Designing a 2.1 Channel Amplifier With the TDA2030

Full Specifications: https://docs.google.com/document/d/11Hutb2XuUZJ_NZS31ArYTHtnT9LSCabwxx69DxiAypk/edit?usp=sharing

I built this amplifier mainly as an excuse to learn two things properly: printed circuit board design and analog filter theory. Reading about both in isolation only gets you so far, so I decided to design, build and solder an actual working amplifier rather than leave the knowledge purely theoretical.

Three Amplifiers and a Crossover

The design uses three TDA2030 power amplifier stages, split by a second order Sallen Key Butterworth active crossover set at 120 hertz that sends the right frequencies to the satellite speakers and the rest down to the subwoofer. Getting that crossover point right meant actually working through the filter math rather than copying values from a reference design and hoping for the best.

Power, Heat and a Few Small Improvements

Power comes from a full wave split supply built around a center tapped transformer, with local decoupling and a shared heatsink to keep everything at a reasonable temperature under load. I did the schematic capture and board layout myself in KiCad, then added volume and bass trim potentiometers as a practical improvement over the base reference design, since being able to adjust the sound after the fact felt worth the extra components.

Where the Filter Math Goes Next

One detail I am particularly glad I took the time to work through is using the crossover's transfer functions and bilinear transforms to model the equivalent digital IIR biquad filters. That gives me a clear bridge toward eventually porting the same crossover logic onto a microcontroller, so the next version of this project could replace analog filtering with digital signal processing entirely.