You could call it the magical mystery chord. The opening clang  of the Beatles’ 1964 hit, “A Hard Day’s Night,” is one of the most  famous and distinctive sounds in rock and roll history, and yet for a  long time no one could quite figure out what it was.

In this fascinating clip from the CBC radio show, Randy’s Vinyl Tap, the legendary Guess Who and Bachman-Turner Overdrive guitarist Randy Bachman  unravels the mystery. The segment (which comes to us via  singer-songwriter Mick Dalla-Vee) is from a special live performance,  “Guitarology 101,” taped in front of an audience at the Glenn Gould  Studio in Toronto back in January, 2010. As journalist Matthew McAndrew wrote, “the two-and-a-half hour event was as much an educational experience as it was a rock’n’roll concert.”