extremely complicated and high-tech but also incredibly simple and hands-on, controlled by human beings... in that sense, it's still a live performance." This flexibility allowed for improvisations and deviations from the planned programme. Eno recommended that U2 film their own video tapes so that they could be edited and looped on the video displays more easily, instead of relying entirely on pre-sequenced video. Eno explained: "their show depends on some kind of response to what's happening at the moment in that place. So if it turns out they want to do a song for five minutes longer, they can actually loop through the material again so that you're not suddenly stuck with black screens halfway through the fifth verse." The band shot new video for the displays over the course of the tour. The set featured a B-stage, a smaller, secondary performance area that connected to the main stage via a catwalk. Zoo TV was U2's first tour to use a B-stage; the band had pursued the idea on previous tours because Bono wanted proximity to the audience, but they had been unsuccessful due to building and fire code restrictions. Equipment for the sound system was provided by Clair Brothers Audio, which had been working with U2 since 1982. The company's S4 Series II speaker cabinet was the standard model used for Zoo TV; it was based on a prototype designed for the tour and featured built-in time-alignment. The sound engineers decided not to supplement the traditional public address system with delayed speakers for time-alignment, as they wanted the audience to focus their attention on the stage and the multimedia aspects of the show. The stage monitor system used on the Zoo TV Tour was one of the largest and most complex systems at the time. Through "quad monitoring", the monitor engineer used a joystick to pan each band member's mix around the monitor speakers to "follow" their movements on stage. The band members also wore in-ear monitors, which was necessitated by their performing on the B-stage, where they experienced an audio delay from the primary PA speakers behind them and where fewer monitor wedges could be positioned. Lighting equipment was provided by LSD. Supplementing the traditional lighting rigs were several suspended Trabants that had been retrofitted with light fixtures. The cars were purchased for US$500–600 each, and when stripped of their interiors, they weighed . Approximately US$10,000 of lighting