Many guitarists will know how to play the “Hendrix” chord even if some of them might be a little shaky on giving it the more technical name of x7#9. It is named after Jimi Hendrix because he used it to great effect on tunes like Foxy Lady and Purple Haze. Both of those songs are in E, so you start with an E7 chord (E G# B D), drop the fifth (B) and add in not just a 9 (F#) but one that has been raised by a semitone, leaving you with E G. That will leave you with E G# D F##. At this point most guitarists will say “but isn’t that just a G at the top?” It sounds the same (an enharmonic equivalence) but it gives you the tension of the way the G# and F## rub together without the new challenge of explaining why you are doing different things to the “same” note in different octaves.

I haven’t listened to a lot of Hendrix recently but I’ve come across two instances in the last few days in entirely different musical contexts where it has been an ideal resolution to what a particular chord should be called. One was a song written by Simon, the guitarist I was playing with last night. He is a “literate” musician but had it down as a dominant 7 chord with a minor third on top. I spotted that it could instead be a 7#9 chord, which fitted coherently with the rest of the song.

Tonight at choir, I found an even less expected context. We were singing I Am Come into My Garden by William Billings, an American composer, published in 1794. There was some discussion about a bar where the altos had an F# and the sopranos had an F natural, an octave higher. The conductor had listened to a recording and was sure that the rub of those two notes was intentional… and then it struck me that a #9 could be the answer. If the sopranos were actually singing an E#, that would place the notes from low to high as D (bass), A (tenor), F# (alto) and E# (soprano). It isn’t quite the classic Hendrix chord since it spans almost two octaves and has 1/5 at the bottom rather than 1/3 but it would be a way to resolve the fact the song features the F# and a note 11 semitones above it. American music, eh!