人们对音质的需求表现在无止境地要求音频机器的优质。其中,音频放大器则显示出当代技术的精华,有的失真率小于0.01%。尽管达到如此低的失真率,但目前放大器尚不能满足人们的需求,所以人们要求原材料、电路和音响技术能测量出五官所不能探测的东西。在这个时期东北大学西泽润一教授于1971年,发表了称之为“具有三极管特性的垂直型 FET”(Vertical Field Effect Transistor)的新型晶体管并试制成功,引起了人们 People's demand for sound quality is manifested in an endless demand for high quality audio equipment. Among them, the audio amplifier shows the essence of contemporary technology, and some distortion rate of less than 0.01%. Despite such low distortion rates, amplifiers are not enough to meet people's needs at the moment, so people are demanding raw materials, circuitry, and sound technology to measure what the senses can not detect. During this period, Prof. Nishizawa Nishizawa of Northeastern University published a new type of transistor called “Vertical Field Effect Transistor” in 1971 and succeeded in trial production, causing people