Loudspeaker Waveguide With Acoustically Transparent Layer
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Solution Overview
Problem
Loudspeakers with multiple drivers face issues with sound diffractions due to discontinuities on the front baffle surface, limiting the effectiveness of waveguides in controlling directivity, especially for low-frequency drivers, which can compromise sound quality and dynamic performance.
Innovation Solution
Positioning non-coaxial drivers on the front surface with an acoustically transparent layer that restricts higher frequencies while allowing low frequencies to pass, forming a continuous waveguide for mid- and high frequencies, and using a three-dimensional waveguide structure with strategically placed ports to optimize sound distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If non-coaxial drivers are positioned on the front surface to improve sound distribution, then sound quality improves, but dynamic performance deteriorates due to air flow restrictions
Solution Approach 1:
The front surface is segmented into distinct functional zones: a waveguide structure for mid/high frequencies and separate regions for low frequency drivers. This segmentation allows each zone to optimize its function without interfering with others, resolving the contradiction between sound quality and dynamic performance.
Solution Approach 2:
Different regions of the front surface are given different acoustic properties. The waveguide region has specific geometric features for directing mid/high frequencies, while low frequency driver regions have optimized port configurations for air flow. This local differentiation allows simultaneous optimization of sound quality and dynamic performance in different areas.
2Manufacturing precision
If the waveguide area is increased to extend frequency range control, then directivity control improves, but the available baffle area for other drivers decreases
Solution Approach 1:
The waveguide transitions from a two-dimensional surface feature to a three-dimensional structure with depth and volume. This dimensional change allows the waveguide to control a broader frequency range while occupying less surface area, as the acoustic control extends into the third dimension rather than requiring expanded surface coverage.
Solution Approach 2:
The waveguide structure is designed to nest around the coaxial driver assembly, utilizing the space created by the concentric arrangement of midrange and tweeter drivers. This nesting allows the waveguide to achieve extended frequency control without proportionally increasing the overall baffle area, as it integrates with rather than adds to the driver footprint.
3Manufacturing precision
If low frequency drivers are covered with a layer to maintain waveguide continuity, then waveguide effectiveness improves, but air flow for dynamic performance is restricted
Solution Approach 1:
The covering layer is designed with porous or perforated characteristics that allow air flow through the material while maintaining the acoustic continuity of the waveguide structure. This porous construction resolves the contradiction by permitting the air flow necessary for low frequency driver dynamic performance while preserving the waveguide's effectiveness for mid/high frequency directivity control.
4Adaptability or versatility
If drivers are positioned off-center to accommodate waveguide structure, then waveguide design flexibility improves, but sound diffractions increase
Solution Approach 1:
The waveguide structure employs asymmetric geometric features and positioning that are optimized for directing sound energy while minimizing diffraction effects. The asymmetric design allows the waveguide to accommodate non-coaxial driver positions and maintain effectiveness, while the specific asymmetric contours are designed to reduce harmful diffractions compared to symmetric alternatives.
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 configuration allows precise direction of the entire audio range to a 'sweet spot' while ensuring natural sound reflections in other directions, enhancing sound pressure distribution and avoiding dynamic performance issues with low-frequency drivers.
Implementation Method 1
an acoustically transparent layer which is essentially nonpermeable to and at least essentially limiting penetration of higher frequencies emitted by the waveguide driver and at the same time being permeable to other frequencies, more specifically the frequencies radiated by the non-coaxial driver
Implementation Method 2
the surroundings of the tweeter have been the most critical part in this sense. The applicant of the present application has created solutions where the surroundings of the tweeter have been the most critical part in this sense. The applicant of the present application has created solutions where the surroundings of the tweeter have been formed as a continuous waveguide for high and midrange frequency audio signals
Implementation Method 3
the layer used for forming the acoustically transparent layer is of porous material like felt or of expanded plastic with open cell structure or fabric
Data Source
AI summary
The present invention relates to a loudspeaker including an enclosure having front portion, side portions and back portion defining an inner volume, the front portion is formed as a waveguide surface and includes at least one driver in the center of the waveguide surface and is capable to radiate the main acoustic power of the loudspeaker to ambient volume in direction of first acoustic axis, and an additional driver attached to the enclosure. In accordance with the invention the additional driver is attached inside the enclosure such that a sub volume is formed inside the inner volume, the sub volume limited by the driver, spacers between the driver and the front portion, and the front portion of the enclosure, and at least one port is adapted to open from the sub volume to ambient volume either to side portion or back portion of the enclosure.