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I've been learning about modes, and one thing I was interested in at first was to change modes while improvising (to get to know them better technically as well as to have a better understanding of what their flavour is). For instance, I improvised in minor pentatonic, and used its ambiguity with the relative minor modes to try to explore their differences. This lead me to question how to properly change modes in a convincing way, and even how to properly change key.

I don't know anything about the theory of modulation, but I wanted to try and experiment to figure out how it could be done.


I first picked two keys at random : E aeolian and G# aeolian.

I basically did what I think is a common-chord modulation. My idea was to pick the common notes between the two keys, and use them to transition from one key to the other. Here, the common notes are B E F#, which are a Bsus4 triad, so I used that chord to transition between the two keys. Going to E aeolian I let Bsus4 resolve to Bm, and going to G# aeolian I let Bsus4 resolve to B.

I used this very simple progression (on a loop) and improvised in E minor pentatonic/E aeolian, going to G# minor pentatonic/G# aeolian and back, to keep it as simple as I could.

Em Am | Em Am | Bsus4 B | G#m C#m | G#m C#m | Bsus4 Bm

My observation is that I managed to change key in a way that sounded pretty good (at least to me) when the change was from E to G#, but not the other way around, I found it much more difficult to sound even decent.


  • I thought it could be because Bm triad is B D F# and F# is not in Em pentatonic, while the B triad is B D# F# which are all in G# pentatonic. So I changed F# to the closest note in Em pentatonic, G, which means I'm left with a G triad. So I tried this :

    Em Am | Em Am | Bsus4 B | G#m C#m | G#m C#m | Bsus4 G

    But the chord themselves didn't sound that good (even if I tried to play G in first inversion to keep B at the bass, to have some sense of resolution for the suspended chord), and when I tried to improvise the problem remained.

  • I thought it could be because of the resolution sus4 -> minor which isn't as appealing as sus4 -> major, so I tried this progression :

    Em Am | Em Am | Bsus4 B | G#m C#m | G#m C#m | Bsus2 Bm

    Bsus2 isn't part of both keys, but at least the resolution Bsus2 -> Bm sounds better. But alas, improvising a melody that sounded good when going from G# aeolian to E aeolian was still a challenge.


Coming back to my initial progression

Em Am | Em Am | Bsus4 B | G#m C#m | G#m C#m | Bsus4 Bm

I don't get how this doesn't work. I thought it could also be that B doesn't have the same function in both keys, but it happens to be that B is V in E aeolian and III in G# aeolian. Functionnally it should work, even if I'm only mostly going from Em penta to G# penta and back, shouldn't it ? Even if that's the issue, I've tried to change B to G, which is III in E aeolian (see first point above) but it doesn't work !

Since I've never tried modulating while improvising before, I doubt it could be my improvising itself that is the issue. If it is, why is it so easy for me to change from E to G# but not the other way around ? And even if it's just my ear that is not accustomed to this change, why is there a difference really ?

I'm also thinking that maybe from E to G# your going up a major third while from G# to E you're going up a sixth, but I'm not sure I understand why it could be that that makes that much difference. Obviously E and G# are as far away from each other as G# and E are in the circle of fifths.

Is it maybe because of the relative functions of the common notes in both keys ? In E aeolian, E F# B are I, II, VI, and in G# aeolian they are II, VI, VII. I'm not sure were to go from there if that's the reason.


TL;DR : Using a common-chord modulation from E aeolian to G# aeolian and improvising, going from E to G# sounds good pretty easily, but not the other way around. Why is that ? I'm using the same method to come up with the chords, and I've never improvised in such a modulation context before, so there is no apparent reason why one change should be easier than the other.

  • Would you mind clarifying some of your chord qualities? Those G♯ and C♯ chords are all minor, correct? – Richard Aug 8 '18 at 17:05
  • Yes indeed, mistake on my part ! – Sylvain J Aug 8 '18 at 17:25
  • (original post edited) – Sylvain J Aug 8 '18 at 17:39
  • I think the same problems will be there even if you modulate from E major to G# major, and use diatonic notes. When modulating, usually, the ultimate chord before the change is V of the new key. Going from E to G# (majors) will need D#(7), while returning will need B(7). Same problem, I think. That lack of leading note, as Richard spotted, is a bigger problem. – Tim Aug 9 '18 at 11:43
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One possible fix might be found in this sentence:

it happens to be that B is V in E aeolian

I wonder if you're conflating V as a dominant major triad with the triad built on the fifth scale degree. Because the triad built on the fifth scale degree is B minor (v), which doesn't lead back to an E tonic as smoothly as a B-major triad (V) would.

Technically, this B-major chord doesn't fit your stipulation that you want this chord to be diatonic in the subsequent key (in this case, E Aeolian). But when I play your progression, the D♮ in that chord sticks out to me as a "wrong" note. And culturally, we're really accustomed to hearing a B-major triad move to an E tonic. This means that, just by playing a D♯ in that chord, you really strengthen the resolution to E and make clear to your listeners that you're looping back to the beginning.

And this doesn't interrupt your improvisation either; you can continue to use G♯ Aeolian above this chord if you like. It is, after all, the relative key/scale of this B-major chord!

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