Floating Waveguide Loudspeaker for Crossover Directivity Control
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Solution Overview
Problem
Conventional two-way loudspeaker designs with large low-frequency drivers suffer from poor off-axis directivity, cone break-up, and inefficient low-frequency performance due to driver displacement and mechanical resonance issues in the crossover region, leading to distorted sound coverage for audiences.
Innovation Solution
A two-way loudspeaker design with a condensed geometry between high-frequency and low-frequency drivers, featuring a floating waveguide in front of the low-frequency driver, which redirects very low frequency energy through additional radiation paths to improve crossover region performance and mitigate cone break-up modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large low-frequency drivers are used to improve low frequency performance and acoustic output, then the pistonic region performance is improved, but the region above pistonic behavior suffers from cone break-up modes and erratic directivity behavior
Solution Approach 1:
The radiating surface of the low-frequency driver is segmented into multiple zones with different acoustic functions. A central portion radiates sound directly, while outer portions are acoustically coupled to a waveguide structure. This segmentation allows the large driver to operate in its optimal pistonic region while the waveguide handles the problematic upper frequency range, eliminating cone break-up and erratic directivity.
Solution Approach 2:
A waveguide structure is introduced as an intermediary between the low-frequency driver and the acoustic field. The waveguide is acoustically coupled to the outer portions of the driver's radiating surface and serves as a mediator that transforms the problematic acoustic output from the large driver into controlled, predictable radiation patterns, eliminating directivity issues in the crossover region.
2Volume of moving object
If the high frequency driver is positioned close to the low frequency driver to condense geometry, then package size is reduced, but driver displacement and mechanical resonance issues occur in the crossover region
Solution Approach 1:
Instead of positioning the high-frequency driver coaxially with the low-frequency driver (one-dimensional arrangement), the invention uses a waveguide structure that extends in a different spatial dimension. The waveguide is coupled to the outer portions of the LF driver's radiating surface and extends forward, allowing the HF driver to be positioned in a condensed geometry while maintaining proper acoustic separation through the waveguide's three-dimensional structure.
3Adaptability or versatility
If the proximal opening area of the waveguide is smaller than the radiating surface opening area, then a second radiation path is defined around the waveguide, but acoustic energy distribution becomes complex
Solution Approach 1:
The waveguide structure is designed with locally optimized properties: the proximal opening is positioned and sized to create a specific acoustic relationship with the LF driver's radiating surface. The waveguide's outer surface acts as a reflective boundary that shapes the second radiation path, while the distal opening is sized to control the first radiation path. This local quality control simplifies the overall acoustic energy distribution despite multiple radiation paths.
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
This design enhances crossover region performance by aligning acoustic centers closer together, reducing erratic directivity and cone break-up, resulting in improved sound coverage and uniform acoustic output across a larger audience area.
Implementation Method 1
The LF waveguide may define a first radiation path for LF acoustic energy. The proximal opening may have a proximal opening area that is smaller than a radiating surface opening area to define a second radiation path for the LF acoustic energy around an outer surface of the LF waveguide.
Implementation Method 2
When an alternating current electrical audio signal is applied to its voice coil (a coil of wire suspended in a circular gap between the poles of a permanent magnet), the voice coil is forced to move rapidly back and forth due to Faraday's law of induction, which causes a diaphragm (usually conically shaped) attached to the coil to move back and forth, pushing on the air to create sound waves.
Data Source
AI summary
One or more embodiments of the present disclosure relate to a two-way loudspeaker design that forces a condensed geometry between low frequency (LF) and high frequency (HF) drivers and then “floats” a midrange waveguide in front of the LF driver. This is a hybrid design meant to benefit from the close proximity of acoustic centers without introducing a central axis obstruction for the LF driver. In addition, the LF and HF waveguides and associated acoustic elements are used to redirect very low frequency energy not supported adequately by the LF waveguide to exit freely using other paths.