A class-D amplifier includes measurement of speaker current via the low-side drive transistors of the amplifier. In one embodiment, a class-D amplifier includes two high-side transistors, two low-side transistors, a first sense resistor, a second sense resistor, and a sigma delta analog to digital converter (σΔ ADC). The two high-side transistors and two low-side transistors are connected as a bridge to drive a bridge tied speaker. The first sense resistor is connected between a first of the low-side transistors and a low-side reference voltage. The second sense resistor is connected between a second of the low-side transistors and the low-side reference voltage. The ΣΔ ADC is coupled to the bridge to measure voltage across the first sense resistor and the second sense resistor.

Voice coil actuators and loudspeakers containing same. The voice coil actuators include moving voice coil assemblies that have multiple segments. Each segment of a moving voice coil assembly is separately controlled by an amplifier, one channel of an amplifier, and combinations thereof utilized in combination with a position sensor that senses the position of the moving voice coil assembly. By this arrangement, the voice coil actuators produce a linear force per unit current throughout the range of motion while obtaining the benefits and advantages associated with both over-hung and under-hung voice coil actuator designs.

A modular headphone system that can afford the wearer configurable choices of hearing protection and quality sound delivery for music and programming is provided. In an embodiment, a modular headphone includes a headband and an earpiece mounted to the headband. The earpiece comprises a can comprising a speaker, the can secured to the headband. A removable and replaceable music ear cup is removably mountable to the can to overlie the speaker. A removable and replaceable hearing protection/sound amplification (HP/amp) ear cup is removably mountable to the can to overlie the speaker.

A class D amplifier circuit receives an analog audio signal with a first reference voltage as its center level, and outputs an output pulse signal having a duty cycle that corresponds to the analog audio signal. A bias circuit generates a second reference voltage having a voltage level obtained as a division of the first reference voltage and the power supply voltage. A periodic voltage generating circuit of the class D amplifier circuit generates a periodic voltage having a triangle waveform or otherwise a sawtooth waveform having an amplitude that corresponds to the second reference voltage.

Aspects of the present disclosure relate to apparatus and methods for dynamically adjusting the common-mode input signal of a power amplifier, such as a class-D power amplifier. One example power amplifier circuit generally includes a first amplifier having a signal input and a power input; and a common-mode adjustment circuit having a first input coupled to the power input of the first amplifier, having an output coupled to the signal input of the first amplifier, and being configured to generate a common-mode signal to apply to the signal input of the first amplifier, based on a power supply voltage on the power input of the first 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 sound signal processing device supplies an output sound signal to an amplification device configured to supply a first sound signal to a high-frequency speaker and a low-frequency speaker. The sound signal processing device includes a high-pass filter, an amplitude limitation circuit, a low-pass filter, and a synthesis circuit. The high-pass filter removes a low-frequency component from an input sound signal to generate a high-frequency sound signal. The amplitude limitation circuit limits an amplitude of the input sound signal at or below a reference value to generate a second sound signal. The reference value corresponds to a clipping voltage of the amplification device. The low-pass filter removes a high-frequency component from the second sound signal to generate a low-frequency sound signal. The synthesis circuit synthesizes the high-frequency sound signal and the low-frequency sound signal to generate the output sound signal.

The application relates to a sound quality output method. The method includes: obtaining the current volume level input by the user; determine the audio signal gain difference between the current volume level and the baseline volume level according to the current volume level and the preset baseline volume level, determining an equal loudness curve difference between the current volume level and the baseline volume level according to the audio signal gain difference, and the current volume level and the baseline volume level, determining the audio quality response curve corresponding to the current volume level according to the equal loudness curve difference and the pre-stored audio quality response curve corresponding to the baseline volume level, determining the output signal parameters of multiple audio output channels according to the audio quality response curve corresponding to the current volume level. The application optimizes the sound quality effect and enhances acoustic experience.

An audio preamplifier (1) for a microphone, including: a chassis (2) with at least one audio input (17) and at least one audio output, a control panel (3) including a gain selector (10) being arranged on one of the sides of the chassis (2), the chassis (2) further including a receiving compartment inside which a first connector is arranged; and a cartridge (6) comprising a preamplification circuit and a gain control circuit, the cartridge (6) further having a second connector complementary to the first connector, the cartridge (6) being configured for being inserted in a removable manner into the receiving compartment of the chassis (2) so as to connect the first and second connectors. An audio preamplification kit includes an audio preamplifier (1) and a plurality of additional cartridges.

A portable digital audio system for a musician. The digital audio system includes an amplifier for processing an audio signal from a musical instrument or microphone electronically connected to the digital audio system and a speaker for playing a sound associated with the audio signal processed by the amplifier. The portable digital audio system also includes an audio control system providing operational control of the digital audio system and a primary housing for supporting the amplifier, the audio control system, and the speaker. Further, the digital audio system has a touch screen display in electronic communication with the audio control system and supported by the primary housing.