Mehdi Sadaghdar’s ElectroBOOM channel has become legendary for its unique combination of rigorous electrical engineering education and comedic presentation involving deliberate (and sometimes accidental) electrical mishaps. With over 5 million subscribers, Mehdi’s approach to teaching electronics through entertainment makes complex topics accessible while never compromising technical accuracy. His power amplifier tutorials exemplify this approach, breaking down intimidating audio circuits into understandable concepts while keeping viewers thoroughly entertained.
The ElectroBOOM Educational Philosophy
What makes ElectroBOOM’s teaching style so effective is the willingness to directly address misconceptions and explain why common approaches fail. Rather than simply presenting working designs, Mehdi often demonstrates what doesn’t work and explains precisely why. This negative-space learning—showing boundaries of what’s possible—builds deeper understanding than positive examples alone. When Mehdi deliberately shorts an output or forgets proper biasing, the dramatic (sometimes pyrotechnic) results make the underlying principles unforgettable.
The combination of whiteboard theory, circuit simulation, and physical construction creates multiple learning modalities. Mehdi derives equations explaining circuit behavior, simulates designs in SPICE to verify theoretical predictions, then builds actual hardware to validate both theory and simulation. This progression from abstract math through idealized simulation to real-world hardware demonstrates engineering methodology in action.
Power Amplifier Fundamentals
Mehdi’s amplifier tutorials typically begin with the most basic question: what does an amplifier actually do? By starting from first principles—an amplifier increases signal amplitude while preserving waveform shape—he builds up to practical implementations. The distinction between voltage amplification and power amplification becomes clear through examples showing how op-amps provide voltage gain but can’t deliver significant current, necessitating output stages for driving actual speaker loads.
Transistor operation gets thorough treatment. Rather than treating transistors as mysterious components, Mehdi explains how semiconductor physics enables current control, how biasing determines operating point, and why proper thermal management prevents thermal runaway. The NPN and PNP complementary push-pull output stage receives particular attention since it forms the heart of most audio power amplifiers. Understanding how one transistor sources current during positive half-cycles while the other sinks current during negative half-cycles clarifies why this topology works so well for audio.
Crossover distortion—the nasty artifact that occurs when complementary transistors don’t hand off smoothly—gets demonstrated both theoretically and practically. Mehdi shows how the dead zone where neither transistor conducts creates visible notches in output waveforms. The solution, biasing both transistors slightly on continuously (Class AB operation), eliminates crossover distortion while maintaining reasonable efficiency. Watching oscilloscope traces before and after proper biasing makes the improvement obvious.
Practical Design Considerations
Real power amplifiers require more than just the basic amplification stage. Input stages typically use op-amps for voltage gain and setting input impedance. Differential inputs enable balanced connections that reject common-mode noise. Mehdi explains how these input configurations work and when different approaches make sense, connecting abstract circuit topology to practical considerations like noise immunity and ground loop prevention.
Feedback networks stabilize amplifier behavior and set overall gain. Negative feedback reduces distortion dramatically by comparing output against input and correcting differences. Mehdi demonstrates both the benefits of feedback and potential pitfalls—too much loop gain at high frequencies causes oscillation, requiring careful compensation. Watching feedback networks oscillate then seeing how compensation components tame instability makes frequency-domain concepts concrete.
Power supply design deserves attention since amplifier performance depends critically on clean, stiff power delivery. Mehdi shows proper reservoir capacitor sizing, explains why separate power supplies for preamp and power stages reduce crosstalk, and demonstrates the importance of star grounding to prevent ground loops. These often-overlooked details separate reliable amplifiers from frustrating breadboard experiments that work erratically.
Thermal management cannot be ignored in power amplifiers. Output transistors dissipate significant heat, especially in Class AB designs where both transistors conduct simultaneously. Mehdi calculates power dissipation, shows proper heatsink selection using thermal resistance calculations, and demonstrates thermal runaway by deliberately omitting proper heatsinking—complete with smoke and drama that drives the point home memorably.
Safety and Protection Circuits
Mehdi takes safety seriously despite his comedic persona. Power amplifiers work with voltages that can shock and currents that can start fires if mishandled. Proper safety practices—working with one hand when possible, using isolation transformers, discharging capacitors before touching circuits—get emphasized repeatedly. The entertaining presentation doesn’t diminish these critical safety messages; if anything, the memorable delivery ensures viewers remember safety precautions.
Protection circuits save expensive speakers and prevent amplifier destruction. Output short-circuit protection limits current to safe levels when outputs accidentally short to ground or each other. Thermal shutdown circuits monitor heatsink temperature and disable the amplifier before damage occurs. DC offset protection prevents DC voltage reaching speakers if something fails in the amplifier chain. Mehdi explains not just how these circuits work but why they’re necessary, often by demonstrating spectacular failures they prevent.
Common Mistakes and Troubleshooting
Part of ElectroBOOM’s charm involves deliberately making mistakes then debugging them. This approach teaches troubleshooting methodology: when an amplifier doesn’t work, systematically check power supplies, verify biasing, look for oscillation, measure DC offset, and examine signal path stage-by-stage. Watching Mehdi work through problems models the debugging process all builders face.
Oscillation represents a particularly common power amplifier problem. Insufficient power supply bypassing, poor PCB layout, inadequate compensation—numerous factors can cause amplifiers to break into spontaneous oscillation. Mehdi demonstrates how to identify oscillation on oscilloscope, explains why it happens from feedback theory, and shows solutions. The combination of theoretical understanding and practical fixes equips viewers to tackle their own stability problems.
Ground loops and hum often plague amplifier builds. Mehdi explains how multiple ground return paths create voltage differences that amplify into audible hum. The star grounding solution—routing all grounds to a single point—breaks ground loops. Seeing hum disappear when proper grounding is implemented provides satisfying confirmation that theory matches practice.
Advanced Topics
More advanced ElectroBOOM content explores Class D switching amplifiers. The fundamental principle—modulating audio onto high-frequency carrier then filtering the carrier while retaining audio—gets explained from basic PWM through practical implementations using comparators and MOSFETs. Class D efficiency advantages become clear when comparing heatsink sizes between Class AB and Class D designs with equivalent output power.
Operational transconductance amplifiers (OTAs) appear in some tutorial as alternative topologies for power amplification. While less common than traditional voltage amplifiers, OTA-based designs offer certain advantages in specific applications. Mehdi’s willingness to explore alternative approaches broadens viewers’ understanding beyond cookbook designs.
Educational Value Beyond Audio
ElectroBOOM’s amplifier tutorials teach skills applicable throughout electronics. Transistor biasing, feedback analysis, frequency response, thermal calculations, layout considerations—these fundamentals extend well beyond audio applications. Viewers learning power amplifier design simultaneously develop general electronics competency that serves them in any project.
The channel also combats dangerous misinformation proliferating online. Mehdi regularly debunks bogus “free energy” devices, impossible amplifier claims, and snake-oil audio products. By rigorously applying electrical engineering principles and demonstrating why certain claims violate physics, he helps viewers develop critical thinking skills to evaluate extraordinary claims skeptically.
Conclusion
ElectroBOOM’s power amplifier tutorials represent electrical engineering education at its finest: technically rigorous, thoroughly practical, and genuinely entertaining. Mehdi’s unique presentation style makes intimidating topics approachable without dumbing down content or sacrificing accuracy. Whether you’re building your first audio amplifier or the hundredth, ElectroBOOM’s combination of theory, simulation, and hands-on construction provides insights that stick long after the video ends—sometimes quite literally, if you too learn what happens when things go wrong!
Watch and learn from ElectroBOOM on YouTube and support his educational mission on Patreon to ensure these valuable resources remain available for future generations of DIY audio enthusiasts.