The Sixth-To-Diminished is a chord scale which alternates between Major Sixth Chords and Diminished Chords to provide a chord for every note of the Major scale.  It is just sandwiching a Diminished chord between each inversion of the Major Sixth chord.  If you run up this chord-scale,  you will quickly hear a sound which harkens the chord solos of Wes Montgomery.

Wes Montgomery's octave solos are perhaps the most distinctive part of his sound, but nearly all of his solos were like a three act play:  First, he started with single lines, then he moved to octaves, finally he moved to chords.  Just by the sheer number of strings, he was 'building' up his solo.

There are a few different approaches to chord soloing, most of which involve targeting the note on a chord's highest string as the 'Melody Note' with the bottom strings 'fleshing out' what chord is being stated below.  The Sixth-to-Diminished approach is a quick-and-dirty chord-scale which you can learn on the cheap.

The Sixth-to-Diminished concept is championed by Barry Harris.  I did a blog post on the Barry Harris 'origin' story, but there is no context of what to do with that information.   The  basic takeaway should be that, through these philosophical machinations, the 'Sixth' chord has some interesting 'genes' in its DNA -- specifically related to the Diminished scale.  I imagine early jazzers started heavily exploring the Diminished because they heard the leading tones in an altered functional dominant.

The two-dollar explanation of the sixth-to-diminished is that the chord-scale is continually going from Five-to-One.  As outlined in the PDF, the diminished fingering is really an altered Dominant - a Dom.7b9 chord.  The ensuing chord is the 'One' chord, the Maj6.  Now -- what do jazzers love to do with any harmony?  Take any opportunity to add a 'V to I' cadence.  The Sixth-to-Diminished has the V to I in spades.  Every movement along the chord scale is a V going to a I.  

The beauty of the Maj6 chord is you can easily interpret it as Major or Minor.  Any Maj6 is an inversion of a min7. You may notice that the diminished chords -- spelled out in the chart as Dom.7b9 -- consistently have a note outside the Diatonic Major scale.  The flat-9 of these Dominants are actually the same as a Major#5.  I don't have the complete story on the Barry Harris method, but I know the Maj#5 chord is a big part of it.

If you take a look at the Diatonic chords of the Harmonic Minor, you see the Maj#5 is the Third Mode there.  If we used the Harmonic Minor's Maj#5 as the 'One' chord, the II mode would be the Harmonic Minor's vi  -- Dorian#11.  Let's take a look at the Sixth-to-Diminished harmonization of the II in the PDF.  It shows a Dom.7b9 to the V, but looking from the perspective of the II, we have the Root, the flat third, the sixth, and the #11.  Are the chord tones are outlining the Harmonic Minor starting from the III? Perhaps a discussion for another post.

​This is my first attempt at a chord melody.  I was told creating a chord melody would help me memorize the chord changes for a particular song.  It has also helped me figure out a few new fingerings.

I put chord boxes above the chords, stacking alternates at times.  The hollow circles are the second or third note to play holding the position (or en route to the next chord).  If you know the melody, you should be able to figure it out -- some go to a hollow dot and back to a solid dot.

The premise of constructing the chord melody is relatively simple -- the melody should run on the top two or three strings so you can stack the rest of the chord on the bottom strings.  The melody note should always have the highest pitch of all the notes in a chord.  It is not necessary to have a chord for every single note.  I always tried to aim to have at least the essential tones (3rd and 7th of the chord) and, if possible, the root note.  Often this required some inversions.

Please let me know if I have an error or typo.