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Alfatron PA2B

The ALF-PA2B is a compact-sized digital amplifier (Class-D) with 3 inputs (2 lines in and 1 balanced MIC). It is integrated with powerful functions, including bridge connection, dual-mono, EQ control, microphone mixer etc. It is a good application in different spaces, including classrooms, small meeting rooms, lecture halls, bars, pubs, etc.


Product Features

  • 2 x 20 Watt @ 4 0hm as the default amplifier output
  • Bridge connection function. Users can switch the PA2B to be 1 x 40 Watt @ 8 0hm by bridge connection
  • Two stereo audio inputs, switchable by panel button, IR remote and RS232
  • Volume / Bass / Treble controllable by panel buttons IR remote and RS232
  • MIC port can support balanced/unbalanced signal, suppresses the external noise effectively. Line audio output via 3.5mm jack, with controllable volume
  • Dual-mono 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. 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 and this allows multiple PA2B to be powered on simultaneously without overloading power circuits
  • Convection cooled, a fan is not needed
  • Anti-static case design: providing good protection for long-term and stable performance


Audio Input  Audio Output 
Input  2 stereo audio, 


1 MIC 

Output  1 amplifier, 


1 stereo audio 



Input Connector 

2 RCA 


1 3.5mm jack 

1 pluggable terminal block (3P,3.81mm), 



Output Connector 

1 3.5mm jack 


1 pluggable terminal block (4P, 5.08mm) 

Input Impedance  >10KΩ  Output Impedance  50Ω/stereo, 4~8Ω/Amplifier 
Audio General 
Frequency Response  20Hz ~ 20KHz  CMRR  >70dB@20Hz~20KH 



SNR  80dB at maximum output  Bandwidth  20Hz ~ 25KHz 
Stereo Channel 



>75dB@20Hz to 20KHz   


THD + Noise 




at nominal level 

Voltage Gain  32dB  Power Output  2×20 Watts (4 Ohms) 
Control Function 
RS232 Control  3-hole phoenix connector  Panel Control  Optional button control 
IR Remote  Optional IR remote 
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