Global Bass Online                                                                      August/September  2001

                                                                                                By: Lucas Pickford

In my last few columns we’ve looked closely at the Symmetric Diminished Scales (SDS) and how they can be applied over dominant seventh chords. Another scale that is very useful over dominant chords is the one called the Altered Dominant Scale (ADS). The ADS looks like this: C-Db-Eb-E-Gb-Ab-Bb-C.  

The ADS is different by only one note from its SDS counterpart but that one note is very crucial in determining when to use it. The note that is different is the 13^th degree of the scale. The 13^th is also referred to as the 6^th degree of a scale but when you extend the scale up beyond one octave, the 6^th degree becomes the 13^th degree. In a SDS, the 13^th degree is natural. A SDS starting on C would look like this: C-Db-Eb-E-F#-G-A-Bb-C. 

Notice that the A note is natural. In an ADS, the 13^th degree is flatted so the A becomes Ab. What’s the big deal if the scale is only different by one note? It’s a big deal because you use the ADS when the harmony indicates a  II-V-I chord progression going to minor. The 13^th degree of the scale you use on the dominant chord becomes the 3^rd degree of the scale of the I chord. 

Ex.1- In a common II-V-I progression such as Gmi7 – C7 – Fmaj7, the A note (which is in the SDS scale we would use over the C7, it’s the natural 13^th) becomes the 3^rd of the Fmaj7 chord. A is the third note in an F major scale. Make sense?

Ex. 2 – In a II-V-I progression that ends up on a minor chord such as Gmin(b5) – C7(b13)- Fmin7, we must anticipate the harmony of the Fmin7 by playing the flat 13^th in the scale right before it which is the ADS played over the C7(b13) chord. That Ab note makes the ear hear that the I chord is going to be minor in tonality.

This all might seem like it’s very intricate and to some degree it is, but the main thing to remember is that when the chord progression is heading towards major, like in Ex1, play the SDS.  When it’s heading toward minor like in Ex.2, play the ADS. Of course you can break these rules as all good improvisers do but please learn the rules first, then break them. The ADS fits any dominant chord but it is not symmetrical like the SDS. Use it in place of the SDS in the appropriate places. More on this and all things having to do with scales in the next issue.

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