A loudspeaker controller for estimating a fundamental resonance frequency of a loudspeaker includes: an amplifier circuit, arranged to generate a driving signal of the loudspeaker according to an audio input signal; a sensing circuit, arranged to sense characteristics of the driving signal to generate a measurement signal; a plurality of band pass filter circuits, arranged to filter the measurement signal to generate a plurality of filter outputs, respectively, wherein the plurality of band pass filter circuits have different passbands; and an estimation circuit, arranged to estimate the fundamental resonance frequency according to the plurality of filter outputs.

In at least one embodiment, an audio amplifier system is provided. The system includes a loudspeaker and an audio amplifier. The loudspeaker transmits an audio output into a listening environment. The audio amplifier is programmed to receive an audio input signal and to generate an excursion signal corresponding to a first excursion level of the voice coil based on the audio input signal. The audio amplifier is further programmed to limit the excursion signal to reach a maximum excursion level and to determine a target pressure for an enclosure of the loudspeaker based on the maximum excursion level. The audio amplifier is further programmed to generate a target current signal based at least on the target pressure and to convert the target current signal into a target voltage signal to a target driving signal to drive the voice coil to reach the maximum excursion level.

Systems, methods, and apparatus are provided for recording high output power levels of sound at low sound pressure levels. For example, an apparatus comprises an enclosure, a speaker disposed within the enclosure, a microphone disposed within the enclosure, and an evacuation port. The evacuation port is configured to connect to a system that reduces a pressure level within the enclosure to a level that is less than an ambient air pressure level outside the enclosure. The enclosure is sealed or otherwise configured to provide a sealed enclosure, to maintain the reduced air pressure within the enclosure. The speaker can be driven by an amplifier at high output power levels to generate a distorted sound of an amplified electric musical instrument for recording purposes, while the reduced pressure level within the enclosure serves to attenuate the sound pressure level and perceived loudness which emanates from the speaker.

A controller for an electromechanical transducer is provided. The controller comprises driving means operable to actuate a mechanical output of the transducer; impedance cancelling means operable to at least partially cancel an electrical impedance of the transducer; and linearising means between an input of the controller and the driving means. The linearising means are operable to generate an output signal by modifying an input signal of the linearising means to compensate for nonlinear behaviour of the transducer. The linearising means are operable to receive one or more state signals indicative of one or more state variables of the transducer, the one or more state signals comprising a velocity signal indicative of a velocity of the mechanical output of the transducer.

A method for determining a displacement offset of a voice coil of a speaker, comprising: providing a drive signal comprised of a program content signal and a test signal to the voice coil of the speaker; determining at least one value representative of an impedance of the voice coil according to a voice coil voltage and a voice coil current, wherein the voice coil voltage and the voice coil current result from, at least, the test signal; determining whether the at least one value indicates that an offset displacement of the voice coil exceeds a predetermined offset distance; and reducing a magnitude of the drive signal provided to the voice coil if the at least one value indicates that the offset displacement of the voice coil exceeds the predetermined offset threshold.

In at least one embodiment, an audio system for extracting online parameters is provided. The system includes a loudspeaker and at least controller. The loudspeaker transmits an audio signal in a listening environment. The at least one controller includes a signal processing block and an adaptive filter. The signal processing block is programmed to provide a driving signal u(n) to drive the loudspeaker to transmit the audio signal. The adaptive filter is programmed to receive the driving signal and to receive a first varying signal i(n) from the loudspeaker in response to the loudspeaker transmitting audio signal. The adaptive filter is further programmed to generate an admittance curve for the loudspeaker based at least on the driving signal and the first varying signal.

The present disclosure relates to a speaker device including a circuit housing, an ear hook, a rear hook, and a speaker assembly. The speaker assembly may include a headphone core and a housing for accommodating the headphone core, the housing may include a housing panel facing a human body and a housing back opposite to the housing panel, and the headphone core may cause the housing panel and the housing back to vibrate. An absolute value of a difference between a first phase of a vibration of the housing panel and a second phase of a vibration of the housing back may be less than 60 degrees when a frequency of each of the vibration of the housing panel and the vibration of the housing back is between 2000 Hz and 3000 Hz.

A method of regulating power supply to a speaker and a system for regulating power supply to a speaker comprising a generating of a low frequency signal output to the speaker, sensing a current and a voltage of the speaker after the low frequency signal is output to the speaker, measuring an impedance of the speaker based on the current and voltage, determining a temperature of the speaker and comparing with a threshold value, and lowering a power supply to the speaker where the temperature is above the threshold value.

Acoustic transducer systems and methods of operating acoustic transducer systems are provided. The methods can involve: receiving an input audio signal; determining a position of a diaphragm; determining a correction factor, a motor force factor, a spring error factor, and a system spring factor based at least on the position of the diaphragm; determining a corrected voice coil current based at least on the input audio signal, the correction factor, the spring error factor, and a velocity of the diaphragm; and applying a corrected audio signal to a voice coil fixed to the diaphragm based at least on the corrected voice coil current, wherein the corrected audio signal corrects the input audio signal to compensate for non-linear characteristics of the acoustic transducer system.

Loudspeaker parameters are measured separately for various forward and rearward cone displacements, using a test signal that permits measurement of parameters at various degrees of either forward or rearward cone movement. The test signal uses a brief frequency sweep signal such as a logarithmic sweep signal, in combination with a very low frequency (VLF) audio tone having a fundamental frequency below, e.g., 10 Hz. The very low frequency audio tone may have a sine wave shape, a square wave shape or a clipped sine wave shape.