Carrillo studied at the National Conservatory in Mexico City and also at the conservatories in Ghent and Leipzig. Early in his career, Carrillo developed an interest in fractional intervals, calling the first two-octave harmonic on the violin's fourth string sonido 13. Reaching beyond quarter-tone limitations, he developed special instruments to play the new intervals, including the octavina for eighth tones and the arpa citera for 16th tones. His microtonal works were embraced by Stokowski, who conducted some of his works. Carrillo formed a complete orchestra capable of playing microtones in 1930.