I'm in a rush, off to Mobile to play a show, so I'll try to do this quickly.

Seventh chords do not define a key in the larger sense. You can be in the key of C and have a C7 move you to F then go to G to come back to C. Very strictly speaking, this would have you in the key of F, but in modern music this would be considered a chromatic passing tone moving the Bb note (the seventh in the C chord) down by a half step to the A note (the third in the F chord), If the Bb was a small part of the piece, it would be in the key of C.

Another example: what if you played F, G7, then Am. Are you in the key of C? or Am?

Determining key is a little more complicated than either looking for the seventh chord or looking for the last note in the melody. These are good indicators, but not definitive.

I'll be happy to debate when I get back on Monday [Linked Image]

All the Best,
Mike

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You have to practice improvisation. -Art Tatum

Mike Dunbar Music

You've got to know your limitations. I don't know what your limitations are. I found out what mine were when I was twelve. I found out that there weren't too many limitations, if I did it my way. -Johnny Cash

It's only music.
-niteshift

Mike Dunbar Music