Using a Flat Five Chord on Guitar
Chords can be built on each degree of the major scale. Using a thirds sequence (every other note) there are three types of triads (groups of three notes that make basic chords) that naturally occur using the notes of a major scale. Using the key of C as an example, the chords derived from the scale are:
C major scale
1 2 3 4 5 6 7
C D E F G A B
1. C-E-G = C major
2. D-F-A = D minor
3. E-G-B = E minor
4. F-A-C = F major
5. G-B-D = G major
6. A-C-E = A minor
7. B-D-F = B minor flat five (also known as a diminished triad)
The most unusually chord in the major scale is the one built on the 7th degree. It has a minor third, but unlike all the other chords in the scale it does not have what’s called a perfect fifth. Instead, its fifth is flattened a semi-tone (half-step or one fret). For this reason it’s called a minor flat five chord (mb5). This triad, 1-b3-b5, is also know as a diminished triad.
Most music avoids the mb5 chord. If it comes up at all, it’s usually in a minor key and in a minor seven form, m7b5, which is also called a half-diminished chord. A good example is the changes Bm7b5-E7-Am.
You hear these changes used in sections of “Smooth” by Santana, “Still Got the Blues” by Gary Moore, and “I Will Survive” by Gloria Gaynor.
In the sample progression above the tonic (primary chord) is Am, which means that the music is in the key of A minor. When you renumber the chords from C major starting on A, you get:
A minor scale
1 2 3 4 5 6 7
A B C D E F G
1. A-C-E = A minor
2. B-D-F = B minor flat five (dim. triad)
3. C-E-G = C major
4. D-F-A = D minor
5. E-G-B = E minor
6. F-A-C = F major
7. G-B-D = G major
So the chord changes Bm7b5-E7-Am become a type of two-five-one in a minor key. The Em chord is played as E7 (featuring G# as opposed to the scale’s G natural) which produces a dominant push to the the tonic chord, Am, and temporarily creates the so-called harmonic minor scale. You might see musician’s write these chord changes out in Roman numerals as II-V-I or maybe even ii-V-i with lowercase Roman numerals representing minor chords. Other possibilities include iib5-V-i and iim7b5-V7-i.
Your method of presentation makes this material entirely logical and easy to understand.
Thanks Desi. Keep it coming. And I do play until my fingers bleed.
These posts really help keeping the knowledge fresh, Desi. Thank you for your hard work keeping them up.
How do you eat an elephant? One bite at a time.
How do you learn music theory? One bite at a time. Short, simplified and to the point. Thanks Desi for simplifying music theory and making these points short and easy to digest.
This is really helpful in taking something complex and making it understandable. I love the Santana song “Smooth” and it’s great example of what you’re talking about here.
Good stuff Desi, thanks for explaining that so well
Researching, I saw your site.
Cool, I’ll look more, Thanks
What chords come before a 1/2 dim chord ?
I’ve used a; Major 7th chord a step below, as in; A Ma 7 to b -7 b5
and Major 7th to 1/2 dim a triton away, as in; Amaj7 to d# -7b5 ( to EbM7 )
= AM7 , B7(9) , EbM7
What else ya got ?
Looking for ideas for improvising chord subs, and for writing new tunes.
Not sure I follow your examples. Songs that make good use of minorb5 chords (a.k.a. half-diminished) are “Smooth” by Santana, “Still Got the Blues” by Gary Moore, “I Will Survive” by Gloria Gaynor, and the jazz standard “Blue Bossa.” Look up these chord progressions and play through them.
the way you present is easy to understand, thanks Desi
Thanks for your clearly guiding.
It’s really helpful for me.