How to know what key a song is in by the chords you are playing.

Discussion in 'Guitar Lessons' started by blakem, Apr 17, 2009.

  1. blakem

    blakem Senior Member

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    Ok , I want to explain how to tell what key a chord progression is in by the chords you are playing without it being really complicated.
    If you didn't know, keys are based off of the Major Scale. The major scale consists of 7 notes. The 8th note is the octave of the first note. So, think of the melody of a major scale...Doe, ray, me ,fa ,so, la, ti, doe..
    ok.. this formula always is the same, for every key...
    I will use the Key of C as an example.
    the note of the scale has its corresponding # in front of it..
    1.C
    2.D
    3.E
    4.F
    5.G
    6.A
    7.B
    So you see the major scale numbered 1 to 7, with its corresponding note next to it.
    The 1, 4, 5, are major chords
    the 2, 3, 6 are minor chords
    the 7 is a diminished chord.
    so your jamin a tune...lets say The chords you are playing are D minor, A minor, G Major, F major. Using this major scale method, you know that the song is in the Key of C. Because using this method the key of C (Ill put the scale # next to the chord) has a D minor chord (#2), a G Major Chord(#5), an F major chord(#4) an A minor chord(#6)...So you have to know how to play a major scale..
    remember that on a guitar the steps to a major scale are whole step(with a fret space inbetween) ,whole ,whole , half(no space inbetween), Whole, Whole, Half
    This works for every key..
    Hope this wasn't to complicated...
     
    tintin and nicolaidenmark like this.
  2. tintin

    tintin Senior Member

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    Thanks. Major scale pattern: W-W-H-W-W-W-H, no?
     
  3. huw

    huw V.I.P. Member

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    Great post, but can I just add two things to what you've said there:

    First:

    You should say that the major keys are based off the major scale. But the minor keys are based on the minor scales. Just trying to avoid confusing anyone coming to this for the first time. :)

    Second:

    :hmm:

    Using that method you can know that the song is in a mode based on the key of C major, but you have to look at the context to tell you which one. For instance, the list of chords you give doesn't have a C. For the tune to be "in C" it will have to arrive at the "tonic" (or "home") chord sometime.

    No C chord = not in C major. It's in one of the modes derived from C major instead.

    Depending on the chord progression one of the chords will be emphasised in a way to make it feel like "home" - that will give you the key/mode.

    From the chords Dm, Am, G, F you could be in Am (natural minor); Dm (dorian minor); F (lydian) or G (mixolydian). It all depends which chord is presented as the tonic.

    Still - once you've identified the key or mode, you're off & running with a tune, so you're dead on to highlight this as a basic skill for folks to learn.

    :dude:
     
  4. matthornet

    matthornet Senior Member

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    You're correct!

    You're correct too! Good one huw, you could spot them out so quickly.
     
  5. mrpesca

    mrpesca Senior Member

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    So will you just "know" where the tonic center is? Also, if say G is the home chord, what scale do you use to solo?
     
  6. matthornet

    matthornet Senior Member

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    It depends on the composition of that particular piece. However the tonic chord could be determined by reading the musical notations or simply by listening to how its played.

    If in the key of G, your choice of scales for solo is too vast.. You could easily dial in your G major scale (which will sound amateurish if repeated too much), E minor pentatonic (E being the relative minor of the G major), or the different modes derrived off the G major scale. (dorian to locrian) - Ionian being the major scale. Etc, this could go on & on depending on the chord progression. When you advance in your playing & theory knowledge you could also play different scales according to the different chords played within one progression. Meaning you solo chord by chord & not only focus oround the G major scale.
     
  7. huw

    huw V.I.P. Member

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    Basically, yes: the "home" chord should stand out as where the music resolves to your ear. It could be because it's the chord played the most frequently, or for longest, or just the one that ends a section of the music. Whichever, there should be some sence of resolution to the music when it lands on that chord.

    Now the scale? Assuming that you are refering to a G chord in reference to the Dm, Am, G, F progression that the OP quoted, then I already answered that: G mixolydian.

    The reason is that we've identified that the progression uses a mode of C major. The mode of C that you get for the G chord is the mixolydian.
     
  8. nicolaidenmark

    nicolaidenmark Senior Member

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  9. huw

    huw V.I.P. Member

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    Just because the G is the 2nd chord played doesn't necessarily mean that it's the 2nd chord of the home key...

    The verse patten there is a simple repeating F to G resolving up to Am at the end of the phrase. Those are the IV, V & VI chords of C major, so we're clearly in one of the modes of C major (look back at post #1 for how I got that)

    So far so easy-peasy...

    But which one? F lydian, G mixolydian or A aolian? Where is "home"?

    The answer comes from the chorus: G Am C D. That's clearly the I ii IV & V of G major.

    So the way I'd describe that, looking for the simplest way to describe it all clearly, is that the song is basically in a G tonality, with a verse in G mixolydian with a chorus in G major.

    Incidentaly, the middle 8 is interesting because there's a lovely temporary key change & then back again:

    It goes to a repeating Bb to C figure, similar to the verse. This is implying a mode of F major, as those are the IV & V chords of that key. But at the end of the phrase, instead of the Dm that we are expecting (from the verse pattern) we get a D major before hitting the chorus again. In this situation the D is functioning as the V chord of the key of G major (just like it does in the chorus itself).
     

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