U2 stalled the release of their new album last year (16), so they could perfect their new songs for a concert run.

The band began work on Songs of Experience in 2014, and wrapped up the project a year ago, but guitarist The Edge and his bandmates held off on releasing the album so they could polish the tracks.

"What we wanted to do was sit back and see how we felt about it coming out into a world that had taken a big lurch in a different direction," he tells Rolling Stone.

"We had all of the songs figured out and most of them recorded to the extent that they were releasable towards September of last year. But a year ago we were kind of feeling that we wanted to explore other production approaches and other ways the songs could be arranged and performed. We felt the band chemistry wasn't as represented as we thought it maybe ought to be.

"So in the fall of last year we went back into a room as a band, initially without Bono and then he joined us for a couple of days at the end of the period, and we just played the songs. We played them with half an eye and ear to how they might be performed in a live concert setting.

"Part of the reason for doing that is that we always went through this kind of routine where we'd record an album, put it out and then we'd start rearranging the songs live. Our producers would show up halfway through the tour and they'd be like, 'Oh, s**t man, that tune is sounding so cool now. I really wish we'd had that arrangement on the album'."

The rocker admits that by going back to the rehearsal space and re-recording some of the songs, the band was able to find "a synthesis of the raw band performances and some of the stuff we had created before".

"It's given it a more interesting aesthetic," he says.