Introduction
We have already discussed why you can use different scales over the same chord in a previous lesson. In short, you can use a particular scale over a particular chord if that scale contains the 3rd and the 7th (Guide Tones) of the chord. So for example, the 3rd and 7th of Am7 are C and G, so you can theoretically use any scale with the notes C and G in it over an Am7.
But we have not yet discussed which scale you should (generally) use over a particular chord.
Selecting Scales
So, let’s take the chord Am7 = A C E G
Let’s also take four of the most common minor scales, which are the four minor modes of the Major scale:
- A Dorian (G Major) = A B C D E F# G
- A Phrygian (F Major) = A B♭ C D E F G
- A Aeolian (C Major) = A B C D E F G
- A Locrian (Bb Major) = A B♭ C D E♭ F G
Now, all four of these scales contain the notes C and G, so in theory all four of these scales can be used over an Am7 chord.
Minimise Avoid Notes
But this brings us to the next concept, that of Avoid Notes. An avoid note is a note in a particular scale that clashes with a particular chord. This occurs when a scale note is one semitone above a chord tone. The scale you use over a particular chord will determine the number of avoid notes in that scale. I have bolded the chord tones and put the avoid notes in Red.
(Aside: Some people believe the 6th in the Dorian mode is an avoid note over a m7 chord (F# in the above example) because it is a tritone (another dissonant interval) above the 3rd of the chord (C in the above example). I disagree (avoid notes are a little subjective). For the purposes of this lesson and all past and future lessons, let’s say the Dorian Mode does NOT contain any avoid notes, and as such the F# is NOT an avoid note).
- Locrian mode
- Used for Half-diminished chord (because of the ♭5)
- Has two Avoid Notes
- Phrygian mode
- Used for Phrygian chord
- Has two Avoid Notes
- Aeolian mode
- Has one Avoid Notes
- Dorian mode
- Has zero avoid notes
So, while you can use all the above modes over the Am7 in theory, because the Dorian and Aeolian modes have zero and one avoid notes respectively (rather than 2), most Jazz musicians play the Dorian or Aeolian modes over a m7 chord in practice.
Now, let’s look at the chord AmMaj7, where the 3rd and 7th are C and G# respectively. We can use the following scales over this chord:
- A Melodic Minor = A B C D E F# G# – No Avoid Notes
- A Harmonic Minor = A B C D E F G# – One Avoid Note
- A Double Harmonic Minor = A B C D# E F G# – One Avoid Note
And again, we find that while in theory all of the above scales are perfectly fine to use over an AmMaj7 chord, in practice most Jazz musicians play the melodic minor scale (because it has no avoid notes as opposed to one).
The same can be done with the chord CMaj7. The following scales can be used over this chord:
- C Ionian (C Major) = C D E F G A B – One Avoid Note
- C Lydian (G Major) = C D E F# G A B – No Avoid Notes
Notice that C Lydian Mode does not have any avoid notes. And you will find that many Jazz musicians use the Lydian mode to improvise over Maj7 chords.
Minimise Note Changes
Another thing to consider is how many notes change between two consecutive modes. The fewer notes change (the more note the two scales have in common), the smoother the transition will sound (e.g. D Dorian to C Lydian – only 1 note difference). If you want a more disjointed sounds, then pick two modes that share few notes in common (e.g. D Dorian to G♭ Ionian).
Practicing Playing Modes
Finally, the last video below describes how to go about practicing modes. This can be a bit challenging precisely because we change modes on every chord. For this reason playing using modes can sometimes sound a bit disjointed. But, like everything, start slow and simple and gradually build up in complexity, and over time you’ll be able to master improvising smoothly use modes. To do this you should follow the below steps:
- Select a song you want to learn
- Select Modes for Improvisation
- Play modes ascending from tonic using melodic continuity
- Play modes descending from tonic using melodic continuity
- Play modes stepwise up & down connecting them smoothly using melodic continuity
- Play modes stepwise & arpeggios up & down connecting smoothly using melodic continuity
- Play modes using stepwise movement, arpeggios & larger leaps up & down connecting smoothly using melodic continuity
- Play modes using stepwise movement, arpeggios & larger leaps up & down connecting smoothly using phrases & varying your rhythm
- Play modes & chromatic passing notes using stepwise movement, arpeggios & larger leaps up & down connecting smoothly using phrases & varying your rhythm
Conclusion
So in conclusion, when selecting a scale to play over a chord, you should generally try to pick one which has as few avoid notes as possible. Note the use of the word ‘generally’ in the above sentence. You CAN use any of the above scales, and many others. That’s perfectly fine. But you should always keep in mind the number of avoid notes in a scale over a particular chord. And, IN GENERAL, try to select scales that minimise the number of avoid notes over that particular chord.
Selecting Scales without Avoid Notes
Selecting Scales to Minimise Note Changes
Practicing Modes
