A Situation Where Mono Still Rules
When you go to any concert, you see at least two sets of speakers on either side of the stage. That’s because 99.99% of every concert you see is done in stereo.
You got your left channel and you got your right channel, just like with your stereo at home or the ear buds with your iPod. This is what mades U2’s PopMart tour rather remarkable.
When the band was designing the production, they wanted to make sure that the stage was wide open and as visible as possible. That’s when they made the decision to forego the usual stacks of speakers on the left and right side of the stage, going instead for a large mono array of speakers hanging 100 feet in the air right in the middle.
So that’s right: for the entire PopMart tour, Bono was in mono. It wasn’t until the Elevation tour that U2 returned to mixing their live sound in stereo.