Horn Passageway Driver Coupling for Acoustic Phase Control
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Solution Overview
Problem
Existing sound reproduction systems with multiple drivers face challenges in achieving a flat acoustic power response across a wide frequency range, particularly above 2 or 3 kHz, due to the limitations of horn designs which result in severe high-frequency roll-off when listeners are not on-axis, and the need for sophisticated signal processing to compensate for overlapping frequency ranges.
Innovation Solution
A sound reproduction system where high-frequency and lower-frequency drivers are mutually coupled to a horn passageway, with the lower driver's upper frequency limited below the first cancellation notch and positioned at a preselected location along the horn with a specific cross-sectional area and expansion rate, to minimize phase shift and achieve a single acoustic source radiation pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If curved wall horns are used to achieve flat on-axis response, then low-frequency performance is improved, but high-frequency roll-off occurs off-axis
Solution Approach 1:
The horn is divided into multiple sections with different expansion rates: a first section with a first expansion rate for low-frequency loading, and a second section with a second expansion rate for high-frequency directivity control. This segmentation allows each section to optimize for its specific frequency range, resolving the contradiction between low-frequency performance and high-frequency off-axis response.
Solution Approach 2:
Different portions of the horn are given different local properties: the first section has properties optimized for low-frequency acoustic loading, while the second section has properties optimized for high-frequency directivity. This local differentiation allows the horn to simultaneously achieve good low-frequency response and controlled high-frequency radiation pattern.
2Object-affected harmful factors
If constant directivity horns are used to provide consistent sound quality, then off-axis response is improved, but low-frequency loading on drivers is reduced
Solution Approach 1:
The horn is segmented into a first section for low-frequency loading and a second section for high-frequency constant directivity. This allows the first section to provide strong low-frequency loading while the second section ensures consistent off-axis response, overcoming the limitation of conventional constant directivity horns that lack adequate low-frequency loading.
Solution Approach 2:
The first section of the horn is designed with local properties that maximize low-frequency acoustic loading on the driver, while the second section is designed with properties that provide constant directivity. This local quality differentiation resolves the contradiction between off-axis response consistency and low-frequency loading.
3Adaptability or versatility
If multiple horns are combined to cover wide frequency range, then frequency coverage is improved, but interference and dispersion patterns occur
Solution Approach 1:
Multiple frequency ranges are merged into a single horn structure with different sections handling different frequencies. The first section handles low frequencies while the second section handles high frequencies, eliminating the need for separate horns and the associated interference and dispersion problems.
Solution Approach 2:
The single horn is segmented into functional sections for different frequency ranges, allowing smooth frequency transition without the interference and dispersion patterns that occur when combining separate horns. The segmentation is designed to minimize phase differences and maintain coherent radiation.
4Reliability
If sophisticated signal processing is used to compensate for time origins, then frequency response is improved, but system complexity increases
Solution Approach 1:
The patent replaces sophisticated electronic signal processing with an acoustic solution using a multi-section horn. The horn's physical structure naturally manages phase and time differences through its geometry, eliminating the need for complex digital signal processing while achieving improved frequency response.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides improved frequency response and reduced phase shift, allowing for a smoother amplitude response and tighter radiation pattern control, effectively simulating a single acoustic source in time with minimal group delay and increased electroacoustic efficiency.
Implementation Method 1
at least one high frequency range driver and at least one lower frequency range driver are mutually coupled to the horn passageway
Implementation Method 2
reduced phase shift, allowing for a smoother amplitude response and tighter radiation pattern control, effectively simulating a single acoustic source in time with minimal group delay
Data Source
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AI summary
A sound reproduction system is disclosed in which a sound barrier defines a horn passageway having a first end and a second open end. A high frequency range driver is provided at the first end, and is mutually coupled with a lower driver to the horn passageway. The lower driver has an upper frequency end lower than a frequency of a first cancellation notch for the drivers. The lower driver is located at a position along the horn passageway at which the passageway has a preselected cross-sectional area which is no greater than an area of a round cross section having a circumference equal to one wavelength at the upper frequency end.