Chord Numbers

[Chili]

i really dont get chord numbers for some reson, i think i might have a little idea, but the book i have doesnt explain it clearly at all, i used to think a chord was like, two or more notes bein played at the same time lol, can someone help me out with this plz?

[cowsgomoo]

when you say 'chord numbers', am I right in thinking you're referring to roman numeral chord descriptions like: I - IV - V - vi etc ?

if so, the numerals refer to basic 3-note chords built on the different degrees of the major scale

so, in the key of C major, your I chord is C major, your IV chord is F major etc...

to denote a minor chord, the roman numeral is written in lower case... so in our example, a D minor chord, which will be built on the 2nd degree of the major scale, will be written as ii (lower case roman numeral for '2')

so if you see a chord sequence that says:

I - iii - vi - V

and you want to play it in C, the chords would be:

C - Em - Am - G


that's the very basics of chord numbers... they're there to enable you to play a piece regardless of the key... useful if you have to back different singers or transposing instruments, because you're not tied to any one key

[dlloyd]

Or is it the Dm7, C9, A6/9, Bsus2 thing?

Those numbers tell you which notes to play (or rather, which you can play).

The first letter tells you which root note to use, which note to start building the chord from.

If it has an "m" after it, you make a minor triad, which is root, minor 3rd, 5th
If there's no "m", it's a major triad, where you use a major 3rd instead of the minor 3rd.
Unless it says "sus" in which case it will usually say either sus2 or sus4 when you'd use root, 2nd, 5th or root, 4th, 5th instead.

The other numbers are extensions, additional notes you'd add on top.

If it says 7, you'd add a minor 7th
If it says maj7, you'd add a major 7th
If it says 9, you'd add a minor 7th and a major 9th
If it says add9, you'd only add the major 9th

And so on...

If this is all foreign to you, do a search on "intervals"

[Turock]

Originally Posted by Chili

i used to think a chord was like, two or more notes bein played at the same time lol, can someone help me out with this plz?

A chord is three or more notes; two notes does not give enough information to identify a chord.

[Chili]

so is major 7th just the 7th note in the major scale? and it gets called a chord?

[thewanderer24]

No, a Major 7th chord, is Root+Major3rd+Perfect 5th+Major7th= 4 notes.

Also in terms of major scale it's 1st note + 3rd note + 5th note + 7th note

[dlloyd]

Originally Posted by Chili

so is major 7th just the 7th note in the major scale? and it gets called a chord?

It's, as the other poster said, a major triad with a major 7th note on top.

The major seventh note is a note that is an interval of a major seventh above the root. Don't think of it in terms of the seventh note of a major scale... in this case that would work, but in other cases (e.g. a minor 2nd) it doesn't.

Here's a quick list of intervals (a semitone is the pitch difference between two adjacent frets)...

Unison = 0 semitones (i.e. the same note)
Minor 2nd = 1 semitone
Major 2nd = 2 semitones
Minor 3rd = 3 semitones
Major 3rd = 4 semitones
Perfect 4th = 5 semitones (often just called a 4th)
Diminished 5th = 6 semitones
Perfect 5th = 7 semitones (often just called a 5th)
Minor 6th = 8 semitones
Major 6th = 9 semitones
Minor 7th = 10 semitones
Major 7th = 11 semitones
Octave = 12 semitones
Minor 9th = 13 semitones
Major 9th = 14 semitones
Minor 10th = 15 semitones
Major 10th = 16 semitones
Perfect 11th = 17 semitones (often just called an 11th)
Diminished 12th = 18 semitones
Perfect 12th = 19 semitones (often just called a 12th)
Minor 13th = 20 semitones
Major 13th = 21 semitones
Minor 14th = 22 semitones
Major 14th = 23 semitones
Double Octave = 24 semitones

There's a lot there that you won't come across very often. I've put the ones that will be most immediately useful to you in bold.

There are also some that are given different names depending on how the notes are being used. You might see an "augmented 4th", which is a fourth that is raised a semitone from the perfect fourth. It's the same distance from the root as the diminished 5th, but it's not used the same way. To add to the confusion, it's also called a tritone. Just don't worry about it too much at the moment!

The most common chords are built on the following "triads"

Major = root, major 3rd, perfect 5th
Minor = root, minor 3rd, perfect 5th
Diminished = root, minor 3rd, diminished 5th
Augmented = root, major 3rd, augmented 5th
Suspended 2nd = root, major 2nd, perfect 5th
Suspended 4th = root, perfect 4th, perfect 5th.

Again, the ones you'll come across most are in bold.

In a lot of simple pop music (let's ignore jazz for now!), you stick mostly to the same key throughout the song. The chords you find will all be built on the same major scale.

If you were playing in C major, what is called the "I" chord is built on a C root, using the C major scale:

C,E,G which is a major triad

If you were playing in C major and built a chord from a D root (D is the second note of the major scale, so you'd call it the "ii" chord, using Roman Numerals), you would still use the C major scale:

D,F,A which is a minor triad.

And so on. If you follow this pattern, you'll get:

I = major triad
ii = minor triad
iii = minor triad
IV = major triad
V = major triad
vi = minor triad

Note the use of upper case and lower case to denote major/minor. The vii chord is a special case...

vii = diminished triad

Now, adding the numbers, we'll add a fourth note, the seventh to all of these, using the same rules. What you end up getting is this...

I = major triad + major 7th Major 7 chord eg Cmaj7
ii = minor triad + minor 7th Minor 7 chord eg Dm7
iii = minor triad + minor 7th Minor 7 chord eg Em7
IV = major triad + major 7th Major 7 chord eg Fmaj7
V = major triad + minor 7th 7 chord eg G7
vi = minor triad + minor 7th Minor 7 chord eg Am7

The vii is a special case again...

vii = diminished triad + minor 7th Half diminished or minor 7 flat 5 chord

Usually you'll either see that as e.g. Bm7b5. Sometimes you'll see a little circle with a line through it followed by 7. It means the same thing.

[geoffkhan]

Or do you mean chord numbers as in the way classical theory refers to inversions? (I.E. Cmaj 6/4)

[Snarf]

You guys crack me up.