There are a number of 7th chords available. This post is concerned with the following three types
Major 7th
Minor 7th
Dominant 7th (this is the one most guitarists know when they're asked to play a 7th chord i.e. C7)

Major 7th
Going back to my earlier post on major chord construction you'll see that
major triads are made up from the 1st, 3rd and 5th notes from the major scale. 
To create a major 7th chord you simply add the 7th note of the major scale.

So using the good old C Major scale as an example. You get
C (1st note of the scale)
E (3rd note of the scale)
G (5th note of the scale) and
B (7th note of the scale)

Therefore the scale spelling of a major 7th chord is 1, 3, 5, 7

Dominant 7th
Slightly different from a major 7th chord. This chord uses a flattened/minor 7th note. So in the case of a C dominant 7th (or C7 to you and me) you get the notes.

C (1st note of the scale)
E (3rd note of the scale)
G (5th note of the scale) and
Bb (flattened/minor 7th note of the scale).

Therefore the scale spelling of a dominant 7th chord is 1, 3, 5, b7

Minor 7th
This chord is an extension of the minor triad and as such is based on the natural minor scale and uses the 1st, 3rd, 5th and 7th notes from that scale.

C (1st note of the scale)
Eb (2nd note of the scale)
G (5th note of the scale)
Bb (7th note of the scale)

Therefore the scale spelling of a minor 7th chord is 1 b3, 5, b7 (don't forget scale spellings are relative to the major scale not the minor scale).

So if you review my other posts on major scale construction and the circle of fifths you should (in theory at least - pardon the pun) be able to work these chords out in any key.

We'll discuss diminished 7ths later when I cover diminished chords.

Carrying on from the last post. I'll now do the same for Flat keys. No idea why it's really called the Circle of fifths because that only really works for sharp keys. Flat keys could be called the circle of fourths. You'll see why in a sec.

So using similar logic to the circle of fifths if you take the notes of the C Major scale, BUT stop at the fourth note rather than the fifth.
1 = C
2 = D
3 = E
4 = F

You get F Major. So what's the key signature for that. Well sticking with the number four. If you write out the scale of F Major but FLATTEN the fourth note you get.

1 = F
2 = G
3 = A
4 = Bb (remember flatten the fourth note)
5 = C
6 = D
7 = E
8 = F

So the key of F Major as one flat which is Bb.

Again as you can see the fourth note of F Major is Bb so lets start with that.

1 = Bb
2 = C
3 = D
4 = Eb (remember you have to flatten the fourth note)
5 = F
6 = G
7 = A
8 = Bb

So the key of Bb has two flats in it Bb and Eb

Back to you all, I'm sure you can work the rest out.

Been away for a while, very busy, lots of new students.

Ok so you've looked at the previous posts and you know that the C Major scale has the notes C D E F G A B and C in. You also know that it has a neutral key signature (i.e. no sharps or flats).

But you now want to know which scales have which sharps or flats in the key signature and as part of the scale. Well there's two ways to do this. You can either memorise them all or, if you're like me, you can remember  a logical way to figure it all out.

So I'll give you the mechanism I use and the first couple of keys in each direction (sharp or flat) and leave you to work the rest out yourself (don't want to make it too easy).

So, let's look at sharp keys first. 

You take the 5th note of the scale and use that as the starting note of the next scale (hence the term circle of fifths). Using C Major as an example you get.

1 = C
2 = D
3 = E
4 = F
5 = G

So the new scale starts with a G, runs through the 8 notes back to G. The trick is that the 7th note of the new scale is sharpened by a semi tone, which gives you.

1 = G
2 = A
3 = B
4 = C
5 = D
6 = E
7 = F# (remember it has to be sharpened by a semi-tone or half-step)
8 = G

So there is the scale of G Major which has one sharp (F#) as it's key signature.

From the above then you can see that the next one (5th note in the key of G) is D which gives you.

1 = D
2 = E
3 = F#
4 = G
5 = A
6 = B
7 = C# (remember you have to sharpen the 7th note)
8 = D

Ok over to you, I'm sure you can figure the rest out.

Flat keys in the next post.

Ok I've covered scale spellings and how they apply to major and natural minor scales. But how do you work out a scale if you don't know the notes?

Well for major scales you can follow a pattern and that pattern is:
W W H W W W H or if you prefer T T S T T T S.

WHAT!!!! I hear you cry.

Popular musicians (by that I mean musicians who play popular music rather that the latest fad band) tend to use the W H version. This is where the W stands for whole note and the H stands for (you guessed it) half note.

If you're more of a classical persuation the T stands for Tone and the S for semi-tone.

Either way the W or T means two frets on a guitar fingerboard and the H or S means one. For the purposes of this I'll stick with the W H version.

So let's apply this to the good old C major scale to see where it gets us.

C major starts on the note of C (doh!) so you go up two frets on the guitar (a whole note) and you get - a D. Another two frets and you get - an E. So that's the W W, so next comes the H, as I said that's one fret (half a note) which gives you a F (no E#). Next is another W which gives you a G, another W gives you an A, yet another W gives you a B and the last H gives you another C.

So in summary you get
      W W H W W W H
C   D   E  F   G  A  B   C

So let's try  another starting note. In this case G.

    W W H W W W    H
G  A  B  C  D   E   F#  G

Obviously helps though if you know where the notes are on a guitar fingerboard and if you know that you can actually work out loads of fingerings for all the scales.

Going back to the C major scale. The frets the notes apply to in this case are (on the 5th string)
C = 3, D = 5, E = 7, F = 8, G = 10, A = 12, B = 14 and C = 15.

Not much use though if you're trying to play something. That's why a guitar has six strings. Your hand would be moving back and forth like crazy just to play a few notes. So how do you spread that across the guitar.

In standard guitar tuning (where the strings are tune E, A ,D, G, B, E)
the strings are generally tuned so that the next string up is tuned as though you were fingering the fifth fret (one exception which is the B string which is tuned as though you were fingering the fourth fret on the G string)

So this means that you can play the scale either like I outlined above or you
can skip across the strings.
C = 3rd fret 5th string
D = 5th fret 5th string
E = 2nd fret 4th string
F = 3rd fret 4th string
G = 5th fret 4th string
A = 2nd fret 3rd string
B = 4th fret 3rd string
C = 5th fret 3rd string

Which looks like (if you don't know how tabulature works don't worry, in a nutshell the lines are each string and the number is the fret on that string you put your finger on)

E -----------------------------------------------
B -----------------------------------------------
G ---------------2-4-5-------------------------
D -------2-3-5---------------------------------
A --3-5-----------------------------------------
E -----------------------------------------------

This is just one octave (group of 8 notes). See if you can work out the rest upwards and downwards.

The A minor triad follows the standard formula for all minor triads. This means you take the 1st, 3rd and 5th notes from the related natural minor scale (obviously in this case A natural minor).

So if you look at the notes in the A natural minor scale
A B C D E F G A

So from this scale the 1st, 3rd and 5th notes are A, C and E which gives you

5th string  open = A
4th string 2nd fret = E
3rd string 2nd fret = A
2nd string 1st fret = C
1st string open = E

As with the C Major scale last month, some notes are doubled. 

Once you know the notes in the triad then you can figure out where else on the guitar you can play the same chord. Like this.

6th string 5th fret = A (same note as the open 5th string)
5th string 7th fret = E
4th string 7th fret = A
3rd string 5th fret = C
2nd string 5th fret = E
1st string 5th fret = A

Which is the standard 'E' shape bar chord version of A minor. 

Following on from last months C Major the A Natural Minor scale is another easy scale to remember in terms of notes.

As the C Major scale is a scale with no sharps or flats, so is A Natural Minor and is what is known as the 'Relative Minor' to C Major. It is made up from the following notes:

A B C D E F G A

If you look at the notes in this scale against the notes in the C Major scale (C D E F G A B C) you can see that the relative minor scale begins on the 6th note of the major scale.
(1 = C, 2 = D, 3 = E, 4 = F, 5 = G and 6 = A).

This relationship is standard for all natural minor scales, with all natural minor scales having a related major scale and all major scales having a relative minor scale.

As with last months scale this scale also has a scale spelling.

As a natural minor scale it's scale spelling is:

1 2 b3 4 5 b6 b7 8

The important point to remember with scale spellings is that they are all number in relation to the major scale. Have a look at the thread on Scale spelling for more on this.

One of the items you'll find in this blog and also in the RGT syllabus is the concept of scale spelling. In practise this is something that can be a bit confusing so I thought I'd try and explain it here using examples.

So the first thing is 'What is a scale spelling'. Simply put this is just giving each note in the scale a number. Each major scale has 8 notes (including the octave, more on what an octave is to follow), so the numbers run from 1 to 8.

The two main things to bear in mind with scale spellings is that they are all intended to show how the scale you are looking at relates to a major scale and secondly, that just because a scale spelling might contain a flattened note it doesn't mean that the actual note you play is a flattened note (see told you it could be confusing).

Let's use the C Major, A Major and C Natural Minor, A Natural minor scales to explain this.

If you read last months scale of the month (C Major) you'll see that the scale spelling for major scales is 1 2 3 4 5 6 7 8. This means that the notes in the C Major scale are
1 = C, 2 = D, 3 = E, 4 = F, 5 = G, 6 = A, 7 = B, 8 = C
as they say in the meerkat add 'simples'.

Now the scale spelling for a Natural minor scale is
1 2 b3 4 5 b6 b7 8.
So if you take the 3rd, 6th and 7th notes of the C Major scale (E, A and B) and take them down a fret on your guitar So the E becomes Eb, A becomes Ab and B becomes Bb. Which means the notes for a C Natural minor scale are
C, D, Eb, F, G Ab, Bb and C with the scale spelling underneath.
1    2   b3  4  5   b6   b7         8

So what's confusing about that. Not a lot really until you apply the same logic so something like the A Major and A Natural minor scales.

The key signature for the A Major scale is 3 sharps so whilst the scale spelling remains the same some of the notes are sharpened thus.
1 = A, 2 = B, 3 = C#, 4 = D, 5 = E, 6 = F#, 7 = G#, 8 = A.

So where does the confusion come in?. Well if you take the scale spelling for the natural minor scale again to this scale you'll have to again take those notes down by a fret on your guitar. BUT whilst you're flattening a note (remember is b3, b6, b7) the notes that you're applying that to are already sharpened by the key signature (C#, F# and G#.) so what you end up with is that the C# becomes a C (not a Cb), the F# becomes a F (not a Fb), and the G# becomes a G (not a Gb), so the notes in the A Natural minor scale are
A B   C  D E   F   G  A, again with the scale spelling underneath.
1  2  b3 4  5 b6 b7 8

Once you get your head around this you can then use the same logic to work out any scale from it's scale spelling as long as you know the key signature of the major scale your applying it to.

More on key signatures later.