Is the 'Major seventh chord' wikipedia page correct?

[Rxkimo]

On the wikipedia page for 'Major seventh chord' there is a chord table. For Amaj7 it has the following pitches:

Amaj7 A C♯ E G♯

And so I have the following questions:

1) Are those pitches the correct ones for Amaj7? I thought it would be A C# E G (not G#).

2) Is there some flexibility when picking what notes make up a seventh chord? For example, does A7 have to contain A and C#, but the next notes could be 3 semi-tones away or 4 semi-tones away? It seems like the second note (C#) MUST be 4 semi-tones away or it wouldn't be a major chord. But what about the other notes?

3) If I want to create a triad by counting semi-tones away from the root, does the song's key restrict what notes you count? For example, if I'm writing a song in the key of A major, and I want an A major chord, I count 4 semitones from A and I get C# as the second pitch in the A major chord. I count C when counting semi-tones, even know that pitch is not in the key of A. It seems like the key of the song doesn't matter, but I was curious if the method of "counting semi-tones away from the root" was foolproof.

I appreciate any help with the above - thanks!

[walternewton]

I'd suggest looking at chord construction in terms of scale degrees, rather than counting semitones.

An A major scale is A B C# D E F# G# A.

A "Maj7" chord by definition contains the 1 3 5 7 notes, so A C# E G#.

A "7" chord (also called dominant 7 - and maybe what you were thinking of) consists of 1 3 5 b7 - so A C# E G.

[Malcolm]

On the wikipedia page for 'Major seventh chord' there is a chord table. For Amaj7 it has the following pitches:

Amaj7 A C♯ E G♯

And so I have the following questions:

1) Are those pitches the correct ones for Amaj7? I thought it would be A C# E G (not G#).

Wikipedia is correct.

2) Is there some flexibility when picking what notes make up a seventh chord?

No, I'll go into detail.

Let's take Amaj7 first.

A scale is; A, B, C#, D, E, F#, G# and if we stack 3rds (every other note) we get the chords built from the A scale notes.

First chord would have the A, C#, E, G# and if you would compare those notes to the A scale you would have the 1-3-5-7 intervals of the A scale. Thus the spelling tells me -- the 3 tells me the chord is major. The 5 tells me the chord is not diminished or augmented and the 7 tells me the chord has a major seventh. That combination always gives an Amaj7 chord.

Next chord in the key starts with the B - then skip every other note for - B, D, F#, A and when we compare this to the B major scale of B, C#, D#, E, F#, G#, A# we find that we have a 1-b3-5-b7 spelling. The b3 tells me we have a minor chord (all minor chords have a b3) the 5 tells me this is not a diminished or an augmented chord and the b7 tells me we have a minor seventh or Bm7.

Now for fun start with the E and see how you get a major dominant seventh chord.

Here is the seventh story:

Basic Chords
Major Triad = R-3-5
Minor Triad = R-b3-5
Diminished Chord = R-b3-b5

7th Chords
Maj7 = R-3-5-7
Minor 7 = R-b3-5-b7
Dominant 7 = R-3-5-b7
½ diminished = R-b3-b5-b7
Full diminished = R-b3-b5-bb7 Harmonic minor and melodic minor will use the full bb7

Scales
Major Pentatonic = R-2-3-5-6
Minor Pentatonic = R-b3-4-5-b7
Blues = R-b3-4-b5-5-b7
Major Scale = R-2-3-4-5-6-7
Natural Minor Scale = R-2-b3-4-5-b6-b7
Harmonic Minor Scale = R-2-b3-4-5-b6-7
Melodic Minor Scale = R-2-b3-4-5-6-7

You are on the right track, I think if you will look at every other note, it will make it simpler.

[JonR]

EDIT: dang, I knew people would post before I finished my pedantic lecture... Well, here it is anyway...

On the wikipedia page for 'Major seventh chord' there is a chord table. For Amaj7 it has the following pitches:

Amaj7 A C♯ E G♯

And so I have the following questions:

1) Are those pitches the correct ones for Amaj7? I thought it would be A C# E G (not G#).

2) Is there some flexibility when picking what notes make up a seventh chord? For example, does A7 have to contain A and C#, but the next notes could be 3 semi-tones away or 4 semi-tones away? It seems like the second note (C#) MUST be 4 semi-tones away or it wouldn't be a major chord. But what about the other notes?

Interval terminology is useful to explain this.

1. "Major" and "minor" only mean "bigger" and "smaller", in reference to an interval which can be of two common sizes; such as 2nds, 3rds, 6ths and 7ths.

2. MAJOR 3rd = 4 semitones from root
MINOR 3rd = 3 semitones from root

This interval determines whether the chord (the basic "triad") is major or minor.

3. There are two kinds of 7th extension on a triad:
MINOR 7th = 10 semitones from root
MAJOR 7th = 11 semitones from root

An important consideration is that each kind can be added to either a major or a minor chord - IOW, to a chord with a major or minor third.

4. IOW, we can have all the following combinations:

major triad plus major 7th
major triad plus minor 7th
minor triad plus major 7th
minor triad plus minor 7th

So how are we to label chords in a neat, economical way, avoiding confusion as much as possible?

The answer is to take the MAJOR TRIAD and the MINOR 7TH as standard, and not to refer to those in chord names - take them as read. We only refer to the less common minor triad and major 7th when they occur.
(In harmonizing a major scale, there are actually an equal number of major and minor triads: 3 of each. But major chords are regarded as primary. With 7th intervals, there are five minor 7ths and only two major 7ths, so the former is obviously the most common.)

This means our chord naming system can be concise. Here's the possible variations on an A root:

A C# E G (major triad with minor 7th) = "A7"
A C# E G# (major triad with major 7th) = "Amaj7"
A C E G (minor triad with minor 7th) = "Am7"
A C E G# (minor triad with major 7th) = "Am(maj7)"

So the most commonly occurring combination gets the shortest name - and the rarest one the longest name.
Ie, the word "maj" in a chord symbol refers to the 7th, not the basic triad. ("A7" is also based on a major chord.)

Here's the derivation and usage of each type:

A7 = V chord in keys of D major and D minor. Common blues chord in A major and E major.
Amaj7 = I chord in A major and IV chord in E major
Am7 = vi chord in C major, ii chord in G major, iii chord in F major, iv chord in E minor
Am(maj7) = i chord in A minor (from harmonic or melodic minor).

NB: both "maj7" chords are not always used. The plain triad version is probably more common, esp in pop and rock. Maj7 extensions have a very distinctive sound, usually reserved for specific purposes.

3) If I want to create a triad by counting semi-tones away from the root, does the song's key restrict what notes you count?

Yes.
That is, it guides you rather than restricts you. (You can build a chord anyway you like )

For example, if I'm writing a song in the key of A major, and I want an A major chord, I count 4 semitones from A and I get C# as the second pitch in the A major chord. I count C when counting semi-tones, even know that pitch is not in the key of A. It seems like the key of the song doesn't matter, but I was curious if the method of "counting semi-tones away from the root" was foolproof.

It is, as long as you count correctly.
The number of the interval (3rd, 5th, 7th etc) is an "ordinal" number. That means you count the one you start from, as the "1st". And to begin with, you only count letters.
So, A-C# and A-C are both "3rds", because A is "1st" and C is the 3rd letter in the series.
When we differentiate between the two 3rds, we measure the distance in semitones. We don't then count the first step, just the distance from that step.
So A-C# is 4 semitones and A-C is 3. That makes them major and minor as explained.

Chord names are independent of key. Eg an "A7" chord has the same notes wherever you might find it: A C# E G, even when it occurs in the keys of A or E (which it often does). IOW, there is no need to refer to a scale when determining a chord structure - other than the basic C major scale (ABCDEFG) of course, and its structure.
Of course, if you start by harmonizing a specific scale, then you name the chords according to the notes you end up with. In the keys of A or E major, the 7th note up from A is G#, so that chord will be "Amaj7".
When composing a song, you still have the choice to reject the chords the scale gives you, if you don't like the sound.

[Malcolm]

Major chord = Root + 4 + 3.
Minor chord = Root + 3 + 4.

Once again the keyboard is much easier to work things out on. The fretboard is confusing.

[Rxkimo]

walternewton, Malcolm, and JonR,

Thanks for the ton of info. It definitely answers my questions.

One more question....what's the typical way an accomplished musician "knows" what pitches are in a chord? For example, say an Amaj7 chord?

a) From years of playing, they know off the top of their head it A C# E G#
b) At one point they memorized all the popular chords using flash cards
c) They might not know the pitches, and to figure it out they count semi-tones from A
d) They might not know the pitches, and to figure it out they think of the key and count scale degrees
e) It varies, everybody has their own way
f) They search google
g) Some other way

[walternewton]

One more question....what's the typical way an accomplished musician "knows" what pitches are in a chord?

Start by studing the basics of music theory - the major scale and how it is harmonized into triads and 4-note (seventh) chords.

Learn all your major scales, and it from there it will be simple to figure out the notes that comprise any chord.

[Malcolm]

a) From years of playing, they know off the top of their head it A C# E G# Kinda, yes
b) At one point they memorized all the popular chords using flash cards Memorized
c) They might not know the pitches, and to figure it out they count semi-tones from A You could.
d) They might not know the pitches, and to figure it out they think of the key and count scale degrees Could
e) It varies, everybody has their own way Yep, I think this hits it on the head.
f) They search google Or use a chord generator.
g) Some other way Yep, back to "e".

Good question. Depends on what instrument you are playing how you went about knowing what notes are in a chord -- IMHO.

Rhythm guitar. All you really need to know is how to finger the pattern, to get the right notes. I let the pattern take care of having the correct notes.

So if I am using fake chord or lead sheet music the sheet music will give me the chord name - all I need to know is how to finger the pattern that gives that chord. However, when I play bass guitar I'm expected to play the notes of the chord one note at a time and we do not strum so our pattern is going to be different - however patterns still work, if I know what notes I will need.

On bass I see the Amaj7 chord and I say to self; OK it's major and has a major 7. So I'm looking for a root, a 3, 5 & 7. Now I'm always looking for a root, 3, 5, & 7 and if I know where the root is on my fretboard the 3 is always in the same spot relative to the root. The 5 and 7 are also in the same spot relative to the root - just waiting for me to use them. Now the notes I use in my bass line can be:

Major Scale Box. 

G|---2---|-------|---3---|---4---| 1st string
D|---6---|-------|---7---|---8---|
A|---3---|---4---|-------|---5---|
E|-------|---R---|-------|---2---|4th string

Just roots, i.e. A-A-A-A to the beat of the song when I'm under the Amaj7 chord.
Or R-5-R-5 or R-5-8-5 or any combination of those three notes.
And if I really want (or need) the rest of the chord tones then I could throw in the major 3 and major 7 into the mix. http://www.youtube.com/watch?v=obFcsEtFIKA

It kinda depends on the instrument you are using and whether or not you rely upon The Pattern or need to be involved with individual notes, i.e. playing piano you will need to know what notes are in each chord or rely upon a "frozen hand" pattern to sound those notes. Google frozen hand, piano.

Here is a cheat sheet - you are always hunting for the correct root, 3, 5 & 7:
Major chords will have a 3. Minor chords will have a b3. Diminished chords will have a b3 and a b5, augmented chords will have a sharped 5. Then we get into the sevens. It's not hard to put that to memory.

Basic Chords
Major Triad = R-3-5
Minor Triad = R-b3-5
Diminished Chord = R-b3-b5

7th Chords
Maj7 = R-3-5-7
Minor 7 = R-b3-5-b7
Dominant 7 = R-3-5-b7
½ diminished = R-b3-b5-b7
Full diminished = R-b3-b5-bb7 Harmonic minor and melodic minor will use the full bb7

Scales
Major Pentatonic = R-2-3-5-6
Minor Pentatonic = R-b3-4-5-b7
Blues = R-b3-4-b5-5-b7
Major Scale = R-2-3-4-5-6-7
Natural Minor Scale = R-2-b3-4-5-b6-b7
Harmonic Minor Scale = R-2-b3-4-5-b6-7
Melodic Minor Scale = R-2-b3-4-5-6-7

Major modes
Ionian same as the Major Scale.
Lydian use the major scale and sharp the 4 - yes, it’s that simple.
Mixolydian use the major scale and flat the 7.

Minor Modes
Aeolian same as the Natural Minor scale.
Dorian use the Natural Minor scale and sharp the b6 back to a natural 6.
Phrygian use the Natural Minor scale and flat the 2.
Locrian use the Natural Minor scale and flat the 2 and the 5.

Generic Notes.
The root, five and eight are generic and fit most any chord. Remember the diminished has a flatted 5.
The 3 is generic to all major chords. See a major chord R-3-5-8 is a generic bass line that will work.
The b3 is generic to all minor chords. See a minor chord R-b3-5-8 is a generic bass line that will work.
The 7 is generic to all maj7 chords. R-3-5-7.
The b7 is generic to all dominant seventh and minor seventh chords. R-3-5-b7 or R-b3-5-b7.
The 6 is neutral and adds color, help yourself to 6’s. I like R-3-5-6 for major chords. Has a great sound.
The 2 and 4 make good passing notes. Don’t linger on them or stop on them, keep them passing.
In making your bass line help yourself to those notes, just use them correctly.
Remember roots, fives, eights and the correct 3 will play a lot of bass.

See if that turns the light on.

Good luck.

[JonR]

walternewton, Malcolm, and JonR,

Thanks for the ton of info. It definitely answers my questions.

One more question....what's the typical way an accomplished musician "knows" what pitches are in a chord? For example, say an Amaj7 chord?

a) From years of playing, they know off the top of their head it A C# E G#

Yes.

b) At one point they memorized all the popular chords using flash cards

Not me. Could be done that way I guess.

c) They might not know the pitches, and to figure it out they count semi-tones from A

That would work, provided you know the chord and scale formulas.

d) They might not know the pitches, and to figure it out they think of the key and count scale degrees

Too long-winded. If you just want to know what's in an Amaj7, you don't need to refer to a key scale (and that could be misleading with some chord types). You only need to know what the symbol means:
"A" = A major tirad = A C# E
"maj7" = major 7th interval from A = G# (the higher of the two 7th options, G or G#).

e) It varies, everybody has their own way
f) They search google
g) Some other way

Sure. And maybe all of the above! Eventually you don't need any method to work it out; it just comes down to (a) - you just know.