what is I-IV-V chord progression

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stebob
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what is I-IV-V chord progression

Postby stebob » August 30th, 2004, 11:57 pm

I have been playing for a few months now and keep seeing I-IV-V chord progression popping up - what is it guys I'm confused?

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Musenfreund
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Postby Musenfreund » August 31st, 2004, 1:40 am

It's the first, fourth, and fifth chord of a progression and the basic formula for the twelve bar blues.

Read David's lesson on Before You Accuse Me. It's an excellent explanation of the I IV V formula.

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markminni
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Postby markminni » August 31st, 2004, 5:23 am

Example in the key of A

A Major Scale: A,B,C#,D,E,F#,G#,A
I chord would be an A chord
II chord would be a B chord
III chord would be a C# chord
IV chord would be a D chord
V chord would be an E chord
VI chord would be F# chord
VII chord would be G# chord

I,IV,V would be an A,D,E chord progression
I,IV,V7 would be an A,D,E7 chord progression
I,ii,IV,V would be an A,Bm,D,E (lower case Roman numerals imply minor)

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Slydog
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Postby Slydog » August 31st, 2004, 11:51 am

To expand on what Markminni said, in each key you have a standard seven chord progression. Find the scale for the key, then you get this pattern:

I - ii - iii - IV - V - vi - VIIdim
Major-minor-minor-Major-Major-minor-diminished

So in the key of C, the scale is:

C-D-E-F-G-A-B

and the chords are:

C maj - D minor - E minor - F maj - G maj - A minor - B diminished
which are the I-ii-iii-IV-V-vi-VIIDim chords respectively.

So, I-IV-V would be C-F-G

This works for any key, with the notes in the scale giving rise to the chord in the progression.
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Musenfreund
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Postby Musenfreund » August 31st, 2004, 2:23 pm

Be sure you know how to build a scale as well.
The chord progression follows the notes of the scale. Markminni gave you the scale for A (key of A).
This article --Theory without Tears explains the basics of key and scale if you need that info too.
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stebob
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Postby stebob » September 1st, 2004, 9:37 am

thanks guys - great info, things are becoming clear :D

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Postby hbriem » September 2nd, 2004, 3:19 am

There are 12 notes in the equal tempered instruments everybody uses these days, hence 12 keys. Each key uses 7 out of those 12 notes. Here are the notes for the different keys:

Code: Select all


Key        Minor     Signature      1   2   3   4   5   6   7
C  major   A  minor                 C   D   E   F   G   A   B
G  major   E  minor  #              G   A   B   C   D   E   F#
D  major   B  minor  ##             D   E   F#  G   A   B   C#
A  major   F# minor  ###            A   B   C#  D   E   F#  G#
E  major   C# minor  ####           E   F#  G#  A   B   C#  D#
B  major   G# minor  #####          B   C#  D#  E   F#  G#  A#
F# major   D# minor  ######         F#  G#  A#  B   C#  D#  E# 
F  major   D  minor  b              F   G   A   Bb  C   D   E
Bb major   G  minor  bb             Bb  C   D   Eb  F   G   A
Eb major   C  minor  bbb            Eb  F   G   Ab  Bb  C   D
Ab major   F  minor  bbbb           Ab  Bb  C   Db  Eb  F   G
Db major   Bb minor  bbbbb          Db  Eb  F   Gb  Ab  Bb  C
Gb major   Eb minor  bbbbbb         Gb  Ab  Bb  Cb  Db  Eb  F


Now, building chords from those notes, is known as "harmonising the scale and is done by picking every other note from the scale (note that 9=2, 10=3, 11=4 and 13=6):

Code: Select all

Degrees of notes         C major scale notes
1 2 3 4 5 6 7 8          C D E F G A B C         Chord no.  Chord name. 
-------------------------------------------------------------------------
1   3   5                C   E   G               I          C major
  2   4   6                D   F   A             ii         D minor
    3   5   7                E   G   B           iii        E minor
      4   6   8                F   A   C         IV         F major
        5   7    9               G   B   D       V          G major
          6   8     10             A   C   E     vi         A minor
            7    9     11            B   D   F   vii°       B diminished


Thus the primary chords of each key, the I, IV and V are major and the secondary chords, the ii, iii and vi, are minor. The diminished chord, the vii°, can be thought of as a substitute for the V7 (5-7-9-11) and they function the same.

Minor keys are a little more complicated. In Aeolian mode or natural minor (1-2-b3-4-5-b6-b7-8), the i, iv and v are minor. In practice, that sounds very sedate and undramatic, so in practice people usually use a major or dominant V or or V7. This gives rise to the harmonic (1-2-b3-4-5-b6-7-8), and melodic (1-2-b3-4-5-6-7-8), minor scales.