Episode 45 Question

[Anonymous]

Can somebody please explain to me why the chords A minor and d7 work together. Since the licks are based off A minor pentatonic, the A minor chord makes sense but I don’t understand the d7 as it isn’t even a part of the key. If I understand correctly, it’s part of G major and leads tonally to a G. It sounds great however so I’m trying to understand why.

Thanks

[willise]

No expert here, but this is my understanding.

From a jazz perspective, there is a common progression of ii-V7-i which would be Am, D7, G. The diatonic chords in the key of G are G, C, D7, Am, Bm, Em. If you try playing some kind of progression using those chords and end on the D7, it will sound unresolved. Try the same progression again, but this time play a G after the D7 and you should be able to hear the tension relieves into the G.

The V7 chord is also often used when there is a change in key.

Try this: play 2 bars of G, 2 bars of B, 2 bars of Eb and finally 2 bars of G (G,G,B,B,Eb, Eb, G, G). Probably doesn’t sound very good. However, if you substitute the first bar of each key with a V7, it will sound better. So play D7, G, F#7, B, Bb7, Eb, D7, G

[bluesbird]

@willise wrote:

No expert here, but this is my understanding.

Me either! This is a really good question. Hopefully someone with a good theoretical background will weigh in and help us out here. I immediately thought of the chord progression for House of the Rising Sun (Am C D F Am C E7) which is either in the key of A with a forced Am or the key of Am with a forced Dmaj. I would consider this progression to be similar but have no idea why it works!

[Anonymous]

@willise wrote:

No expert here, but this is my understanding.

From a jazz perspective, there is a common progression of ii-V7-i which would be Am, D7, G. The diatonic chords in the key of G are G, C, D7, Am, Bm, Em. If you try playing some kind of progression using those chords and end on the D7, it will sound unresolved. Try the same progression again, but this time play a G after the D7 and you should be able to hear the tension relieves into the G.

The V7 chord is also often used when there is a change in key.

Try this: play 2 bars of G, 2 bars of B, 2 bars of Eb and finally 2 bars of G (G,G,B,B,Eb, Eb, G, G). Probably doesn’t sound very good. However, if you substitute the first bar of each key with a V7, it will sound better. So play D7, G, F#7, B, Bb7, Eb, D7, G

hmm, I think i kind of get what you are trying to say, thanks for breaking it down for me.

[Anonymous]

I know just enough basic music theory to be dangerous and give out bad information, 🙂 But here’s my take on this.
Am and D7 are closely related in that they have 2 notes in common:

Am = A C E
D7= D F# A C

I believe this has something to do with what’s called secondary dominants. These chords can often be substituted for each other.
This is a good question and reinforces my desire to learn more theory.

Phil

[Author]

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