Art in the San Francisco Bay Area, 1945-80. by Thomas Albright University of California Press, Copyright 1985. typed 1july1996 134w

For Hedrick painting was only one of several outlets for a brash, irreverent energy. As early as 1948 he had begun to experiment with modulated light, and by 1953 he had created a "light machine"--an electrical contraption with a keyboard, glass cake-plates, and other bric-a-bric that he played as an instrument in jam sessions. The machine went through several permutations, but in general speakers were attached to lights that responded with different color mixtures and levels of intensity to changes in pitch, register and volume. Hedrick also assembled junk sculpture, such as his 1953 Christmas Tree made of tin cans and other debris, which included the functioning speaker of an old radio. p. 89