A diminished 7 chord on guitar is four notes stacked in minor 3rds, like B, D, F and A flat. Because it’s symmetrical, one shape moved three frets up or down is the same chord. You can use it as a dominant with a flat 9, as a passing chord between two shapes, or as a line.
That diminished sound is really cool and super beautiful. We know it from a lot of heavy classical music, but it’s also applicable to pop songs, to rock, to anything. In this lesson I go through five levels of using it, starting with how it makes you feel and ending with lines you can play.
Level 1: what does a diminished chord sound like?
Play it and ask yourself what it actually makes you feel, in a non-verbal way, before you name anything.
When I’m trying to learn a new piece of music, I try to first understand how I’m interacting with it. What is the sound in a non-verbal way? Because it’s music, right? So I ask myself that question, and I’m hanging the color emotionally while I do it. That’s the first step.
Level 2: where does the diminished chord come from?
It comes from the 7th degree of the major scale. In C major, the 7th degree is B, so the chord built there is B diminished.
Inside the scale, that chord is half diminished: B, D, F, A. I’m going to alter it and play B diminished 7, fully diminished, by lowering the A to A flat. Now it’s B, D, F, A flat, all minor 3rds, a very symmetrical chord.
On piano that’s a little easier. On guitar, one fingering is really not convenient, and low on the neck it’s almost impossible, so we play it in a different shape. Maybe you know the first shape I show in the video already, but it’s important to really understand what’s going on in it, because we’re going to do a few cool things with it. Sing it too, so you understand and feel the tension.
The cool thing about diminished is that it’s symmetrical. The shape stays exactly the same when you move it in minor 3rds, three frets at a time, which is super important, and it’s going to be very important for jazz too, in the context of the bebop scale and dominants. You can also take it from the 4th string and play F diminished, which is basically an inversion of B diminished. All of these are the same four notes, just arranged differently.
Level 3: how do you use a diminished chord over a dominant 7?
Move the bass of the dominant up a half step. Over C7, change the C in the bass to C sharp, and you get C sharp diminished. In jazz we call that sound a flat 9.
This is where things start to get interesting for me. Say we’re not in the key of C anymore, we just have a C7, and I want to add some tension to it. If I change the bass from C to C sharp, look what a miracle: now I have C sharp diminished. I’m playing a C7, but I’m putting the flat 9 in the bass, so I’m getting the diminished sound. C sharp diminished 7 is C sharp, E, G, B flat, and those are the 3rd, 5th and 7th of C7 with the flat 9 on the bottom.
It depends on how you hear it. C7 can be the V of F. But the same C sharp diminished can also function as a secondary dominant of D minor, the 6th degree of F major. C sharp is the 7th degree of D minor, so it’s like playing an A7 in the key of F: the five of six, leading us to D minor.
So we can use this chord as a dominant, as the seventh of a chord, and change keys or tonalities with it. We can go anywhere, which is really cool. A lot of the romantic composers did this, Chopin and Liszt among them.
This is a very, very strong device in music. So I think starting to work on the shapes, and starting to even just explore it, is super, super helpful.
Rotem Sivan
If you want to see how flat 9 sounds work inside a full progression, the ii-V-I guitar lesson uses diminished ideas over the V chord.
Level 4: the diminished as a passing chord
Slip a diminished chord between two shapes of the same chord to connect them. It works between two G7 voicings, and between C major and C major in first inversion.
- Two G7 shapes. Play G7 in root position, then G7 in third inversion, and connect them with a passing diminished chord. It’s the same chord, G7, in a couple of shapes, and the diminished connects them. It’s going to work quite a few times. The diminished is kind of a filler in a way.
- C, diminished, C first inversion. Play C major, a little diminished, then C major in first inversion. Just try it and see how cool this sounds.
The second one is used a lot in classical music, because it establishes the tonality in three chords. You’re playing the one chord, the tonic, then the seventh degree in first inversion, then the one again in first inversion. You’re telling the listener, hey, we’re here.
That chord gives a lot of color, but its function is a dominant chord. It gives us tension and gravity toward the tonic, the one. If you want to use this move on 7th chords in a groove, the 7th chords lesson walks a C major 7 through its inversions with a passing diminished in between.
Level 5: how do you play diminished lines on guitar?
Arpeggiate the chord shape across the strings. I show two fingerings I use a lot: one that follows the chord shape, and one with two notes per string.
There are quite a few options to finger these, but these two work really well. While I play, I’m thinking B diminished: minor 3rd, minor 3rd, minor 3rd. It’s all minor 3rds. I’m also aware of the notes, B, D, F, A flat, B, D, F. As long as you’re aware of the sound and color you’re hearing and what you’re playing, there’s no problem.
The two-notes-per-string fingering is literally the same shape moved around, and sometimes you can play it on the faster side of things. Do it really slowly first, and keep seeing the notes.
A practice idea for today
- Feel it. Play B diminished 7 and give the sound a feeling before you name it.
- Move it. Shift the same shape up three frets at a time and say the notes: B, D, F, A flat.
- Use it. Play C, then the diminished, then C major in first inversion, slowly, and listen to the pull back to C.
- Make music. Put it into something you’re playing. If you do something cool with it, drop a comment on the video. I’m super curious what you come up with.
If you want your 7th chords rebuilt from the ground up, Jazz Chord Essentials covers how a 7th chord is built, the four main colors (major 7, dominant 7, minor 7 and half diminished), and every inversion on the 4th, 5th and 6th string sets.
Frequently asked questions
What notes are in a diminished 7 chord?
B diminished 7 is B, D, F and A flat, all minor 3rds apart. Because it’s symmetrical, D, F and A flat diminished 7 contain the same four notes, just arranged differently, so one shape covers four chord names.
What’s the difference between diminished and half diminished?
The 7th. The chord built on the 7th degree of C major is half diminished: B, D, F, A. Lower the A to A flat and it becomes fully diminished, B, D, F, A flat, which is all minor 3rds and symmetrical.
How do you use a diminished chord over a dominant 7 chord?
Raise the bass a half step. Over C7, put C sharp in the bass and you get C sharp diminished, which gives the C7 a flat 9 sound. It can also lead to other keys, like a secondary dominant pulling to D minor in F.
How far apart do diminished shapes repeat on guitar?
Every minor 3rd, which is three frets. The shape stays exactly the same as you move it, and every position holds the same four notes in a different order. That symmetry is also what makes diminished so useful in jazz.
Take the diminished shape and move it three frets at a time, then put it into a song you already play.
