PA amplifier history began with Lee De Forest's 1906 invention of the triode vacuum tube, enabling the first electronic amplification, leading to early systems by Pridham & Jensen (Magnavox) in 1915 for public speech; vacuum tubes dominated until the 1960s transistor revolution, making smaller, portable systems possible, while the 1970s-80s saw huge concerts drive innovations in power, efficiency (like Tycobrahe, Crown amps), and speaker design, evolving into today's high-efficiency, digital PA systems.