Audio refers to a set of audio systems that make sounds from a combination of electrical devices.

The sound system generally contains:

1. Sound source equipment: (listed as: DVD, CD, MP3, MP4, computer, mobile phone, microphone, etc.)

2, audio signal dynamic processing equipment (compressor, amplifier, mixer, audio processor, equalizer and other audio signal processing equipment)

3, audio signal amplification equipment (pre-stage power amplifier, post-stage power amplifier, digital power amplifier and other analog power amplifiers, equipment)

4, sound reduction equipment (full-range speakers, ceiling speakers, sound columns, line array speakers, array speakers, tweeters, subwoofers, etc.). The history of technology can be divided into four stages: electron tube, transistor, integrated circuit, and FET.