Something I've never understood, is when creating larger chords, ie Am11, how to determine the expression of the 7,9,11.

For example, Am11 is comprised of 1, b3, 5, 7, 9, 11?
Or because it is a minor chord, do you determine that the 7 should be a minor 7, and so on and so forth.

How is it decided; does it simply rely on the key you're in, or is there an entirely different way of notating it, ie Am11 (b7 b9)? Help me out here, and I hope my question was clear enough. Thanks in advance! :|
The basic triad is Am. Those notes are A C E. Am7 adds a G, so you have A C E G. The 7th on a minor chord is always b7 unless the chord is Am/maj7, in which case you play the Am triad plus the maj7, G#, forming A C E G#.

Once you start putting extensions above the 7th such as 9s, 11s, and 13s, the 7th is assumed (this applies to dom7, maj7, and m/maj7 chords as well). Am9 would be assumed to contain the G note. If it were A C E B and no G note, it would be called Am add9.

When you add extensions past the 9th, notes are often left out. While the notes in an Am11 chord are technically A C E G B D, the fifth and ninth aren't that important, so either or both can be left out at the performers discretion. The same applies to 13 chords. The 5, 9, and 11 aren't so important, so they too can be omitted if you prefer that sound. However, whether you omit those tones or not, it is still Am13.

When you alter the extensions, you write the 7 and then the altered extension. Amb9 would be incorrect notation. It should be written as Am7b9. A common chord using this is the "Purple Haze Hendrix Chord," E7#9. The rules of omission are the same here as well. E7#9 technically contains the notes E G# B D *Fx. However, Jimi played only the notes E G# D Fx.

The reason behind this note omission is that certain notes have little to do with the overall harmony. In a C13 chord, the notes are C D E F G A Bb. However, the notes that specifically make it C13 are the root, C, the third, E, the seventh, Bb, and the 13th, A. Adding other tones doesn't make it any more of a C13 chord, but can make the chord muddy, especially in a big jazz band where such a chord would typically be found. You cannot, however, leave out any altered notes. If the chord were C13#11, you couldn't leave out the #11.

*Fx is sometimes written F## and is enharmonic to G but can't be written as G because Western music does not allow for the same letter to appear twice in a chord or scale. For instance, the B major scale is B C# D# E F# G# A# instead of F# G# B.

I hope this helps. I'll be glad to clarify any points of confusion, but please do ask a question; no "I don't get it," garbage. This is a lot of information at once, so read it a few times and try to understand each concept as I bring it up before moving on.

Edit:
You may be interested by the following thread. It gets a bit off-topic, but oh well: http://ultimate-guitar.com/forum/showthread.php?t=918682&page=1&pp=20
Last edited by bangoodcharlote at Jul 26, 2008,
Quote by bangoodcharlote
The basic triad is Am. Those notes are A C E. Am7 adds a G, so you have A C E G. The 7th on a minor chord is always b7 unless the chord is Am/maj7, in which case you play the Am triad plus the maj7, G#, forming A C E G#.

A minor triad with a major seven is called dominant, isn't it? If not can you briefly explain what makes up a dominant 7 chord for me?

Quote by bangoodcharlote

When you add extensions past the 9th, notes are often left out. While the notes in an Am11 chord are technically A C E G B D, the fifth and ninth aren't that important, so either or both can be left out at the performers discretion. The same applies to 13 chords. The 5, 9, and 11 aren't so important, so they too can be omitted if you prefer that sound. However, whether you omit those tones or not, it is still Am13.

More than knowing which tones to omit, I was looking for a way to tell, which tones are flattened/sharped and which are left natural. Does the 13 in an Am13 chord have a default tone - automatically a pure tone (13 from A : an F) or does it rely on the key you're currently in? If the scale has an F# in it, would the 13 default to #13, or does it have to specify that in the chord, is essentially what I need to know
Quote by bangoodcharlote

When you alter the extensions, you write the 7 and then the altered extension. Amb9 would be incorrect notation. It should be written as Am7b9. A common chord using this is the "Purple Haze Hendrix Chord," E7#9. The rules of omission are the same here as well. E7#9 technically contains the notes E G# B D *Fx. However, Jimi played only the notes E G# D Fx.

What if the 9 was already sharped in the key signature? DOes it apply at all?

Quote by bangoodcharlote

I hope this helps. I'll be glad to clarify any points of confusion, but please do ask a question; no "I don't get it," garbage. This is a lot of information at once, so read it a few times and try to understand each concept as I bring it up before moving on.

Thanks for writing such a detailed answer for me =)
A minor triad with a major seven is called dominant, isn't it? If not can you briefly explain what makes up a dominant 7 chord for me?

A dominant chord consists of a root, a major third, a perfect fifth, and a minor seventh (1-3-5-b7)

More than knowing which tones to omit, I was looking for a way to tell, which tones are flattened/sharped and which are left natural. Does the 13 in an Am13 chord have a default tone - automatically a pure tone (13 from A : an F) or does it rely on the key you're currently in? If the scale has an F# in it, would the 13 default to #13, or does it have to specify that in the chord, is essentially what I need to know

The name of the chord will generally tell you, though there are a few conventions regarding how this is done. The 7th, for instance, is considered to be minor unless explicitly describes as major (e.g. a simple x7 chord is describes as 1-3-5-b7). In addition, any extensions beyond the seventh (e.g. an x9 chord) imply a b7 as well, unless the chord is called an "add-x" chord, in which case the extension is simply tacked on by itself.

What if the 9 was already sharped in the key signature? DOes it apply at all?

Amb9 always describes the same chord, regardless of the key signature.
Someones knowledge of guitar companies spelling determines what amps you can own. Really smart people can own things like Framus because they sound like they might be spelled with a "y" but they aren't.
Quote by Archeo Avis
A dominant chord consists of a root, a major third, a perfect fifth, and a minor seventh (1-3-5-b7)

Okay, thanks
Quote by Archeo Avis

The name of the chord will generally tell you, though there are a few conventions regarding how this is done. The 7th, for instance, is considered to be minor unless explicitly describes as major (e.g. a simple x7 chord is describes as 1-3-5-b7). In addition, any extensions beyond the seventh (e.g. an x9 chord) imply a b7 as well, unless the chord is called an "add-x" chord, in which case the extension is simply tacked on by itself.

Okay, this implication of a b7 is exactly what I'm looking for; are there any more rules in this respect? 9's, 11's?

Quote by Archeo Avis

Amb9 always describes the same chord, regardless of the key signature.

Right, that should have been obvious, silly me

Quote by InTheFlesh!
Okay, this implication of a b7 is exactly what I'm looking for; are there any more rules in this respect? 9's, 11's?
I don't think so, but if you form a more specific question we may be able to help.
Quote by Archeo Avis
A dominant chord consists of a root, a major third, a perfect fifth, and a minor seventh (1-3-5-b7)

I dont claim to know much theory, but isnt that a 7 chord? like:

e--2- =3
B--1- =b7
G--2- =5
D--0- =1
A-----
E-----

Edit: you also said "x7 chord is 1 3 5 b7" - is there a difference?
if i'm wrong, correct me; i'm looking to learn more theory, not get bashed for being wrong

Saying the Red Hot Chili Peppers have no talent is like saying Guy Fawkes didn't have an epic mustache.
Last edited by chipmunksurfer at Jul 27, 2008,
Quote by chipmunksurfer
I dont claim to know much theory, but isnt that a 7 chord? like:

e--2- =3
B--1- =b7
G--2- =5
D--0- =1
A-----
E-----

Edit: you also said "x7 chord is 1 3 5 b7" - is there a difference?
if i'm wrong, correct me; i'm looking to learn more theory, not get bashed for being wrong

_7 (dominant 7th): 1 3 5 b7

maj7 (major 7th) : 1 3 5 7

m7 (minor 7th) : 1 b3 5 b7

It needs to have the notes for the chord, but it doesn't have to be in that order, except for the root. The root is usually the note on top, or the bottom.
oh so i was just an idiot. my bad. thanks for explaining

Saying the Red Hot Chili Peppers have no talent is like saying Guy Fawkes didn't have an epic mustache.