Passive Radiator Clipping Prevention via Dynamic Excursion Control
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Solution Overview
Problem
Existing media playback systems face issues with audible distortion due to audio clipping caused by the passive radiator exceeding its excursion limits, leading to suboptimal sound pressure output.
Innovation Solution
Implementing a forward prediction model to predict the excursion of a passive radiator based on the voltage applied to active speakers, modifying the audio content to prevent clipping by limiting excursion within physical limits, and using feedback to adjust the prediction model for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the passive radiator is driven to high excursion to increase sound pressure output, then the sound pressure level is improved, but audible distortion occurs due to clipping when exceeding physical limits
Solution Approach 1:
The system performs preliminary detection of clipping conditions before they occur by monitoring the excursion signal against predetermined thresholds. When clipping is detected or predicted, the system proactively adjusts the gain of the passive radiator channel to prevent distortion, rather than reacting after distortion has occurred. This advance intervention maintains high sound pressure output while preventing audible distortion artifacts.
Solution Approach 2:
The system implements a feedback mechanism where the excursion signal from the passive radiator is continuously monitored and fed back to the processing circuitry. This feedback loop enables real-time detection of clipping conditions and dynamic adjustment of the passive radiator gain, allowing the system to maintain optimal sound pressure output while automatically preventing distortion when excursion limits are approached.
2Object-affected harmful factors
If the excursion limit is set conservatively to prevent clipping, then distortion is reduced, but the sound pressure output is limited
Solution Approach 1:
The system dynamically adjusts the effective excursion limit based on real-time signal conditions rather than using a fixed conservative threshold. The processing circuitry continuously monitors the excursion signal and adapts the gain control accordingly, allowing the passive radiator to operate closer to its true physical limits when conditions permit, while maintaining safety margins when needed. This dynamic approach maximizes sound pressure output without sacrificing distortion prevention.
Data Source
AI summary
Example techniques may involve controlling a passive radiator. An implementation may include a device receiving, via a network interface, audio content and generating an audio signal representing the audio content. Generating the audio signal involves modifying portions of the audio content to limit excursion of the speaker driver to less than an excursion limit when a forward prediction model indicates that the portions of the audio content are predicted to cause the speaker driver to move beyond the excursion limit. While playing back the generated audio signal via the audio stage, the device detects, via a sensor, clipping of the speaker driver and generates a feedback signal based on the detected clipping of the speaker driver. The device adjusts the forward prediction model based on the generated feedback signal.