Barrel-Shaped Open-Back Speaker Cabinet Design

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Solution Overview

Problem

Conventional audio speaker cabinet designs suffer from destructive interference and distortion due to the cancellation of sound pressure waves generated by the front and back of the driver, leading to reduced sound quality and inefficiency, with sealed cabinets being cumbersome and ported cabinets being difficult to design and build.

Innovation Solution

A barrel-shaped cabinet with two opposing open ends and an internal mounting ring for a round, open-back, cone type driver, which separates and directs sound pressure waves linearly through the cabinet, simulating a genuine infinite baffle to minimize cancellation and distortion, allowing efficient use of both front and back sound waves.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If sound pressure waves from front and back of driver are allowed to combine, then both waves are utilized efficiently, but destructive interference occurs causing sound wave cancellation and reduced sound quality

Engineering Contradiction:

Improveutilization of sound pressure wavesVSAvoidsound wave cancellation

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The cabinet is divided into two separate chambers (front chamber and rear chamber) that are acoustically isolated from each other. The driver divides the cabinet into these two discrete open chambers, preventing sound pressure waves from the front and back of the driver from meeting and canceling each other, while still allowing both waves to be utilized efficiently in their respective chambers.

Inventive Principle:

Principle #1Segmentation

2Object-affected harmful factors

If sealed cabinet is used to isolate sound pressure waves, then destructive interference is prevented, but cabinet size increases and design becomes cumbersome

Engineering Contradiction:

Improvedestructive interferenceVSAvoidcabinet design complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Instead of enclosing the cabinet to prevent sound wave interaction, the invention inverts the approach by leaving the cabinet open at both ends. The open barrel-shaped design with two open ends allows sound pressure waves to escape freely while the internal mounting ring and chamber division maintain acoustic separation, simplifying the design while preventing destructive interference.

Inventive Principle:

Principle #13The other way round (Inversion)

3Object-affected harmful factors

If ported cabinet is used to transform sound pressure waves, then destructive interference is avoided, but cabinet design and construction becomes more difficult

Engineering Contradiction:

Improvedestructive interferenceVSAvoidcabinet construction ease

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The invention extracts the port/vent mechanism entirely from the cabinet design. Instead of using a ported cabinet that requires careful design and construction of vents and ports to transform sound pressure waves, the solution takes out the need for such mechanisms by using an open cabinet design where sound pressure waves naturally escape through the open ends without requiring any additional components or complex construction.

Inventive Principle:

Principle #2Taking out (Extraction)

4Object-affected harmful factors

If sound pressure waves are trapped in sealed cabinet, then interference is prevented, but pressure build-up occurs causing distortion

Engineering Contradiction:

Improvesound wave interferenceVSAvoidpressure build-up distortion

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

Instead of trapping sound pressure waves in a sealed cabinet, the invention inverts the approach by making the cabinet open at both ends. This allows sound pressure waves to escape freely through the open ends, preventing pressure build-up and the resulting distortion while still preventing destructive interference through the internal chamber division.

Inventive Principle:

Principle #13The other way round (Inversion)

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 solution effectively mitigates sound wave cancellation and distortion, allowing for a more efficient and cost-effective use of sound pressure waves, enabling a lightweight and simple design that maintains sound quality without pressure build-up, suitable for various driver types and room configurations.

Implementation Method 1

sound pressure waves generated by the front of a driver are a half cycle (180 degrees) out of phase with those generated by the back of the driver. Consequently, when sound pressure waves from the front of a driver meet sound pressure waves from the back of the driver, destructive interference can occur

Methodology Applied

Scientific EffectDestructive interference: Interference

Implementation Method 2

sound pressure waves generated by both the front and back of the round, open-back, cone type driver can pass linearly and substantially unobstructed through the respective front and back chambers and through the open ends of the cabinet

Methodology Applied

Scientific EffectSound pressure wave propagation: Sound

Data Source

PatentUS11272284B2Open-back linear bi-directional cabinet for speaker driver

Publication Date: 2022.03.08 NORTH JEFFREY P

AI summary

A cabinet for housing a round, open-back, cone type driver. The cabinet includes a barrel-shaped internal wall that has first and second opposing open ends and a substantially circular cross section. The diameter of the cross section at the midpoint of the internal wall is greater than the diameter of the internal wall at the opposing open ends. A mounting ring is secured to the internal wall between approximately a front quarter and a back quarter of the cabinet, configured for receiving the driver.