Motional feedback system
AssigneeHarman International Industries, Incorporated
InventorGerald R. Stanley
Life of this patent
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Abstract
An audio amplifier is operated in an audio system with optimized source impedance to minimize distortion in a loudspeaker that is paired with the audio amplifier. The audio amplifier provides an amplified audio signal to drive the loudspeaker. A variable output impedance of the audio amplifier is controlled using a feedback control loop to allow negative output impedance at low frequencies that changes to positive output impedance at higher frequencies. The change from negative output impedance to positive output impedance occurs at a determined threshold frequency or determined transitional frequency band.
Claims26
A motional feedback system for minimizing non-linear distortion of loudspeakers comprising:
- an audio amplifier having an output with a variable output impedance, the output configured to supply an amplified audio signal to drive a loudspeaker;
- an impedance control module included in the audio amplifier, the impedance control module configured to control the variable output impedance as a function of the frequency of the audio signal;
- the impedance control module configured to vary the output impedance to represent a negative impedance below a determined threshold frequency;
- and
- the impedance control module further configured to vary the output impedance to represent a positive impedance above the determined threshold frequency.
A method of minimizing non-linear distortion of a loudspeaker comprising:
- receiving an audio signal from an audio source;
- amplifying the audio signal with an audio amplifier;
- driving a loudspeaker with the amplified audio signal using an output of the audio amplifier, the output having a controlled output impedance;
- controlling the output impedance to present a negative impedance below a determined threshold frequency;
- and
- controlling the output impedance to present a positive impedance above the determined threshold frequency.
A computer readable storage media configured to store computer readable instructions that are executable by a processor to minimizing non-linear distortion of loudspeakers, the computer readable storage media comprising:
- instructions to receive an audio signal from an audio source, the audio source including a plurality of frequencies;
- instructions to process the audio signal with an audio amplifier;
- instructions to enable output of the processed audio signal on an audio output of the audio amplifier to drive a loudspeaker, the audio output having an output impedance;
- instructions to control the output impedance of the audio amplifier to a negative impedance for a first band of frequencies of the audio signal below a determined threshold frequency;
- and
- instructions to control the output impedance of the audio amplifier to a positive impedance for a second band of frequencies of the audio signal above the determined threshold frequency.
A motional feedback system for loudspeakers comprising:
- an audio amplifier having an input and an output, the input configured to receive an audio signal, and the output configured to supply an amplified version of the audio signal, the amplified version of the audio signal used to drive a loudspeaker;
- a current sensor configured to sense a current of the amplified audio signal supplied at the output, and supply the current as a feedback current to the audio amplifier to minimize distortion of the loudspeaker;
- and
- a filter included in the audio amplifier and coupled with the current sensor, the filter configured to selectively transition the feedback current between a positive feedback current in a first range of frequencies, and a negative feedback current in a second range of frequencies that are higher than the first range of frequencies.
A method of minimizing non-linear distortion of loudspeakers comprising:
- receiving an audio signal from an audio source, the audio source including a plurality of frequencies;
- amplifying the audio signal with an audio amplifier;
- driving a loudspeaker with the amplified audio signal;
- monitoring a current supplied in the amplified audio signal;
- controlling an output impedance of the audio amplifier to be a negative impedance for those frequencies below a determined threshold frequency based on the current;
- and
- controlling the output impedance of the audio amplifier to be a positive impedance for those frequencies above the determined threshold frequency based on the current.
Dependencies are inferred from the claim text.