Music Theory Tip - the Diminished

Stu's Music Theory Tip o' the Day: 

(disclaimer: this is wordy) 

Flat Five Chords (diminished). 

Why would you ever do something so
odd as to flat, or diminish, or lower, the
the fifth of any chord? Well, most of
the time, a flat five is used on the minor
two chord, on its way to the Five chord,
back to the One. It adds a little tension,
or motion, or depth, to the minor two,
and typically includes the 7, which
adds tension also. 

So, in the key of C: If your chord
progression is C Am7 Dm7 G7
you can flat the five of the Dm7 (the minor
two chord) for extra tension.
If your chord progression
is G Em7 Am7 D7, then you can flat the five
of the Am7, the two chord in G. 

Yes, you can also flat the five of the
other minor chords in the above examples,
which are the "minor six" chords in each
progression. 

Why? Because, basically flatting the
five adds momentum to the movement
UP a FOURTH. It leads the minor chord
even more feverishly toward its jump. 

Flatting the five of Em7 makes it
really eager to go to A. Cmflat5
wants to go to F REALLY bad!
Up that fourth! 

The 7 does the same thing...propels
all chords up a fourth, so you'll see
the flat5 and the 7 together. Maybe
the 9 too, or the 11, or 13, but fear not! 

A 9 or 11 or 13 chord is is just a
seven chord with more energy, more
momentum pulling it up that fourth.
(A 9 Chord inlcudes the 7.
An 11 Chord includes the 9 and 7.
13 Chord includes the 11, 9, and 7)

Now, add the flat five to that family
of chords, the ones that pull you up
that fourth. It's just typically used
on the minor two and six chords
of a progression. (other uses include
using it in a modulation to another key,
but again on a minor chord headed up
a fourth). 

Now, before you ask. Moving from
the One to Four. Major chords.
That's a jump up a fourth. Why not
use it there? Nah. And the Five to the One.
Major chords. Here you can use the
7,9,11,13, but you want to AUGMENT
your five here. 

That's what we'll reveal next time:
that the augmented chord is typically
appropriate, according to the mathematical
laws of our galaxy, as an extra weight
for major chords moving up a fourth,
most commonly the Five back to the One.