But a pocket of audio enthusiasts still values the tubes' warm tones.
Ewing was an audio enthusiast and inventor.
Carillon, based in Britain, has a United States division (www.carillonusa.com) and makes a line of computers for audio enthusiasts.
Sansui's amplifiers and tuners from the 1960s and 1970s remain in demand by audio enthusiasts.
"This is for audio enthusiasts," he said.
Despite having a loyal customer base (primarily musicians and audio enthusiasts), MiniDisc met with only limited success.
Some audio enthusiasts prefer the sound of vinyl records over that of a CD.
Both of these designs are becoming more popular with audio enthusiasts, but traditional dynamic drivers are still the most prevalent technology, far and away.
Technical improvements and less expensive mass-production technologies have made high-quality bookshelf speakers affordable for most audio enthusiasts.
"I thought it was stunning," said John Atkinson, editor of Stereophile, a magazine for audio enthusiasts.