digital Amplifier has three modes, and different modes
use different connections, as the picture below:
2.2.1. 48V Phantom Power Input
When the switch is set to “48V”, the MIC input will provide 48V phantom power. This is
usually used as the power supply for a condenser microphone, Connection is:
“+” connects to positive, “-” connects to negative and “╧” to ground.
Note: In this mode, only a condenser microphone can be connected.
2.2.2. MIC Input
When the switch is set to “MIC”, the microphone input is used to connect with a
dynamic microphone. There are two different connections:
1) Unbalanced connection:
“╧” connects to ground, and “-” connects to signal.
“╧” connects to ground, and “+” connects to signal.
2) Balanced connection: “+” connects to positive, “-” connects to negative and “╧”
connects to ground.
2.2.3. LINE Input
When the switch is set to “LINE”, the microphone input is used for connecting with
normal audio or wireless microphone output. There are two different connections:
1) Unbalanced connection:
“╧” connects to ground, and “-” connects to signal.
“╧” connects to ground, and “+” connects to signal.
2) Balanced connection:
“+” connects to positive, “-” connects to negative and “╧” connects to ground.

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3. Panel Control
The panel buttons control the volume/EQ and switching. The following content
introduces audio switching and EQ control in detail.
3.1. Audio Switching
There are two switchable stereo audio inputs, one 2xRCA input, and one 3.5mm jack
input, switchable through the source selection buttons as pictured below:
3.2. Volume/EQ controlling
The line volume and MIC volume can be controlled via the panel buttons.
The MIC Volume/LINE volume/LINE bass/LINE treble must be selected via the
function button and only then can the up/down/mute via the buttons on the right be
done. Pictured below:
Firstly,
select the
function
from this
menu.
Then
,
turn
down/up the
level, or
mute the
output.
S
ource
Selection

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For example, to turn up the line volume, you should select the “LINE” first, and then
press the button “ ”.
4. IR Remote Control (Optional)
Note: The IR remote, the IR receiver, and required batteries for the IR remote are all
optional accessories available for purchase.
Mute Mode:
MIC: Mute microphone
audio.
LINE: Mute line audio.
SPEAKER: Unmute.
Used to transmit the
infrared signal sent by the
IR remote.
Volume Control:
MIC: Volume up or down
microphone audio.
LINE: Volume up or down
line volume.
BASS: Bass adjustment.
TREBLE: Treble
adjustment.
Audio Inputs
1: RCA dual-mono audio
input.
2: 3.5mm jack.
IR receiver head
works in conjunction
with the IR remote.
Please point the IR
remote at the IR
receiver as it is
dependent on line-of-
sight.
3.5mm jack, insert it
into the specialized
socket (3.5mm) to
connect the IR receiver
with the amplifier

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5. System Diagram

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6. RS232 Command
After setting all required input and output devices according to the system connection
introduction, connect a PC for control to the RS232 port. Then install the RS232
control software (e.g. docklight) into the control PC to send RS232 commands to
control the amplifier.
After installing the RS232 control software, please set the parameters of COM number,
bound rate, data bit, stop bit and the parity bit correctly, you will then be able to send
commands in command sending area.
The serial port settings for all RS232 commands are:
Baud rate: 9600 Data bit: 8 Stop bit:1 Parity bit: none
Command Function Description Feedback Code
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 Noise Gate. Gate On
4A0. Switch off Noise Gate. Gate Off
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

ALF-PA2B
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607% Treble level up. Treble of LINE: 04
608% Treble level down. Treble of LINE: 04
609% Initialization, back to the default setting. Init OK
5[x][x]% Preset MIC volume, [xx] arranges from
[00] to [60].
61 degrees in total.
Volume of MIC: 50
7[x][x]% Preset line volume, [xx] arranges from
[00] to [60].
61 degrees in total.
Volume of LINE: 50
8[x][x]% Preset the bass level, [xx] arranges from
[00] to [08].
9 degrees in total.
Bass of LINE: 04
9[x][x]% Preset the treble level, [xx] arranges from
[00] to [08].
9 degrees in total.
Treble of LINE: 04
Note:
The letter inside bracket [ ] is the variable code, which is changeable.
The bracket [ ] is not included to the RS232 commands.
Any dot “.” after the letters is part of the command.
Example 1:
Switching the input 2 to the line out, RS232 command is: [2A1.].
Example 2:
Turning up the volume of line audio, RS232 command is: [603%].
Example 3:
Preset the MIC volume to level “21”, RS232 command is: [521%].
Example 4:
Checking the working status of PA2B Mini Digital Amplifier, the RS232 command is:
[600%].

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7. Specifications
Audio Input
Input (2) Stereo Audio, (1) MIC
Input Connector (2) RCA, (1) 3.5mm Jack,
(1) Pluggable Terminal Block (3 P, 3.81mm)
Audio Output
Output (1) Amplifier, (1) Stereo Audio
Output Connector (1) 3.5mm Jack,
(1) Pluggable Terminal Block ( 4 P, 5.08mm)
Audio Performance
Input Impedance >10kΩ
Output Impedance 50Ω Analog Output; 4/8Ω Speaker Output
Maximum Rated Power Output 2x20 watts (4 Ohms)
Frequency Response 20Hz ~ 20kHz
Common Mode Rejection Ratio
(CMRR) >70dB@20Hz~20kHz
Signal to Noise Ratio (SNR) 80dB (Max)
Total Harmonic Distortion + Noise
(THD+N) 1% at 1kHz; 0.3% at 20kHz at Nominal Level
General
Power Supply Input Voltage 100-240v AC at 50/60 Hz
Power Supply
24V DC at 2.71A
Maximum Power Consumption
45 watts
Operation Temperature
0℃~ +40℃
Storage Temperature
-10℃~ +60℃
Storage Humidity 10%-90%
Dimensions (W*H*D)
123mm x40mm x87mm
Net Weight
720g

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8. Troubleshooting & Maintenance
1) When there is no output audio:
Check if there is any signal at the input.
Check if there is any signal at the output.
We can check these by using an oscilloscope or a multimeter. If there is no
signal input/output, perhaps the input/output cables are broken, or the
connectors have come loose, please change for another cable.
Check if the output port number is the same with the controlled one.
If none of the above, please contact your dealer for assessment.
2) If the POWER indicator does not work or no response to any operation, please
ensure the power cord is properly connected.
3) If there is interference on the output sound, please ensure the system is
grounded well.
4) If the static becomes stronger when connecting the audio connectors, please
inspect the grounding and ensure it is well connected, if not, it could damage the
converter.
5) If the PA2B mini digital amplifier cannot be controlled by the buttons on the panel,
RS232 port, nor IR remote, the unit may be damaged. Please send it to the
dealer for repairing.

Mini Digital Amplifier
13
9. After-sales Service
Should you experience problems using the ALF-PA2B, please refer to the manual and
troubleshooting and maintenance section (8). Should the error persist, note that any
transport costs of the equipment to the distributor are borne by the user during the
warranty.
1) Product Limited Warranty: Alfatron warrants that its products will be free from
defects in materials and workmanship for seven years, which starts from the first
day of purchase.
Proof of purchase in the form of a bill of sale or receipted invoice which is evidence
that the unit is within the warranty period must be presented to obtain warranty
service.
2) What the warranty does not cover (servicing available for a fee):
●Warranty expiration.
●Factory applied serial number has been altered or removed from the product.
●Damage, deterioration, or malfunction caused by:
●Normal wear and tear.
●Use of supplies or parts not meeting product specifications.
●No certificate or invoice as the proof of warranty.
●The product model showed on the warranty card does not match with the
product or if the product had been altered.
●Damage caused by force majeure.
●Servicing not authorized by Alfatron.
●Any other causes which do not relate to a product defect.
●Delivery, installation or labour charges for installation or setup of the
product.
3) Technical Support: Contact our after-sales department at
www.alfatronelectronics.com

Mini Digital Amplifier
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Limited warranty in respect of Alfatron Products Only
1.1 This limited warranty covers defects in materials and workmanship in this product.
1.2 Should warranty service be required, proof of purchase must be presented to the
Company. The serial number on the product must be clearly visible and not have been
tampered with in any way whatsoever.
1.3 This limited warranty does not cover any damage, deterioration or malfunction
resulting from any alteration, modification, improper or unreasonable use or
maintenance, misuse, abuse, accident, neglect, exposure to excess moisture, fire,
improper packing and shipping (such claims must be presented to the carrier), lightning,
power surges, or other acts of nature. This limited warranty does not cover any damage,
deterioration or malfunction resulting from the installation or removal of this product
from any installation, any unauthorized tampering with this product, any repairs
attempted by anyone unauthorized by the Company to make such repairs, or any other
cause which does not relate directly to a defect in materials and/or workmanship of this
product. This limited warranty does not cover equipment enclosures, cables or
accessories used in conjunction with this product.
This limited warranty does not cover the cost of normal maintenance. Failure of the
product due to insufficient or improper maintenance is not covered.
1.4 The Company does not warrant that the product covered hereby, including, without
limitation, the technology and/or integrated circuit(s) included in the product, will not
become obsolete or that such items are or will remain compatible with any other
product or technology with which the product may be used.
1.5 Only the original purchaser of this product is covered under this limited warranty.
This limited warranty is not transferable to subsequent purchasers or owners of this
product.
1.6 Unless otherwise specified, the goods are warranted in accordance with the
manufacturer’s product specific warranties against any defect attributable to faulty
workmanship or materials, fair wear and tear being excluded.
1.7 This limited warranty only covers the cost of faulty goods and does not include the
cost of labor and travel to return the goods to the Company’s premises.
1.8 In the event of any improper maintenance, repair or service being carried out by any
third persons during the warranty period without the Company’s written authorization,
the limited warranty shall be void.
1.9 A 7 (seven) year limited warranty is given on the aforesaid product where used
correctly according to the Company’s instructions, and only with the use of the
Company’s components.

Mini Digital Amplifier
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1.10 The Company will, at its sole option, provide one of the following three remedies to
whatever extent it shall deem necessary to satisfy a proper claim under this limited
warranty:
1.10.1 Elect to repair or facilitate the repair of any defective parts within a reasonable
period of time, free of any charge for the necessary parts and labor to complete the
repair and restore this product to its proper operating condition.; or
1.10.2 Replace this product with a direct replacement or with a similar product deemed
by the Company to perform substantially the same function as the original product; or
1.10.3 Issue a refund of the original purchase price less depreciation to be determined
based on the age of the product at the time remedy is sought under this limited
warranty.
1.11 The Company is not obligated to provide the Customer with a substitute unit during
the limited warranty period or at any time thereafter.
1.12 If this product is returned to the Company this product must be insured during
shipment, with the insurance and shipping charges prepaid by the Customer. If this
product is returned uninsured, the Customer assumes all risks of loss or damage during
shipment. The Company will not be responsible for any costs related to the removal or
reinstallation of this product from or into any installation. The Company will not be
responsible for any costs related to any setting up this product, any adjustment of user
controls or any programming required for a specific installation of this product.
1.13 Please be aware that the Company’s products and components have not been
tested with competitor’s products and therefore the Company cannot warrant products
and/or components used in conjunction with competitor’s products.
1.14 The appropriateness of the goods for the purpose intended is only warranted to
the extent that the goods are used in accordance with the Company’s installation,
classification, and usage instructions.
1.15 Any claim by the Customer which is based on any defect in the quality or condition
of the goods or their failure to correspond with specification shall be notified in writing to
the Company within 7 days of delivery or (where the defect or failure was not apparent
on reasonable inspection by the Customer) within a reasonable time after discovery of
the defect or failure, but, in any event, within 6 months of delivery.
1.16 If delivery is not refused, and the Customer does not notify the Company
accordingly, the Customer may not reject the goods and the Company shall have no
liability and the Customer shall pay the price as if the goods had been delivered in
accordance with the Agreement.
1.17 THE MAXIMUM LIABILITY OF THE COMPANY UNDER THIS LIMITED
WARRANTY SHALL NOT EXCEED THE ACTUAL PURCHASE PRICE PAID FOR
THE PRODUCT.