Eric Johnson's ability to solo with chords always impressed me when I was starting to play guitar. It was so much to take in, it's hard enough to make single note solos interesting and here he was using a whole bunch of notes all at once. A lot of what he does is based on triads, every inversion and position, be it open or closed. This lessons covers open position triads, their inversions and how they relate to each other with voice leading and melodization.
Example 1 is a simple C major triad with it's inversions. The first voicing is C,G,E, it's first inversion is E,C,G and the second inversion is G,E,C. Arpeggiate it like Example 2 and you can hear how these voicings can be used for intervallic sounding lead lines.
Example 3 is the same voicing and inversion idea on an F chord so we can get a progression going like Example 4, changing from C to F. The idea here is smooth voice leading. each chord taking the shortest possible route to the next. Look for common tones between chords, see how the C note doesn't move in the first chord of the first bar in Example 4? That's voice leading. That's the ticket. Example 5 arpeggiates the same progression. Remember, these voicings can be used for soloing with a distorted lead tone as well as chords with a clean tone. EJ is all over this stuff, it gives a real solid sense of harmony and freedom to the player when you can hear the changes going by without accompaniment.
Example 6 gives an A minor chord the same treatment. Now we have three chords to voice lead into. Example 7 shows a few possibilities with C, Aminor and F.
This is were things get a little more advanced. Example 8 is the entire chord scale from the key of C. Example 9 is an arpeggiated chord scale. Don't forget to try these examples as single note leads as well. Examples 10 and 11 are all the inversions. This is a lot to take in so be patient with this stuff before you try the next examples.
This is when it starts to sound like music. A standard diatonic cycle of fourths applied to the key of C gives us a chord progression of C-F-Bdim.-Em-Am-Dm-G. Example 12 shows a couple possible permutations of said progression using all the voicings we have worked on so far. The next step is, how do we incorporate some single note stuff to play melodies on top of the chords?
Examples 13 to 15 show how a scale note can be applied BETWEEN the chord changes to give some melodic flavour. Example 13 is the same cycle of fourths progression in Example 12 but with a scale on the highest voice in the chord. This scale will always descend into the highest voice of each chord change. Example 14 does the same thing except on the mid voice. Example 15 is a little different considering the smooth voice leading between every chord. The bass note doesn't move much so a scale note below each new chord was added. If this is all starting to sound like a really remedial Bach piece than you are correct. J.S Bach was a master of voice leading and inner melodies (AKA Counterpoint). Listen to Glenn Gould performing Bach's Inventions to hear a master at work.