Theory & Impro How do you spell a Co7 chord?

[jimmylh]

It is basically the same chord. The only difference is if a G# note gets actually played somewhere.
Let me try in C
C|Am7|Dm7|G7|| are the "barber chords". Everything in C major
To spice it up, the third of the second chord is raised (C note on the Am7 chord) and we get
C|A7|Dm7|G7||
To get more flavour of that A7 being a dominant of Dm7, we add a b9
C|A7b9|Dm7|G7||
Now the bass player gets bored of jumping up and down like he is playing C&W and omits the root of the second chord.
C|C#dim|Dm7|G7||

Transpose it a semitone down, and we have your Polkadots bridge.

The four progressions are pretty much interchangeable (with caution) when improvising.
Please note that the only note outside the original C key are C# on A7, Bb and C# on A7b9 (try to use them to build a line)

Maybe someday I'll understand all that... lol

 

[aldevis]

Maybe someday I'll understand all that... lol

Feel free to ask. Often other members can be less technical and more effective than me.

 

[jbtsax]

Thanks Aldevis. You have given me another way to look at chord substitutions. Doesn't the "tri-tone substitution" for the dominant 7th apply the same principal. To help see the relationships, I have written out the chords to show the enharmonic tones shared between the C diminished, and the G#7b9.