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The Clock of Keys

The Clock of Keys
We’ve seen that when we come across a turnaround we can use a simplifying device, instead of making the scales match every chord we can just play over one scale while the turnaround unfolds. So it’s a simplifying device. That’s really what the “Clock of Keys” is. It’s a mechanism for analysing chord sequences in jazz and it often suggests that over sequences of the chords you can just improvise on one scale. It’s an analysing tool and a simplifying tool. The Clock of Keys according to my version consists of one diagram and 3 rules. Not all authors agree on this but this is my version.
The diagram consists of a clock face and over the top of the clock face are the letters starting form 1 F, 2 B flat, 3 E flat, and so on. This is called the “Cycle of Fifths”. We have met it before. If we want to go home to a particular chord - let’s be specific, supposing you want to go home to C major then we get there from a chord rooted on a note a fifth above the home chord. Take C, fifth above is G, so we have a chord rooted on G that takes us home to C. If we have a whole sequence of chords then they too can be related by this cycle of fifths.
For example, if we start from F which is at 1 o’clock, F takes us to B flat which is at 2 o’clock (or A sharp). B flat takes us to E flat (or D sharp), which is at 3 o’clock. E flat takes us to A flat (or G sharp). A flat takes us to D flat (or C sharp). D flat takes us to G flat (or F sharp). F sharp takes us to B, which takes us to E, which takes us A, which takes us to D, which takes us to G, which takes us to C. So the standard way to change to any chord in a sequence is from a fifth above and that’s called the “Cycle of Fifths”.
It’s going round clockwise on our clock face. Rule 2 says that any point other than home - you can’t alter the home chord - but at any other point you can use the “flat five substitute”. The flat five substitute is what you get when you go diametrically opposite on the clock. For example, if we take G, which is at 11 o’clock, and go diametrically opposite we get to 5 o’clock which is D flat. So instead of going from G to C, we can go from D flat to C. Now that’s just “chromatic alteration” - getting to a chord from chromatically above. But chromaticism is right at the heart of the harmony of Bebop.
It’s a very chromatic music, so we need to understand this
device: the flat five substitute.
For example, suppose I want to go from E to A: I take E, I go up to its fifth, I flatten it, I get a B flat. A chord rooted on B flat in the key of A is II♭ - II♭to I. Tonality - that’s whether a chord is major or minor - is in rule 3 and it says tonality may be major or minor at any stage of the sequence (apart from home where you can’t alter things) as long as it doesn’t clash with the “tune”.
I’ve written tune in italics because tune can mean tune in the sense of the standard that we are playing - the tune of the standard that we are playing - or the tune in the sense of the improvisation - the tune we are making up when we improvise. So, for example, supposing there’s an E flat in the tune, then if the chord is C-based we wouldn’t play a major chord because we get this clash. So it’s a minor chord. Similarly if the tune has a note E in it we wouldn’t play a minor chord because we get that horrible sound - that minor ninth sound - we’d have a major chord.
In that sense, the chords need to agree with the tune. When we were looking at turnarounds we made the chord agree with the scale that we were heading for. For example, if we did a turnaround in C, VI-II-V-I, then our VI was minor, because that’s in the scale of C major; our II was minor, because that’s in the scale of D minor (C major); our V was major, because that’s in the scale of C major; and I is I. It’s quite rare to have a V-I that uses a minor V. There are a few examples, but not very many. Generally speaking, that V has a major tonality. But the other two chords can have either.
For example, our A could be a major chord. Our D could be a major chord. Our V, which we have said is usually a major chord, and then I is a major chord. For example, supposing we are playing a blues and we have a turnaround then we could use A 13 with a major third in, D 9 with a major third in, G 13 and C 6/9, or sorry, C7 if it’s a blues. So we get this sound. 1,2,3,4. … So the tonality may be minor or major at any point as long as it doesn’t clash with the tune.
What does this mean in terms of the possible sequences we can have if we’re going home? Supposing we have only one chord to get home?
We’ve discussed that: we can go V-I, or the flat five substitute of V which is a chord rooted on D flat in our case, so that’s II♭— which is just II♭-I.
Two possibilities: V-I or II♭-I. What about if there’s two chords to take us home?
Well the first rule says cycle of fifths: D takes us to G takes us to C. So that’s II-V-I. I’m really only interested in roots at this stage. What are the possibilities? For the first chord you can either have D or its flat five substitute - so there are 2 possibilities there. For the second chord you can either have a chord rooted on G or its flat five substitute.
So there are 2 possibilities there: 2 times 2 is 4. So there are 4 possibilities in all. What are they explicitly? In the case of our chords, there’s a II-V-I. Or II-II♭-I. That’s going down chromatically. Or there’s VI♭-V-I -(using the flat 5 substitute for the first chord). Using the flat 5 substitute for both chords, the II and the V, you get VI♭-II♭-I. What about if there’s 3 chords to take you home? The first rule says cycle of fifths, VI-II-V-I. In our case an A chord, a D chord, a G chord and a I. In other words, our old friend the turnaround.
… Now there are 3 chords, at each stage there are 2 possibilities - the original chord or its flat five substitute - 2 times 2 times 2 is 8. So there are 8 possibilities. To be specific, I can either leave the first chord alone - the VIth - and then there are the 4 possibilities that we’ve discussed under two chords - or I can use the flat five substitute which is III♭and then there are again 4 possibilities. So there are 8 altogether. Let’s just discuss them quickly. There’s VI-II-V-I Then there’s VI-II-II♭-I. Then there’s VI-VI♭-V-I — taking us down chromatically from VI to V before we go home to I. Then there’s VI-VI♭-II♭-I.
That’s 4 possibilities where the first chord is VI. Now if we replace VI by its flat five substitute - we go up to the fifth, take its flat, we get III♭. In the case of C the chord is rooted on E flat. We get III♭-II-V-I. III♭-II-II♭-I — which is going down chromatically. III♭-VI♭-V-I. And then where it’s all flat five substitutes, apart from obviously the home chord, we get III♭-VI♭-II♭ and home to I. I put Bill Evans in brackets there because this is a device he uses sometimes for a turnaround, So instead of using VI-II-V-I he uses III♭-VI♭-II♭-I.
For example in the key of C, say the final chord is C major7, then if he uses major - he can use major sevenths - he will use for the turnaround C major7, E flat major7, A flat major7, D flat major7 and home. You can again just play over C if you want or you can actually match the scales to the chords, because remember we said that major sevenths are very strong and so that sometimes what he does.
You get this sort of sound: C, E flat, A flat, D flat, home to C. …
With the right hand … So that’s the Bill Evans turnaround using flat five substitutes for VI, II and V.

We introduce the “Clock of Keys”, discuss its use as a simplifying tool and apply it to the turnaround.

You can download “The Clock of Keys”, “Blues Turnaround in C”, “Flat Five Substitution”, and “Bill Evans Turmaround in C” in PDF format at the bottom of this step.

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