So along the major scale, we have our regular major 7th chords in the I and III positions, and then we have our dominant 7th chord in the V position of the major scale. The same goes for the 7b5 chord in the VII position, but for minor. My question is: is it also possible to use the regular major 7th chord in the V position as well as the dominant chord, e.g. in C major, are G7 and Gmaj7 both valid chords in that key? If not, why not?
Thanks so much for all your help and advice!
Yes and no.
Gmaj7 is NOT a valid chord in the key of C. It has an F#.
It can’t really work as a V chord in the traditional sense. The dominant chord creates a tension that gives a feeling of needing to be resolved, i.e., G7 to C sounds resolved.
If you play a I-IV-V in the key of C, it would be quite difficult to get a Gmaj7 to sound right without perhaps modulating to a different key.
Then again, the old cliche about “if it sounds good …” always holds true. If you like the sound, then it’s fine. In terms of theory, you probably wouldn’t call it a V chord. Whatever you call it would depend on context. Personally I wouldn’t worry about conventional theory for something like this, I’d just call it an outside chord and adjust my melody or solo to suit.
