Audio power amplifier inside the chassis of the main product. The audio amplifier was invented around 1912 by Lee De Forest, made possible by his invention of the first practical amplifying electrical component, the triode vacuum tube (or "valve" in British English) in 1907. The triode was a three terminal device with a control grid that can modulate the flow of electrons from the filament to the plate. The triode vacuum amplifier was used to make the first AM radio. Early audio power amplifiers were based on vacuum tubes and some of these achieved notably high audio quality (e.g., the Williamson amplifier of
Xiaodong Wang (electrical engineer) Conference. Wang has many research interests, but chooses to focus on the areas of information theory, signal processing, and communications. Furthermore, he has influential published research in the areas of wireless communications, statistical signal processing, parallel and distributed computing, nanoelectronics, and quantum computing. In 2003 he published a book entitled "Wireless Communication Systems: Advanced Techniques for Signal Reception", published by Prentice Hall. Recently he is also working on the emerging field of genomics signal processing and information theoretic genomics. Xiaodong Wang (electrical engineer) Xiaodong Wang () is an information theorist and professor of Electrical Engineering at Columbia University. He earned