Hard Rock

Hard rock takes the basic rock kit and saturates it: rhythm guitars run a hotter distortion, drums get bigger fills and louder kicks, and the bass locks tightly to the guitar riff in unison rather than tracing root notes. Tempos sit 90-140 BPM. Vocals are the give-away — a Robert Plant, Steven Tyler, or David Coverdale style high tenor pushed to the edge of cracking. Lyrics tend to road life, women, cars, freedom, and mythic excess. Production splits by era: the early 1970s favored open, ambient room mics, while the late 1980s went for compressed, gated 'wall of guitars.'

Hard rock emerged in 1968-70 as Led Zeppelin, Deep Purple, and Black Sabbath (in the UK) plus Steppenwolf, Grand Funk Railroad, and Mountain (in the US) all took blues-rock and made it heavier in parallel. Aerosmith, Queen, AC/DC, and KISS carried it through the 1970s as the dominant arena format. The Sunset Strip scene of the mid-1980s produced Mötley Crüe, Guns N' Roses, and Bon Jovi, and 'Appetite for Destruction' (1987) was the last hard-rock album to dominate the charts before grunge displaced it. The line with heavy metal has always been porous — Sabbath and Zeppelin sit on both sides depending on who's writing.

The test of a hard-rock riff is whether you can hum it: 'Smoke on the Water,' 'Iron Man,' 'Back in Black' all pass. Listen for the singer's top notes — the moment of 'will-he-or-won't-he-hit-it' is half the drama. Drum fills are showcase moments; John Bonham's triplet around the kit on 'When the Levee Breaks' is the genre's most-copied figure. Live, the audience's fist-pumps and chorus singalongs are part of the arrangement.

Led Zeppelin's 'Whole Lotta Love' (1969) for one track; Deep Purple's 'Machine Head' (1972) for an album that includes 'Smoke on the Water' and 'Highway Star.' For the 1980s peak, Guns N' Roses' 'Appetite for Destruction' (1987).

Deep Purple's 'Smoke on the Water' tells the literal story of a December 1971 fire at Montreux Casino during a Frank Zappa concert; the band was in town to record and watched the building burn from across Lake Geneva. Ritchie Blackmore wrote the four-note riff within days of the fire — and once said he based it on an inverted figure from Beethoven's Fifth.