In 1959, Solid State Tone Generation (transistors) replaced vacuum tube oscillators in the entire Allen line. This technological breakthrough greatly reduced the size of the tone generation circuitry and improved reliability and longevity.
Allen TC-1
Introduced by Allen in 1958, the TC-1 was the world's first transistor church organ.
A collage of the factory in Macungie, Pennsylvania in the early 1960s.