From: bobm@Ingres.COM (Bob McQueer)
Subject: Re: chord theory
Date: 10 Oct 92 01:54:48 GMT

<LEAVE BLANK LINE AFTER HEADERS (you may delete this line)>
In <14171.2ad59e07@ohstpy.mps.ohio-state.edu>,
	dated 9 Oct 92 14:58:15 EDT,
	egras@ohstpy.mps.ohio-state.edu writes:

I thought BrianE's post very good.  I thought I'd try an addenda to a
couple items.

> In classical music, there are very strict rules for all of the above.
> 
> 1)  In Major: the diatonic chords (i.e. chords appearing naturally in a key
> such that the chords don't need any sharps or flats) are
> 	I ii iii IV V vi vii'  ( where caps are major, lower case are minor,
> 				 and the apostrophe means diminished)
> 
>     In minor:  the diatonic chords are:
> 	i ii' III iv V VI vii' (remember in minor keys the 7th note of the
> 				scale is raised a half step. e.g. in a minor
> 				you have a g# rather than a g natural)

In fact, if you take the notes forming the standard scale (do, re, mi, etc.)
for a given key (start on "la" or VI for the minor), the chord given above
may be formed by constructing triads using the alternate notes out of the
given scale.  For instance, the ii chord is constructed from the second
fourth and sixth - D F and A in the case of key of C, for instance.  You will
find that guitar chords for any of these consist of the appropriate triad
notes in some combination (inversion, to use the correct term).  Without
inverting them, triads form standard patterns in terms of number of half steps
between the notes:

	major - note <skip three half steps> note <skip two half steps> note
	minor - note <skip two half steps> note <skip three half steps> note
	diminished - note <skip two half steps> note <skip two half steps> note

In the case of standard chord positions for guitar, diminished chords are
generally shown as one of three positions which actually stacks another
minor third on top:

	note <skip 2> note <skip 2> note <skip 2> note

	or

	* - * -
        - * - *

	on the upper 4 strings, moved to one of three positions to cover
	all possible notes.

An augmented triad consists of stacked MAJOR thirds

	note <skip 3> note <skip 3> note.

You can work out 4 chords on guitar which will cover inversions of these.  They
generally sound, however, like shit.

> 4) You can modulate to any key but some are smoother than others.
>    Closely related keys differ by one sharp or flat at most.  These are the
>    smoothest.  e.g. G,F,a,e,d are all closely related to C.  There are many
>    more ways to modulate but this is the simplest.

There is a neat little thing called the circle of fifths to remember related
keys.  Turns out that jumping a fifth means you are adding a sharp:

	c  g  d  a  e  b  g_ d_ a_ e_ b_ f

where _ indicates "flat".  Draw that around in a circle with "c" at
twelve o'clock, and the rest drawn around clockwise.  A pnemonic crutch -
you can remember the word "bead" embedded backwards in the circle.  Now,
as you go around clockwise from c, add sharps.  As you go around counter-
clockwise, add flats - so key of g is one sharp, d two sharps, and so on.

Closely related keys are neighbors on the circle, and will share
several chords - for instance the 3 principal majors for D are
D, G, and A.  For G, they are G, C and D.  Real easy to modulate
between key of D and key of G - they share six notes.

Incidently, if you start with the fact that in the key of g it will be
the f which gets sharped, and in the key of f, it is the b which gets
flatted, you can also chase fifths clockwise, or fourths counterclockwise
around the circle to see which notes are getting added as flats or sharps:

	e is 4 sharps - f, c, g and d

A sus or "suspension" chord is formed by raising the note you would lower
to form the minor.  For instance, the stock A position goes to minor
by lowering the c# on the second string to a c.  Raising it to a d produces
the suspension.  You, too, can be Pete Townshend.

A <something><numberth> chord indicates the something with the extra interval
from the root thrown in - C6, for instance is an C chord with a sixth, ie
an A tossed into it.

Seventh has a funny terminology in popular music <something>-seventh means
not to toss on the 7th, but the flatted-seventh, for instance, adding a
b-flat to your C chord (yep, third fret G string is b flat).  To classical
people, this is called the "dominant" seventh chord, and usually sounds
very "right" when applied to the V triad.  If you actually place the unflatted
seventh on your triad, you get what is called the "major seventh".

Enough.  I hoped I haven't made any major slipups here.  Most of my theory
moved into the dustier parts of my mind long ago.