Patent Review: Bose Transmission Line Loudspeaker

In this Voice Coil Acoustic Patents article, James Croft discusses an interesting Transmission Line Loudspeaker patent assigned to three engineers from Bose regarding an electro-acoustic driver and acoustic waveguide that includes “an enclosure, an acoustic transmission line formed within the enclosure, and a plurality of acoustic transducers contained within the enclosure and disposed along a length of the acoustic transmission line.” As Croft notes, this seems to be an improvement over the Tapped Horn loudspeaker architecture patented by Tom Danley, assigned 10 years ago. This article was originally published in Voice Coil, June 2015

In September 2020, British brand KEF updated its extremely popular LS50 speaker design and introduced the LS50 Meta, an improved version of the original LS50 passive design, now featuring a new Uni-Q driver that is coupled to an interesting new metamaterial absorber in the back. audioXpress requested a pair of the loudspeakers for review. Oliver Masciarotte did the listening, and Kent Peterson confirmed their impressions with extensive measurements. This article was originally published in audioXpress, June 2021.

After conducting a serious listening session of the KEF LS50 Meta with Oliver Masciarotte and Pete Quirsfeld, Kent Peterson took the speakers to Warkwyn to determine if their listening impressions could be confirmed with actual measurements. The KEF LS50 Meta was measured at Warkwyn’s facility using the Klippel Near-Field Scanning (NFS) system. This article was originally published in audioXpress, June 2021.

A design by John Hilliard, Altec Lansing Voice of the Theatre systems originally targeted movie theaters. The entire series was gradually expanded for use in general sound reinforcement and later converted in extreme high-end audio segments for hi-fi home use. Dorsey knows cinema sound inside and out, and in this article he shares his personal thoughts about these highly valued horn designs, and provides valuable tips on how to restore them. This article was originally published in audioXpress, September 2020.

Celebrating the reintroduction of the famous Western Electric 300B triode, now out of Rossville, GA, in this article, Richard Honeycutt asked key questions to entrepreneur Charles Whitener, the main force behind the revived Western Electric venture, which is also investing in new tube audio amplifiers and tube related electronics. Since a visit to the facilities wasn't yet possible but production had resumed, audioXpress provided an inside look at Western Electric and its reestablished operations. This article was originally published in audioXpress, May 2021.

Originally published as part of the Automotive Audio Solutions Market Update feature in audioXpress June 2021, this article offers an overview on how British audio pioneer Meridian Audio is transforming listening experiences with new technologies for the car. For more than 10 years, Meridian has built a strong presence within the automotive market, with outstanding recent examples available for McLaren Automotive, Jaguar Land Rover, Human Horizons, Rivian, and Kia. The article details the company's approach with 3D surround sound and immersive in-car audio systems that combine all its digital processing solutions.

DIY audio pioneer and author David B. Weems passed away on April 4, 2021 at his Newtonia Missouri home after a short illness. Mr. Weems is known to many in the speaker design and building community for his prolific authorship of DIY books, and articles for such publications as Audio, Popular Electronics, Radio Electronics, Audio Amateur, Speaker Builder, and AudioXpress.

Adding a valuable perspective to the topic of True Wireless Stereo (TWS) earbuds and hearables development, Jean-Marc Luneau (7 Sensing Software) details meaningful new features and improvements for brands to differentiate their products and make them stand out in today’s crowded market. This article was originally published in audioXpress April 2021.

As part of its focus on voice convergence, in its April 2021 edition, audioXpress featured a contributed article by the founder and CEO of Fluent.ai, describing how increasing consumer demand for personalized experiences has sparked the creation of the company’s speaker ID technology, and exploring the challenges that this type of technology still faces. A valuable perspective from a company positioned right at the edge of voice recognition using AI and edge processing. This article was originally published in audioXpress, April 2021.

The patent in review was granted in February 2015 to inventor Zhijun Zhao (West Bloomfield, MI) on behalf of Harman International Industries. As James Croft notes, planar magnetic transducers are often preferred for their thin form factor, ideal for shallow mounting spaces where a standard transducer may not fit, such as in-wall systems and automotive applications. The patent in review offers a practical solution for an oval or circular format planar magnetic transducer for such applications. This article was original published in Voice Coil, April 2015.