Secondary dominant

ah yes right Rem becomes I

thanks a thousand for the help!!!!!!

You're welcome, bye!

A secondary dominant is a first-species seventh chord built on a degree other than the V.

This is the definition; now let's see how this thing is realized: let's start from a sequence of chords in the key of C, for example the C progression harmonized with 4 sounds (C M7, Am7, Dm7, G7); in it we find only one first-species seventh chord (G7) and two second-species seventh chords (Am7 and Dm7), which are not found on the V degree of the reference key, but rather on the VI and II respectively.

Now, based on the phenomenon of RAISING THE THIRD (this is the fundamental step to understand...) those two second-species seventh chords can become first-species, i.e., A7 and D7 respectively, simply by raising the note C to C# in the Am chord and the note F to F# in the Dm chord.

This solution already exists in Baroque authors and was used when there was no way to prepare the seventh in the second-species seventh chord. Which indeed requires preparation, meaning that the note constituting the seventh of the chord must already be present in the previous chord. Sometimes this was not possible; however, to avoid giving up the sonority of the seventh, the expedient of raising the third was used so that the seventh would become first-species and therefore would not require preparation.

Later, this was also done for euphonic reasons because, as others have already said, the secondary dominant necessarily contains a note that is not part of the home key, and this creates in the ear a sensation of openness, of expansion of the tonality. The secondary dominant should not be understood as a process of modulation or micro-modulation; it should be understood as a tonal expansion, precisely because it makes sense since we introduce an altered note that does not exist in THAT tonality.

Jazz makes extensive use of secondary dominants; indeed, the structure of the so-called anatole or rhythm changes, usually in the key of B-flat, has a section B composed of 4 of these chords following one after another: D7, G7, C7, F7, before returning to Bb.

I hope I have added something interesting to the discussion....

Thank you so much!

Yes! Certainly! You have added something very interesting to the discussion!

now I'm taking notes immediately!