Loudspeaker Equalization Filters With Low-Phase-Distortion Shaping
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Solution Overview
Problem
Conventional loudspeaker equalization filters, including graphic and parametric filters, fail to create the necessary filter shapes for advanced loudspeaker system equalization and often introduce phase distortion due to fixed frequency bands and interactions between adjacent bands.
Innovation Solution
A filtering system comprising a single pole filtering section for overall frequency response shaping and a parametric filtering section for localized corrections, using cascaded single pole filters and second-order parametric filters with adjustable control parameters to minimize phase distortion and accommodate various acoustic environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fixed frequency band filters (graphic equalizers) are used for loudspeaker equalization, then the tonal balance can be adjusted, but the frequency bands do not correspond to the necessary bands for loudspeaker system equalization and phase distortion occurs when adjacent bands are set incorrectly
Solution Approach 1:
The equalization system is divided into two independent sections: a first section with multiple single pole filters for overall frequency response shaping, and a second section with parametric filters for localized corrections. This segmentation allows each section to operate independently, preventing phase distortion from interacting across adjacent bands while maintaining versatile frequency response shaping capability.
Solution Approach 2:
The first filtering section uses single pole filters with break frequencies specifically positioned to address overall frequency response characteristics without creating phase distortion. The second filtering section uses parametric filters only for localized corrections where they are most effective. This local quality approach ensures that phase distortion is minimized in the critical frequency regions while maintaining equalization versatility.
2Ease of operation
If parametric filters are used for loudspeaker equalization, then localized corrections can be made, but in isolation they cannot create the filter shapes necessary for advanced loudspeaker equalization and setup
Solution Approach 1:
The system merges two different filtering approaches into a unified equalization solution: the first section combines multiple single pole filters to create complex overall frequency response shapes, while the second section uses parametric filters for localized corrections. This combination allows the system to achieve both the filter shapes necessary for advanced loudspeaker equalization and the localized correction capability of parametric filters.
Solution Approach 2:
The dual-section filtering system serves multiple functions: the first section handles overall frequency response shaping across the entire audible spectrum, while the second section provides localized parametric corrections. This multi-functionality allows a single system to address both broad frequency response issues and specific localized problems, making it universally applicable to various loudspeaker equalization needs.
3Adaptability or versatility
If high order filters are used for loudspeaker equalization, then various filter shapes can be created, but phase distortion is introduced
Solution Approach 1:
The system segments the filtering function into two parts: the first section uses multiple single pole filters (first order) to create the overall frequency response shapes without introducing significant phase distortion, while the second section uses parametric filters only for localized corrections. This segmentation allows filter shape variety to be achieved through the combination of multiple first-order filters rather than relying on high-order filters that would introduce phase distortion.
Solution Approach 2:
The system dynamically adjusts the equalization by using multiple single pole filters with independently adjustable break frequencies and gains in the first section, allowing flexible frequency response shaping without the phase distortion problems of fixed high-order filters. The second section dynamically applies parametric corrections only where needed, maintaining phase integrity in the critical frequency regions.
Data Source
AI summary
An improved filtering system for loudspeaker equalization is comprised of two filtering sections, a single pole filtering section having single pole filters for shaping the frequency response of the audio signal over the operative bandwidth of the equalized loudspeaker system, and a parametric filtering section that provides for localized parametric equalization for compensating for room or other environmental resonances. The filtering system of the invention can be used to create a wide variety of useful filter shapes, while minimizing phase distortion that can harm the transient response of phase-aligned loudspeakers of a loudspeaker system.