The major bebop scale has been in common knowledge for decades. I have outlined the tonic/dominant (IMa6 iiDim) polarity in an earlier blog (March, 2012). So check that out and you’ll see a few examples of some ideas for expanding upon that idea. OK, then comes Barry Harris (a well known jazz piano/educator) who instructs us with some mysterious sounding, but not necessarily rocket-science, ideas for the bebop scale. The scale: in C major: C D E F G G# A B C.
For starters, most jazz players these days will study the scale-tone sevenths of at least four or five different scale types, so most are familiar with playing scale-tone sevenths for example, in major scales in a step-wise root motion as in C major:
CMa7 Dmi7 Emi7 FMa7 G7 Ami7 Bmi7(b5) CMa7 and learning the modes that are often associated with those chords.
I chanced upon a youtube video of Barry Harris working with (astonished) students and he did a similar thing except he played them over the bebop major scale. While paying strict attention to voice leading, each of the four voices, leads to the next note in the scale, creating a very interesting take on the bebop scale. This approach has a very similar effect to the C6 Ddim toggling-polarity application mentioned earlier, yet they sounded different and interesting. Scale-tone sevenths here start out as normal but quickly run into that added note G# (#5 or b6) so the chord qualities start to change quickly from that of the scale-tone sevenths in the pure major scale. I’ve outlined a few ideas from what I heard in B.H’s you-tube video, but basically here is the main theme:
Notice there are eight scale-tone sevenths chords as opposed to seven in a major scale. Also notice that there are two mi7(b5) chords in the bebop major scale.
Barry Harris played them as triads over a bass note which are outlined below:
The triads (numerator) over the bass notes can be inverted giving a greater range.
For more information on this and related topics, check out An Approach to Jazz Piano.