I remember my first loop experiment was taking the flexidisc record of Pinnochio off a box of cereal and using airplane cement to make it repeat only the phrase "because he was a bad boy" endlessly on my sister's Barbie turntable. True story. As a teen in the 1970's and living in the hip city of Madison WI I was exposed to every kind of musical influence, from John Cage to the Velvet Underground. I purchased an EMS Synthi in 1979, one of the great analog digital hybrid 3 oscillator synths made back then. Before loops I played with audio tape, in experiments where I purchased 1 dozen Grundig Dict-A-Phone-style tape recorders at a high school rummage sale, then wound sound fragments on hand-spliced tape in figure 8's between them and mic'ed everything and ran it through an rackmount echoplex.
Stockhausen, Cage, the Beats, the Mothers, the Velvets,the Stooges, Glam, Eno, Fripp, Suicide, Popol Vu, noise and everything before, after and between them.