To talk about what is an active speaker, it is necessary to talk about the composition of the sound system. In its simplest form, a sound system consists of several components: the source, the amplifier, and the speakers. Sound source refers to sound broadcasting equipment such as radio, deck, CD player, VCD, DVD, MP3, etc. When it comes to computers, optical drives and sound cards are both audio source devices. Generally, the output voltage of the audio source equipment is small, about hundreds of millivolts to two volts, if it is directly connected to the speaker, the sound may be very small or even silent.

And because the impedance of the speaker is generally very low, the vast majority of it is between 4~8 ohms, and the impedance of some specially planned speakers in some frequency bands is even less than two ohms, close to short circuit, it is easy to overload the sound source equipment, and even the damage to the sound source equipment may be formed when it is severe. Therefore, it is necessary to add a power amplifier (referred to as power amplifier) between the sound source and the speaker to expand the weak signal output by the audio source to the satisfactory power to promote the speaker, so that the speaker announces the satisfactory volume.

The amplifier has a high input impedance (generally tens of thousands of ohms) and a low output impedance (a few tenths of an ohm), which can play a buffering effect between the sound source and the speaker, which will not overload the sound source equipment and can easily advance the speaker. Functional effectGenerally, each link of Hi-Fi audio is relatively independent, and a complete audio system can be formed through the connection of various connections.