Tung-Sol started off in 1907 when they developed the first successful tungsten filament headlight bulb for automotive use.
The experienced gained allowed them to pioneer in 1913 the two filament high and low beam headlight in a single bulb. They also developed the flashing indicator, inventing the bi-metallic relay for virtually every American car manufacturer until the 1970's
In the 1920's they entered the electronics field and applied their basic company policy "make the best that can be made." They were leaders in the development of sophisticated, statistical quality control systems hence the legendary consistancy that Tung-Sol are known for.! Tung-Sol's were the inventors of the 6550, much renowned for hi-fi today but introduced during 1955 not for hifi!!!!