After handling audio engineering for the recording of "Achtung Baby", Robbie Adams was invited by U2 to manage sound mixing on the Zoo TV Tour. Adams also recorded the group's tour soundchecks. In January 1993, the band asked him to compile these recordings and create loops of interesting parts that they could play to in the studio. After Adams spent a few weeks assembling loops, the group entered The Factory in Dublin that February to begin composing rough demos. Bono and the Edge were most involved during this initial demoing process, which lasted six weeks. Audio services company Audio Engineering installed recording equipment at the Factory that included a Soundcraft 6000 mixing console, an Otari MTR100 multi-track recorder, and four Neve console modules. The company also provided outboard gear such as a UREI 1176 Peak Limiter, a dbx 120X-DS subharmonic synthesizer, two Summit and two LA compressors, a Focusrite 115HD equaliser, a Yamaha SPX1000 multi-effects unit, Lexicon PCM-70 and AMS RMX-16 reverb units, and Yamaha NS-10 and EGV monitor speakers.