Control of loudspeaker output

Abstract

A method of controlling a loudspeaker output comprises deriving (10) an admittance function (y[k],16) over time from the voice coil voltage (v[k]) and current (i[k]). In combination with a delta function (´[k]), the force factor (¦) of the loudspeaker and the blocked electrical impedance (R e ), the input-voltage-to-excursion transfer function (h vx [k]) over time is obtained. This is used to control audio processing for the loudspeaker thereby to implement loudspeaker protection and / or acoustic signal processing. The invention provides a modelling and control approach which is not based on a parametric model. As a consequence, it does not require prior knowledge regarding the enclosure (e.g. closed or vented box) and can cope with complex designs of the enclosure.

Description

technical field [0001] The present invention relates to the control of loudspeaker output. Background technique [0002] It is known that the output of a loudspeaker should be controlled such that it cannot be simply driven by any input signal. For example, a significant cause of loudspeaker failure is a mechanical defect that occurs when the loudspeaker diaphragm displaces beyond a certain limit, usually provided by the manufacturer. Exceeding this displacement limit can damage the loudspeaker immediately, or can drastically reduce its expected lifetime. [0003] There are several methods for limiting the displacement of the loudspeaker's diaphragm, such as processing the input signal with a variable cutoff filter (high pass or otherwise) whose characteristics are controlled via a feedforward or feedback control loop. The measured control signal is called a displacement predictor, and this requires modeling the loudspeaker characteristics such that displacement can be pre...

AI Technical Summary

Problems solved by technology

Other discrepancies between expected and actual behavior can be attributed to defects caused during the production process or caused by mechanical damage (e.g. loudspeakers falling to the floor, and closed boxes becoming leaky due to small cracks), which may cause the model to no longer be valid

For example, if a closed box model is used, but the loudspeaker becomes an open box due to a mechanical defect, the closed box model is no longer valid

[0007] When the model is not valid, and thus the loudspeaker transfer function (e.g. voltage versus displacement function) and its parameters obtained from the model are not valid, the prediction of the diaphragm displacement cannot be precise

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