Approach to chord substitution

[redrooster]

Hi, my teacher has showed me some things about chord substitution in order to apply this stuff in a blues progression, but i don't understand some parts about this.

If we are in A, my teacher in the turnaround instead of E7/DMaj7/A7/A7, he plays G#m7(b5)/F#m7/A7/A7. I think that i understand the first change, because he told me that the dominant can be substituted for the VII degree of the scale (in this case G# half-diminished) but the second change i don't understand at all. I think that he told me that the fourth equals to the second, but at this moment i don't know if equals to the second of the Dmaj7 (F#m7) or equals to the second of A7. Hope someone can help with this substitution!

thanks!!

[cruisemates]

I think it is a question of being more clear about exactly where the chords go.

In the key of A, it is easy to substitute G#minorb5 for the E7 because it is all the same notes - you have just put the G# in the bass.

G#min7b5 = G# B D (natural) F#... (if you add an E this is basically an E9 chord)

same with using F#min7b5 for D9

But sometimes those chords are added to the progression - like in the song Stormy Monday, they aren't really substituted. Also, he may just be saying you can substitute them in terms of lead scales or chords your guitar plays while the rest of the band actually plays the straight blues chords.

[redrooster]

thanks! i think that i begin to understand this...so it's more a question of "voicing" than substitution? or this concept would be wrong?

Another example that showed me (of course i don't understand) is instead of playing the typical turnaround (playing in A) he plays the third instead the fifth, and the second instead the fourth (and then the two measures of A). I don't understand what he does.

lots of thanks cruisemates!

[DeaconBlues]

So, in the case of "Stormy Monday" these substitute chords can be used for a contrast between the actual chords in the song?