Tung-Sol was founded as Tung-Sol Lamp Works Inc. in Newark, New Jersey in 1907. Their early products were mainly geared towards the automotive market and included headlamps, pilot lights, and flashlight bulbs.
The company entered the electronics field in the 1920s. In time they established themselves as leaders in the development and production of vacuum tubes, with their main competition including RCA and Sylvania. By 1951, they began doing business as Tung-Sol Electric Inc. Soon after, they were acquired by Wagner Electric, which itself merged into Studebaker-Worthington in 1967. Tung-Sol was also active in the semiconductor industry, with its transistors being easily recognizable by their sky blue color.
Tung-Sol was privately held and run like a laboratory. This gave Tung-Sol vacuum tubes a reputation of having some of the best metallurgy and chemistry that has ever been pulled off in actual production. The Tung-Sol brand name is now owned by the New Sensor Corporation, the same company that owns the brands Sovtek and Electro-Harmonix.
Tung-Sol developed the first successful car headlight in 1907, followed in 1913 by a single bulb two filament high and low beam headlight. Other Tung-Sol inventions included the flashing turn signal. Tung-Sol created the 6550 vacuum tube, a specialized Hi-Fi audio tube in 1955.
The 6550 was developed by Tung-Sol in 1955 originally for use as a servo amplifier. It was used in audio equipment before semiconductor power amplifiers came into use, and continues in production today. It is often found in valve-driven bass amplifiers such as Marshall and Ampeg guitar amplifiers and the Leslie speaker system.
Based on the 6L6 vacuum tube, the 6550 was designed to have higher output power and better stability. It operates with a plate voltage of 600VDC, a screen voltage of 400VDC, and plate dissipation of 35 watts. The KT88, KT90, and 6550, although not identical, are often interchangeable, dependent on external circuit parameters. The 6550's glass envelope was originally wider in the middle than at the top and bottom, but a straight-sided design was later introduced by GE and Philips.
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- The History of Tung-Sol
- The New Sensor Corporation
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