Some key events in the History of Power Amplifiers
The key to electronic amplification was first unlocked by Fleming’s patent for the two element ‘diode’ valve, inspired by a meeting with Edison. The diode could not amplify but only one more step would be needed.
Electronic audio amplification may have been first heard in the year Lee de Forest applied for a patent on the three element, triode tube he’d developed, on 25th October, 1906. By 1907, music had been informally broadcast by wireless for the first time.
The first mass use of amplification to reproduce speech and subsequently music dated from the experimental efforts of Pridham and others at the Magnavox Co. beginning in 1915. ...