200W 2.1 Amplifier

Class: This project was created at the beginning of the forth grade of the HTC.

Layouts & PCBs:
All circuits and PCBs were designed and calculated by myself.
All files can be downloaded at Downloads.


The output stage is powered by a 2x15V 300W toroidal core transformer.
By rectification and 60mF capacity you get under full load a DC voltage of + -20V.
The audio signal is filtered and pre-amplified before it enters the real power amp.
Two amplifiers are responsible for the stereo sound and the other two power amplifiers
are bridged and are responsible for the subwoofer.

Technical Data & Features:

  • Output (not bridged): 35Wpeak / 25Wrms
  • Output (bridged): 140Wpeak / 100Wrms
  • Efficiency: 66%
  • THD: 0.147% @ max. power
  • Slewrate: 25.4V/us

  • Active Filtering: Stereo Filtering, Subsonic filter with bass boost, Total, bass and treble volume control
  • two stereo power amplifiers: each output stage for left / right channel with 25Wrms output power
  • bridged power amplifier: bridged power amplifier for subwoofers with 100Wrms output power
  • PWM fan control: Fans are controlled by temperature sensors from the heat sink and PWM
  • VU-Meter: LEDs light up with the bass
  • LCD-Display: LCD displays heatsink temperature and RPM of fans

Building the project:

Final result:


Power amplifier for the HTL

The amplifier has been completely redesigned and rebuilt for the 5th year in the HTC.
The PCBs also were produced professionally by JLC PCB.
Due to that, the power amplifier has a way better quality.

All measurements (THD, linearity, Slew Rate and efficiency) can be downloaded at Downloads .

By developing and calculating the power amp, my knowledge of amplifiers has been improved a lot.
The construction of Class A, B and AB amplifiers with the additional precursors is now very easy for me.
Furthermore, for the first time I developed, calculated and realized active filter circuits.
The power supply construction was also refreshed.

At Downloads , all important things can be downloaded and looked up.

At Contact Me , you can ask questions and give tips for improving the project.
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