A fan that secretly recorded over 10,000 live shows has started sharing the collection online.

Jacobs surreptitiously recorded the performance, documenting the fledgling band in raw, fiery form more than two years before Nirvana’s global breakthrough with the album “Nevermind.”

Jacobs went on to record more than 10,000 concerts, with increasingly sophisticated equipment, over four decades in Chicago and other cities. Now a group of devoted volunteers in the U.S. and Europe is methodically cataloging, digitizing and uploading them one by one.