A power tube connection structure includes a substrate, a printed circuit board, and a power tube, where a through groove allowing the power tube to pass through is cut into the printed circuit board, a mounting groove is cut into the upper surface of the substrate at a location corresponding to the through groove, one end of the power tube extends through the through groove, and is welded onto a bottom face of the mounting groove, the end of the power tube that extends into the mounting groove abuts onto a side wall of the mounting groove close to an output end of the power amplifier, and a solder flux escape channel is made into the side wall of the mounting groove close to the output end of the power amplifier.

An audio amplifier includes an output stage including a first toroidal transformer with a first pair of secondary windings that are coupled in parallel across an output terminal. The output stage further includes a second toroidal transformer with a second pair of secondary windings that are connected in a series combination that is coupled across the output terminal.

An audio amplifier includes an output stage including a first toroidal transformer with a first pair of secondary windings that are coupled in parallel across an output terminal. The output stage further includes a second toroidal transformer with a second pair of secondary windings that are connected in a series combination that is coupled across the output terminal.

A power tube connection structure includes a substrate, a printed circuit board, and a power tube, where a through groove allowing the power tube to pass through is cut into the printed circuit board, a mounting groove is cut into the upper surface of the substrate at a location corresponding to the through groove, one end of the power tube extends through the through groove, and is welded onto a bottom face of the mounting groove, the end of the power tube that extends into the mounting groove abuts onto a side wall of the mounting groove close to an output end of the power amplifier, and a solder flux escape channel is made into the side wall of the mounting groove close to the output end of the power amplifier.

A power tube connection structure includes a substrate, a printed circuit board, and a power tube, where a through groove allowing the power tube to pass through is cut into the printed circuit board, a mounting groove is cut into the upper surface of the substrate at a location corresponding to the through groove, one end of the power tube extends through the through groove, and is welded onto a bottom face of the mounting groove, the end of the power tube that extends into the mounting groove abuts onto a side wall of the mounting groove close to an output end of the power amplifier, and a solder flux escape channel is made into the side wall of the mounting groove close to the output end of the power amplifier.

An audio amplifier includes an output stage including a first toroidal transformer with a first pair of secondary windings that are coupled in parallel across an output terminal. The output stage further includes a second toroidal transformer with a second pair of secondary windings that are connected in a series combination that is coupled across the output terminal.

An audio amplifier includes an output stage including a first toroidal transformer with a first pair of secondary windings that are coupled in parallel across an output terminal. The output stage further includes a second toroidal transformer with a second pair of secondary windings that are connected in a series combination that is coupled across the output terminal.

An amplifier device includes a back-EMF voltage shorting circuit between a power supply terminal located on a primary side of an output transformer and a constant potential terminal grounded. The back-EMF voltage shorting circuit is provided with a capacitor and a diode in parallel. When a back-EMF voltage input into a circuit of an amplifier device is a positive potential, a back-EMF current flows from the power supply terminal toward the constant potential terminal, and the back-EMF current is short-circuited by the capacitor at this time. On the other hand, when the input back-EMF voltage is a negative potential, the back-EMF current flows from the constant potential terminal toward the power supply terminal, and is short-circuited by the diode at this time.

The present disclosure discloses an audio output circuit including an audio power amplifier, a mute control circuit and a microcontroller, the audio power amplifier includes a power input terminal, a mute control terminal and an audio signal output terminal, the power input terminal is used to connect a power supply to obtain a power supply voltage, the mute control terminal is connected with the microcontroller through the mute control circuit and is grounded by a pull-down resistor, the audio signal output terminal is used to output an audio signal, the mute control circuit is also connected to the power supply for disconnecting the mute control terminal from the microcontroller when the power supply voltage is less than a preset voltage. The present disclosure also provides an audio device. According to the present disclosure, it is possible to effectively prevent the POP sound of the speaker of the audio device.

The present disclosure discloses an audio output circuit including an audio power amplifier, a mute control circuit and a microcontroller, the audio power amplifier includes a power input terminal, a mute control terminal and an audio signal output terminal, the power input terminal is used to connect a power supply to obtain a power supply voltage, the mute control terminal is connected with the microcontroller through the mute control circuit and is grounded by a pull-down resistor, the audio signal output terminal is used to output an audio signal, the mute control circuit is also connected to the power supply for disconnecting the mute control terminal from the microcontroller when the power supply voltage is less than a preset voltage. The present disclosure also provides an audio device. According to the present disclosure, it is possible to effectively prevent the POP sound of the speaker of the audio device.