Ok, it's a trick question. The answer is it depends on which octaves the notes are in, and specifically which note is higher. That's the concept of interval inversions that I will talk about here. I suggest reviewing my lessons on The Musical Alphabet and Intervals.

For reference, here is the table of interval names.

A good first guess answer to the above question would be minor third, since there are three half-steps moving upward from A to C (from A to A#, from A# to B, and from B to C).

But what if we take the A and raise it up an octave. Then we're counting half-steps starting from C instead of from A. Like so:

1. C to C#
2. C# to D
3. D to D#
4. D# to E
5. E to F
6. F to F#
7. F# to G
8. G to G#
9. G# to A

We can see that is nine half-steps. Or, if we're clever (which we are), we can remember that an octave is 12 half-steps, so just subtract three from 12, and get nine that way. Either way, we see that the inversion of a minor third is a major sixth.

This process is called inverting an interval. That is, it's when you take the lower note in an interval and increase it by an octave.

One important thing to notice is that if you invert an interval twice, you wind up with the same interval you started with. Using the above example, this becomes obvious. Start with the minor 3rd from A to C. First, raise the A an octave, giving a major 6th interval from C to the A above. Then raise the C an octave, and we're back to the minor 3rd from A to C.

So what?

When dealing with harmonies, an interval and its inversion are like cousins, really close-knit cousins. Because they are really built from the same notes, but moved to different octaves, one can be substituted for each other. In isolation the we're looking at them now, that's not such a big deal, but use them to build chords, and it becomes a hugiferously important tool for making interesting harmonies. Next lesson, I'll cover chord inversions, and you'll see more clearly what I mean.

Special case: the tritone

If you're good at math, you may notice that 12 - 6 = 6. Interesting, eh? That means that the interval of six half-steps is it's own inversion. Checking the table, this is the awkwardly named diminished fifth / augmented fourth (those are actually two alternate names). It also has a third name, the tritone. It's exactly half an octave, and actually not a particularly pleasant sounding interval. So much for cosmic balance.

Reference

Here is a listing of intervals and their inversions.

Ooo, look at all those high numbers. Those must be really complicated, difficult chords! Probably sound craaaazy!

Ok, so maybe not.

These chord names may sound impressive, but they're really just continuations of the same patterns we've already been using. A ninth chord is just a seventh chord with the added interval of the major ninth. An eleventh chord is just a ninth chord with the added interval of the perfect eleventh, and a thirteenth chord has the added interval of the major thirteenth.

Before continuing, I suggest reviewing my intervals lesson and seventh chord lesson.

I only covered intervals up to a seventh in my intervals lesson, and that's because after seven they just start over. So that means, if you see an interval greater than a seventh, all you need to do is subtract seven, like so:

• Major ninth --> major second
• Perfect eleventh --> perfect fourth
• Major thirteenth --> major sixth

Constructing a thirteenth chord

Let's walk through the construction of a G13 chord, to see how it works. Start with G7, which we know has the following notes:

» G, B, D, F.

Next, add the major ninth, which is just the major second, which is A:

» G, B, D, F, A.

Next, the eleventh, which is the fourth, which is C:

» G, B, D, F, A, C.

Then finally, the thirteenth, E:

» G, B, D, F, A, C, E.

I know what you're thinking, and yes, that's a lot of notes. Yes, that's more notes than can be played at once on a six-string guitar. I think we need to get rid of some.

What can we get rid of? Well, not the G, since that's part of the chord name. It would be silly to have a G chord without a G in it, wouldn't it? And not the E, since that's the thirteenth interval, and also part of what gives the chord its name.

We also can't get rid of the major third, the B, since that's what makes this a major chord (rather than a minor or suspended chord).

Next, we also need to keep the dominant seventh, the F. This one's a little less obvious, and it comes from a rule: high-numbered chords always contain the dominant seventh. Yes, it's another one of those arbitrary rules that we just have to live with. (Otherwise it would be called an "add13" chord. Read more about "add chords.")

The rest we can consider optional (though the perfect fifth, the D, is almost always there). That makes things easier, doesn't it?

• Required notes: G, B, F, E
• Optional notes: D, A, C

And of course, the ninth and eleventh chords are similar, but don't go all the way up to 13.

Now you can play them!

• See how to play a G9 chord at the Chorderator.
• See how to play a G11 chord at the Chorderator.
• See how to play a G13 chord at the Chorderator.

When can they be used?

Since high-numbered chords are just seventh chords with added notes, you can play them any time you would normally play a seventh chord.

But what's the point?

Why do we need all these big numbered chords? What's wrong with nice major and minor triads, maybe a seventh chord thrown in just for craziness sake once in a while? Doesn't this all see a bit... much?

Well, yes and no.

You definitely don't want to overuse these chords if you're playing a Woody Guthrie cover, but they can come in handy in certain circumstances. Here are some examples, which I will cover in more depth in future lessons.

Chord/melody: A lot of times, you'll find yourself playing lead guitar and rhythm guitar at the same time. Since these chords have more possible notes, you have more options for including the melody line along with the backup.

Chord substitution: This is when you substitute one chord for another one. For example, you can play a G13 when the song calls for a Dm, since the G13 already contains the D, F, and A notes. Again, the more possible notes a chord has the more chances you have to substitute it for another chord. (This is a pretty advanced topic I will cover later on.)

General funkiness: These high-numbered chords sound "different." They sound "jazzy," "funky," "strange." If that's what you're going for, they can be just the ticket.

Now go play

Theory's all well and good, but to appreciate these chords, you gotta play them. Start plugging them into your songs, start jamming around with them. The more you know, the more you can do. So go play.

I covered major and minor chords in a previous lesson. A suspended chord is what you get when you take a major or minor chord and replace the interval of the third with another interval.

To review, here are the interval formulas for major and minor chords.

(You can refer back to my intervals lesson if you don't remember what the interval names mean.)

You'll notice that the two chord formulas only differ in the second note added, which is an interval of either a major third or a minor third. So if you take that out there is nothing to distinguish a major chord from a minor chord. In fact, a suspended chord is neither major nor minor. This makes them very useful, since they can be played anywhere a major or minor chord would be played. The most common intervals to substitute for the third are the perfect fourth and the major second.

Never mind why they're called "suspended." They don't really hang from the ceiling or anything like that.

Suspended fourth chords

A suspended fourth chord has the following formula.

• root, perfect fourth, perfect fifth

It's as if you took a major chord and replaced the major third with a perfect fourth. (Or you could take a minor chord and replace the minor third with the perfect fourth.) So, for example, an A suspended fourth chord, written as Asus4 (or sometimes just Asus), has the notes A, D, and E. Here is one way to play it.

0

1

2

3

4

5

x

A E A D E

• See more ways to play Asus4 using the Chorderator.
• See how to play Csus4 using the Chorderator.
• See how to play Dsus4 using the Chorderator.

Suspended second chords

A suspended second chord has the following formula.

• root, major second, perfect fifth

Again, it's as if you took a major or minor chord, and removed the interval of a third, either major or minor. This time, the third was replaced with the major second. For example, an A suspended second chord, written as Asus2, has the notes A, B, and E. Here is one way to play it.

0

1

2

3

4

5

x

A E A B E

• See more ways to play Asus2 using the Chorderator.
• See how to play Csus2 using the Chorderator.
• See how to play Dsus2 using the Chorderator.

When to use them

Suspended chords can be very useful in songwriting. You can substitute a suspended chord for either a major chord or a minor chord, since suspended chords are neither major nor minor. They are very much like power chords in that way.

It's also fun to switch back and forth suspended chords and regular chords. This can make it sound like you're playing both rhythm and lead guitar at the same time. It's a technique that's been used in a ton of songs, from Led Zeppelin's Tangerine to The Beatles' You've Got To Hide Your Love Away. From Tom Petty's Free Fallin' to The Indigo Girls' Gallileo.

Here's a simple example, in tablature.

  D                 Dsus4            D               Dsus2
E +-2======-2==-2==-3======-3==-3==+-2======-2==-2==-0======-0==-0==+
B |-3======-3==-3==-3======-3==-3==|-3======-3==-3==-3======-3==-3==|
G |-2======-2==-2==-2======-2==-2==|-2======-2==-2==-2======-2==-2==|
D |-0======-0==-0==-0======-0==-0==|-0======-0==-0==-0======-0==-0==|
A |--------------------------------|--------------------------------|
E +--------------------------------+--------------------------------+
	

• Hear the example
• Hear a more complex example

Have fun with these

Knowing a few suspended chords, especially A and D, can really expand your guitar-playing possibilities. Practice going back and forth between suspended and "normal" chords. Try them next time you're playing a song, to add more interest to the rhythm guitar. And most of all, have fun!

This will be a fun lesson. Pentatonic scales are easy to learn, easy to play, and they sound like rock 'n' roll. If you want to start improvising or creating solos on guitar, chances are you'll want to learn at least one or two pentatonic scale shapes. Most blues guitar parts are based around the pentatonic minor scale, or a close variation of it.

The best part about pentatonic scales is that if you know the major scale, you already know how to play the pentatonic major scale and the pentatonic minor scale. (If you don't, don't worry. I'll teach you here, or you can read about major scales.)

First things first: penta means "five." Think of a pentagon, a five-sided shape. A pentatonic scale has five notes in it before starting over an octave higher. Remember that a major scale has seven notes, so we would expect the pentatonic scale would be easier. In fact, we would expect to be able to find the pentatonic scale by taking a major scale and removing two notes. And amazingly, enough, we can do just that! Finally, something about music theory that makes logical sense!

The pentatonic scales might as well be custom made for guitar soloing. Basically, there are a couple of notes in the major scale that sound good when played over all chords in the major key. They may sound good over some chords, but not others. Rather than trying to remember when to use them, musicians, in their practicality, decided to just remove them. Simple as that. What was left over was the pentatonic.

There are two commonly used pentatonic scales: the pentatonic major and the pentatonic minor. In rock music, the pentatonic minor is used more frequently, so I'll present that one first. It's good to learn them both, and in fact, if you know one you know the other, as I'll explain.

The pentatonic minor scale

If you only learn one scale pattern on guitar ever, learn the pentatonic minor box pattern. It's easy, fun to play, and sounds cool. I'll start with an illustration of the pattern, then explain some more of the theory.

Here is how to play an A pentatonic minor scale in the classic "box pattern."

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III

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V

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VII

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IX

XII

●

●

E

A C

A

D E

D

G A

G

C D

B

E G

E

A C

What you're looking at is a representation of the guitar fretboard, with the bridge to the left, and the low E string on the bottom. The horizontal lines are the strings, and the vertical lines are the frets. The dots with letters in them represent notes to be played. So, for example, the lowest note in the scale is on the sixth string, at the fifth fret. Next, the sixth string, eighth fret, then the fifth string, fifth fret, and so on.

Here's the same pattern written out in tablature.

5

8

5

7

5

7

5

7

5

8

5

8

E

A

D

G

B

E

There are five established patterns for the pentatonic minor, depending on where you start on the fretboard, but this is by far the most common, and the one you should learn first. I've listed the rest in the reference section at the end, and they are useful to learn as well. You can also use my Scalerator application to tweak where exactly on the fretboard you want to play the scale.

• Discover more ways to play an A pentatonic minor scale with the Scalerator.

Other keys

One nice thing about these patterns is that they are moveable. If you started the above pattern on the eighth fret instead of the fifth fret, you'd have a C pentatonic minor scale. If you start at the open position, you'd have an E pentatonic minor.

• See how to play a C pentatonic minor scale using the Scalerator.
• See how to play an E pentatonic minor scale using the Scalerator.

The notes

The A pentatonic minor scale is exactly like the A natural minor scale, but with two notes removed. These are the notes that on occasion can sound dissonant over the chords in the key of A minor. Here are the notes, for comparison:

As you can see, there is no B and no F, but other than that it's the same. Here is the pattern of intervals in the pentatonic minor scale. (Review intervals)

This pattern holds no matter what key you're in.

When to play it

Blues, blues, blues, and anything based on blues. This scale sounds awesome over a standard twelve-bar blues progression. If it's blues in A, you can play A pentatonic minor and you'll never go wrong.

Rock is based on blues, so pretty much the same thing applies. A lot of country songs are, too. On the other hand, the more ballady, folky stuff works better with the pentatonic major scale, which I will present next. If you're not sure which to go with, try them both, and use whichever sounds better. Like everything in music, play what sounds good is all that matters.

The pentatonic major scale

To get the pentatonic major scale, we can start with a major scale and remove the fourth and seventh notes. So here's how it goes in the key of C.

No B and no F.

If you're clever, or even just observant, you will notice that those are the same notes as the A pentatonic minor I talked about above. This is another example of the concept of relative major and relative minor keys, which I discussed in my natural minor scale lesson. Essentially, if you want to play a C pentatonic major scale but you don't know how, you can just play the A pentatonic minor, but just finish on the C instead of the A. Easy as pie.

In fact, that works for any key. To play a pentatonic major scale, you can always just play the pentatonic minor scale three frets to the left (that is, lowered by a minor third). And vice versa.

So you already know one pentatonic major pattern. Here's another one. This is C pentatonic major. As you may have guessed, this shape can also be used to play an A pentatonic minor.

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III

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V

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VII

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IX

XII

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E

C D

A

E G

D

A C

G

D E

B

G A

E

C D

And here it is in tablature.

8

10

7

10

7

10

7

9

8

10

8

10

E

A

D

G

B

E

And here is the pattern of intervals in the pentatonic major scale.

• Discover more ways to play an C pentatonic major scale with the Scalerator.

When to play it

Notes from the pentatonic major can be happily played over any song in a major key. While the pentatonic minor is used for a bluesy sound, over an electric rhythm section, pentatonic major is used more often over strummy, ballady songs. There are really no rules, though, other than play what sounds good, of course. If you can't decide between major and minor, try them both!

Reference

A pentatonic minor scale, position 3

(Note: Position 1 is above. Position 2 is the same as the C pentatonic major, presented above)

(Note also: Any of these A pentatonic minor shapes also represent C pentatonic major.)

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III

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V

●

VII

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IX

XII

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●

E

D E

A

G A

D

C D

G

E G

B

A C

E

D E

As tablature:

10

12

10

12

10

12

9

12

10

13

10

12

E

A

D

G

B

E

A pentatonic minor scale, position 4

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III

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V

●

VII

●

IX

XII

●

●

E

E G

A

A C

D

D E

G

G A

B

C D

E

E G

As tablature:

0

3

0

3

0

2

0

2

1

3

0

3

E

A

D

G

B

E

A pentatonic minor scale, position 5

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III

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V

●

VII

●

IX

XII

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●

E

G A

A

C D

D

E G

G

A C

B

D E

E

G A

As tablature:

3

5

3

5

2

5

2

5

3

5

3

5

E

A

D

G

B

E

Related lessons

• Major scales
• Natural minor scales
• Harmonic minor scales
• Melodic minor scales

Previously, I talked about the basic three-note chord types, the triads. To review, there are four basic types that are commonly used. Here they are with their interval formulas:

To each of these chord types, we can add more notes to create more complicated chords. There is no limit to what we can add, but the most common type of note to add is a seventh, either a minor seventh, major seventh, or diminished seventh. As you can imagine, when combined with the four chord types we have to start with, this leads to, like, a million different chords (ok, actually 12, but you get the idea). Fortunately, some are used more frequently than others, and some are almost never used, so I'll present the most common ones first.

Dominant Seventh Chords

The first and most important type of seventh chord to learn is the dominant seventh chord. In fact, this type is so common that it is usually referred to simply as a seventh chord. It is a major chord with an added minor seventh note. The minor seventh interval is also sometimes referred to as a dominant seventh, so that's where the name comes from.

Dominant seventh chord interval formula: root, major third, perfect fifth, minor seventh.

So, for example, the notes in a G dominant seventh chord, written simply as G7, are G, B, D, and F. Notice that all those notes come from the C major scale. And this is a pattern. The seventh chord formed starting with the fifth note in a major scale and taking every other note is a dominant seventh. So just remember, the fifth chord is a seventh. Easy, right? To increase confusion, this is often written as V7. Notice also that this chord contains the two notes on either side of the tonic: that B and that D straddle the C. Along with the natural tension that a minor seventh chord contains, this makes the dominant sevent great for leading into the tonic chord. Try playing a G7, then a C major a few times. You will clearly hear the tension and resolution. This is a powerful tool that is used a lot in song composition. In fact, the song Sweet Dream Baby, by Roy Orbison uses only two chords: F, and C7 (which is the V7 chord in the key of F).

Here are some common dominant seventh chords and the most common ways to play them. One thing to note is that the C7 shape that is most commonly played in the open position on guitar is not technically a complete seventh chord, since it doesn't include the fifth note, the G. This would more properly be written as C7(no 5). It sounds close enough to a full C7 that most people don't care, though. Click on any chord name to see more ways to play it at The Chorderator.

A7

Notes: A, C#, E, G

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1

2

3

4

5

x

A E G C# E

B7

Notes: B, D#, F#, A

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1

2

3

4

5

x

B D# A B F#

C7

Notes: C, E, G, Bb

0

1

2

3

4

5

x

C E A# C E

D7

Notes: D, F#, A, C

0

1

2

3

4

5

x

x

D A C F#

E7

Notes: E, G#, B, D

0

1

2

3

4

5

E B D G# B E

G7

Notes: G, B, D, F

0

1

2

3

4

5

G B D G B F

Major Seventh Chords

A major seventh chord is a major chord with a major seventh note added.

Major seventh chord interval formula: root, major third, perfect fifth, major seventh.

A C major seventh chord, for example, is written as Cmaj7 or CM7 (with a capital M), and contains the notes C, E, G, B. In the major scale, the four-note chords formed off of the root note and the fourth note are major sevenths. So in the key of C, the C and the F. These are often written as Imaj7 and IVmaj7.

A major seventh chord builds less tension than a dominant seventh, and so is a good chord to end a song on, if you want to go for a jazzy but kind of relaxed feel. I consider it to have an almost island-y sound.

Here are some common major seventh chords and the most common ways to play them:

Amaj7

Notes: A, C#, E, G#

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1

2

3

4

5

x

A E G# C# E

Cmaj7

Notes: C, E, G, B

0

1

2

3

4

5

x

C E G B E

Dmaj7

Notes: D, F#, B, C#

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1

2

3

4

5

x

x

D A C# F#

Emaj7

Notes: E, G#, B, D#

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1

2

3

4

5

E B D# G# B E

Fmaj7

Notes: F, A, C, E

0

1

2

3

4

5

x

x

F A C E

Gmaj7

Notes: G, B, D, F#

0

1

2

3

4

5

G B D G B F#

Minor Seventh Chords

A minor seventh chord is a minor chord with the dominant seventh added

Minor seventh chord interval formula: root, minor third, perfect fifth, minor seventh.

A D minor seventh chord, for example, is written as Dm7, and contains the notes D, F, A, C. In the major scale, the four-note chords formed off of the second, third, and sixth notes are minor sevenths. So in the key of C, you have Dm7, Em7 and Am7. These are often written as iim7, iiim7, and vim7.

A minor seventh chord can be used any place the regular minor chord would normally be used if you want a slightly more complex sound. One nice thing about minor sevenths is they are very close to the relative major chord. For example, if you look at the shape of the Am7, you'll notice it's like a C major chord, but you just pick up your third finger and play the fifth string open. So if you have a song where you're transitioning from a C to an Am, you can play an Am7 instead, and keep a sense of continuity. (Read about relative minors.)

Here are some common minor seventh chords and the most common ways to play them. Click on any chord name to see more ways to play it at The Chorderator.

Am7

Notes: A, C, E, G

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1

2

3

4

5

x

A E G C E

Bm7

Notes: B, D, F#, A

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1

2

3

4

5

x

B D A B F#

Dm7

Notes: D, F, A, C

0

1

2

3

4

5

x

x

D A C F

Em7

Notes: E, G, B, D

0

1

2

3

4

5

E B D G B E

Minor Major Seventh Chords

Yes, it is really called "minor major seventh." It's a minor chord with an added major seventh note.

Minor seventh chord interval formula: root, minor third, perfect fifth, major seventh.

We're starting to get into the lesser used chords, at least in popular music. The minor major seventh chords come about when we form four-note chords from the harmonic minor scale. Starting from the first and third notes, specifically. For example, taking every other note in the A harmonic minor scale, we get an AmMaj7, which contains the notes A, C, E, G#.

I actually really like the sound of these chords, though they may sound a bit "dated" in modern music. They're like the chord you hear when the gritty private detective learns a startling new clue in a 1940s movie. They're pretty easy to play, so give them a shot and see if you can work them into some songs. Again, they can be used in place of any minor chord, but probably should be used a little more sparingly than minor sevenths. Let's see if we can create a rebirth of their popularity.

"Common" may be too strong a word, but here are some major minor seventh chords that are relatively easy to play (for such a little-used chord type, it has some surprisingly easy open shapes):

AmMaj7

Notes: A, C, E, G#

0

1

2

3

4

5

x

A E G# C E

BmMaj7

Notes: B, D, F#, A#

0

1

2

3

4

5

x

B D A# B F#

CmMaj7

Notes: C, Eb, G, B

0

1

2

3

4

5

x

C Eb G B G

DmMaj7

Notes: D, F, A, C#

0

1

2

3

4

5

x

x

D A C# F

EmMaj7

Notes: E, G, B, D#

0

1

2

3

4

5

E B D# G B E

And so on, and so on...

That's probably enough chord types for one lesson. If there is interest, in the future I will tackle diminished sevenths, half-diminished sevenths, augmented sevenths, and all kinds of happy extensions.

Reference

Here is how the C major scale harmonizes with four-note chords:

Four-note chords in the C major scale

Imaj77	iim7	iiim7	IVmaj7	V7	vim7	viidim7
C major seventh	D minor seventh	E minor seventh	F major seventh	G dominant seventh	A minor seventh	B diminished seventh

Here are the chord types covered in this lesson:

Common seventh chord types

Triad	Added seventh	Chord name	Example
major	minor 7th	dominant seventh	C7
	major 7th	major seventh	Cmaj7
minor	minor 7th	minor seventh	Cm7
	major 7th	minor major seventh	CmMaj7