All items written by James Croft

Patent Review: Externally Coupled Loudspeaker System for a Vehicle, and an Externally Ducted Vehicle Loudspeaker

August 20, 2025 by James Croft

Patent Review: Externally Coupled Loudspeaker System for a Vehicle, and an Externally Ducted Vehicle Loudspeaker

In this review, James Croft (Croft Acoustical) focuses on two patents. One granted to Harman Becker Automotive, and another granted the same year to Bose. The first describes a loudspeaker system arranged in a baffle inside a vehicle, configured to radiate an acoustical signal to the passenger compartment using an active noise control system.The second describes various implementations of “vehicle loudspeakers and related vehicle audio systems,” including the use of passive radiators.

Patent Review: Loudspeaker Enclosure with a Sealed Acoustic Suspension Chamber

August 13, 2025 by James Croft

Patent Review: Loudspeaker Enclosure with a Sealed Acoustic Suspension Chamber

James Croft reviews a design, invented in Sweden, and patented in 2018, of a new approach to an area that has been extensively researched in an effort to improve low-frequency performance in speakers. The specific design under review describes a loudspeaker enclosure housing a sealed acoustic suspension chamber, where a driver and a passive acoustic diaphragm on opposite sides are combined with a first bandpass chamber connected to the sealed chamber by the passive unit in a curved structure.

Patent Review: Multiple Path Acoustic Wall Coupling for Surface-Mounted Speakers

February 19, 2025 by James Croft

Patent Review: Multiple Path Acoustic Wall Coupling for Surface-Mounted Speakers

This article reviews a patent awarded to Paul Wayne Peace Jr. and Derrick Rodgers, on behalf of Harman International Industries. The patent describes a surface-mounted loudspeaker design that mitigates the interference between direct low-frequency (LF) energy and reflected LF energy by breaking the LF energy from an LF driver into multiple paths using one or more of waveguides, driver load plates, and enclosure ports to diffuse the reflected energy and minimize frequency response errors.

Patent Review: Loudspeaker Apparatus

January 15, 2025 by James Croft

Patent Review: Loudspeaker Apparatus

This article reviews a patent awarded to Teppei Yamada, on behalf of Zorzo Co., Ltd. (Tokyo, Japan), describing an original design of a low-frequency enclosure system incorporating multiple woofers inter-coupled in a manner similar to what is known as an isobaric or compound woofer enclosure. James Croft reviews other approaches to the concept, starting in 1954 with a patent granted to Harry F. Olson on a dual, compound woofer system and later "reinvented" and popularized by Linn Corp., in 1975. In the new patent, the inventor uses an enclosure with as many as 12 woofers, all seriously coupled through individual air chambers

Patent Review: Coaxial Centerbody Point-Source (CCPS) Horn Speaker System

January 8, 2025 by James Croft

Patent Review: Coaxial Centerbody Point-Source (CCPS) Horn Speaker System

This article reviews a patent awarded directly to inventors Anthony Allen Bisset (Oakland, CA) and Quang-Viet Nguyen (Aldie, VA), for a coaxial horn speaker design. In his review, James Croft looks back at multiple multi-driver horn topologies and compares the unique aspects of the CCPS Horn Speaker System, highlighting the positive attributes and benefits of the invention, to deliver both increased acoustic quality and increased power density.

Patent Review: Head-Related Transfer Function Equalization and Transducer Aiming of Stereo Dimensional Array (SDA) Loudspeakers

June 26, 2024 by James Croft

Patent Review: Head-Related Transfer Function Equalization and Transducer Aiming of Stereo Dimensional Array (SDA) Loudspeakers

This patent, awarded to Polk Audio, describes a very specific loudspeaker design that claims to be able to achieve better stereo sound reproduction with “a realistic ambient field and a larger, and more stable acoustic image.” This obviously aims at achieving something that Polk Audio actually patented nearly 40 years ago, with its original Stereo Dimensional Array (SDA) loudspeaker, and for which the new updated patent now provides a new improved version. This article was originally published in Voice Coil, February 2019.

Patent Review: Multi-Layer Voice Coil Plate and Flat-Type Speaker Comprising the Same

June 19, 2024 by James Croft

Patent Review: Multi-Layer Voice Coil Plate and Flat-Type Speaker Comprising the Same

In this patent review, James Croft (Croft Acoustical) looks closely at a new patent of a multilayer voice coil plate and a flat speaker including the same type of multilayer voice coil plate, granted to three inventors from South Korea, on behalf of ICUBES Co., Ltd., Gyeongi-do, Korea. Detailing multiple configurations of this interesting concept, this patent offers an interesting take on the quest for the realization of a high-performance, one way, full-range electrodynamic transducer.

Patent Review: Acoustic Passive Radiator Rocking Mode Reducing

June 12, 2024 by James Croft

Patent Review: Acoustic Passive Radiator Rocking Mode Reducing

With the increasing popularity of miniaturized systems, the application of the passive diaphragm radiator, as the acoustic mass component in a bass reflex enclosure, is becoming standard practice in the low-frequency portion of the system. And these systems have a few parameter demands that can exceed the capability of many conventional approaches to passive radiator design. In order to solve those challenges, including rocking modes, Bose proposed an effective design.

Patent Review: Acoustic Filter for Omnidirectional Loudspeaker

June 5, 2024 by James Croft

Patent Review: Acoustic Filter for Omnidirectional Loudspeaker

This is an interesting patent awarded to Lakshmikanth Tipparaju, Allan Devantier, William Decanio, and Andri Bezzola, on behalf of Samsung Electronics - effectively the audio research team that Samsung created in Valencia, CA. The industry has attempted to achieve a successful implementation of acoustic radiation closely coupled to a boundary surface for omnidirectional and subwoofer applications - unfortunately, mostly plagued by resonances generated by the waveguide or reflector surface. This new approach appears to be an effective solution.

Voice Coil Patent Review: Controlled Passive Radiator

March 27, 2024 by James Croft

Voice Coil Patent Review: Controlled Passive Radiator

James Croft has fun reviewing a Controlled Passive Radiator patent awarded to inventor Tony Doy, on behalf of Sonos (Santa Barbara, CA.) The patent details multiple techniques to control a passive radiator, including a device buffering successive samples of audio content and predictive techniques on active designs. With this extensive review, Voice Coil readers will gain a valuable perspective on key possible innovation areas. This article was originally published in Voice Coil, October 2018.

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