HiFi Power Amplifier
High-fidelity 2-channel power amplifier outputting up to 150W per channel, driven by complementary discrete audio MOSFET transistors.
After building my Visaton acoustic speakers, I embarked on designing a matching high-performance power amplifier. I channeled extensive audio engineering experience into this device, keeping the front panel uncluttered with only a power switch and a genuine Japanese ALPS volume potentiometer. The amplifier focuses entirely on pristine, uncolored signal reproduction without tone controls or phase-distorting networks.
Front Panel & System Setup
A dedicated comparator switch unit was built to conduct instant blind A/B sound comparison between two amplifiers connected to identical speakers:
Internal Architecture & Pure Audio Path
Power MOSFETs are fastened directly to heavy aluminum heatsinks directly beneath the PCB, completely eliminating extra wiring that introduces stray inductance and degrades transient response. Active current limiting protections were avoided in favor of fast-acting DC rail fuses to preserve sonic transparency and microdynamics. The linear power supply features a massive 400W toroidal transformer and high-capacitance filtering banks.
Stress Testing & Output Measurements
Stress testing was conducted under heavy simulated loads. With ±55V rails, dummy loads were constructed using halogen arrays (3 × 50W + 3 × 35W = 255W per channel). Sinusoidal and square-wave excitation signals across 20 Hz to 20 kHz were verified. Even connecting cold tungsten filaments at full power (sub-ohm instantaneous load) caused no instability.
Mains power consumption measurements: idle consumption versus full continuous power output (+600W drawn from mains, ~50% efficiency):
