ALEXANDRIA, Va., Aug. 12 -- United States Patent no. 12,388,406, issued on Aug. 12, was assigned to Yamaha Corp. (Hamamatsu, Japan).
"Acoustic apparatus" was invented by Yohei Ohtani (Iwata, Japan) and Masao Noro (Hamamatsu, Japan).
According to the abstract* released by the U.S. Patent & Trademark Office: "An acoustic apparatus includes a class-D amplifier including a current feedback circuit, and a speaker system including a voice coil driven by the class-D amplifier. The speaker system is configured such that, in a case where the speaker system is driven by an ordinary amplifier having a first output resistance lower than a second output impedance of the class-D amplifier, a Q factor of the speaker system falls below a predetermined lo...