Almost every budding axe hero of a certain age used to play the seminal heavy rock riff that opens “Smoke on the Water”, from Deep Purple’s 1972 album Machine Head and the more exciting live version from Made in Japan. Almost every budding axe hero played it wrong. You can even watch Jack Black playing it wrong in the film “School of Rock”.
For a start, Ritchie Blackmore does not use a pick (plectrum) when playing that riff, but more importantly he doesn’t play the root note of the implicit chords. The fledgling guitarist assume it’s power chords all the way, but it’s not. Blackmore lops off those roots and leaves them to Glover’s pounding bass, which comes in later. Instead, what we have is an interveted G5, the D fretted at the fifth of the A string and a G on the D string, same fret, plucked with thumb and index finger in unison. Set your guitar tone right and you can hear it’s true, but Blackmore has explained all this several times in interviews. You can give a thumbsdown to any tutorial where the guitarist is using a pick for the intro to this song and/or playing the root note on the bottom E string. Here’s Steve Morse showing it’s done properly.