Patent Review: Diaphragm for Full Range Boxless Rotary Loudspeaker Driver

Following a recent exchange with loudspeaker designer and inventor John J. Gaudreault, we decided to revisit the very original Planar-Pivot (Planot) Transducer, and make available the two related articles that were published by Voice Coil in its May 2011 edition, and the respective Patent Review by James Croft published in the August edition of that same year. Hoping this will inspire some commercial implementations of this interesting concept, available for licensing.

James Croft reviews two loudspeaker-related patents as a tribute to David John Graebener, who passed away on January 3, 2015. First James Croft reviews the planar-magnetic electro-acoustic transducer he patented together with Graebener, followed by a single-end planar magnetic speaker system, David’s key patent. These were the first and second of the Single-Ended, Neodymium planar magnetic transducer patents David Graebener was granted. This article was originally published in Voice Coil, March 2015.

This patent review looks at a “Loudspeaker with a Wave Guide” (Patent Number: US20140369543) by inventors Jussi Vaisanen and Ilpo Martikainen from Finish company Genelec. This patent relates to the Genelec 8351 Acoustically Coaxial Smart Active Monitor (SAM) monitor, originally launched in 2016. Later in 2017, Genelec expanded the concept into a complete series of Coaxial Active Monitors, “The Ones”. This article was originally published in Voice Coil, February 2015.

James Croft looks at an interesting new patent covering a “Compact Stand-Alone Stereo Loudspeaker” by inventor Jes Mosgaard from Libratone A/S (Denmark). This patent submitted in 2010, was granted in 2013, and describes a compact and portable stereo loudspeaker system that is capable of providing a spacious sound field using an internal stereo pair of loudspeakers arranged in a dipole configuration. This article was originally published in Voice Coil, February 2015.

James Croft reviews a patent claimed by Polk Audio and granted in 2015, describing “a single-enclosure loudspeaker system that projects multichannel surround sound into a listener’s room, and so replaces multiple conventional surround channel loudspeakers.” The patent also describes, in one embodiment of the invention, that the “surround channel program material is pre-processed by an integrated wireless transmission device that performs certain digital signal processing and channel mixing steps in advance of wireless surround signal broadcast to a receiver.” This article was originally published in Voice Coil, January 2015.

Every month on his Voice Coil's Acoustic Patents column, James Croft (Croft Acoustical) discusses different loudspeaker patents and inventions that are relevant to the audio industry. In the January 2015 edition. Croft reviewed a “Loudspeaker for Eliminating a Frequency Response Dip” patent, granted in November 12, 2014 to Harman International Industries, describing “a speaker system that includes a speaker enclosure having a front end, a rear end, and a first transducer. This article was originally published in Voice Coil, January 2015.