The tapes were ready. The sequence was set. So was the new light show. Pink Floyd were about to play the entirety of The Dark Side of the Moon before an audience for the first time. The band members wanted the performance to go perfectly, even though they hadn’t even begun to professionally record the new album.

Prompted by bassist and lyricist Roger Waters’ idea for a concept album about all of the factors that prevent humanity from progressing, Pink Floyd had been working on new material after the 1971 release of Meddle. The band took some existing musical ideas, including the music for “Us and Them” and the beginning of “Breathe,” and demoed some new ones as the four members began assembling a suite of songs. Lyrically, the goal was to take a simpler approach.

“I think we all thought – and Roger definitely thought – that a lot of the lyrics we had been using were a little too indirect,” guitarist and singer David Gilmour told Rolling Stone. “There was definitely a feeling that the words were going to be very clear and specific. That was a leap forward. Things would mean what they meant. That was a distinct step away from what we had done before.”

After a band meeting at drummer Nick Mason’s house, Pink Floyd agreed to road test the new material before recording it for release. The band spent the bulk of January 1972 rehearsing the new songs, sequencing them the way they’d like them to appear on the album and crafting a light show to accompany the performance. Because of the complicated nature of some of the songs, they also worked up tapes – including the reciting of Bible verses and prayers – to complement the live instrumentation.

Pink Floyd planned to debut its new work (which was sometimes called Eclipse because another band had made an album called Dark Side of the Moon) during a British tour, beginning on Jan. 20, 1972, at Brighton Dome. In ambitious fashion, the band wouldn’t be giving fans just a taste of the upcoming album, but a full-blown run-through of the entire piece at the beginning of the show.

“I think all of us feel more excited that we have for ages,” Mason told NME at the time, “because we have new material and new equipment.” The problem with new equipment is that you and your crew have to learn how to use it, something that was happening frantically in the days before (and of) Pink Floyd’s tour opener. They wanted the performance to come off perfectly. And for a while, it almost did.

According to reports, the audience was quickly enraptured by the new material, which one reviewer thought was establishing a new, jazzy sound for the band. Pink Floyd played Dark Side in some ways that would become familiar to millions (the song order was the same, the famous melodies of “Breathe” and “Time” intact) and in other ways a bit alien (“On the Run” was a drum and guitar jam named “The Travel Section,” “The Great Gig in the Sky” was titled “The Mortality Sequence” and featured recorded preachers over Rick Wright’s organ).

And then, in the middle of “Money,” everything fell apart. A sustained noise and hiss started coming through the PA, drowning out anything Pink Floyd played. The bandmates conferred, stopped performing and took a break. Mason later gave an explanation to the NME.

“The new lighting system is run off a separate circuit, and due to some power failure somewhere we had to double up on the circuit, so it was on the same circuit,” the drummer said. “There was a variac on the lighting system, which went wrong and shorted out the PA. So it was impossible to get any tapes through, any sounds through, and we stopped because there was nothing we could do.”

However, Floyd didn’t end the show. The band members returned to the stage, with Waters explaining that they’d have to play something else, and continued the show with older material, including “Atom Heart Mother,” “One of These Days” and “Echoes.” The group encored with “A Saucerful of Secrets.”

Disappointed, but not deterred, Pink Floyd attempted to play the entirety of The Dark Side of the Moon the next evening in Portsmouth and were successful on the second try. The band debuted the suite in February for the London press – a performance that became a hot item on the bootleg circuit.

Gilmour, Waters, Wright and Mason continued to play the whole album throughout the 1972 tour (which took them to continental Europe, Japan and North America), tinkering with the tracks and adding new elements to the songs as Dark Side grew closer to its finished state. In the middle of those 90-plus dates, Pink Floyd also made and released Obscured by Clouds and took time to begin the Abbey Road sessions for The Dark Side of the Moon – which would see release in March 1973, 14 months after the band’s first attempt to perform it.