Diatonic

[triniatlarge]

Hi Pete, Thanks for your page. I am learning so much. However I am not understanding the diatonic theory. I am sure it is simple. I read "Chord VI is a diatonic 3rd away from chord I and chord IV " What does diatonic mean here? What note is a 3rd away? If you can break it down for me that would be great.
Thanks

 

[Pete Thomas]

a diatonic 3rd is an interval of 3 steps, using the scale of the key that the tune is in.

E.G. a major scale is made up of whole tones and half tones, so in C major the interval between C and E is a 3rd (3 steps = C-D-E). The interval between E and G is also a 35d (E-F-G), but not quite the same .

C to D to E is two whole tones, but E to F to G is one half tone (semitone) and one whole tone. So we call the first interval (C to E) a major 3rd, the second one (E to G) a minor 3rd.

So in the example you are talking about, if this was the key of C also, we would be talking about an A minor chord which is a minor 3rd interval below C (ABC) and also a major 3rd interval above F (FGA).

 

[triniatlarge]

Thanks I appreciate the info