If you are looking for Small PA amplifier circuit using transistors. This may be first choice for you. The output is 100 watts power, very loud and very durable, easy to builds. Is is real?
This is three Simple 50w OTL audio amplifier circuit by 2N3055, can build easy and cheap, It's durable and very loud sound , Not needed speaker Protection. [...]
This is 60W RMS OTL integrated audio amplifier circuit using 2N3055 and normal transistor so cheap and can build easily and It's durable and very loud sound [...]
This is TBA820m Amplifier circuit stereo 2W+2W, supply voltage 12V, Easy to build and cheap. on DIP-8pins same LM386. but TBA820M use easy better. [...]