Today I was listening Héctor Lavoe, accurately the song "Plato de Segunda Mesa":

I heard something that captured my attention, the substitution of B♭m by D♭, and I would like to know when I can do this.

In the first part of the song they do the typical F F7 B♭ B♭m cycle, but in the chorus they change the air of the song with this chord.

Any explanation is appreciated!

  • It's not clear what you are asking. Are you saying that the cycle becomes F F7 Bb Db? – ggcg May 29 at 14:53
  • No, no, what I told is that the progresion in the beggining is F to F7 to Bb to Bbm; in the chorus they change Bb and Bbm by Db. And that sounds curious to me. Sorry if haven't explained myself well. @ggcg – sopach96 May 29 at 14:58
  • All these answers talk about the relationship between Bbm and Db chords in general but I would like to know exactly where this occurs in the song in minutes and seconds. Is it before the coro /guía? I listened and heard no Db chord. There is a Db7sus4 briefly in the mambo section. – John Belzaguy May 29 at 21:52
  • @JohnBelzaguy I heard it in 3:00, 3:10, 3:20... And like this, every time that repeats. Today when I was sitting in my piano, I realized that it wasn't a Bbm as in the section before the chorus... It sounds to me as a Db, and for this reason is why I asked the question, when we can do this... And at the end it had sense, I mean it where a reason to do this ... But as you say, the bass I think that mantains in Bb... But the chord that pianist play is Bb Db Ab... That sounds to me as a Db... Sorry If haven't explained me good... – sopach96 May 29 at 22:04

Thanks for your reference times in the comments. This is the coro/guía (or montuno) section where the lead singer trades phrases with the chorus. It is an 8 bar progression but there is no D♭. Here is the progression:

||: B♭m7 |B♭m6 |Fmaj7 F6 |Am7 D7 |Gm7 |C7 |Fmaj7 F6 |Cm7 F7 :||

In the first bar the pianist is actually playing the notes of a D♭ triad in his tumbao (also called a montuno), rhythmically alternating the A♭ by itself with the D♭ and F together. The thing to keep in mind is that in this style of music when playing tumbao the pianist does not play the roots of the chords, he plays lines that carry the voice leading of the harmony (7-3, 7-6, 5-6, etc.) The bassist is in charge of playing the roots of the chords and he is playing B♭. B♭ under a D♭ triad is a B♭m7.

As a side note the term montuno has 2 different meanings. It can refer to the rhythmic syncopated part the pianist plays. It also is the name of the section of the song where the lead singer trades with the chorus. That’s why I and many others who play this style like to call it “coro/guía”, translation: chorus/guide.

Tumbao originally meant the part played by the bass but nowadays it has evolved to refer to both the bass and piano part.

I should have mentioned, what a great song, arrangement and performance! The arrangement sounds like it might have even written by Jose Febles, the greatest arranger in that style from that era in my book.

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I would add to the answer provided by Albrecht. Any major chord and its relative minor are very strongly related. In fact the major 6th chord and the relative minor 7 chord are identical, X6 = (1, 3, 5, 6) and vi-7 = (6, 1, 3, 5). The pair (X, vi(X)) can be used as substitutes, where vi(X) means "the relative minor chord of X". The most common place to use it, in my experience, is in modulating from the key of X to its rel minor but in fact it can be used anywhere. In any key you have this relationship in the following pairs of chords, (I, vi), (IV, ii), and (V, iii). The transition from IV to iv going to I is a typical resolution (and a beautiful one), this opens the door to replacing the iv with its relative Major, in this case the bvi of the original key. Personally I do not think of this as the bvi rather I think of it relative to the chord being replaced. Think of that as a temporary vi, and go to its relative major. You can learn more about these types of devices in a book called "How to Create Jazz Chord Progressions" by Chuck Marohnic.

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  • Thank you for the recommendation of the book, and for the answer too! – sopach96 May 29 at 16:00

Not surprising! This substitution is quite common:

IVm and ♭VI have common tones, as IVm7 and ♭VI 6 are identical chords when you take the 1st. inversion.

in solfege fa-lu-do-ma = lu-do-ma-fa (ma = mi flat, lu = la flat)

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  • Thaks for the answer! @AlbrechtHügli – sopach96 May 29 at 13:56
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    Is this a typo VIm6 and bVI ? Are we comparing the IVm to bVI. – ggcg May 29 at 14:55
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    True, thanks. I’ve edited the mistake. – Albrecht Hügli May 29 at 15:56

I don't think we need any deeper explanation than pointing out that B♭m and D♭ triads have two notes in common. Adding or varying one note, particularly to another diatonic note, is such a common variation as to barely rate the label 'substitition'.

(What would be a full-blown substitution? Perhaps Db7 as a substitute dominant in C major, where the only common factor (with G7) is the F-B tritone. What would be the lowest level? Perhaps colouring a tonic chord with an added 6th - replacing a plain C triad with C6. But they could both legitimately be labelled as a 'substitution'.)

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  • Thank you, I will change the name of the post. – sopach96 May 29 at 15:58
  • It's interesting that you seem opposed to using "substitution" citing that the chords have common notes but as I recall overlapping notes is the criterion for chords to be substitutes for each other. So when is it more appropriate to use the term substitute in your opinion? – ggcg May 30 at 14:11

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