I am trying to understand why in a progression in C# major there is an A major chord, the chords are to be precise: C# Bbm F# A, where did this A come from?

I thought it might be a secondary dominant that does not resolve but still, A would resolve on a D which is not present in the C# scale, so why does it fit in this key?

The song is "gua10" by "tha Supreme & Lazza", the chords in question are the first four at the beginning of the song and are repeated throughout, the song is in the key of C# major.

  • 4
    A#m would probably be a better name than Bbm, given key C#.
    – Tim
    Jun 27, 2022 at 15:21
  • 1
    Have you tried writing your own melodies over the chords? Which notes seem to fit over the A chord? Jun 27, 2022 at 16:02
  • 3
    @Tim but D flat major would probably be a better name for the key in the first place (making the A major chord a B double-flat major chord, of course).
    – phoog
    Jun 27, 2022 at 17:49
  • 1
    @Salmone It is hard to make a recommendation without knowing what you already do know. However, if you know that the scale of C# major has 7 sharps, it suffices to say that all chords that can be formed within the scale are spelled using the notes from the scale (and the notes from A#m are, whereas those from Bbm clearly aren’t). If you don’t know that, you need to first study key signatures and the circle of fifths.
    – 11684
    Jun 28, 2022 at 18:22
  • 2
    @Salmone then you need to study key signatures and the circle of fifths. Also, in major and minor scales each letter appears exactly once. You couldn’t have Gb in a G major scale, because you would then have G twice (once flat and once natural) and no f (skipping from e to Gb). But all this becomes clear when you see the derivation from the circle of fifths.
    – 11684
    Jun 28, 2022 at 18:25

4 Answers 4


It's a very common thing, mixing in harmony from the parallel key. It doesn't necessarily move the tonic anywhere, but it opens the door for it. In this song they never use that option.

Two variations of the same idea:

  • C# A#m F# F#m (use F#m instead of A)

  • C# A#m F# A/B

If you want to test the parallel-key hypothesis, don't go back to C#, but take advantage of the opened door and move to the suggested E major:

  • C# A#m F# A ... E C#m A C

and why not continue even further

  • C# A#m F# A ... E C#m A C ... G Em C Eb ... Bb Gm Eb F# ... start over

To really explicate the key changes:

  • C# A#m F# A/B ... E C#m A C/D ... G Em C Eb/F ... Bb Gm Eb F#/G#
  • 1
    Where did the 'suggested E major' come from? Did you mean D major?
    – Tim
    Jun 27, 2022 at 16:23
  • 1
    @Tim It's in C# and mixes in stuff from C# minor, suggesting a possible move one-and-a-half steps up --> E major. With the proper bass it's more obvious, C# A#m F# A/B ... E C#m A C/D ... G Em C Eb/F ... Bb Gm Eb F#/G# ... repeat. Jun 27, 2022 at 16:27
  • 1
    @Salmone Did you try the alternative versions, one that goes from A to E, or from A/B to E? A/B means that over a B bass note there's an A chord. Maybe "suggest" was not the best word, but when I hear the A chord, I immediately expect the good old major/minor mixture trick. Going to D is not near the top of my list of expectations, even though an A chord of course makes that a plausible option as well. In my mind, the tonic is set to C#, and an A major in that situation is, to me, a modal mixture as the first interpretation. I feel that relative keys are two sides of one dual key. Jun 27, 2022 at 20:45
  • 1
    @Salmone Maybe I wasn't clear ... since C# minor and E major, being relative minor and major, are kind of the same thing and go hand-in-hand, then mixing in things from C# minor into C# major is the same as mixing in things from E major. Relative minor and major are so tighty connected in the music I make and am used to, I don't consider a shift-of-balance from C#m to E any sort of "modulation". Jun 27, 2022 at 21:00
  • 1
    @Salmone - C#m quite often does follow A in songs.
    – Tim
    Jun 28, 2022 at 7:55

It's often considered that the A here would come from the parallel key of C♯ minor. It's a fairly well used contraption, using notes and chords from the key (major or minor) which has the same root, here C♯.

It is quite often used as the dominant of the key one semitone above (here, D), so doesn't really come into the secondary dominant category - unless there is that actual key change into key D, in which case it would belong to the new key more than the previous one - and not be secondary dominant, but simply dominant.


Let’s take this to C major to be less confusing. Then we’d have C - Am - F - Ab. Ab can be seen as low altered mediant of C, which is not an uncommon thing to do. Basically what you’re doing there is to take the mediant from the minor scale instead of the major scale.

  • I mostly find talking about as if the key were C major to be more confusing, not less. But that’s probably just my personal preference. Sometimes the chord based on the sixth scale degree is called the submediant to distinguish it from chord based on the third degree Jun 27, 2022 at 20:46

I would suggest looking at it in Db major.

This makes the analysis a lot easier and is the key that it would be written in in a chart 🙂

(Others are writing about it in C# major because you’ve asked that way, but unless you’ve modulated from another key, you wouldn’t use that key in most situations.)

From a quick listen I would transcribe this progression as Db, Db7/Cb, Gb, Gbm/Bbb. Here, the last chord is the 4 chord, but minor instead of major. This gives it a nostalgic kinda feel.

Here are some links to videos describing how this is used:

  • In my progression A is not the 4th grade of Db, A is not in the major scale of Db
    – Salmon
    Jun 27, 2022 at 22:35
  • 1
    Sorry, I made a mistake and should have clarified: The 'A' is there, but it's the 3rd of the Gbm chord, being played in first inversion. Because it's a Gbm chord, it's spelled as Bbb (B double flat).
    – Turnaround
    Jun 27, 2022 at 22:40
  • Sorry I still can't understand, the 4th of Db isn't Gb? Which is different from A? In my chord progression I've got an A major as the last chord.
    – Salmon
    Jun 27, 2022 at 22:49
  • In Db major, Gb is the fourth note in the scale. Building a chord upon that gives you a major chord, but then the artist alters it by flattening the 3rd (Bb) to Bbb (which sounds the same as an A). What you're thinking is an 'A', is actually part of this minor chord - is it not the root, but the 3rd. Here it is spelled as a Bbb. He then takes that note, and puts it in the bass, making it a first inversion chord. If you aren't familiar with inversions there are lots of resources online.
    – Turnaround
    Jun 27, 2022 at 23:07
  • Don't we need an E note to obtain an A? A Gbm is different from A chord
    – Salmon
    Jun 27, 2022 at 23:39

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