For 40 years, 13 reel-to-reel tapes containing live Bob Marley songs sat in a cardboard box in a London hotel basement. They might have landed in the trash if they hadn’t been discovered in a building clean-out by a friend of the London businessman Joe Gatt, who alerted his colleague Louis Hoover. Mr. Hoover recognized the value of the tapes immediately. “I was speechless,” he told The Guardian.

The analog tapes contain the original recordings of Mr. Marley’s concerts between 1974 and 1978, at European venues like the Lyceum Theater in London and the Pavillon de Paris.

At first, the two men thought the tapes were unsalvageable because of water damage. “There was literally plasticized gunk oozing from every inch and, in truth, saving the sound quality of the recordings looked like it was going to be a hopeless task,” Mr. Hoover said. But a sound technician worked for a year to restore the sound quality of 10 out of the 13 tapes to a condition that “made the hair on the back of our necks stand up,” Mr. Hoover said. The Guardian reported that the project cost about $31,000.