César Carrillo Díaz (July 13, 1951 - April 26, 2002 [1]) was a Puerto Rican born guitar amplifier technician and guitarist who worked with a number of high-profile musicians, most notably Stevie Ray Vaughan, as well as Bob Dylan, Eric Clapton, Keith Richards, Neil Young, and others.
Guitar World dubbed him "The Amp Doctor" for his work in tube amplifier repair and modification.