It is said that the original 1962 recording of "Watermelon Man" by Herbie Hancock is in the key of F. It makes a lot of sense given it's a bluesy piece, so we have a typical I-IV-V based chord progression.

However, here is where it gets confusing to me: the first chord is F7, but there is no minor seventh in the F major scale. Why is it then that people still say it's in F? Wouldn't it make more sense to call it F mixolydian? Or is it implied?

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    You can't mix keys and modes. It's in F and, as you say, it's bluesy. There are F7s in the accompaniment and there are Abs in the tune. That's what happens in jazz and blues. There's too much daft analysis in here! Commented Mar 15, 2020 at 6:45
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    So, what do people mean when they say that a song is "in" a key, and why do songs supposedly in some key use notes outside the most obvious scale that comes to mind? There are several questions about that music.stackexchange.com/questions/38939/… music.stackexchange.com/questions/42650/… music.stackexchange.com/questions/80604/… I particularly like the idea in the last question that it's all just a big historical accident. It wasn't designed. Commented Mar 15, 2020 at 9:20
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    @piiperiReinstateMonica - seems like more of a question than a comment!! However, there's usually a sort of 'home key' which gives most of what's needed, and it strays from there. Scale and key aren't synonymous anyway - particularly in minors! Trouble is, as said previously, humans love to try to pigeon-hole things, but music just cocks a snook at that.
    – Tim
    Commented Mar 15, 2020 at 12:50
  • @Tim I meant to imply that the question is probably just about terminology and that there are several answered questions about the same thing already. Commented Mar 15, 2020 at 16:09
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    @secondcitysaint You're not alone in this, it's a very common idea to equate scale and key, because we say things like, "this is in D major" or "this is in A minor", and there's this thing called "key signature", which implies a scale. But all of these notations and idioms are really approximations, compromises or historical accidents, just like everything about our communication. No expression "cuts it" from all possible angles, there's always a chance of misunderstanding, and you'll learn to make better guesses only by taking part in the culture, by making music with others. :) Commented Mar 15, 2020 at 17:58

3 Answers 3


There isn't a 'rule' about what notes fit into what key - not really even an unwritten one!

Especially when considering jazz and blues.

Yes, I suppose 'F Mixolydian' might be a more accurate way to describe the key here, but all the transcriptions I've played from use the key sig. of 1♭, (Fmajor) rather than 2♭s (B♭/F Mix.).

It's what blues and jazz do: use a basic key, and use flat 3s, flat 5s and flat 7s. It's become the norm over many decades, and doesn't present a problem to us - not even pedants such as myself!

  • Thanks, it makes sense! I'm probably trying to be overly pedantic while learning to make sure I'm not missing anything. The good old "learn the rules before breaking them" kind of thing :) Commented Mar 15, 2020 at 17:43

Listen to the recording (on the Herbie Hancock album "Takin' Off") with the sheet music and try to see if it makes aural sense to you. If you haven't listened to much blues-oriented music it might not make any sense at all! But listening to "Watermelon Man" is a good start. Then, try to understand why it sounds good! Remember that music theory is only observations and explanations about what our ears think sounds good.


Blues is a style that's non-diatonic (it does not conform to diatonicity rules whereby you stick to 7 notes in a scale). There a few guidelines that apply to blues (except when they don't)

In major blues, all chords are dominant (ie: major chords with a minor 7th).

Note that further on in the progression you find a C7, which has an E, which conforms to Fmajor (vs the Eb that F7 would have).

Major blues compositions are both minor and major at the same time (ie: you can play both the minor 7th and the major 7th).

The blues scale uses the flatted 5th.

It's these chromatisms that give a tune the 'bluesy' sound.

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