Want to talk about what calls active sound box, it is necessary to talk about the composition of sound system first. The simplest sound system contains a few links: sound source, power amplifier and sound box. Audio source refers to sound broadcasting equipment such as radio, booth, CD player, VCD, DVD, MP3, etc. In the case of computers, optical drives and sound cards are sound source devices. The output voltage of general audio source equipment is small, about hundreds of millivolts to two volts, if directly connected to the speaker box may sound very small and even silent base.

And because the impedance of sound box is generally very low, the vast majority is between 4~8 ohms, the impedance of some special sound box in some frequency band and even less than two ohms, near short circuit, easy to make sound source equipment overload, severe and even the damage of the formation of sound source equipment. Thus, it is necessary to add a power amplifier between sound source and sound box (abbreviation of power put), the power that the weak signal of sound source output expands to satisfy goes to advance sound box, make sound box announces the volume that satisfies.

Work put has higher input impedance (general dozens of thousands ohm) and lower output impedance (a few zero ohm), can have buffer effect between sound source and sound box, won't make sound source equipment overload already, can advance sound box easily again. Function effect general Hi-Fi sound each link is relatively independent, through all kinds of connection can constitute sound system.