Early Vacuum Tube
Early vacuum tubes were used to amplify signals for radio and other audio devices. This one was made in 1915. Tubes were not used as switches in calculating machines until 1939. (Image courtesy of AT&T.)
Tubes in the 21st Century
Vacuum tubes are still used and not just for CRTs. Many audiophiles swear that tubes are the only electronics that can faithfully reproduce musical sounds, and they would be delighted with these Model One amplifiers from Red Rose Music (www.redrosemusic.com). Designed by legendary audio engineer Mark Levinson, for a mere $25,000, you can own all 212 pounds of this top-of-the-line equipment.
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