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Two CD 40th Anniversary edition includes quad mixes on the second disc. Machine Head is the sixth studio album released by the English hard rock band Deep Purple. It was recorded through December 1971 in Montreux, Switzerland, and released in March 1972. Machine Head is often cited as a major influence in the early development of the heavy metal music genre. Commercially, it is Deep Purple's most successful album, topping the charts in several countries following it's release. The album reached #1 in the United Kingdom and stayed in the Top 40 for 20 weeks. It reached #7 in the United States, remaining on the Billboard 200 for 118 weeks.