0005. Types of chords vs types of pentatonics

Everybody knows that minor pentatonic reflects features of most minor chords, scales or modes (must be with b7 and 4), because of it`s evident structure: 1 b3 4 5 b7.

Measured from b3 (considered as new root), the same tones give structure of major pentatonic: b3 4 5 b7 1 = 1 2 3 5 6. It covers qualities of many major chords, scales or modes.

Following explanation is written with particular letters, to emphasize close relation between pairs of relative pentatonics, which in fact are the same thing.

  1. Minor pentatonic equaly reflects features of m7, maj7 and similar chords:

Am7 fits Cmaj7 as 1 b3 4 5 b7 (A C D E G) fits 1 2 3 5 6 (C D E G A)

Let`s discuss remaining asymmetric seventh chord types: dom7, 7alt, m7b5, m maj7, maj7#5.

  1. Features of dominant seventh chords are well reflected by minor pentatonic with major third (M3). Measured from 3rd degree it also perfectly fits with 7alt (enharmonically = m7b5).

A7 fits C#7alt (= C#m7b5) as 1 3 4 5 b7 (A C# D E G) fits 1 b2 #2(b3) b5 #5(b6) (C# D E G A)

  1. m maj7 features are reflected by minor pentatonic with major seventh (M7). Measured from b3rd degree it also covers maj7#5.

Am maj7 fits Cmaj7#5 as 1 b3 4 5 7 (A C D E G#) fits 1 2 3 #5 6 (A C D E G#)

Newly introduced types of pentatonic contain not only plenty of missing m2, M7 and tritone intervals, but also all four possible kinds of triad: major, minor, diminished and augmented. I dare to state, that three types of pentatonics, shown above, are various and versatile enough to act properly in whole range of musical situations.

That also could be proved by mathematical research, which shows us where pentatonics could be used as superimpositions (five-voiced chords).

pentatonics as superimpositions


0004. Density of vertical texture

Density of chosen harmonic devices (quantity of degrees within) affects few crucial parameters of music: construction of arpeggio based melodic phrases, mix of prevailing intervals and force of functional gravity.

Triads have thinnest texture; prevailing intervals are thirds, fourths and their inversions. Functional gravity is evident (heavily determined by Western cultural environment).

In seventh chords we observe denser texture and greater variety of intervals: seconds and sevenths become common, tritones are much more frequent. Functional gravity is the same, excepting dominant seventh chords – those pull even stronger.

Pentatonics also could be considered as vertical formations, with very dense texture. In such conditions fourths, seconds and their inversions start prevail. Functional gravity becomes weak. Looks like the vertical and horizontal of music got really close to each other. Some modes have no more than five harmonically stable tones (phrygian, for instance), all remaining act like passing or chromatic.

Next list shows how superimpositions could be categorized by density of texture: into triads, seventh chords and pentatonics. Pentatonics are marked in bold font; some of them are not common minor/major type and would be explained in further posts.

superimpositions as triads, 7th chords and pentatonics

Pentatonic is powerful but yet underestimated harmonic device. I think it is because of limited intervalic structure of minor/major pentatonic (which lack some of characteristic intervals: m2, M7, tritone). Musicians are trying to alter pentatonics to fit whole range of musical structures, but they often fail to discover fundamental unifying principle. Hope I found simple and sufficient method how to overcome intervalic limitations of pentatonics and control them vertically. Great deal of upcoming materials would be entirely dedicated to this subject.


0002. Superimpositions – avoid tones avoided

If we are able to define what chord substitutions do not contain avoid tones (modal, but vertically unstable) or chromatics, we could get a great list of harmonic substitutes surely suitable for vertical use. Let`s call them superimpositions.

Superimpositions also should not provoke arpeggio conflicts with basic chords. For instance, there is no place for 7 and b7 or 5 and #5 together (also check alternate spellings).

Every tone of superimposition whether duplicates arpeggio of basic chord, whether works as colorful and stable modal feature – so called tension (2 or 9th, 4 or 11th, 6 or 13th).

Just to be sure: avoid tones are modal upper structures – 9, 11 and 13th`s, – working only as passing or chromatic notes, because of their harmonic instability.

For instance, upper structures of ionian mode are 2, 4, 6; but only 4th (11th) is harmonically unstable. It`s avoid tone. Upper structures of lydian mode are 2, #4, 6; all of them stable, so there`s no avoid tones in lydian mode at all.

Let us hear and compare 4th and #4th vs maj7 chord. Avoids tend to be immediately resolved, until then we feel kind of anxiety.

Most avoid tones meet one basic criteria: they are by minor second (including interval inversions and octave displacement) above the tones of triad (1, 3 and 5). But not always. Perception of harmonic stability is cultural and quite subjective question, therefore some of avoid tones are just recommendable.

There is my personal list of 28 asymmetric scales / modes (suitable for vertical use), with avoid tones marked grey. It will serve as basis for further construction.

avoid tones in 28 modes


001. When and why chord substitutions are not reliable?

Did you ever noticed, when playing in a band or with backing track, that some of traditional chord substitutions do not sound well over original changes? There are reasonable answers why it is so, and what could be done to avoid such irritating effect, without limiting (and even expanding) palette of handy harmonic devices.

At first, let us define what traditional chord substitutions are. They are harmonic devices for creative reconstruction of already known chord changes, without doing any damage to their functional features. Chord substitutions developed gradually, as more and more sophisticated and modern recipes of harmonic variation.

We all know at least few of those:

Diatonic substitutions (Em7 instead of Cmaj7)

Secondary dominants (C C7 | F G7)

Secondary II V`s (C   Gm7 C7 | F G7)

Tritone substitutions (Db7 instead of G7, or Abm instead of Dm)

Sudden change of chord type (Ebmaj7 instead of Eb7 – tritone sub for Am7 or A7)

Passing chords (C C#dim7 | Dm G7)

Coltrane substitutions (Dm7 Eb7 | Abmaj7 B7 | Emaj7 G7 | Cmaj7 instead of Dm7 | G7 | Cmaj7 | Cmaj7)

Root movement by minor third (Bb7 instead of G7 or Db7)

Backcycling (E7 A7 | D7 G7 | C7 | C7 instead of G7 | G7 | C7 | C7)

Side-slipping (Ebm7 Ab7 | Dm7 G7 instead of Dm7 | G7)

Chromatic approach chords (C Bb7 | Am C#m | Dm Ab7 | G7 B7 instead of C | Am | Dm | G7)

You name it…

When using as melodic (arpeggio) devices, chord substitutions could work really well, if played in fast and convincing phrases. Predictably structured series of notes become relatively independent of harmonic context until the point of resolution. They are self content to the listeners` ear, because of very dynamic nature.

Audible conflict between original changes and substitutes occurs in slower tempo, when trying to accent or lean on notes of substitute arpeggio, also in chordal improvisation. It happens because some of chord substitutions have been created foremost as compositional devices and are not really suitable for vertical improvisation, because of avoid tones and chromaticisms (vertically unstable notes) they contain. Riddle of vertically stable and unstable substitutions emerged historically and I will propose clear technical solution for it in progress of series of following articles.

Once more: we could alter original chord changes using any of traditional chord substitutions and still retain the same functional logic, but we could not always do that during spontaneous jam session – original changes and their substitutions sometimes may not sound well, played simultaneously.

Let us analyse and hear few examples, when original chord and common traditional substitute misfit:

Ex. 1:

G7 (V7) ≠ Abm7 (tritone substitution of Dm7 (IIm7), quite common before Db7 (bII7) instead of G7).

Notes of G7: G B D F, it is 1 3 5 b7.

Notes of Abm7: Ab Cb(B) Eb Gb(F#), it is b2, 3, b6, 7, according to G7.

Both summarized: 1, b2, 3, 5, b6, b7, 7. b2 and b6 are avoid tones, b7 and 7 – arpeggio conflict.

Ex. 2:

Am7 (VIm7) ≠ Ebmaj7 (tritone substitution of VIm7, chord type changed, as in common cadence Cmaj7 Ebmaj7 | Abmaj7 Dbmaj7)

Notes of Am7: A C E G, it is 1 b3 5 b7.

Notes of Ebmaj7: Eb G Bb D, it is b5 b7 b2 4, according to Am7.

Both summarized: 1 b2 b3 4 b5 5 b7. b2 is avoid tone, b5 and 5 – arpeggio conflict.

If these examples did hurt your ears (sorry for that), you are ripe for further studies, which will follow here shortly.