In Deep With.. 7b5

For the last couple of months, as per my 2019 practice plan, I've been mucking around with 7b5 chord voicings and arpeggio patterns. Now, at first I must admit I really didn't expect to find anything much of use with them other than as a slightly skronky jazz passing chord, but I have to say they've grown on me and I'm starting to like the quirky majo-but-dissonant sound they produce, particularly from the arpeggio ideas.

So, first up, a little bit of theory, and then it's on to some cool practice ideas.

The 7b5 belongs to the dominant family of chords – you can tell because there's nothing denoting major or minor and dominant is the “default” status of extended chords. For those of you whose eyes are already starting to glaze over, any chord with a 7, 9, 11 or 13 after it is an extended chord. If it doesn't say major or minor, that means it's dominant, as that's the most common kind of extended chord, and ain't nobody got time to go around writing “dominant” after each chord.

A chord is made dominant by the presence of both major 3^rd and b7 intervals, so a regular 7 is made up of R 3 5 7, our 7b5 takes this composition and alters it slightly – R 3 b5 b7.

Now this creates a quirky, unresolved sound, and the reason for this is quite simple:

R – 4 semitones – 3 – 2 semitones – b5 – 4 semitones – b7 – 2 semitones – R

So as you can see, a symmetrical pattern of intervals. Now, pretty much all my students have heard my rants about symmetry (and I will be posting something along those lines in the next few weeks) , but suffice it to say that humanity has evolved to see perfect symmetry as unnatural and to react accordingly – and we react to sound the same way.

More on this another time.

This also means that a chord starting on the b5 interval actually works out to be the same as the original chord: C7b5 is built from C (root), E (3rd), Gb (b5), Bb (b7), and Gb7b5 consists of Gb (root), Bb (3^rd), C (b5) and E (b7).

Let's look at some arpeggio patterns:

Mapped across 3 octaves:

Notice the two shapes even though there are four notes in the chord – this harks back to the symmetry mentioned earlier.

Sequencing these shapes gives some interesting and fun results:

Looking at chord voicings, we can see the same thing

All of these shapes are relatively accessible, and make for excellent passing chords or substitutions in any kind of jazzy blues track - for example, in a 12 bar, using it as walk from the I to the IV introduces a cool chromatic twist (C 7 – C E G Bb, C7b5 - C E Gb Bb - F7 F A C Eb Note the C note remains common, but the other notes shift chromatically – Gb to F, Bb to A, E to Eb). Sequencing the arpeggios makes for a great fun quirky alternative to blues scale and minor pentatonic runs too.

So experiment with these shapes and see what you can come up with – back next month with a TUNEICEF update and a look at the composition process itself!