So.. what Key am I in?

The Anatomy of a progression

Let’s take a chord progression and look at what information we need in order to be able to maximise our ability with it.

For the purposes of this I shall pick a progression consisting of the following chords

A ¦ f#m9 ¦ Bmin7¦ Dmaj7¦C#min7¦Bmin7¦C#min7¦D6¦¦

The first thing to ascertain is the key that the progression is in.
Do you know how to work out the key of something? If not the next section is just for you.

Firstly we need to work out which key the chords are from. I am going to take the long and thorough method of working this out. This is just to make sure you understand why we are in the key we are in.

Taking each of the above chords we first need to identify the notes that constitute the chord in question.

A = A C# E
F#min9 = F# A C# E G#
Bmin7 = B D F# A
Dmaj7 = D F# A C#
C#min7 = C# E G# B
D6 = D F# A B

If we place these notes into an order we can see if they add up to a scale.

A B C# D E F# G#

The scale here is made up of a series of steps.

A – B Tone
B – C# Tone
C# – D Semitone
D – E Tone
E – F# Tone
F# – G# Tone
G# – A Semitone

This tone tone semitone tone tone tone semitone pattern is a Major Scale.
Thus this scale is A major.

In order to play a blanket approach over the top of this progression we could take the A major scale and play ideas from it.
This as an approach would be absolutely fine and would mean we address all the notes in the progression.

Another way of analysing the above progression would be to be able to recognise the harmony patterns in the scales.

The Major scale consists of a unique combination of chords which can help us to identify keys very quickly once we can see the patterns

Lets take the notes in scale and try to make chords with them, basically the reverse process of what we did above. In order to make chords we take intervals of a third and stack them on top of each other. By this I mean :

A C# E. Each of these notes are 3 letter names apart from the last inclusive and sharpened or flattened according the available note in the scale.
We then apply the same principal to the next not in the scale
B D F#
C# E G#
D F# A
E G# B
F# A C#
G# B D

If we play these triad chords we will see that the chords we get are

A, Bmin C#min, D, E F# G#dim

This pattern of Maj/min/min/Maj/Maj/min/dim is unique to the Major( Ionian) scale and can be used as a template for all the major keys.
So if we were in the key of D we could take the D major scale.
D E F’# G A B C# and then pop the template over the top.
This would give us
D
Emin
F#min
G
A
Bmin
C#dim

Try playing the scale and then the chords. You will hear that the chords sound like the scale moving up but in harmony. This is exactly what it is.

Within this template there are some patterns that can be easily recognisable. For myself there are several I look for in a chord progression that allow me to make quick calculations as to which key something is in.
The 2 major chords a tone apart on the 4th and 5th scale degrees are usually good indicators to me. Above that would be G and A. In those to chords we have 6 different notes and as the major scale only contains 7 most of the options have already been shown.
The other main pattern I look for is the 2 min chords a tone apart on scale degrees 2 and 3. In the above instance they would be Emin and F#min. Again these 2 combined will suggest 6 of the 7 available notes.

When another notes is added to each of chords making them 7ths it becomes even easier to spot keys.

This would give us the following chords
D maj7
E min7
F#min7
G maj7
A Dom 7
B min7
C # min7b5

From this we can see 4 types of chord Maj7 Min7 Dom7 and Min7b5.
The most identifiable is the Dom7 chord. Often if you can spot where it is you can treat it as the 5th chord and thus work out the key. This isn’t fail safe but is a good starting point. I would also cross reference the other chords as before to see if they were present. So our new template consists of

I maj7 / II min7 / III min7 / IV maj7 / V Dom7 / VI min7 / VII min7b5.

There are several areas here that can identify keys to you relatively quickly. The first I have mentioned with regard to the Dominant 7 chord on the 5th degree. Another is the two Min7 chords on the 2nd and 3rd degrees. These are a tone apart. If I spot this in a progression again I will cross reference the other chords, but it is a good indication of the 2nd and 3rd chords. Maj7 chord can appear on the 1st or 4th degree’s, again this can be a good indicator. I find the min7b5 chord not particularly useful because it tends to appear more often as a II chord derived from a harmonic minor harmony, but again it is good to check to see if it is functioning in normal major based harmony.

I used to devour guitar magazines, busker books, anything with chord progressions in an attempt to improve at this skill. Now I am pretty good at it and it is invaluable in my day to day playing. Please feel free to do the same.

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~ by Geoff Lea Guitar on July 18, 2010.

One Response to “So.. what Key am I in?”

  1. Reblogged this on Geoffleaguitar's Blog.

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