Arc is a montage of feedback, guitar noise and vocal fragments taken from various shows on the 1991 Neil Young and Crazy Horse US tour that was originally released with Weld in a special edition 3-cd set called Arc-Weld. Arc bears no small resemblance to the music of Sonic Youth who were one of the support acts on the tour.
According to an interview with Steve Martin of Agnostic Front which appeared in the December 1991 Pulse! magazine, Arc had its genesis in a film that Neil made (which he referred to as Muddy Track in an interview with David Fricke in the November 28, 1991 Rolling Stone) that consisted of beginnings and endings of various songs from a mid-80s European Tour. Neil Young showed the video to Sonic Youth's Thurston Moore who suggested he put out an entire album recorded in a similar manner. Neil placed a video camera on his amp during the 1991 tour and recorded the beginnings and endings of various songs which were later edited down into the single track of Arc. "It was the sound of the entire band being sucked into this little limiter, being compressed and fuckin' distorted to hell," Neil said to Martin.