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.

Below is the the Harmonic Minor Scale and it's diatonic arpeggios.  This PDF is similar to those for the Major Scale and Melodic Minor Scale, so check out those posts if you haven't.  The PDF outlines the Harmonic Minor, it's seven modes and the diatonic arpeggios.

As with the other Scale PDFs, it might be worthwhile to start with the arpeggios for each mode.  Not only are they less notes to focus on, but they are lines in themselves that make succinct, harmonic 'sense' out of the modes.  Once you understand the chord tones for a mode, then you can 'flesh out' the rest of the scale around it.

For the novice jazzer, it is less useful to understand this material for compositional movements, than to just be aware of the arpeggios that are buried within this scale.  While the Harmonic Minor is a great choice for the Min-Maj7 chords and sounds in tunes like Nica's Dream and Nardis, the harmonic minor is probably most used in jazz for altered sounds -- using the Phrygian Dominant over a #11 chord or the Ultra-Locrian for tri-tone colors over a functional Dominant.  Just learning the harmonic scale will give you access to these sounds, but being able to pick out all the arpeggios within it can give you a richer starting point for your lines.

Another key use of the Harmonic Minor in jazz is the 'Barry Harris' approach.  Barry Harris has a whole cosmology of scales and tones that starts with chromatics, splits into diminished and ends with sixth chords.  The 'Barry Harris' scale -- the Major#5 -- is really the third mode of the Harmonic Minor in this PDF.  Check out his 'Sixth-to-Diminished' theory which is at the heart of his teachings.  If you act as if the Third Mode of the Harmonic Minor is the 'One' chord for Major tunes, you can develop a unique perspective into the tunes of the Swing and BeBop era.  Either way, if you are familiar with the arpeggios in the Harmonic Minor and Melodic Minor scales, you will be able to spot them when transcribing the lines of Charlie Parker and other boppers when they go 'outside' the harmony.

​Frank Gambale offered this exercise for playing over chord changes on the 'No Guitar Is Safe' podcast.

Mr. Gambale uses the same strategy so many others use to play over chord changes, which -- in the music he plays -- can come as much as four times in a bar.  The secret is targeting one or two notes in an arpeggio -- essential tones.  The 3rd and 7th intervals are the ones that immediately state the quality of the chord, so that is the obviously place to start.  But being able to get to any interval will help you see the fretboard in a way that lets you play effortlessly over changes.

The Exercise:
Start simple -- looping two bars of E-minor and two bars of G-minor. Play the root 'E' first beat of Emin and Play 'G' on the first beat of G-minor.  Slowly work in the accompanying dorian scale as you feel ready.

From there, target the third of each chord.  Count up the dorian scale tones to the 3rd note from the E for Emin and the 3rd scale tone up from G on Gmin (Hint: you now play G at the start of Emin and Bb at the start of Gmin). Play this note on the first beat of each new chord. Make sure you are finding the equivalent note everywhere in a position, and eventually everywhere on the neck.  The 3rd of a minor is flatted -- it's one fret down from where it appears if the chord were major.

Next, target the flat-7th for each chord.  Loop the four bars and play the 7th on the first beat of each chord, adding notes after it.

From there you can move on to the five, and eventually all the tones, the 9, the 13, the 11. 

If you want to get fancy, target the tone for a specific beat of the chord, or try targeting two non-adjacent tones in a row.

Do the exercise moving two different chords -- Major to Minor, The V Dominant of a Major to the Major, etc.  Find the tones you like for each chord.  Find the tones everywhere on the neck.  After all that has been mastered, find the tones that are 'outside' the scale and know what they are.

Every time you get stuck on a passage of a tune, like a turnaround, break out that chord change and loop it.  Stretch it out and start slow as you can.  Target the 3rd and 7th of each chord.  Next, target all the arpeggio tones, then all the scale tones, finally all the 'altered' tones.  Make sure you are practicing in every position or visualization you have on the neck.

Your voice is the first melodic instrument you probably ever learned, and is the most accessible to the breadth of your audience.  I would argue the more a lead instrument sounds like someone singing, the broader appeal it will have.

I am not a singer and hate singing, BUT -- there are a number of exercises involving singing that will still help with jazz guitar.  Some are more of a time investment than others, where you may feel it takes away from practicing more 'practical' things, but remember that singing is completely portable.  Even just singing around the house washing dishes will keep you creatively developing melodic 'muscles' in your brain.

1) Sing when nobody is around the house or in your car.
Just coming up with melodies when you don't have your guitar is like calisthenics for the melody muscles in your brain.  Imagine a chord or a bar in a standard you are learning and sing a line over it, or come up with a melody and imagine an arpeggiated chord behind it.  Even if you have no idea what chords or notes you are singing, you are still connecting with the art and vibrations of improvisational music.  Or just sing what comes in your brain -- your are still crossing that important bridge from brain to muscle.

2) Sing along to music while it is playing.
Sing along to jazz or even pop music, even if you are just improvising over the harmony.  Try repeating phrases you hear in a solo on the fly.  I like to do this driving to a session -- it's like my first warm-up.  It makes my ear more more acute to what is going on. It exercises your listening muscles.  Listening is as important as anything else playing jazz and singing back a line can give you instant feedback on how acutely you are listening.

3) Sing when you are playing a solo.
Try to sing along with your solo.  This obviously helps with one of singing's biggest rewards: phrasing.  It's not difficult to play sixteenth notes for 32 bars straight without a rest and the fact that you cannot sing along to such a solo should tell you something.  Rests define melody as much as harmonic choices -- they are the 'negative space' that pop the melody out and encapsulate emphasis.  Jazz, not to mention music as a whole, was largely developed by instruments which require human breath.  Musical phrases often 'work' precisely because they emulate phrases of speech from a particular language.  Stewart Copeland likes to explain that even the most complex 12/8 rhythms from the farthest reaches of the world are really just templates of phrases in the local dialect for "I went down to the corner store to buy some milk" or something similar.  Even if it feels dumb, even if you are not playing the same note you singing, even if you are just grunting, even if you have never tried it -- try singing to your solos!  You will be amazed at how your timing suddenly becomes more direct and fluid.  Even non-melodic grunts will give your solo a 'conversational' reference point. 

4) Play a chord, sing a line, play the chord again, play the line.
Even if you know you are going to stumble, do it. It exercises all your jazz muscles.  It will take you out of the visual strategies you've built up eyeing where your fingers should go, what notes go with what chords, etc.  This is something I saw Barney Kessel teach in a video.  It helps build a personal vocabulary.  It gives you lines with 'real' phrasing.  It gives you a fresh and even personal perspective on improvisation over a harmony.

5) Play a note, sing a note, sing an interval of the note, play the interval.
This helps train your ears.  Even if you are getting in the ballpark, you are working your ear, but pay attention to your progress.

6) Transcribe a solo and be able to sing every note.
Transcribing from a master is one of the most beneficial things you can do to help learn the language of jazz.  This helps you really, really learn a solo.  Transcribing it to your voice puts it in your body, not just your fingers.  This exercise will also help you with your phrasing when you play it on guitar.  This is an extreme exercise, but you will get results from it.  When you are able to sing a solo, that solo is part of you, just like all those advertisement jingles and TV themes from your childhood.

You have probably heard someone talk about these exercises before so consider this is just a "blue-moon" reminder.  It will wake up something very deep inside your improvisational ability.  If you are like me, one reason you are playing instrumental guitar music is precisely because you *can't* sing (or rather don't sing well).  Even if you can't sing, don't sing or won't sing, singing will still improve your guitar playing.

Below is a chart of the Major Scale and Diatonic Arpeggios on guitar.

The pdf contains the Major scale with the seven modes, broken out into positions of the fretboard for a vertical fingering of each mode.  These 'boxes' of fingerings -- which I've termed R6 mode boxes -- are the shapes I memorized to learn the fretboard.  I call them R6 Mode Boxes, because they are distinct shapes of vertical fingerings for each mode with the Root on the 6 string.  They are chunks of the fretboard I can instantly visualize and distinguish -- giving me bearings on where everything else is.

By learning vertical diatonic arpeggios over these chunks -- the vertical scale boxes -- you will begin to learn the layout of the Major scale over the entire fretboard.  As you learn the Major Diatonic Chord Progression moving up the neck rooted on the sixth string, these arpeggio shapes can be 'landmarks' of where you are on the neck.  From an arpeggio, you can fill in the rest of the notes that make up a particular mode.  To have complete fluency, you must understand how to arpeggiate any chord within these seven R6 Mode boxes -- with the chord's root falling on any of the six strings. That is where the third and final section of the pdf comes in -- it shows the arpeggios for each of the seven degrees within each R6 mode box position.  For each 'chunk' of the Major scale, you should be able to visualize all the arpeggios in the Diatonic Chord Progression.

When playing over changes, every nanosecond counts. For each chord in a bar of music, the 'harmonic hierarchy' below is the order in which I visualize the 'best' notes to play:

1) the 'essential' chord tones -- third and seventh -- which have a colored outline on the chart
2) the arpeggio of the chord (root, third, fifth, seventh)
3) the chord's mode, or scale tones

An advanced player will also evaluate the harmonic hierarchy of the next chord to the the equation, not to mention arpeggios and scales of substitutions or altered sounds, outside the scope of this chart.

​The Major scale is perhaps 'the' cornerstone of Western music.  The Major scale is a seven-note selection of notes within the chromatic scale (the chromatic scale contains every note on the guitar).  Each of the Major scale's seven notes (or 'degrees') have a Mode and Arpeggio linked to them.

If you shift the root of the scale to a different note of the scale, you will be playing a different mode.  As the Major scale has seven notes or degrees, there are seven Modes in the Major scale.  The 'Ionian' mode is identical to the Major scale because they have the same Root -- the first note of a scale that sounds like 'home.'  When you play the notes of the Major scale starting from the second note, you are playing the Dorian mode. This is the mode for the second degree of the Major scale.  The degrees are usually notated as roman numerals.  So we associate Dorian with the roman numeral 'II'.  While 'II' is common -- it is more correct to use a lower case 'ii' for Dorian, but that will be discussed later.  Just know that 'II' or 'ii' refers to 'the Two Chord' in a Diatonic progression.

Moving the root note along each of the degrees of the Major scale gives you each of the seven modes.  If you play all seven notes of the Major scale starting from the second note, it 'sounds Dorian.'  Eight notes up, you reach a note that sounds like you've completed a circle.  If that 'home' tone happens to be the second note of the Major scale -- you are in the Dorian mode of the Major key.

Each degree or Major scale tone (one of the 'dots' on the chart) also has an 'arpeggio' associated with its mode.  Arpeggios are a selected group of notes in a scale played sequentially.  If the notes of an arpeggio are strummed at once, that is called a chord.  Arpeggios and chords have the same notes.

The chords associated with each of the seven degrees of the Major scale are called the 'Major Diatonic Progression':

​The diatonic '7th' chords are found by skipping every other note in a given mode.  Going back to the second degree and the Dorian mode -- if we play every other note in the Dorian mode to the next octave, we get and arpeggio for 'the Two chord' -- the diatonic chord for the second degree (represented by the roman numeral 'II' or 'ii').

The arpeggio for the I and the ii in a Major key have a different quality.  The 'One' chord has a Major third and a Perfect Seventh -- creating a Major 7th chord.  The 'third' scale tone of the 'One' chord is the third 'dot' in the scale (Ionian, in this case) when ascending  from the root.  The 'seven' is the seventh 'dot' in the scale, the note just before the next octave is reached. 

The 'Two' chord in the Major Diatonic Progression is a Minor 7th chord.  That is because we are now skipping notes of the mode starting on the II (second note in a major scale now functioning as the root).  The distance from dot 'one' to dot 'three' in the Dorian scale is shorter than the distance from 'one' to 'three' for Ionian.  With Ionian, the 'third' note of the scale is four frets from the root.  However, when you count scale notes (dots) starting on the Root of the Dorian mode/scale, the 'third' note in Dorian is only three frets away from the Dorian root.  We say the Dorian's 'third' is 'flatted' one semi-tone , or one fret. 

The distance between scale tones (dots) is called an 'interval.'  Distance is measured on the guitar in frets.  The distance of one fret is a 'semi-tone'.  Two frets on the guitar represents a 'whole-tone.'  The interval's quality always depends on how the distances line up with the Major scale.

A 'flatted third' is also called a Minor 3rd, because it signals that a chord is Minor.  Major thirds (four frets) and flat-thirds (three frets) are both 'intervals.'  

All the minor chords in the Major Scale also have 'flatted 7ths.'  The 'sevenths' of these Minor chords are one fret (or semi-tone) closer to the root than with a Major chord -- they are 'flatted' from the Perfect 7th of the Ionian Major.  The differences of intervals, especially 'thirds' and 'sevenths', are what give chords their quality -- a 'Major' or 'Minor' sound.

There are four qualities of chords in the Major Diatonic Chord Progression:

• Major: Major 3rd, Perfect 7th
• Minor: Minor 3rd, Flat 7th
• Dominant: Major 3rd, Flat 7th
• Half-Diminished (aka Min7b5): Minor 3rd, Flat 5, Flat 7

Even though we have three 'Minor-Seven' chords in the Major Diatonic Progression (plus a Half-diminished -- a minor with a flatted-five), each chord's associated scales are different.  This is because at least one of the intervals (fret distances) of scale tones is different in every mode.  Every mode in the Major scale has seven notes and seven intervals.  Once again, scale tones are black dots and an interval is the fret distance from the root to said dot.  Every mode has a 'Root', a 'two', a 'three', a 'four', a 'five', a 'six' and a 'seven'.

To make things slightly more confusing (but 'hipper' for the jazzbo) all the black dots we skipped over to make any Diatonic chord will have an 'alias' called an 'extension.'  It is not important to understand extension right now -- that's something that will make more sense when you move beyond the Diatonic chords we are focusing on here.  It is useful to learn that the 'two' has a secret 'code-name' -- which is 'nine.'  An 'eleven' is code for 'four', and a 'thirteen' is code for 'sixth.'  Just be aware that each of these following equations represent the same tone harmonically speaking:

• 2nd  = '9'
• 4th = '11'
• 6th ='13'

Notice these are the notes we are skipping to make a chord.  They are outside a given scale's arpeggio or chord tones.  It is not essential to learn these code-names immediately, but I've notated the charts this way for the jazzbo.

There are three minor-seven chords plus the minor-seven-flat-five in the Major Diatonic Progression.  It is most correct to cite the Roman Numerals for minor modes with lower-case Roman numerals.  Therefore, the Diatonic minors are: the ii, the iii, the vi and a special half-diminished minor -- the vii -- which has a flatted fifth.  Again -- these roman numerals are all scale degrees counting up along our original Major scale in the Ionian mode.

While the chords of the ii, iii, and vi all have the same intervallic formula (Root, b3, 5, b7), the intervallic formula of the scale for the ii, iii, vi (Dorian, Phrygian, Aeolian) are all different.  The differences in the minor modes lay in the notes we happened to skip over making the particular mode's minor chord.  For instance, the Phrygian scale has a b9 (remember, 9 is code for 2 -- the second note in the scale). 

The point is that while the three minor-seven chords in the Diatonic progression all have the same intervals in their arpeggio (R, b3, 5, b7), the intervals of the scale associated with them are different.   Look at the sixth scale tone of Aeolian versus Dorian. If you try and play the Dorian scale over each of the minor chords in a Diatonic progression -- it might sound a little 'off' if the rest of the band is thinking iii chord or vi chord.

If you understand all of the above, you will have an excellent foundation for playing jazz or any type of western music.  The Diatonic Chords in a song's given key are what make up the vast majority of popular chord progressions.  If a song's chords are all Diatonic chords in a Major key, any note in that key's Major scale are 'safe' notes to play -- all those dots will be 'consonant.'  If you are able to play an arpeggio for a given chord when it appears in a chord progression (black dots in the second section of the PDF), those arpeggiated notes will sound extremely 'strong' harmonically.  If you orient a line with a chord's mode/scale (e.g. play Dorian over a ii chord), that will also sound very 'harmonic.'  Of course, you may well know that jazz stretches 'outside' what is is 'safe' and toys with what is 'harmonic', but I vote for learning how to walk before trying to run.

The goal is for your eyes, ears and fingers to instantly know where all the 'strong' notes (black dots) are when a particular chord is playing.  The configuration of these dots should be constantly changing in your mind with each chord.  This will take a lot of practice -- probably at least a year for a beginner working incessantly with a teacher and very likely more.  I am still finding holes in what I know many years in.  But it is possible and it is worth it! Being able to visualize all the Diatonic modes and chords of the Major scale from anywhere on the fretboard is a must for the jazz guitar player.

Below is a reference for learning the Melodic Minor Scale diatonically.  The Melodic Minor is sometimes referred to as the 'Jazz Minor' due to its applications to Jazz.  You may have gotten hip to the fact that the 7th mode of the Melodic Minor can be used serve up altered sounds over a functional Dominant (a V going to a I).  At some point I also realized that the fourth mode of the Melodic Minor can be used over #11 Dominants.  Learning the totality of the scale with diatonic context of all the arpeggios will give much greater command over these sounds.

While the Melodic Minor only differs from the Major scale by one note, I still find myself struggling to visualize it thoroughly over the fretboard, certainly more than Major scale.  My ability to visualize the Major scale was significantly bolstered by learning all the diatonic arpeggios in the scale, across all the scale 'boxes' where the modes sit with the root on the sixth string.  Learning arpeggios also significantly strengthened my ability to generate lines strongly outlining the harmony. 

You can focus on parts of the neck by breaking it up into 'r6 mode boxes'.  These scale 'boxes' I term with the 'r6' meaning 'root is on the 6th string.'  For instance, 'III-r6' represents the way the notes sit when you play the Phrygian scale with its root on the sixth string.  This lines up as a box, or chunk of the fretboard which is easier to concentrate on, especially at first.

Just like the the Major scale, there are seven notes in the Melodic Minor.  Each of these seven 'degrees' has a mode, chord, and arpeggio associated with it.  Modes are simply the same notes of a scale arranged with a different note serving as the root.  The arpeggio for each degree can be found by skipping every other note in the mode until the next octave is reached.  An arpeggio is basically the notes of a chord played sequentially.

Below are the scales and chords for each degree of the Melodic Minor Scale:

​The Melodic Minor scales are:
I  - Melodic Minor (R, 2, b3, 4, 5, 6, 7)
II - Phrygian #6 (R, b9, b3, 4, 5, 6, #6)
III - Lydian Augmented (R, 2, 3, #4, #5, 6, 7)
IV - Dominant #11 (R, 2, 3, #4, 5, 6, b7)
​V - Mixolydian b6 (R, 2, 3, 4, 5, b6, b7)
VI - Locrian #2 (R, 2, #2, 4, b5, #5, b7)
VII - Super Locrian (R, b9, b3, 3, b5, #5, b7)

The accompanying chords are:
I  - Min-Maj7 (R, b3, 5, 7)
II - Min #6 (R, b3, 5, b7)
III - Maj7 #5 (R, 3, #5, 7)
IV - Dom.7 #11 (R, 3, 5, b7)(#11)
​V - Dom.7 b13 (R,3, 5, b7)(#13)
VI - Min7b5 (R, b3, b5, b7)
VII -Min7b5 (R, b3, b5, b7)
​
I recommend starting with the Melodic Minor arpeggios in the middle section of the PDF.  Take four or five days and run over the arpeggios for one mode (probably start with Min/Maj7) in all the different r6 mode boxes.  Maybe put on a relevant backing track and definitely a metronome.  By the fifth day, you should really concentrate on connecting between the boxes and try to work horizontally or diagonally.

After you have the arpeggios, the scales are just the rest of the notes to flesh them out.  Start with the most useful scales for playing over Dominants, like the Lydian Augmented and Super Locrian.

Finally, learn to run all the arpeggios within a particular mode box.  This will reinforce both the scale pattern and the diatonic progression within the Melodic Minor.

While you are not going to necessarily find a lot of complex harmonic movements of the Melodic Minor in Jazz tunes, learning the diatonics of the Jazz Minor will give you greater facility at minor two-fives and the ability to super-impose these scales in other applications.