Continuing with the theoretical expansion and referring again to the dominant chords (those who missed it can see: #22 – 5 Types of Dominant Seventh Chords), after understanding the existence and purpose of the Primary Dominant in Major Harmony (Check out: #13 – Major Scale Harmonic Functions and #14 – Major Scale Harmonic/ Melodic Tensions), and having developed the Secondary Dominants (#29 – Secondary Dominants Major Scale), a very good step forward is the Tritonal Substitute Dominants.
A brief definition for tuning in: “Tritonal Substitute Dominants are dominant chords that appear from replace the root of the concerned Dominants by their Fourth Augmented Fourth/ Diminished Fifth” (Tritone). This replacement is possible because both dominant chords share their most important notes (Third and Seventh).
The difference between a Primary/ Secondary Dominant with a Tritonal Substitute is the way in which they resolve. The last one are done by half step (1/2 tone).
In the following example, the Tritonal Substitute Dominants are applied to the cadence IIm7/ V7/ Imaj7/ VI7 on the C major key.
These Dominants are found very frequently in all kinds of popular songs/ standards of jazz, etc … and in many cases they resolve the chord expected by intervals of half step (1/2 tone); Although many other times they do not (deceptive resolution) generating some confusion in the analysis/ interpretation of the same ones. However, they should always be viewed/ analyzed as such, unless it is another type of Dominant chord. (you can see: #16 – 3 Steps to Harmonic Analysis).
Until next post!