Deep Purple's 1972 masterpiece Machine Head raised the bar for hard rock and heavy metal and its importance is recognized 30 years later with a volume in Eagle Vision's Classic Albums documentary DVD series. Even if "Smoke on the Water" was the only great track, that's important enough to make it worthy, but factor in other monsters like "Highway Star," "Pictures of Home," and "Space Truckin'" and you've got a keeper for the time capsule. Pretty amazing for an album recorded quickly during wintertime in the corridors of the Grand Hotel in Montreux, Switzerland. As with any music documentary, the most thrilling thing is seeing rare archive footage, and this one is no exception. All five members of the definitive "Mark II" lineup -- vocalist Ian Gillan, guitarist Ritchie Blackmore, keyboardist Jon Lord, bass guitarist Roger Glover, and drummer Ian Paice -- are also featured in extensive new interviews, as is engineer Martin Birch. Blackmore is a brilliant guitarist, yet it's Guitar World editor Brad Tolinski who makes the key point that what separated Deep Purple from other hard rock bands was the sound of Lord's organ work. Lord demonstrates how he got his vicious sound from his Hammond organ, named "The Beast," by running it through a Marshall guitar amplifier. Blackmore discusses his "Smoke on the Water" and "Space Truckin'" riffs while playing them on an acoustic guitar. Machine Head was self-produced, which meant the power plays bubbled up during mixing when each member jockeyed for prominence. Traces of sadness creep in the interviews when the splintering of the lineup is examined. Paice believes a six-month break would have prevented it, and Glover says they were too afraid to stop working and therefore burned themselves out. Classic Albums recognizes Deep Purple's greatness -- maybe the Rock and Roll Hall of Fame will someday too.