Frippertronics is a tape looping technique used by the English guitarist Robert Fripp. It marked the first real-time tape looping device, evolving from a system developed in the electronic music studios of the early 1960s by composers Terry Riley and Pauline Oliveros and made popular through its use in ambient music by composer Brian Eno, as on his album Discreet Music (1975). The effect is now routinely found in many commercial loop station guitar digital effects boxes such as the Boss RC-3
The term "Frippertronics" (or "frippertronics") was coined around May 1977 by poet Joanna Walton, Fripp's girlfriend at the time, for a performance they planned to do together at The Kitchen performing arts space.
Frippertronics is an analogue delay system consisting of two side-by-side reel-to-reel tape recorders. The machines are configured so that the tape travels from the supply reel of the first machine to the take-up reel of the second, allowing sound recorded by the first machine to be played back on the second machine. The audio of the second machine is then routed back to the first, causing the delayed signal to repeat, while new audio is mixed in with it. The length of the delay (usually three to five seconds) is controlled by the distance between the two machines, and the number of repeats is controlled by the volume on the second machine.
Fripp used this technique to dynamically create recordings containing layer upon layer of electric guitar sounds in real time. An added advantage was that, by nature of the technique, the complete performances were recorded in their entirety on the original looped tape. (Pasted from Wikipedia)