Electron tube
In 1906, American Deforest invented the vacuum triode, which created the beginning of human electroacoustic technology. Baer laboratory in 1927 invented the negative feedback technology, the development of audio technology has entered a new era, as more representative of the Williamson amplifier, is the successful use of the negative feedback amplifier, the distortion is greatly reduced. In the 50s of last century, the development of electron tube amplifier reached a high tide period, and various electron tube amplifiers emerge one after another. As the main technical indicators of electronic tubes, amplifiers are sweet and mellow, is still favored by fans.
Transistor
The emergence of transistors in the last century, 60s, so that the vast number of audio enthusiasts into a broader sound world. The transistor amplifier has the characteristics of fine and striking tone, low distortion, wide frequency response and dynamic range.
Integrated circuit
The last century at the beginning of 60s, the United States launched the first new member in audio technology integrated circuit, to the last century at the beginning of 70s, the integrated circuit with its high quality and low price, small volume, multiple functions and other characteristics, gradually recognized by the audio industry. Up to now, thick film audio integrated circuit and operational amplifying integrated circuit have been widely used in acoustic circuit.
Field effect transistor
In the mid 70s of the last century, Japan produced the first field effect power tube. Because of the field effect, the audio power tube has the characteristics of pure, thick and sweet tone of the electronic tube and the dynamic range of 90dB and THD<0.01% (100kHz), and is soon popular in the audio industry. Many amplifiers nowadays use field effect transistors as the last stage output.
