How do Roman numerals equate to chord progressions? Teach me like I'm 5...

[arkmabat]

I don't understand when people talk about a "VI V II" progression or whatever. How does that equate to key signature and chords? I'm really trying hard to buckle down and get more theory down.

[someone called simon]

Ok, those numbers you wrote are 6, 5 and 2, obviously. If we take the key of C as an example (because that scale uses all the white notes on a keyboard, so it's easiest), we can label the chord C as I (or 1, same thing), and the chord on each note higher on the scale gets a higher number, like so…
C = I
D = II
E = III
F = IV
G = V
A = VI
B = VII

(this also applies for the notes in the scale, not only chords. So if you're in C, and someone tells you to sing a 5th, you'd sing a G)

Now, at the simplest level, some of these chords will, by default, be major, some minor. Normally the II, the III, the IV will be minor, the rest major (except for the VII which we'll leave out for simplicity's sake here).

So in the Key of C, your chords will be Am, G, Dm.

The advantage of using numbers is that you can change key, say to E, to suit a vocalist's range, and your chord chart will still apply. An experienced player will know what the chord 'numbers' are in any key).

Another variation you may come across is that people sometimes use capitals for a major chord, lower case for a minor chord, so (in C as per our example) your 'II' may mean D major, and 'ii' would mean D minor. But this is not used universally. If you see lower case letters, it probably is.

You've probably heard of the I IV V (1, 4, 5) progression, one of the most common chord sequences. In C, that would be C F G, in A it would be A D E, etc.

hope that's helpful...

[arkmabat]

Yes, thank you.

[jancivil]

You have a typo up there I think, vi will be minor in major key, not IV.

Typically minor is expressed as lower case. I ii iii IV V vi; and vii is 'diminished' quality. Root, minor 3rd, diminished 5th. Dim. 5th from root is two minor thirds.

[lingyai]

OP: investigate this:

http://www.amazon.com/The-Chord-Wheel-U ... 0634021427

[jancivil]

The Chord Wheel is a revolutionary device
it isn't. That's not what that word means.

Maybe it's a eureka moment for some and better organized than some people's internet search is going to provide. Used for six dollars eleven cents though.

[Michael L]

By revolutionary, I believe they mean that the chord wheel "moves in a circle on a central axis," that little rivet....

[jancivil]

I read about half of what they shared from the thing, it actually looks pretty spot-on. I'm allergic to hype that insults the intelligence, though.
It being an actual wheel you turn strikes me as childish, but if it works, whatever.

[NKF]

a nomenclature devised or at least formalized by late 19th century theorists that tried to apply similar naturalism that was popular in germany at the time and apply it to music forcing a sort o hierarchy.

As jancivil mentioned , the system initially used all major characters as chord quality was considered irrelevant as minor was not considered an actual key but major with alterations.

Nowadays, it serves as a demarcation of diatonic chords. It no longer is used by a certain school of theorists and has become a shortcut to describe chords both minor and major tonality

[PurpleCatfishBettie]

also, you have '°' for diminished triads such as ii° in natural minor, or vii° in harmonic minor. (i forget if vii° for example is notated as 'vii°' or rather '#vii°' because it's built off of the raised 7th note of the minor scale. if memory serves, the sharp is understood.)

then, there's '+' for augmented triads such as the III+ in harmonic minor.

[Michael L]

A developer Rand Scullard designed an interactive circle of fifths with User Guide that may help make numeral/chord relationships clear:
http://randscullard.com/CircleOfFifths
You can download it as a Web Archive to use offline