A matching circuit structure for effectively suppressing the low-frequency clutter of a power amplifier of a mobile phone, falling within the technical field of radio frequency Pas is provided. The circuit structure includes an input end, a blocking capacitor, a power amplifier (PA), an output matching network and an output end connected in series; and the matching circuit structure further includes a negative feedback network connected in parallel to a transmission end of the PA; the negative feedback network includes a resonant capacitor, a resonant inductor and a matching inductor; the resonant capacitor and the resonant inductor are connected in parallel to form a frequency selecting network, and the frequency selecting network is connected in series with the matching inductor and to the ground. The matching circuit structure above can be used to effectively suppress the low-frequency clutter of a power amplifier.

A sound emitting device includes a speaker box, a loudspeaker, a temperature sensor, a central processing unit and a signal amplifier. The speaker box includes a sound hole. The temperature sensor detects a temperature of the sound emitting device and generates a detection signal. The central processing unit pre-stores a default audio signal. When the central processing unit determines that the loudspeaker is in a standby state and the temperature of the sound emitting device exceeds a threshold value, the central processing unit issues the default audio signal. The signal amplifier is connected to and disposed between the central processing unit and the loudspeaker for amplifying the default audio signal and transmitting the amplified default audio signal to the loudspeaker. A vibration diaphragm of the loudspeaker undergoes a vibration action according to the amplified default audio signal.

A method of operating a headphone configured to be removed from and placed in close proximity to a user's ear can include generating an input signal by an input signal generating device. The method can also include determining whether an insertion event has occurred based on the generated input signal and causing the headphone to operate in 5 a low power mode responsive to an absence of an insertion event determination after a first period of time. The method can also include causing the headphone to operate in an ultra-low power mode responsive to the absence of an insertion event determination after a second period of time that occurs after the first period of time, the ultra-low power mode having a lower power consumption than the low power mode.

Methods, apparatus, systems and articles of manufacture are disclosed for audio equalization. Example instructions disclosed herein cause one or more processors to at least: detect an irregularity in a frequency representation of an audio signal in response to a change in volume between a set of frequency values exceeding a threshold; and adjust a volume at a first frequency value of the set of frequency values to reduce the irregularity.

Methods, apparatus, systems and articles of manufacture are disclosed for audio equalization. Example instructions disclosed herein cause one or more processors to at least: detect an irregularity in a frequency representation of an audio signal in response to a change in volume between a set of frequency values exceeding a threshold; and adjust a volume at a first frequency value of the set of frequency values to reduce the irregularity.

This application relates to driver circuitry (200) for receiving a digital input signal (D) and outputting, at first and second output nodes (203p, 203n), first and second analogue driving signals respectively for driving a transducer (101), e.g. loudspeaker, in a bridge-tied-load configuration. The driver circuitry may particularly be suitable for driving low-impedance transducers. The driver circuitry has first and second digital-to-analogue converters (201p, 201n) configured to receive the digital input signal and the outputs of the first and second digital-to-analogue converters are coupled to the first and second output nodes respectively. A differential-output amplifier circuit (202) has outputs connected to the first and second output nodes and is configured to regulate the outputs of the digital-to-analogue converters at output nodes to provide the analogue driving signals.

This application relates to driver circuitry (200) for receiving a digital input signal (D) and outputting, at first and second output nodes (203p, 203n), first and second analogue driving signals respectively for driving a transducer (101), e.g. loudspeaker, in a bridge-tied-load configuration. The driver circuitry may particularly be suitable for driving low-impedance transducers. The driver circuitry has first and second digital-to-analogue converters (201p, 201n) configured to receive the digital input signal and the outputs of the first and second digital-to-analogue converters are coupled to the first and second output nodes respectively. A differential-output amplifier circuit (202) has outputs connected to the first and second output nodes and is configured to regulate the outputs of the digital-to-analogue converters at output nodes to provide the analogue driving signals.

An example reverberation device configured for use with a musical instrument is disclosed. The example reverberation device comprises: (a) an input amplifier configured to receive an input signal from the musical instrument and output an amplified input signal based on the received input signal; (b) an input transducer connected to the input amplifier and configured to transmit the amplified input signal; (c) a reverberation plate comprising a bended surface, wherein the reverberation plate is connected to the input transducer, and wherein the reverberation plate is configured to output the input signal as an output signal at the bended surface; (d) an output transducer connected to the reverberation plate at the bended surface and configured to transmit the output signal; and (e) an output amplifier configured to receive the transmitted output signal from the output transducer and output an amplified output signal.

An audio signal reproduction apparatus includes a temperature detection unit detecting a temperature of a battery pack, a voltage detection unit detecting a voltage of the battery pack, and a control unit performing an output control on a basis of temperature information detected by the temperature detection unit and voltage information detected by the voltage detection unit.

An audio signal reproduction apparatus includes a temperature detection unit detecting a temperature of a battery pack, a voltage detection unit detecting a voltage of the battery pack, and a control unit performing an output control on a basis of temperature information detected by the temperature detection unit and voltage information detected by the voltage detection unit.