Electroacoustic Actuator Array Impedance Matching
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Solution Overview
Problem
Conventional Bessel-weighted loudspeaker arrays face issues with overall impedance, either being too high when series-connected or too low when parallel-connected, which is not optimal for conventional audio amplifiers, leading to potential amplifier damage or inefficient operation.
Innovation Solution
The electroacoustic actuators are connected in a configuration where parallel branches are mirrored to series connections and vice versa, achieving an overall impedance closer to that of individual loudspeakers, allowing for approximated Bessel weighting without excessive impedance levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If loudspeakers are connected in series to achieve Bessel weighting, then the amplitude distribution is improved, but the overall impedance becomes too high (14Ω or 28Ω) for conventional amplifiers
Solution Approach 1:
The array is divided into multiple parallel branches, each containing series-connected loudspeakers. This segmentation allows the Bessel weighting to be achieved through the combination of branches rather than a single series connection, thereby reducing overall impedance while maintaining amplitude distribution accuracy.
Solution Approach 2:
Multiple parallel branches are combined to achieve the desired Bessel weighting. By merging the impedance characteristics of several branches in parallel, the overall impedance is reduced to a range compatible with conventional amplifiers (4Ω to 8Ω) while preserving the amplitude distribution required for Bessel weighting.
2Ease of manufacture
If loudspeakers are connected in parallel to reduce impedance, then amplifier compatibility is improved, but the overall impedance becomes too low (1.14Ω or 2.29Ω) causing excessive current demand
Solution Approach 1:
Instead of a single parallel connection, the array is segmented into multiple parallel branches with series connections within each branch. This creates an intermediate impedance level that is neither too high nor too low, ensuring amplifier safety by preventing excessive current demand while maintaining compatibility with conventional amplifiers.
Solution Approach 2:
The impedance parameter is adjusted to an optimal range (4Ω to 8Ω) through the specific configuration of parallel branches with series-connected loudspeakers. This parameter change ensures that the impedance is suitable for conventional amplifiers without causing excessive current draw that could damage the amplifier.
3Power
If the number of loudspeakers in the array is increased beyond five, then the radiation area and sound pressure level are improved, but the impedance problem becomes more severe with conventional connection methods
Solution Approach 1:
The array is organized into multiple parallel branches, each containing series-connected loudspeakers. This segmentation provides a scalable framework where additional loudspeakers can be added to increase power output while the branch structure maintains impedance within acceptable ranges, preventing the impedance problems that would otherwise occur with larger arrays.
Solution Approach 2:
The parallel branch configuration serves multiple functions simultaneously: it achieves Bessel weighting for accurate amplitude distribution, maintains impedance within the 4Ω to 8Ω range for amplifier compatibility, and provides a scalable structure for increasing power output by adding more loudspeakers to existing or new branches.
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 enables the use of conventional amplifiers while maintaining a sound pressure level and radiation characteristics similar to ideal Bessel weighting, ensuring manageable impedance and preventing amplifier overload.
Implementation Method 1
an array of at least five electroacoustic actuators (101, 102, 103, 104, 105)
Implementation Method 2
electroacoustic actuators are connected such that, in a first parallel branch (110a), at least two electroacoustic actuators are connected in series
Data Source
AI summary
An array of electroacoustic actuators includes at least five electroacoustic actuators, wherein the electroacoustic actuators are connected such that, in a first parallel branch, at least two electroacoustic actuators are connected in series and, in a second parallel branch, an electroacoustic actuator is connected in series to a parallel connection of two electroacoustic actuators, the first parallel branch being connected in parallel to the second parallel branch, and the parallel branches connected in parallel being configured to be driven by an actuator amplifier, or wherein the electroacoustic actuators are connected such that, in a first serial branch, at least two electroacoustic actuators are connected in parallel and, in a second serial branch, an electroacoustic actuator is connected in parallel to a serial connection of two electroacoustic actuators, the first serial branch being connected in series to the second serial branch, and the parallel branches connected in series being configured to be driven by an actuator amplifier.