The development history of audio technology can be divided into four stages: tube, transistor, integrated circuit and FET.
In 1906 the American Deforest invented the vacuum transistor, creating a precedent for human electro-acoustic technology. 1927 Bell Labs invented the negative feedback technology, so that the development of audio technology into a new era, more representative, such as Williamson amplifier, the more successful use of negative feedback technology, the amplifier greatly reduced the distortion. 50 years of last century, the development of tube amplifier reached a climax, a variety of tube amplifier after another. As the tube amplifier sound sweet, rounded, still enthusiastic favorite.
60 years of the emergence of transistors, so that the majority of audio enthusiasts into a broader audio world. Transistor amplifier with delicate and moving sound, low distortion, wide frequency response and dynamic range and so on.
In the early 1960s, the United States first released the new members of audio technology - integrated circuits, to the early 70s, integrated circuits with its quality and cheap, small size, multi-functional features, and gradually be recognized by the audio industry. Development so far, thick film audio integrated circuits, operational amplifiers integrated circuits are widely used in audio circuits.
Field effect transistor
In the mid-1970s, Japan produced the first field-effect power tube. As the field effect power tube at the same time with a tube thick, sweet tone and dynamic range of 90dB, THD <0.01% (100kHz) characteristics, and soon in the audio sector popular. Many of today's amplifiers use field-effect transistors as final outputs.