Chord Substitution

Substitute that chord!

In the last blog I spoke about how to substitute triads when composing melodies or improvising.

To make a long story short, the trick was to play three different triads off a chord.

In G major, G being chord I, we get G B D as our first triad, building a triad from the note B (chord III) we play the notes B D F# , in relation to G this is 3, 5, 7. This meant we got a maj7 sounding melody.

Going even further, from the D (chord V) we got D F# A, in relation to G this is: 5, 7, 9. We now get a maj9 sound.

This is all very useful stuff and should be practiced extensively if you want to get into jazz since this is how those guys actually thought about it.

In this blog I’d like to continue on this concept but instead of using triads to find melodies, let’s look at what happens when we substitute a whole chord!

Call It Stormy Monday

In Call It Stormy Monday Sandy substitutes the G7 with a Bm7b5, why does this work?

If G is seen as chord V, then chord VII would be a Bm7b5.

In the same way as a Bm triad created a maj7 sound over a G chord, a Bm7b5 creates a dom9 sound over a G root.

G triad: G B D
G7: G B D F
G9: G B D F A
Bm7b5: B D F A

As you can see above, the Bm7b5 and the G9 contain almost the same notes!

These type of substitutions will always work as long as you know what number the chord you play has.

The rule is always to start the substitution on the third or fifth of the chord.

Tritone Substitution

I’ve been getting back into my jazz playing lately and a song that got me hooked for the last few days is A Night In Tunisia, a bebop classic by Dizzie Gillespie.

A Night In Tunisia is often seen as a benchmark for jazz players since it is fast and contain a seemingly new progression: Eb7 – Dm.

The sharp eyed student see that Ebmaj7 – Dm would have been an obvious IV – III and Lydian and Phrygian would have been perfect, but Eb7 complete throws this out the window, so what is it?

It’s a tritone substitution, bear with me…

Imagine that the Dm is chord VI, and the chord leading to this is a modified III chord, so IIIx, this would be A7 – Dm, very common movement, happens all the time.

Altered chords

In order to get tritone substitution you first have to understand what an altered chord is.

An altered chord is a dom7 chord containing one or several of these intervals: b5, #5, b9, #9.

By adding these notes you get more tension, more pull towards the VI chord. For example A7b9 would include the note Bb, which is a semitone away from A, a note of the Dm chord.

The more semitones, the more tension and pull towards the next chord.

Just like we did when we substituted triads and got bigger sounding chords and melodies we can tritone substitute a dom7 chord.

A7: A C# E G
A7b5b9 A C# Eb G Bb
Eb7: Eb G Bb C#

Eb is a tritone (#4 or b5) away from A, so if we play a Eb7 instead of building a full altered chord we hit those important altered notes!

Check again; A7b5b9 would have Eb and Bb as the two altered notes, this is the root and 5th of an Eb, the remaining two notes, the C# and the G are the 3rd and b7 of the A7 chord.

Summary Chord Substitution

Tritone substitution or any substitution for that matter take the actual extension of a chord, and highlight it.

This could be done in both melody and in chord.

In Call It Stormy Monday we substitute a G7 with a Bm7b5 to get a Dom9 sound.

In A Night In Tunisia we tritone substitute an A7 with an Eb7 to get an altered sound.

-Guru

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10 thoughts on “Chord Substitution

  1. cortezthekiller

    Excellent post, thank you very much. You would need to add a +1 Google button to your site, to contribute to spread the article more efficiently.

    Reply
  2. Nal

    It just gets better!

    Ok, this is ahead of me, so I’be got a question…

    Do we substitue over, or instead of? If we substitute Eb7 over A7, do we hear the unaltered notes such as E together with the altered note Eb (a semi tone away)?

    Just trying to wrap my head around it :)

    Reply
    1. Guru Post author

      Cool, so you play Eb7 instead of A7 and in doing so get the juicy altered notes.

      The alternative would be to instead play an altered A chord, like A7b5 for example.

      Reply
  3. Nal

    And another musician wouldn’t be playing the A7 at the same time either?

    And, playing Eb7 (Eb G Bb C#)

    Has a tritone from G to C# (like all dominant chords) which wants to resolve? The C# wants to go up a semitone to D and the G wants to go to F (in contrary motion?)

    So it resolves nicely to Dm (D F A).

    Something like that?

    So many questions… Great post!

    Reply
    1. Guru Post author

      No, nobody plays the A.

      There are two main points to tritone substitution, one is to play the altered notes which is what we’ve discussed.

      The second point is what you bring up now, resolve to next chord.

      The more semitones steps the more pull.

      Eb7 to Dm is packed! Eb-D, Bb-A, Db-D, G is the only note not a semi away!

      Reply
  4. Pingback: Tritone Substitution | Spy Tunes

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