Scales in Solos
Almost everyone starts the same way: someone names the scale that goes with the progression and you play it. That works surprisingly long, until it suddenly does not, because a chord turns up that the scale collides with.
- 1 scale, then 7
- collision points
- the chord is the scale
At which level
- Intermediate
- Any instrument
- Harmony required
In short
Take C, Am, F, G. All four chords are built exclusively from notes of the C major scale, which is what diatonic means. Play C major over the whole thing and no wrong note is available to you. That is a genuinely useful stage and worth staying in longer than most people do.
The freedom ends as soon as one chord contains a note your scale does not. That happens in two situations: the piece modulates, so the whole supply changes, or a secondary dominant appears, borrowing a note from outside to point at a chord that is not the tonic. The second is the more common and the more confusing, because everything else stays put.
How you practise it
Chord-scale thinking is the next stage: every chord carries its own scale, and you change supply as the chords change. It is powerful and it has a known failure mode, which is running scales instead of playing lines. The avoid-note idea is also worse named than it is useful: the note is not forbidden, it just needs resolving rather than parking.
Where you run into this
- A solo that works over four chords and derails on the fifth
- A secondary dominant that makes a whole chorus sound wrong for one bar
- A player who knows every scale and still sounds like exercises
Our own examples
The scale playable over the loop, plus the chord where it collides, so the moment one scale stops being enough is something you locate by ear instead of reading about.