Detailed introduction to the functions and composition of active loudspeakers

To discuss what active speakers are, we must first discuss the composition of the sound system. The simplest sound system consists of several steps: sound source, amplifier, and speakers. A sound source refers to sound playback devices such as radios, cassette players, CD players, VCDs, DVDs, MP3 players, etc. In computers, both optical drives and sound cards are sound source devices. The output voltage of typical sound source devices is relatively low, ranging from a few hundred millivolts to two volts. If connected directly to the speaker, the sound can be very quiet or even nonexistent.

And since the impedance of the speaker is usually very low, most of them between 4 and 8 ohms, and for some specially designed speakers, the impedance is even below 2 ohms in certain frequency bands, which is similar to a short circuit situation and can easily overload the sound source devices. In more extreme cases, it can even damage the sound source devices. Therefore, it is necessary to add an amplifier (or amplifier for short) between the sound source and the speaker to amplify the weak signal output from the sound source to a sufficient power to drive the speaker so that the speaker can produce a sufficient volume level.

At the same time, the amplifier has a higher input impedance (usually several tens of thousands of ohms) and a lower output impedance (a few tenths of an ohm), which can serve as a buffer function between the sound source and the speaker, preventing overloading of the sound source devices and easy driving of the speaker. Functional effect: Typically, each stage of Hi-Fi audio is relatively independent, and a complete audio system can be formed by connecting various terminals.