I'm re-reading Noteboat's theory book. It's a great book and, as my understanding of music and my guitar skills improve, I get something new from it each time I read it.
I have a question concerning his mention of the 2 symmetrical tetra-chords of the major scale, and the 2 asymmetrical tetra-chords of the minor scale. It seems to me that there is something very important about being able to see each of these scales as a pair of chords separated by a whole step, but I can't figure out what it is. I feel like I know just enough to know I'm missing something very significant about this insight. Can anyone give me an example or two that shows me how to actually apply this idea? Thank you in advance for any help.
Dan
A "tetrachord" isn't the same as a chord - it's just a series of four notes. (It comes from the Greek words for 'four strings'). A diatonic scale is made up of two of these sets of four notes:
C major = CDEF (1st tetrachord) and GABC (2nd tetrachord). Each tetrachord is a pattern of WWH, and there's a whole step between them to form the major scale.
Since the two tetrachords in a major scale have exactly the same pattern, when you look at the series CDEF, you don't know if you're looking at the first tetrachord of a C major scale... or the second tetrachord of the F major scale (FGABb CDEF). So each major scale sort of overlaps two others - C major includes the 2nd half of F major, and the 1st half of G major.
That's actually why the circle of fifths works too - follow the overlapping tetrachords and eventually you arrive back at the beginning :)
Guitar teacher offering lessons in Plainfield IL
Wow. The bit about relating the overlapping tetrachords to the circle of fifths is very interesting! Thank you for the response and clearing up my confusion, Noteboat. Please stop whatever you're currently doing and write a follow up book.
Dan
This guitar noise lesson talks about tetrachords.
https://www.guitarnoise.com/lessons/developing-a-practice-session/
Might spark something.
