How Scale Construction Works in Jazz
John McNeil talks about the construction of a scale, conventional construction and converting scales into chords.
In order for a scale to be translated into a chord or vice versa, that scale has to have what we call conventional construction. Now this means that, it cannot contain anything wider than a whole step and to not have consecutive half steps. All the modes we have covered so far have this construction. It would be a good idea at this point to go back and review them if this is not obvious. Now, this does not mean that there are useful scales out there that have lifts and consecutive half steps but you just cannot turn them into anything resembling a normal chord. I will show you what I mean. Let us look at the blues scale. As you can see here, the blue scale has only evil forbidding stopping, it has got lifts of a minor third and it has got consecutive half steps. Does this mean that the blues scale cannot be used? Of course not, I use it all the time, everybody does. It just does not define any chord sound, that is all. I will show you what I mean. This is a C blues scale right? Now, listen to what it fits. Here is the C blue scale played over Cm. [Demonstration] Here it is over C7, [Demonstration] And here it is over F7. [Demonstration] How about E flat 7? [Demonstration] How about Dm to G 7 to see Major? [Demonstration] Do you get the point? This sort of ambiguity is actually very useful. It enables the sole as to have a lot more flexibility and choices for one thing. There is one more thing that has to happen and in order for a scale to exactly define the sound of a chord. Every not of the scale must be a potential point of rest. In other words, every note in the scale has to sound good against the chord. This leads to some surprising results. Here is a CM7 chord. [Demonstration] Now, you think that a CM Scale would fit just fine would you not? But remember when we are talking about the Lydian scales and how the fourth degree sounds lousy when played against the Major code. I like you check this up, play it up and play that scale. [Demonstration] Now, you hear that? That does not sound very good. Let us here the rest of the scale. [Demonstration] Everything else fits fine except the fourth. So know, see that a major scale does not actually defined a sound of a major chord. To make the scale defined the Court, we have to raise the point, make the F and F#. [Demonstration] Does this mean that we cannot play a CM scale over a C Major chord? Of course not, you just have to be careful not to rest on the F natural. Why don’t you play something and just stir on the F there. [Demonstration] You see there are two questions to consider when you are talking about scales. These questions will need to be asked and answered throughout your career so take special note. The first question is what scale defines a particular chord. The second question is what can you play over that chord. There is only one answer to the first question, what scale defines a chord. For example, a C Lydian scale defines a C Major Chord, period, that is it. The second question, what can you play over a chord can add many answers. For example we have just seen that you can play a C Major scale or a C Lydian scale over a C Major chord though only the C Lydian defines the Chord. This distinction between what defines a chord and what you can play on it will be addressed again and again in this series. Just a review, rule number one, a conventional scale can contain anything wider than a whole step. Rule number two, it can have consecutive half steps. Rule number three, every note must be a potential point of rest.