Deep Purple’s early-‘70s hard-rock sound is the product of a series of violent attacking moves and dramatic poses. The first warning comes from Ian Gillan’s warrior scream (“Speed King”), with the fearsome support of Ritchie Blackmore’s razor-sharp, whirling guitar riffs (“Black Night,” “Smoke On the Water”) flailing just behind his head. Listen for the windmilling, eight-armed drum assault of Ian Paice (“Fireball”), while Jon Lord stabs and probes with spiky organ runs (“Child In Time”) designed to mop up any remaining stragglers.