Bridge push-pull amplifier circuit

It is a bridge push-pull low-frequency power amplifier circuit with a very simple structure and an output power of up to 1W.
It can be used as an external power amplifier for a walkman, or as a power amplifier for telephones, intercom doorbells, alarms, etc. o VTI and VT2 form a differential input stage, and the signal
    amplified by the differential input stage directly drives the output stage of the bridge push-pull amplifier. . Since there is no intermediate amplification stage, the differential input stage also serves as a phase splitter. After the input signal is amplified by the differential input stage , it is divided into two signals of equal size and opposite phase, which are output from the collectors of VTi and VT2 respectively.     VT3~VT6 form a bridge push-pull power output stage, which amplifies the signal amplified by the differential input stage and then pushes the speaker o