Constrained Acoustic Modulator Loudspeaker Enclosure Tuning

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Solution Overview

Problem

Conventional loudspeaker designs face limitations in producing a free and natural bass response, especially in the upper and mid-bass regions, due to inefficiencies and unwanted panel resonances, and often require large enclosures or complex tuning devices.

Innovation Solution

The implementation of a constrained acoustic modulator (CAM) within the loudspeaker enclosure, which is not electrically driven, allows for tuning without radiating audible sound, enabling the loudspeaker driver to operate as if in an infinite baffle while mitigating over-excitation and providing additional suspension, thus enhancing frequency response and reducing resonances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a sealed enclosure with acoustic suspension is used, then the loudspeaker becomes compact and easy to build, but it limits low bass frequencies and produces unwanted panel resonances and reflections

Engineering Contradiction:

Improveenclosure volumeVSAvoidfrequency response quality

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The enclosure is divided into two separate chambers: a first chamber housing the driver and a second chamber housing the passive radiator. This segmentation allows each chamber to be optimized independently, with the first chamber providing acoustic suspension and the second chamber providing bass reinforcement through the passive radiator, thereby resolving the contradiction between compact size and frequency response quality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A passive radiator is introduced as an intermediary element between the two chambers. The passive radiator is driven indirectly by pressure waves from the active driver and provides bass enhancement without requiring electrical input or complex tuning devices, thus improving low bass frequencies while maintaining a compact sealed enclosure design.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If an infinite baffle design is used, then the loudspeaker produces an open sound, but it is limited in power handling, sound pressure output, and excessive size

Engineering Contradiction:

Improvesound qualityVSAvoidenclosure volume

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The invention merges the advantages of infinite baffle design (open sound quality) with compact sealed enclosure by using a passive radiator in a sealed chamber. The passive radiator chamber acts as a compact bass reflex system that reproduces low frequencies similarly to an infinite baffle, while the sealed first chamber maintains the driver in a controlled acoustic environment, achieving both open sound and compact size.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If tuning devices such as ports or passive radiators are added to reinforce low frequencies, then low bass frequencies are improved, but the device complexity increases

Engineering Contradiction:

Improvefrequency response qualityVSAvoidenclosure structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The passive radiator is designed to be self-driven by pressure waves from the active driver without requiring external electrical input or complex tuning mechanisms. The system self-regulates the bass response through the interaction between the active driver and passive radiator, eliminating the need for electronically controlled tuning devices and reducing overall system complexity while maintaining improved low bass frequencies.

Inventive Principle:

Principle #25Self-service

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 CAM enables improved loudspeaker performance by allowing the driver to achieve freer movement within a smaller enclosure volume, canceling out resonances and vibrations, and augmenting frequency response, resulting in enhanced mid to low-frequency reproduction and reduced distortion.

Implementation Method 1

caused by the high air pressure changes in the enclosure

Methodology Applied

Scientific EffectAir pressure changes: Pressure Increase

Implementation Method 2

dampen the driver at its resonance frequency

Methodology Applied

Scientific EffectResonance damping: Damping

Implementation Method 3

react to air pressure input exerted on them directly or indirectly

Methodology Applied

Scientific EffectAcoustic radiation pressure: Acoustic Radiation Pressure

Data Source

PatentUS11968495B1Techniques for loudspeaker constrained acoustic modulator (CAM)

Publication Date: 2024.04.23 PAUL KRUEGER

AI summary

A loudspeaker is provided. The loudspeaker includes an enclosure including an opening, a driver, disposed at the opening in the enclosure, which is configured to be electrically driven. and a constrained acoustic modulator (CAM), disposed at the enclosure, which is not configured to be electrically driven. The CAM is configured to tune the enclosure without the CAM substantially radiating audible sound.