Band-Splitting Audio Time Alignment Without Crossover Distortion
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Solution Overview
Problem
Existing band-splitting time compensation signal processing devices for audio systems with multiple speaker units driven by a single amplifier via a crossover network struggle to independently adjust the time axis of each speaker unit while maintaining linearity of transfer characteristics, often resulting in signal loss and frequency distortions near the crossover frequency.
Innovation Solution
A band-splitting time compensation signal processing device that includes a band-splitting circuit to extract high-frequency and low-frequency components, a delay circuit for time adjustment, and a mixing circuit to combine the signals, ensuring independent time axis adjustment and improved linearity of transfer characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a listening position automatic compensation device divides the band at about the same frequencies as the crossover network circuit and passes individual signals through delay circuits, then the bias in the sound field resulting from distance differences is corrected, but a signal is lost through the band-splitting circuit and a signal is added double, deteriorating the linearity of reproduced sounds and producing peaks or dips in the frequency characteristics near the band-splitting frequency
Solution Approach 1:
The patent creates a copy of the crossover network's band-splitting function through the band-splitting circuit (211), allowing time adjustment to be applied to the copied signals before they are combined. This copying approach enables independent time axis control while maintaining the original signal paths intact, avoiding the signal loss and double-addition problems that occur when trying to adjust time directly in the crossover network.
2Measurement precision
If independent amplifiers are prepared for each speaker unit with band splitter and delay circuits, then time alignment processing can be carried out to adjust arrival time of sounds from individual speaker units, but the cost increases, wiring becomes complicated and larger space is required
Solution Approach 1:
The patent merges multiple independent amplifier channels into a single amplifier by combining the band-split signals after time adjustment in the mixing circuit (213). This consolidation maintains the time alignment capability that would otherwise require separate amplifiers, while reducing the overall system complexity, wiring requirements, and space occupation by using one amplifier for all speaker units.
3Measurement precision
If a digital signal processing circuit is used before the amplifier to correct relative time difference between band-split speaker units, then time axis adjustment can be performed, but the frequency characteristics and phase characteristics other than time axis are corrected simultaneously, making it impossible to adjust the time axis alone without changing the other characteristics
Solution Approach 1:
The patent segments the signal processing into distinct functional blocks: band-splitting circuit (211) for frequency separation, delay circuit (212) for time adjustment, and mixing circuit (213) for signal combination. This segmentation allows the delay circuit to operate independently on each band after splitting, enabling precise time axis control without affecting frequency or phase characteristics of the overall system, as each segment handles only its specific function.
Data Source
AI summary
A band-splitting time compensation signal processing device 2 includes a band-splitting circuit 211 for extracting, after extracting a signal of a high-frequency band component or low-frequency band component from an input signal, a signal of the low-frequency band component or high-frequency band component by subtracting the signal of the high-frequency band component or low-frequency band component from the input signal; a delay circuit 212 for delaying, for adjusting arrival time, at least one of the high-frequency band component and low-frequency band component output from the band-splitting circuit 211; and a mixing circuit 213 for combining the high-frequency band component or low-frequency band component output from the delay circuit 212 with the low-frequency band component or high-frequency band component output from the band-splitting circuit 211.