• 1
    Overview

    After several amplifier projects, I wanted to build a compact Hi-Fi stereo amplifier based on the well-known STK4191II power amplifier IC. My goal was not only to build a reliable amplifier but also to design a complete PCB board with an integrated tone control stage, power supply, and speaker protection relay.

    The result is a clean and easy-to-build amplifier that delivers excellent sound quality while remaining simple enough for hobbyists to assemble.

  • 2
    Main Features
    • STK4191II power amplifier
    • Compatible with the STK41xx series
    • Independent Volume, Bass, and Treble controls
    • Power-on delay relay for speaker protection
    • On-board 7812 voltage regulator
    • Compact single PCB board design
    • Easy to assemble and troubleshoot
  • 3
    PCB Board Design

    The entire amplifier was designed on a single PCB board to simplify wiring and improve reliability.

    The board includes:

    • AC to DC rectifier
    • Power supply filter
    • 7812 voltage regulator
    • Tone control circuit
    • Relay delay circuit
    • STK41xx amplifier section

    After completing the design, I uploaded the Gerber files to JLCPCB.

    The manufactured PCB boards arrived about one week later with excellent quality. The silkscreen is sharp, the solder mask is clean, and the drilled holes are accurately aligned, making assembly straightforward.