Each of the above chords consists of a first, third and a fifth. This article focuses on not the altering of chords, but the additions of new ones to be used in conjunction with those above. Therefore, all the chords shown will be basic, and have only a first, third and fifth. The following 7 chords and their usage will be discussed:
C major - C, E, G -- major I D minor - D, F, A -- minor II E minor - E, G, B -- minor III F major - F, A, C -- major IV G major - G, B, D -- major V A minor - A, C, E -- minor VI
When used properly, these chords can improve simple chord progressions to give them a new, fresh sound. These chords can all be altered extensively (i.e. playing D major as F#, A, C, and E), but this article will focus only on the basic first, third, fifth structure of these chords. Chord Progressions Some common 4-chord progressions using chords in the key of C are as follows: Fmaj, Cmaj, Am, Gmaj Am, Dm, Gmaj, Cmaj Cmaj, Dm, Fmaj, Gmaj Cmaj, Gmaj, Em, Fmaj Cmaj, Em, Am, Fmaj In each of the 7 "out of key" chords' explanations (below), the above chord progressions will be changed by substituting one of the "in key" chords for an "out of key" chord. Each of these chord progressions as well as the new ones which will be created below has a sound or feeling. I strongly recommend playing through the chord progression before and after it is altered to understand how the sound/feeling of the chord progression has changed. There are obviously many other common chord progressions using only chords "in key". These chords have been chosen because they can be altered in a way to accompany the "out of key" chords. This is not to say the new chords can not be used in any other fashion, but for the purpose of example, only the above chord progressions will be used as foundations for "out of key" chords. Chords "out Of Key" The D major chord: D, F#, A Since we're in the key of C, it's easy to spot that F# is the odd note out, and the note that makes this chord "out of key" (simply meaning it has a note or notes out of key). The D major chord can be used in several different ways. It is often satisfying to hear the D major chord followed by a G major. In this way, it can replace the Fmaj in the following chord progression: Cmaj, Fmaj, Gmaj, Cmaj Cmaj, Dmaj, Gmaj, Cmaj Another way the D major chord can be added into a chord progression is by replacing a Dm chord with it. Cmaj, Dm, Fmaj, Gmaj Cmaj, Dmaj, Fmaj, Gmaj A third possible use of the D major chord is after an A chord (major or minor) is used (and you may notice that the following change in chord progression uses all three of the D chord uses listed, this is purely coincidence). Am, Dm, Gmaj, Cmaj Am, Dmaj, Gmaj, Cmaj The E major chord: E, G#, B The most common use of the E major chord is before an A chord (major or minor; usually minor). Fmaj, Cmaj, Am, Gmaj Fmaj, Emaj, Am, Gmaj The E major chord is similar to the D major chord in that it also sounds good when replacing its minor, an E minor chord. Cmaj, Em, Am, Fmaj Cmaj, Emaj, Am, Fmaj The A major chord: A, C#, E The A major chord is uncommon, but still usable. It is often used before a D chord (major or minor). Am, Dm, Gmaj, Cmaj Amaj, Dm, Gmaj, Cmaj The B major chord: B, D#, F# The B major chord is very uncommon, probably because it has 2 notes that are out of key, and only 1 in key. It is usually used before an E chord (minor or major) Cmaj, Gmaj, Em, Fmaj Cmaj, Bmaj, Em, Fmaj The sound of the example may not be very pleasing to some ears, but there are some instances where the Bmaj chord can be manipulated to fit into the key of C without much discordance. The C minor chord: C, Eb, G The Eb major chord: Eb, G, Bb The above two chords, as well as the next two pairs of chords below, are grouped because they are practically interchangeable. Whenever one would sound good, so would the other. You may find the feeling achieved by a chord progression using C minor rather than Eb major is slightly different, but it's marginal. In the case of C minor and Eb major, the Eb major chord is much more commonly used, simply because a C minor chord in the key of C major usually doesn't sound very good. The Cm/Ebmaj chord has a powerful sound when used before an F major chord. Cmaj, Dm, Fmaj, Gmaj Cmaj, Ebmaj, Fmaj, Gmaj Random fact: the Cm/Ebmaj chord is often used with the Abmaj and Bbmaj chords. The F minor chord: F, Ab, C The Ab major chord: Ab, C, Eb The F minor chord is used in somewhat different context than the Ab major chord, although they are both relatively interchangeable. The F minor chord sounds better when used with the C major chord, bringing much emotion into the chord progression. The Ab major chord is often used with the Eb major or Bb major chord and is powerful and almost dramatic to some. Am, Dm, Gmaj, Cmaj Am, Dm, Fm, Cmaj Cmaj, Dm, Fmaj, Gmaj Cmaj, Ebmaj, Fmaj, Abmaj The G minor chord: G, Bb, D The Bb major chord: Bb, D, F In my opinion, the G minor and Bb major chords are interchangeable in any chord progression. They often end a chord progression. Cmaj, Em, Am, Fmaj Cmaj, Em, Am, Bbmaj The G minor/Bb major chord also sound alright followed by an F major chord. Cmaj, Em, Am, Fmaj Cmaj, Em, Gm, Fmaj Summary It is evident that using chords with notes outside of the key can greatly improve and change a chord progression, and are fun to experiment with. Don't be afraid to use these new chords with each other, in other keys (as major II instead of D major, minor IV instead of F minor, etc), and in chord progressions with more or less than 4 chords. Hopefully this helped your understanding of chord progressions and/or your songwriting.
D major -- major II E major -- major III A major -- major VI B major -- major VII C minor/Eb major -- minor I F minor/Ab major -- minor IV G minor/Bb major -- minor V