Music theoryists can you help?
If I was to play a I, IV, V chord progression in the key of G on the blues scale I’m left with the following chords: G, C# and D
No quite sure what you mean.
The sound of the blues is essentially playing a minor pentatonic scale over a I, IV, V dominant 7 chord progression so in G you would play G minor pentatonic over G7, C7, D7. The so called blues scale adds the flat 5 to the minor pentatonic so the C#.
You can also play the G major pentatonic over that progression which would be a major blues (just drop whichever pentatonic box you are playing in at the time down three frets and you are playing the major blues). In fact you can mix up minor and major pentatonics in the same tune/jam.
Things can get even more interesting if you incorporate the major 3rd of whichever dominant 7
chord you are playing over at the time especially when playing the I chord.