Types Of Replacement

1. Secondary dominants.

To achieve greater harmonic variety, it is possible to transform a chord into the dominant of the next one.

This will not involve a modulation, only greater tension and consequently a greater harmonic drive from one chord to another.

Generally speaking, to perform this type of substitution, the secondary dominant must be located a fourth below the subsequent chord.

e.g.: in the II V I of C major, we replace the II (Dm7) with D7, the V of V.

in some cases a secondary dominant may not resolve to a IV above:

e.g.: Cmaj7 / E7 / Fmaj7

I would interpret it as I, V of VI, IV; the E7 should resolve to Am7 (VI) but relative to A, it becomes a kind of deceptive cadence.

another one:

D7 / Dm7 G7 / Cmaj

the D7 is effectively a V of V, but its resolution is delayed by the "true" II, the Dm7.

Anyway, it seems to me that in essence we are not straying from traditional harmony.

@ Simone

of course, in this case we were following the initial topic; anyway, this discussion about substitutions can be a pretext for asking and exchanging clarifications of every kind, even by going backwards.

2. Tritone substitution.

In short: a seventh chord can be replaced by another seventh chord placed over a diminished V.

E.g.: we can replace G7 with Db7...

The prerequisite for this substitution is that the seventh chord actually fulfills its function as a dominant (it shouldn't be, for example, a IV of a melodic minor...)

Why do we do this?

It plays on the fact that, enharmonically speaking, the two chords in question share what is at the heart of the dominant chord: the tritone interval.

By leaving this interval unchanged, the bass is modified so that instead of resolving a IV above, it will descend chromatically towards the tonic (or anyway towards its resolution:

even a secondary dominant can undergo a tritone substitution: Ab7 / G7 / Cmaj7.

In the end, we can say that tritone substitution is essentially a bass movement and can be applied in real time during improvisation; naturally, one must be somewhat careful...

Great then.

3. Modal interchange.

In this case, it would be the exchange of chords, having the same harmonic function, between the major mode and the minor mode.

es: in the II V I of C major (D-7 G7 Cmaj7) I can replace the II with the II of C minor: (DØ G7 Cmaj7).

this solution, for example, is one of the "trademark" elements of Cole Porter, see Night and Day, I love you, What is this thing called love and so on...

Another frequent use of modal interchange (in a tonal context) occurs in plagal cadences:

a IV I of C major (Fmaj7 Cmaj7) becomes F-7 (more often -6) Cmaj7.

And why?

Always to have more harmonic variety and consequently be able to have a greater choice of scales, harmonic tensions etc.

as well as to create a lesser expectation that then surprises the listener by opening into the major.

... puff...

coffee

...now, like a good master, you must let some of this material settle, thank you 🙂

Of course, I won't fail to ask you a few questions

Just a few examples, to get practical:

original sequence: I VI II V (e.g.: Cmaj7, A-7, D-7, G7; the infamous "circle of C" or, more nobly, "turnaround", as the jazz players say. ;-)

possible substitutions:

I > E-7 [iii] (as it belongs to the same "family" as the I; not as a conclusive chord) and, consequently, E7 [D.S., V of VI] and its tritone Bb7,

perhaps also Eø [i.M., as preparation for the V of II]

VI > Aø (unusual, perhaps as preparation for the V of V); A7 [D.S., V of II]; Eb7 [tritone of the D.S.]

II > Dø [i.M.]; D7 [D.S., V of V]; Ab7 [tritone of the D.S.]

V > Db7 [tritone], which generally resolves to the I

the suggestion is to use only one substitution at a time, then try various combinations, to understand how they sound and which ones seem most effective to you - some sequences are indeed not used, but you discover which ones and why ;-)

or those that come closest to your taste.

Schematizing (always in relation to this sequence):

Cmaj7 > E-7; E7; Bb7; Eø.

A-7 > Aø; A7; Eb7.

D-7 > Dø; D7; Ab7.

G7 > Db7.

I hope I haven't missed the mark too much...

Clear DrJellyfish, I am referring to point 1.

DrJellyfish wrote:

in some cases a V.7 may not resolve a IV above:

e.g.: Cmaj7 / E7 / Fmaj7

I would interpret it as I, V of VI, IV; the E7 should resolve to Am-7 (VI) but relative to A it becomes a kind of deceptive cadence.

Are you sure we aren't in A minor? So I of C = III of Am-, V, VI

In theory it would be possible, but I find the tonal center of C major more likely since in the original sequence the dominant of A (E7) does not appear

and the D-7 G7 Cmaj7 cadence is quite binding. A VII I of natural A minor (G7 Am7) approaches an almost modal color.

Besides, this tonal ambiguity is widely exploited by composers; many pieces oscillate between major and relative minor keys, one above all Autumn Leaves

(I am assuming that the sequence can be cyclical or ends with Cmaj7).

On second thought, the G7 resolves to Cmaj, which could be a III of A minor, but in the absence of the leading tone, there is no true confirmation of the key, something that occurs for C.

In any case, a good part of the possible substitutions for C are also applicable when thinking of the piece in A minor.

DrJellyfish wrote:

On second thought, the G7 does resolve to Cmaj, which could be a III of A minor, but in the absence of the leading tone, there is no real confirmation of the key, something that happens with the C.

If I understood correctly what you mean, the progression should then continue or be like this (thinking of Cmaj+) Cmaj7 / E7 / Fmaj7 / D7 / G7/ C7

Right?

It could start from the beginning and repeat itself one or more times; it could end with Cmaj or proceed with any chord sequence on which the first chord resolves the G7 (I; VI -deceptive cadence; III, IV and so on).

The second part is very clear, your students and we are lucky to have you here 😉

what is DØ?

The half-diminished chord is an chord formed by the tonic, the minor third, the diminished fifth, and the minor seventh; in your case, the notes are D F Ab C.

It is labeled that way, usually when indicating a chord built on the VII degree of the major scale, whereas to indicate its use as a minor subdominant, it is usually written like this: Dm7b5....it's obviously the same thing.....

For secondary dominants, I would add this:

1- it is a dominant that resolves to a scale degree other than the I

2- It must be diatonic to the key

3- Better if on a weak beat of the measure.

Sec Dom: G7 | A7 | B7 | C7 | D7 | E7 | F# not diatonic, cannot be used|

Key Cmaj7 | Dm7 | Em7 | Fmaj7 | G7 | Am7 | Bsemidim |

V/I V/II V/III V/IV V/V * V/VI

Exceptions:

the V of I is the Primary or Perfect cadence....

The V/V is called Extended Dominant, or Extended Dominant in English.....

regarding their use, you have already spoken....

sorry, I sent the wrong message and I can't delete it 😵

Feliciano wrote:

3- Better if on a weak beat of the measure.

...in 3/4 time? Do you mean that the resolution must be on the downbeat?

AleGozzo wrote:

sorry, I sent the wrong message and I can't delete it 😵

drummers... ;-)

Exactly! I agree with Simone and repeat the question that everyone has ignored. In the chord progressions, I always put the tonic in the bass....trying with inversions etc. anyway, things come out that aren't particularly interesting. How to do it?