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Tip: Replacing the Tonic Minor Chord with a Minor 7b5

We’re looking again at the often over-looked min7b5 chord. Last time we saw how it can replace a dom 7 chord. This time we’ll see how it replaces a tonic minor chord.

The point of doing this substitution is to give ourselves some fresh-sounding options to play, rather than trudging through the same old sounds.

What is a “tonic minor chord” anyway? It’s a minor chord that’s set up as the central, most important chord — even if only for a short time. A non-tonic minor chord is just like a pitstop: we’re just passing through it on our way to something else. An example will better illustrate.

Play a D minor, E7, then A minor. That A minor is a tonic minor. Even if we follow it with a G7, then, C. That A minor feels like a significant place, in whatever musical journey the song it appears in takes us on. Contrast with this: play a G major, A minor, D minor, G7, C. That A minor doesn’t grab our attention in the same way, does it? Same chord, different context, different function, different *feeling.*

Back to our mission here: replacing the tonic minor with a minor 7b5. Let’s try this:

|-1--1--|-0--0--|-0----|
|-3--3--|-3--3--|-1----|
|-2--2--|-1--1--|-2----|
|-0--0--|-0--0--|-2----|
|-------|-2--2--|-0----|
|-------|-0--0--|------|

|-1--1--|-0--0--|------|
|-3--3--|-3--3--|-1----|
|-2--2--|-1--1--|-2----|
|-0--0--|-0--0--|-2----|
|-------|-2--2--|------|
|-------|-0--0--|-2----|

The first progression uses the A minor, but the second uses F# min7b5 in place of the A minor. Hear the mysterious edge that F# min7b5 gives?

How would we know that it’s okay to do this kind of substitution? In other words, it *sounds* pretty cool, but are we just plucking chords out of nowhere and settling on one that sounds good?

No. The F# min7b5 shows up in the A melodic minor scale. And the chords themselves have these notes in common: A, C, and E. Remember our maxim regarding chords substitution? If two chords have two or more notes in common, they can often substitute for each other.

Next time: part three of our mini series on the min7b5: using it as the ii in a minor ii V I progression.

Thanks for reading.

Copyright © 2008 Darrin Koltow

This first appeared in the Guitar Noise News – October 15, 2006 newsletter. Reprinted with permission.

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