Episode 6 : The Mediant Substitution and Other Variations


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This episode looks at the theory and practice behind using the mediant substitution, a useful substitution for chord I. Other substitutions such as chord quality and tritone are revisited as a useful way of negotiating a turnaround is explored.

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Episode 6 : The Mediant Substitution and Other Variations

  1. 1. The Mediant Substitutionand Other VariationsPodcast #6 - Additional notes© Copyright Darren Dutson Bromley 2012
  2. 2. The Mediant Substitution and Other Variations.To understand the term mediant substitution we first need to look at the degrees of a majorscale.Each scale can be given a name:1st 2nd 3rd 4th 5th 6th 7thTonic Supertonic Mediant Subdominant Dominant Submediant LeadingnoteThese are general names which refer to the position of the note, regardless of the key orthe notes name.Here is a C major scale: C D E F G A B CC is the tonicD is the supertonicE is the mediantF is the subdominantG is the dominantA is the submediantB is the leading noteWhere as in the key of Db major:Db is the tonicEb is the supertonicF is the mediantGb is the subdominantAb is the dominantBb is the submediantC is the leading noteChord Construction.Chords are created by harmonising each degree of the scale with a note a 3rd above anda note a 5th above to produce a triad and a 3rd, 5th and 7th to produce a 7th chord.Taking G major as an example.The notes of a G major scale are:
  3. 3. From the note G, the note a 3rd above is B and the note a 5th above is D. From the nextnote in the scale which is A, the note a 3rd above is C and the note a 5th above is E.If we repeat the process with the whole scale we arrive at:G A B C D E F#G B D A C E B D F# C E G D F# A E G B F# A CThese are the triads which are diatonic to the key of G major and they can be given chordnames:G B D is G (major)A C E is AmB D F# is BmC E G is C (major)D F# A is D (major)E G B is EmF# A C is F# diminishedThese triads form the basis for many of the chords played on the guitar, regardless of theposition or the amount of strings played. G major for example only consists of the notes GB and D.We could also add a 7th to each of these triads:G A B C D E F#G B D F# A C E G B D F# A C E G B D F# A C E G B D F# A C E
  4. 4. The chords produced are:G B D F# is Gma7A C E G is Am7B D F# A is Bm7C E G B is Cma7D F# A C is D7E G B D is Em7F# A C E is F#m7b5The chord types are consistently the same regardless of the key and look like this:ItoniciisupertoniciimediantIVsubdominantVdominantvisubmediantviileading noteMajorMajor 7thMinorMinor 7thMinorMinor 7thMajorMajor 7thMajorDominant7thMinorMinor 7thDiminishedMinor 7th b5The Mediant Substitution.A particularly effective chord substitution is replacing chord I in a progression with chordchord iii, the chord built on the mediant. This is known as a mediant substitution and iseffective in breaking the predictability of chord I by adding a more unexpected chord change.In the key of C major, chord iii, the chord built on the 3rd note of a C major scale is Em or Em7.Chord iii is always a minor chord. This can be used as a substitute chord for chord I, Cma7.The progression could be played as:
  5. 5. Em7 has similar qualities to Cma7, mainly due to the fact they share many of the same notes.Cma7 contains the notes C E G BEm7 contains the notes E G B DThe notes E G and B are common to both chords.Looking at a I vi ii V progression in the key of Eb we would have:We can employ a mediant chord substitution to chord I, the Ebma7.Here is an Eb major scale:The third note of an Eb major scale is G, which when harmonised give the chord Gm7. Theprogression using this substitution would look like this:
  6. 6. Applying Chord Substitutions.Taking the last part of the standard Misty as an example. Here it is as a chord/melodyarrangement.This is then followed by the turnaround of Ebma7 Cm7 Fm7 and Bb7 or in this case Bb13.Using a mediant substitution it is possible to substitute Gm7 in place of Ebma7. (G is the3rd of the Ebma7 chord) We’d now have the following sequence.
  7. 7. Chord Quality Substitutions.Chord quality substitutions were discussed in a previous episode and is where it ispossible to change the ‘gender’ of a chord, minor can become major, major 7th couldbecome dominant 7th etc.We can employ chord quality substitutions to our progression to make it more interesting.By turning the m7 chords to dominant7th chords, the chords have a stronger resolve ontoeach other whilst maintaining the ‘harmonic intention’ of the original progression.The progression could now become:The Tritone Substitution.We discussed this substitution in depth in a previous episode so it would be worthreviewing it if it seems a little unclear. It is possible to substitute a dominant 7th chord builton the flattened 5th of another dominant 7th chord.For example C7:Taking a C major scale. From the root note of C it is possible to go up a perfect 5th.C D E F G A B Cand flattening it giving the note Gb.This is the root note of the chord we can use as a substitution for C7, in this case Gb7.
  8. 8. We could apply this to our progression giving us:It is possible to make the progression sound smoother by adding a few extensions andalterations to the chords. By sharpening the 5th of Gb7 it is possible to keep the note D ontop.It would be possible to change Fm7 to F7 by using another chord quality substitution. Itcould then be played as F13 so as to maintain the D top note. This would then be followedby Bb13.
  9. 9. The whole turnaround could be played like this:Try using this turnaround in different songs, you will probably have to transpose it intodifferent keys. Also try applying these techniques to other songs and progressions, theyare useful and can create some interesting sounds.See you next time.