Loudspeaker Crossover Frequency Adjustment for Distortion Reduction
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Solution Overview
Problem
Existing loudspeaker systems face challenges in accurately dividing signals into low and high frequency bands due to overlapping frequency responses of subwoofers and tweeters, and environmental factors affecting the listening experience, necessitating an adaptable method to optimize cross-over frequency.
Innovation Solution
A method involving measurements and an algorithm to design a digital cross-over with minimal distortion, where the cross-over frequency is adjusted to minimize cumulative total harmonic distortion energy across the sound pressure spectrum by using a digital signal processor to divide input signals into optimal frequency bands for subwoofers and tweeters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fixed cross-over frequency is used to divide signals into low and high frequency bands, then the loudspeaker system can operate with simple signal division, but distortion increases due to overlapping frequency responses of subwoofers and tweeters
Solution Approach 1:
The patent implements dynamic adjustment of cross-over frequency based on measured distortion levels. The system continuously monitors total harmonic distortion and automatically modifies the cross-over frequency to minimize distortion, transforming the static signal division into an adaptive process that responds to actual acoustic conditions
Solution Approach 2:
The system employs feedback mechanisms where distortion measurements are fed back to the signal processor. The measured distortion information is used to iteratively adjust the cross-over frequency, creating a closed-loop control system that optimizes frequency separation based on actual performance
2Manufacturing precision
If the cross-over frequency is adjusted to minimize distortion, then frequency separation accuracy improves, but system complexity increases due to required measurements and algorithms
Solution Approach 1:
The system performs self-adjustment by automatically measuring its own distortion and modifying its cross-over frequency accordingly. The loudspeaker system uses its own output as the measurement source, eliminating the need for external calibration equipment or manual intervention
Solution Approach 2:
The system dynamically changes the cross-over frequency parameter based on measured distortion characteristics. By adjusting this critical parameter in response to actual performance data, the system optimizes frequency separation without requiring complex hardware modifications
3Adaptability or versatility
If environmental factors are accommodated to improve listening experience, then adaptability improves, but measurement and adjustment complexity increases
Solution Approach 1:
The system automatically adapts to environmental conditions by measuring distortion in the actual listening environment and adjusting cross-over frequency accordingly. This self-adaptation eliminates the need for manual environmental calibration or complex setup procedures
Data Source
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Figure 3
Figure 4a~4b
AI summary
The invention relates to a method and apparatus for adjusting a cross-over frequency of a loudspeaker system (100). The loudspeaker system (100) comprises at least a first loudspeaker (130) for frequencies below the cross-over frequency and a second loudspeaker (120-128) for frequencies above the cross-over frequency. A level of the first loudspeaker (130) is matched with the second loudspeaker (120-128) using a first test signal and a room response is compensated in the loudspeaker system (100) on the basis of the first test signal. The room response is measured using a second test signal. A maximum frequency for the first loudspeaker (130) and a minimum frequency for the second loudspeaker (120-128) are determined. A cross-over frequency that results in a minimum cumulative total harmonic distortion energy at one or more sound pressure levels is searched between the minimum and maximum frequency.