The Forgotten Diatonic Chord | minor 7 flat 5

Very often, there are chords in the structure of music that get all of the attention. I would say that Major and minor chords get played more often than any others. But, it doesn't take long for music to start sounding pretty boring with just those two types of chords.

You of course have diminished and augmented triads. These will break the monotony of plain sounding chords, but there's actually a diatonic chord (chords native to the key) that often gets overlooked and maybe even forgotten about sometimes.

I'm referring to the minor 7 flat 5 chord. It's also known as a half diminished 7th chord. If we look at the diatonic harmony of a Major key of music, we can see where it fits into the key.

Each tone in a Major key of music has a corresponding chord.

For example, the diatonic harmony of C Major.

As you can see, each one of these chords are Major or minor triads. There's one exception which is the 7th tone. It creates a B diminished triad.

If we extend these diatonic triads and add the 7th tones to them, we have Major and minor 7 chords in our diatonic harmony sequence.

When we arrive at the 7th tone (B) it's not a Major 7 or minor 7 chord. It's a minor 7 flat 5 chord. I'll say again, it's also known has a half diminished 7th.

It's essentially one tone away from a B minor 7 chord.

I have heard some musicians say that they never use the 7th tone as a diminished chord or a half diminished chord. And, they'll just play it as a plain minor chord even though one of the tones they're playing isn't technically in the key. (which would be the 5th of B minor)

But the minor 7 flat 5 chord has an interesting texture that's considered "jazzy" sounding.

Don't confuse the half diminished 7th chord with the diminished 7th chord. This is a common mistake among beginning chord players.

A diminished 7th chord consist of the following tones.A half diminished 7th chord consist of these following tones.

As you can see, the only difference between the two is that the half diminished 7th chord has the dominant 7th tone and the diminished 7th chord has the diminished 7th tone. You may recognize this diminished 7th tone as a 6th. But it's in a different context because of the other tones that are in this chord.

Now that we understand how this chord is constructed and that it occurs on the 7th tone in a Major key of music, it's important to know that you have options when playing this chord. You can play the half diminished 7th chord based on any note of the key.

This is often the case if you want to use it as a chord substitution.

There are many places that you can substitute a diatonic chord for the half diminished 7th. Let's take a simple walkup chord progression in the key of C Major.

We'll start with a simple I to IV walk-up progression C.

IWe'll substitute the D minor 7 chord...
iiWith the D minor 7 flat 5 chord

iiI/iii

IV