Fairlight CMI
A Fairlight CMI synthesiser was used during the demoing phase out of convenience to help fill in placeholder textures and string ideas, marking the first time the instrument had been used on a U2 album. These textures were later replaced with actual string arrangements, although the Fairlight CMI was kept on one song. Clayton said the synthesiser "was only really used as a means to an end, to see if an idea worked". Eno contributed synthesiser parts on a Yamaha DX7, while he and the Edge also played a Yamaha CP-70 electric grand piano.