#1
When and why do composers use inverted chords and non-diatonic chords?
I'm talking about secondary chords, tritone substitution chords and neapolitan chords.
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Last edited by demonofthenight at Sep 22, 2007,
#2
whenever they feel like it, and because they can

/unhelpful reply
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#3
The chords you mentioned are most used in progressive music: Opeth, DT, etc

Anywho, composers employ the use of these chords to break the monotonic pattern of major/minor chords, etc. They break the pattern, which is something the listeners of today want to hear.
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#4
When - whenever it sounds good/when the composer wants to.

Why - it's more musically interesting than the same/similar chord sequences over and over again. It also makes the music slightly less predictable rather than the same old same old.
Tritone subs are usually used over II-V-Is for the dominant chord so you get II-bII-I and have the descending root note, but its not the only situation.
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#5
Inverted chords get used all the time, often to allow nice voice leading.


Neapolitan sixth chords can apparently be used to modulate to a key a semitone below the current key. So in C major, you could go C major, Db major first inversion, B minor. This sound good to me on a keyboard, but I'd wait for someone more knowledgeable to confirm it.


Secondary dominant chords are used for loads of things, a common progression to end a piece is II-V7-I, in which the II 'resolves' to the V7, and the V7 to the I. The V7 chord rather than the V is often used as it contains the natural version of the note altered to make the ii chord major, eg in C major

D major - G dominant 7th - C major

The D major contains an F#, which is not diatonic, and the G7 contains the F natural, which is.


I think tritone substitution is more commonly used in jazz than classical (I'm really not sure though), and it can be used to create chromatic bass lines. So the progression D7-G7-C major (II7-V7-I) can become D7-Db7-C major, or G#7-G7-C7.


edit: gaaar, loads of people posted while I was typing my post
Quote by VR2005
Very good post Marmoseti, you're on the right track.



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#6
Any thing having to do with harmony has much to do with voice leading. Western music is essentially all about having multiple melodies forming at once and the harmony that we can create there in. In general inverted chords are used to ease resolution, often times keep it stepwise or to maintain a more solid bass line. Tritone sub is used to reharmonize a piece of music because dominant 7th chords are unique in that that tritone occurs in two different chords, thus lending it to easy reharmonization. You'll notice that in a C7 chord the E and Bb are the tritone, and that in a Gb7 the Bb and E form a tritone. Non-diatonic chords are used to change keys or to increase the resolution to a diatonic chord. I honestly know very little about the neopolitan chord, so here is the wikipedia article. http://en.wikipedia.org/wiki/Neapolitan_chord

Secondary chords (such as the secondary dominant) are once again, used for voice leading. It is often used just to strength resolution or to change keys, or in a minor progression, to create the harmonic minor scale with the raised 7th.

BTW if you want to hear any of these chords just listen to some late romantic composers and maybe some of the eariler modern ones (who arn't entirely atonal.) Secondary dominants can be heard all over western music, and especially in Bach's fugues.
#7
The Neapolitan is often a dominant prep. That is, it acts like a ii in a ii-V-I; it prepares the dominant. You could also probably get some interesting modulations by using it as a common chord between two keys.

As sinan said, a tritone sub can act as a dominant. However, in classical music, augmented sixth chords could be interpreted as tritone subs that resolve to the dominant, and thus they would be dominant preps. The wiki on augmented sixths: http://en.wikipedia.org/wiki/Augmented_sixth_chord Again, some interesting modulation possibilities here.
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#8
Next question, still about weird chords.

What is the difference between a neapolitan chord and a tritone sub?
In Cmajor the neapolitan chord is Dbmajor, right? And the tritone sub for the G7 is also Dbmajor (Db7). Is the only differnece between a neapolitan chord and a tritone sub that dominant seven?

And thanks everyone for those answers, most of them were helpfull (guess which one wasn't)
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[U]     | \|_ |     |     .-|      [/U]
      *-|-*    (_)     `-’
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        L.
#9
A neapolitan sixth chord has to be first inversion I think, otherwise it's just a bII chord. Db major isn't a tritone sub for G7, it has to by Db7 because you need the shared tritone, which comes between the B and the F in each chord (it's actually a Cb and F in Db7).

G B D F
Db F Ab Cb
Quote by VR2005
Very good post Marmoseti, you're on the right track.



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