Hello elcircuit friends, this time elcircuit will post the TDA7294 power amplifier scheme added with the stepper circuit, this stepper circuit serves to increase the efficiency of the TDA7294 amplifier because it uses 2 power supply voltages, namely low voltage, and higher voltage. so the voltage when standby or output is still below the clip point of the low voltage, the medium used to supply the amplifier is the low voltage. and if it approaches the point of clip, the supply voltage will increase linearly (Class-G Amplifier). The following is a schematic of the reference IC TDA7294 datasheet which changed the value of the part so that it is easy to find the components. In the final stepper transistor section, you can use the TIP3055 / 2955, 2SC2922 / 1943, etc.
To facilitate assembly, elcircuit also provides a PCB file in the form of a Gerber file as shown below. The power in this TDA7294 + stepper amplifier circuit can produce up to 180W. Low Voltage supply 12VAC-25VAC Higher voltage supply 32VAC-45VAC.