How to define the key of a song

Discussion in 'General Instruction [BG]' started by Rockin John, Oct 9, 2002.

  1. It's clear to me that I'm never going to know more than the merest whiff of musical theory. There's hardly the time to do personal practice never mind 'learn about music'. And that put's me at a very distinct disadvantage when it comes to "writing" material or trying to interpret stuff that (say) the guitarist has "written". But I have to accept my limitations and get on with it.

    So here's my current problem, for which I crave advice.

    I messed about with an idea for a song. I used the bass to get the notes right as they sounded to me and sang some words over the top of the bass. The simple progression went:

    D C G Bb C D.

    Leaving out the Bb for a moment, and as far as I understand it, the D,C and G form part of the major scales of those 3 keys. So I find myself being unable to understand what key my simple little tune is in.

    Wisdom please

    :D John
  2. Suburban


    Jan 15, 2001
    lower mid Sweden
    I'm not very wise, but someone who was said to be, in these matters, once told me that if the last chord of a tune sounds good, it's the tonica - which is the ground chord of the key.

    I'd say, from that, that your song is in D major.
  3. moley


    Sep 5, 2002
    Hampshire, UK
    Is D C G Bb C D the tune or the bass line? If it's the tune, knowing what bass part you played with it would help. Just from those notes, you can't really tell what key it is in, you need more context. Just what what you've given it could perhaps be Bb major - starting and ending on the 3rd, it could be G minor - starting and ending on the 5th, or it could be D minor, starting and ending on the tonic. Or it could be none of these - I would need more to go on to say what key it's in.
  4. My little progression is the bass line. For the purpose of the exercise I envisaged the guitar playing those chords as well. The melody lives only in my mind at the moment.:eek: I have no realistic means of writing it down.

    From messing about, I can say that the first note of the melody is a D sung over the D on bass and perhaps guitsr, too: that D is the first note of the song.

  5. JMX

    JMX Vorsprung durch Technik

    Sep 4, 2000
    Cologne, Germany
    It can't be D major because it has a B not a Bb and a C# not a C - unless there's a key change.

    You need to find out what types of chords those are (major/minor, etc.).

    You can't really tell with just the root names.
  6. moley


    Sep 5, 2002
    Hampshire, UK
    Well if that's the bass line, I suppose it looks like D minor - or possibly major. You say you "envisage the guitar playing those chords" - what chords? I presume you mean that bass line is the root notes of the chords, but it would help if you knew what the chords were, e.g. D minor, C major, or whatever.
  7. There are no chords because I've not hummed this little ditty to the guitarist yet. Anyway, even when I do he'll not know exactly what chords he's using outside of the majors. He, like me, knows nothing of written music and even less of theory: we both play entirely by ear. He'll perhaps come up with some odd-ball fingering that he thinks sounds OK. Sure, somewhere that shape will have a name but he won't know it and neither will I.

    I thought I get him to use the major chords first. And, perhaps for this purpose, we could assume that my tune will employ exactly that.

    The Bb is used as a sort-of transition note that nicely brings the pattern all the way back to D, the start and finish note of the progression.

    You see, if I know what key it's in, I speculated that I could find the listing of all the notes in that key to help me find some more notes to make up a chorus.

    Err...does that make any more sense. [Phew...all sound a mite sloppy, doesn't it?!?]

  8. moley


    Sep 5, 2002
    Hampshire, UK
    I would suppose you're looking at D being the key note there - but it could me major or minor, or any other mode!! But, if you ask me it doesn't really matter. As far as composing is concerned, I personally don't think that working out what key it's in and using notes in that key is the way to go. I think possibly you'd come up with something more original if you just see where the music takes you, rather than sticking to one key. One of the pieces I've written for the album I'm working on is like this - I really couldn't say what key it is in! That's not to say it's atonal, but the chord progression is such that it is not really rooted in any one key for long enough for it to be in that key!
  9. mflaherty

    mflaherty Supporting Member

    Oct 9, 2001
    Is there an F or F# in your melody? That will tell you whether it is D maj or min. I'm guessing major.

    This chord progression is outside the rules that classical and jazz follow, but is pretty typical for rock and folk. The C functions as a secondary subdominant, and the G to Bb to C to D as kind of a subdominant turnaround or cadence. But this is theoretician gobbledygook. The only thing that matters in music is, does it sound good to you?

    Start with a D major scale, either diatonic or pentatonic. Also try D mixolydian. Using a pentatonic based on the root of each chord always works, too.
  10. jaybo

    jaybo Guest

    Sep 5, 2001
    Richmond, KY
    Depending on what the guitar and vocal melody does it could be in several different keys. Because you used Bb and C natural D major probably woudln't be the key. It could end up being in G minor. Being in Gm you'd be starting the song with a dominant which is pretty common and descending tonally to the tonic. Really though I wouldn't worry about it, you're used to playing by ear so chances are you're gonna have an idea in your head of what you want and you'll be able to find it.
  11. Bruce Lindfield

    Bruce Lindfield Unprofessional TalkBass Contributor Gold Supporting Member

    If there are no chords then it is ambiguous as far as key is concerned - you need to define chord types before you can say what key.

    So the simplest way to define key is if you see a dominant 7 chord functioning in a sequence - as there is only one dominant 7 in a Major key and that is the V chord - you can work back to the root and you have the key - easy!!

    But if there are no dominant 7th chords then you have to look for other things as people have mentioned.

    A lot of pop/rock songs are ambiguous as to key -especially if they just use root-fifth a lot.
  12. mflaherty

    mflaherty Supporting Member

    Oct 9, 2001
    Well told, Suburban! To follow up, the first chord of a song is usually the key. The last chord is almost always the key. If the first chord and last chord are the same, there's your key.

    You might want to try a D mixolydian scale over the first three chords, and a D natural minor over the last three.
  13. moley


    Sep 5, 2002
    Hampshire, UK
    Well put. (Applauds).
  14. mflaherty

    mflaherty Supporting Member

    Oct 9, 2001
    Still waiting for the name of the song that begins and ends on the same chord, but is in a different key....
  15. Bruce Lindfield

    Bruce Lindfield Unprofessional TalkBass Contributor Gold Supporting Member

    I've played several Jazz tunes where the key centre shifts every few bars - so knowing the first and last chords doesn't help you there. The bulk of the material is in a different key to that in which it starts and finishes.
  16. Perhaps in retrospect my original question was really naive....stupid even.

    Quote by Ed.

    Again, RJC has done nothing to establish a key here.

    That's cos I don't know what I'm doing, Ed. I simply don't have the knowledge to write it down. I guess I could pick out the notes on the bass then write them down as note letter names. But even when that's done I don't have the knowledge to write them with the correct timing against the bass notes I spoke of originally.

    In other words, I don't know anything about written music.:eek: I guess I could do it eventually but it'd be a helluva slog.

    Quote by Ed.

    D C G Bb C D you could play Bbmaj7 - Abmaj7 - Ebmaj 7 etc all major chords with the 3rd in the bass.

    Please explain what this means, Ed.

    Thanks gents.

  17. Bruce Lindfield

    Bruce Lindfield Unprofessional TalkBass Contributor Gold Supporting Member

    All that Ed is saying there is that just because the bass is playing certain notes, doesn't necessarily mean these are the root notes of the chord!

    Bass players are "allowed" to play 3rds, 6ths whatever!! ;)
  18. Hmmm. Then I guess I need to see a chart of what notes comprise what scales. I understand there's some sort of wheel chart for doing this. Can you point me in that direction please, Bruce?

  19. Me too Ed.;) :D
  20. Bruce Lindfield

    Bruce Lindfield Unprofessional TalkBass Contributor Gold Supporting Member

    Well - as I always say - I see it as a lifetime's study!

    There are charts, but it's understanding and application of that, that's important.

    You don't have to write songs like this either - I used to do it just by trial an error - but it helps a lot to have a guitar or keyboard to check chords "sound" right! Or rather how you intended them to sound. ;)

    If you're just picking chords from a chart with no understanding of why or for what effect, then to me you might as well just choose chords at random, until you find one that fits.

    Seriously - I've done it!