I'm analyzing the first movement of "Suite del Plata Nº1" by Máximo Diego Pujol called "Preludio" that it's on D minor, I have encountered the following progression i-VImaj7-V7, I'm not sure what is the role/function of the VImaj7, it has the feeling of a tritonal substitute but lacks the tritone, following Tarchini's Chord function chart we have that the VI as it's coming from a tonic-function chord and it's going to a dominant-function chord it serves the role of a subdominant.

So, my question is the following: Is the VImaj7 replacing or doing the role of a subdominant or it's doing another function that I'm not aware?

2 Answers 2


You're right that it's not a "traditional" tritone substitution since the VI7 chord (B♭–D–F–A) lacks the tritone we would expect in the V7/V (E–G♯–B–D).

But I'm encountering more and more musicians who treat tritone substitutions not as their original, strict definition—of two chords that share the same tritone—but rather with a looser definition: two chords whose roots are a tritone apart. I bring this up in Must a tritone substitution use a dominant functioning seventh chord?

If we go with this looser definition, then, the VI7 here would be a tritone substitution of the V7/V, since the root of the VI7, B♭, is a tritone away from the root of the V7/V, E.

With all of this said, I would argue that this VI7 is simply a predominant. VI can go directly to V, and occasionally (if rarely) this VI can be flavored with an additional chordal seventh. The same is true of ii and IV chords, both of which can increase their push to V with a seventh.

  • As a listener of heavy metal, I find it very hard to believe that "two chords whose roots are a tritone apart" is a legit definition of tritone substitution. I'm not buying for a moment that an Eb power chord is a tritone substitution for an A power chord, especially in an A power-Eb power-A power-Eb power-A power chord progression that alternates between tonic and non-tonic chords.
    – Dekkadeci
    Commented Jan 28, 2022 at 12:44
  • @Dekkadeci I don't disagree! I agree with the stricter definition of "tritone substitution," but I just thought I'd mention the looser definition since I'm seeing more and more people using it.
    – Richard
    Commented Jan 28, 2022 at 14:18

The VImaj7 chord is performing a predominant function, especially since it goes immediately to a dominant-function chord (V7, in this case).

The VImaj7 chord is plausibly replacing a subdominant chord in that progression, but I cannot say it can perform a subdominant function because it cannot go immediately to a tonic chord, unlike a true subdominant chord (at least in common practice period harmony).

  • Are you sure about the I chord not proceeding directly to the vi chord? It's only a one-note change, so seems like an easy transition.
    – Aaron
    Commented Jan 28, 2022 at 3:56
  • @Aaron - I mean that IV-I, iv-I, IV-i, and iv-i are all allowed (at least with common practice period harmony), but VI-i is not.
    – Dekkadeci
    Commented Jan 28, 2022 at 4:00
  • Ah, I misread. So you're saying that "true" predominants can function as P-T cadences. I've only considered predominants as moving to dominants, and if they moved in some other way, they weren't functioning as predominants.
    – Aaron
    Commented Jan 28, 2022 at 4:25
  • @Aaron - No, I mean that "true" subdominants can be substituted for the dominant in D-T cadences. On another note, now I'm wondering what to call a non-tonic, non-(secondary-)dominant chord that just moves to another non-tonic, non-dominant chord.
    – Dekkadeci
    Commented Jan 28, 2022 at 12:39
  • My bad. I've been reading subdominant but thinking predominant this whole time. On that other note, you mean, for example, iii moving to ii?
    – Aaron
    Commented Jan 28, 2022 at 12:46

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