“I don't know whether we played it properly, but the audience loved it”: When Black Sabbath regularly covered Smoke on the Water – and unwittingly inspired Spinal Tap's Stonehenge

Black Sabbath perform in concert, New York, New York, October 29, 1983.

It's no secret that Black Sabbath went through a litany of lineup changes during their near-50-year run as heavy metal's pioneers. 

Though the band's music often shifted to accommodate the different strengths of those members who came and went – the vastly different, but equally powerful vocal styles of Ozzy Osbourne and Ronnie James Dio, for instance – rarely did it get as much of a jolt as when Dio left the group in 1982 and was replaced by then-former Deep Purple frontman Ian Gillan.