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A dominant seventh chord as the fifth degree of a key (notated V7) is often used to build a cadence back to the tonic.

With that function in mind, I've seen people refer to other chords as "it functions as a V7", but without the chord itself being a V7. One example I know of is applying tritone substitution to the V7 chord, which changes the chord but not its function.

When composing, which other chords should I have in mind that function like a V7 but are no the V7 chord? If there are too many possibilities, which are the most common V7 substitutions in western music (pop, rock, jazz, classical)?

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  • Any chord built from a dominant triad can function like a V7. (Ex. 1 for an incomplete list)

  • Diminished chords, both diminished triads and sevenths, can act as dominants with the root truncated. (Ex. 2) Semi-diminished sevenths (Tristan chords) are generally used as pre-dominants, but can stand in for V M9 with the root truncated. (Ex. 2c)

  • Augmented sixth chords - Italian (Ex. 3a), French (Ex. 3b) and German (Ex. 3c) - normally function as pre-dominants, but can function as dominants: they tend to combine a Phrygian cadence with a dominant or dominant-like progression in one or more of the upper voices. (The German sixth really prefers to act as a pre-dominant, though - in Classical music it generally resolves through a 64 chord, as here, to avoid rather bald parallel fifths.)

Your "tritone substitution" is an augmented sixth, by the way: take a look at the makeup of the German sixth. This isn't so much a tritone substitution: it's a modal substitution that has been given mixed function by sharping one of the notes into a leading tone (the Italian sixth) and, in this case, adding another tendency tone. It's an artifact of voice leading that arose from the old Phrygian final cadence (♭vii6-I).

If augmented sixth chords are mostly used now as pre-dominants, it's because the Phrygian cadence fit very neatly into the minor mode as iv6-V. However, they can still be used for cadences to the tonic, and they can be even dropped into a major mode context. I've done so here in m.32.

  • Finally, there is V7♭5 (Ex. 4) and its derivatives. I've shown the basic chord and followed it by its first and second inversions. Note the latter (Ex. 3b)!

Examples

There are undoubtedly variants I've missed. In general a chord can be made to function as a dominant harmony if it possesses the ascending leading tone and (usually) the descending leading tone and/or the fifth of the tonic. Not infrequently, in major modes, major-like modes and Picardy thirds, you'll also have 4-3 (fa-mi) in one of the voices.

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There are only a few chords that really function as a V, i.e. that have a dominant function. Other answers interpreted your question more like "which chords can lead to the I chord", which is actually a different question, because you don't need a chord functioning as a dominant to get back to the I chord (e.g., plagal cadence).

These are the chords that can have a dominant function leading to the I (in the key of C major):

  • G7 (and its variations like G7sus4, G9, etc.)
  • Db7 (tritone sub)
  • Bo (diminished triad, vii dim)
  • Bo7 (diminished seventh chord, and all its inversions: Do7, Fo7, Abo7)

There is a huge number of other chords that resolve to the I chord without a dominant function. A few common examples are (again in the key of C major):

F  -> C
Fm -> C
Db(maj7) -> C
Bb7 -> C
D#07 -> C/E
F#o7 -> C/G

There are many more, but these are the ones that I encounter most frequently (in jazz/popular music). Of course, many of those chords are not purely diatonic chords, but they are used in the key of C major and they also resolve to the I chord (the same is true for some chords with a dominant function).

  • I think it's worth pointing out that Fm6 is inversionally equivalent with Dø, and Dø subs for G7 (well, G7b9sus4), which is dominant. Fm6 is also pretty generally the same chord as Bb9, and Bb7 is also one of the standard subs for G7. – Chris Strickland Nov 8 '18 at 7:18
  • @ChrisStrickland: I'd say that all chords you've mentioned are subdomiant, not dominant. – Matt L. Nov 8 '18 at 10:01
  • It's that because of the lacking subtonic? I just tend to use these where the implied context is dominant. What do you consider the defining characteristics of the dominant and subdominant? – Chris Strickland Nov 8 '18 at 19:12
  • @ChrisStrickland: That's a very good question. I trust my ears here because I've never seen a clear definition of the terms "dominant" and "subdominant". For myself, I have a few criteria but I don't know if they're generally accepted. In short, I'd say either the root of the chord should be the V, or the tritone between leading tone and the 7th of the dominant should be present, then it's a dominant chord. I already thought of formulating a question about that to see what other people think (or if there's a good definition somewhere which I've missed). – Matt L. Nov 8 '18 at 19:41
  • There is already a question asking the same thing. Not sure though if the answers are really conclusive. – Matt L. Nov 8 '18 at 19:44
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One chord which will easily substitute is vii; for the key of C major, this will be the diminished triad B-D-F. V7 would be G7, i.e. G-B-D-F, so the only difference is that V7 has the dominant in the bass whereas vii is lacking this note.

There is also the 'deceptive cadence', which in C would be C#major (or C#7). This works better in minor keys.

  • 1
    A deceptive cadence is a resolution V to vi (i.e. G7 to Am in the key of C major), or V to VI in minor (i.e G7 to Ab, in the key of C minor). Your example would either be a tritone substitution (Db7 -> C) or a subdominant phrygian cadence (Dbmaj7 -> C). – Matt L. Apr 1 '15 at 7:52
  • The deceptive cadence is also known as an interrupted cadence. – Tim Apr 1 '15 at 13:50
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A couple I use instead of V (or V7) - in C - B D F Ab and C D F Ab. The first is Bo, the second Fm6. Bo resolves the B to C and the Ab to G, whereas the Fm6 seems to suspend things before resolving to Cmaj. There's also G+, which is different from G7, with its augmented 5th, leading up to the major 3 of the tonic. Another that works in certain places is B D# F# - Bmaj. Don't know the name of this cadence, but it certainly gets the listener's attention! And, rather like a tritone sub., resolution is only a semitone away.G#7 works in similar vein, with 3 of its notes needing to move that one semitone - although it can seem to herald a key change. I think Mahler used it occasionally.

  • Well, Tim, I'd say that, if C D F A♭ sounds like a suspension, it's because it probably is, i.e., D°/C. That's acting rather like a truncated V m9/I. – user16935 Apr 1 '15 at 7:53
  • Not many people know that ! I certainly wasn't thinking of it ! So is it different from Fm6 ? Only, I guess, that Fm6 is a iv, not a V. – Tim Apr 1 '15 at 7:57
  • Well, if you've got C in the bass, it's not really acting as iv add6, That's a very tricky chord: in the inversion you have it, it acts like a diminished triad over a tonic pedal. If you put D in the bass, it's a semi-diminished (Tristan) chord. If F is in the bass, then it will act as an F add6. – user16935 Apr 1 '15 at 8:04
  • Why have you called it F add6 rather than Fm6? – Tim Apr 1 '15 at 8:10
  • Apologies, F minor added sixth. F minor (F A♭ C) plus D. – user16935 Apr 1 '15 at 8:12
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All chords whose root is V or VII are considered dominant chords, and are interchangeable: V major triad, dominant 7, minor and major dominant 9th (minor 9th in a major scale is common. Major 9th in a minor scale is rare), +11 and 13th. For the VII: diminished triad, diminished 7th, semi-diminished 7th (rare in minor scale). Some of these work as altered too: G7 can have d#, db, or both. Pop uses a lot of triads. Blues dominant 7 everywhere. Jazz all kinds of extensions and altered. Classical, too, depending on period and composer: Mozart, usually dominant 7, while altered and substitution is common in Mahler and Wagner.

  • Minor dominant 9th on ii goes better to I, in my ears. Vm dom9 wants to go to V, making an imperfect cadence. Like the b and # 5ths and 9ths, (altereds) though. – Tim Apr 1 '15 at 7:52

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