Music Theory Q and A Discussion Thread

Discussion in 'Tab & Music Forum' started by davidKOS, Sep 22, 2013.

  1. stratology

    stratology Strat-Talker

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    Chords are constructed by stacking intervals of the same name.

    The most common way is to stack 3rds.
    But there are also chords based on stacking 2nds (Clusters) and 4ths (Quartal chords).


    When you stack 3rds to get a 3-note-chord, you can stack


    - a major 3rd with a minor 3rd > this results in a major triad
    - a minor 3rd with a major 3rd > minor triad
    - a minor 3rd with a minor 3rd > diminished triad
    - a major 3rd with a major 3rd > augmented triad


    You can stack more notes. Stacking 3rds means skipping every other note on a scale.

    So when you take a major scale, and start with C, you take C, skip the next note D, take E, skip F, take G, skip A, take B, skip C, take D, skip E, take F, skip G, take A, skip B.

    So, by doing that, you get
    CEG > C maj
    CEGB > C maj7
    CEGBD > C maj7/9
    CEGBDF > C maj7/9/11
    CEGBDFA > Cmaj7/9/11/13

    When you take the same C major scale, but start building the chord on the 2nd note, you get
    DFACEGB > Dm7/9/11/13


    The different intervals in chords have specific functions:
    - 1 and 5 build the foundation (in a band, you can leave them out of your chords, because the bass player will take care of them)
    - 3 and 7 define the function of the chord (like minor7 or major7)
    - 9, 11, 13 provide additional colours


    Now about the diminished chords:
    When you stack 3 notes of the C major scale starting from B, you get BDF - a Bdim diminished triad.
    But - when you add the next note - BDFA - you get a Bm7/b5 chord, not a diminished 7th chord.


    Diminished 7th chords are based on the diminished scale. Which is just whole step - half step all the way through.
    Diminished 7th chords are constructed by stacking minor 3rds. C-Eb-Gb-Bbb, which you can (mis)spell as C-Eb-Gb-A, for clarity.
    Every note can be the root, so this chord is Cdim7, but also Ebdim7, Gbdim7, and Adim7.


    For added craziness: Check out Pat Martino's approach to chord construction. There's a free pdf, and also books and a Truefire course. He derives all triads from the augmented triad, and all 7th chords from the dim7 chord.
     
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  2. stratology

    stratology Strat-Talker

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    This may have been brought up before, but here are a few practical applications:

    [​IMG]

    1.

    When you have a major scale, you have a number of chords that belong to that scale (diatonic):
    Triads in C major: C Dm Em F G Am Bdim
    Triads in E major: E F#m G#m A B C#m D#dim


    Now look at the circle of 5ths, at the C: surrounding it, right next to it, are F on the left, G on the right, Dm, Am, Em on the inside. So you can see all the triads belonging to C major at a glance (if you want to include the Bdim, think half-step-below-C-dim.). C F G Dm Am Em.
    Yippee.

    Can you see the triads belonging to E at a glance?



    2.

    Remember the A minor pentatonic scale?
    Look at the 'Am' in the circle of 5ths, take the C on the outside right next to it, and step to the right, clockwise, to collect 4 more notes: C G D A E - which are the notes of the Am pentatonic scale.

    Try it for Fm pentatonic. You can see the notes at a glance.


    Try it for Em:
    G D A E B is what you get. Somewhat familiar. The guitar is tuned based on notes of the Em pentatonic scale.
    A different perspective, as opposed to 'stacked 4ths, with a major 3rd in between', which is how I usually see how the guitar is tuned..
     
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  3. Boognish

    Boognish Senior Stratmaster

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    These are really good tips. I thought I knew how to read circle of fifths...now i realize i just knew a small fraction of what all is in this wheel.
     
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  4. Boognish

    Boognish Senior Stratmaster

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    Here are pics of my Circle of fifths. Can someone explain the black box that is just hanging out from the rest of the black boxes? It says III (V of vi) and 7, sus4.

    There is a note on the bottom left but it doesnt say anything about that particular black box. The box I'm talking about outlines the Fb/E in Key of C

    20200827_183800.jpg 20200827_183717.jpg
     
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  5. Boognish

    Boognish Senior Stratmaster

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    I'm noticing a pattern while working on scales.

    To me it seems like the Ionian, Lydian, and Mixolydian modes are based off the Major Pentatonic scale.

    The Dorian ,Phrygian, and Aeolian are based on the Minor Pentatonic Scale.

    Is this true or am I combining scales and making up new ones and it just seems that way?

    I think I may have more questions but I'll wait for an answer before I jump the gun and start confusing myself.
     
  6. Boognish

    Boognish Senior Stratmaster

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    I did some research and it looks like my assumptions were correct.
     
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  7. dogletnoir

    dogletnoir V----V

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    Yes... i usually sort the modes into two main groups.
    The ones i consider major modes are the Ionian, Lydian and Mixolydian, and the minor ones are Aeolian, Dorian, and Phrygian.
    If you look at the harmonised major scale in any key, you will also see that the chords correspond to the character of each mode:
    I / Ionian /Major
    ii / Dorian / minor
    iii / Phrygian / minor
    IV / Lydian / Major
    V / Mixolydian / major (dominant 7 in 4 voices)
    vi / Aeolian / minor

    and finally vii* / Locrian / diminished (mi7b5 in 4 voices)

    Into which class would you sort the Locrian mode?
     
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  8. Boognish

    Boognish Senior Stratmaster

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    Major?
     
  9. dogletnoir

    dogletnoir V----V

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    While Locrian is a bit difficult to classify when viewed uniquely as a scale or mode, figuring it out in 3rds to four voices will yield a minor 7b5 chord.
    This would be vii* in a harmonised major scale progression, and ii* in a harmonised natural minor progression.
    For me, the presence of both flat 3 and flat 7th intervals would put it in the 'minor' subset, and
    when you see the chord written out functionally (ii* or vii*), it is always with lower case Roman numerals.
     
    Last edited: Dec 9, 2020
  10. Boognish

    Boognish Senior Stratmaster

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    Ahh...the flat 3 and flat 7 intervals should have tipped me off as well. when I play in a key and look at circle of fifths,to my ear,the vii* doesnt sound right and so I'm a little intimidated by it
     
  11. fezz parka

    fezz parka fezz parka

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    There are 7 modes.

    Four are minor...three are major.

    All of the basic church modes are based off the major scale ( the parent).

    Pents...have nothing to do with it.

    :)
     
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  12. fezz parka

    fezz parka fezz parka

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    If you can record yourself...

    Play a C major scale. CDEFGABC
    Play it back and play an E Phrygian scale along with it. EFGABCDE
    Record that.
    Then play it back and play a G Mixolydian scale along with it. GABCDEFG.
    Record that.
    Finally play it back and play a B Locrian scale along with it. BCDEFGAB.

    Cmaj7 =CEGB
    1-3-5-7
    1st, 3rd, 5th, and 7th modal degrees.

    The C major chord progression is built this way.

    Also try playing each mode by itself against the parent C major scale.

    Harmony.
     
  13. Pisces One

    Pisces One Strat-Talk Member

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    I'm trying to understand the Bm scale progression, whose notes are B C# D E F# G A.

    Why is it C# -> D, if it's moving from half to whole step? Wouldn't a whole step be C# -> D#?
     
  14. montemerrick

    montemerrick no earthly reason why

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    the B natural minor scale is B whole step C# half step D whole step E whole step F#, half step G, whole step A, whole step B

    Natural B Minor is the relative minor of D major (which is D-E-F#-G-A-B-C#-D) starting from the 6th interval (B)

    in natural minor, the 3rd interval, in this case D, is lowered a half step from the major, and the same is true of the 6th and 7th intervals...
     
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  15. dogletnoir

    dogletnoir V----V

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    In order to understand ANY natural minor scale, the first thing you need to do is refer back to the pattern of whole and half steps in A minor.
    A B/C D E/F G A
    The half steps occur between the 2nd and 3rd and between the 5th and 6th scale degrees.

    All natural minor scales will preserve that pattern, regardless of the root.
    This is where the 'sharps and flats' thing comes in.
    B C#/D E F#/G A B
    Notice how we use the sharps to create the same pattern of whole and half steps, with the half steps between the 2nd and 3rd and 5th and 6th scale degrees?

    Now, just for fun, try writing out E minor.
     
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  16. Boognish

    Boognish Senior Stratmaster

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    Based on those whole/half steps it should be
    E, F#, G, A, B, C, D
     
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  17. dogletnoir

    dogletnoir V----V

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    Correct!
    And the relative major key would be G Major:
    G A BC D E F#G, with the half steps between scale degrees 3 and 4 and 7 and 8.

    Notice that the single altered note is common to both scales.
    This is why the 'key signature' for both G Major and e minor is F#.
     
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  18. dogletnoir

    dogletnoir V----V

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    First off, the Roman numerals on the chart represent functional relationships, which are always determined from a given reference point.
    We are in the key of C here which makes E the 3rd interval based on the C Major scale.
    Diatonically this would be harmonised as the iii chord, e minor.
    That would make E major the III chord (parallel major).

    E is also the 5th scale degree in A minor, which is the vi chord in the key of C Major.
    In three voices (R, 3, 5), E major would be the V of vi (if we take the vi as our reference point and think of it
    as a temporary i, then E Major is the V chord moving up from A minor).

    Finally, 7, sus4... these are not Roman numerals, so they are meant to indicate intervallic relationships.

    Since we just looked at the B minor scale a moment ago, we can see that if you move the shaded box fully to A,
    that's the 7th scale degree of B minor
    , and if we move it fully to E, that's the 7th scale degree of F# minor.

    That leaves us with the sus 4 relationship.
    Since sus4 chords are not formed by stacking 3rds on top of one another, they fall outside of normal diatonic functional harmony.
    These chords omit the 3rd scale degree which would define them as either major or minor, and substitute the 4th instead (sus4).

    Now, in which major scale would E be the 4th scale degree?
    B C# D# E F# G# A# B
    Movement counterclockwise around the Circle represents the interval of a 4th...
    so the sus 4 of any scale is always located immediately one click away in that direction.
    If you want to play a Bsus4, you would take the normal B major triad (B D# F#), and replace the 3rd with a 4th (B E F#).

    My apologies... somehow i missed your question previously.
     
    Last edited: Jan 11, 2021
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  19. Boognish

    Boognish Senior Stratmaster

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    Ok...this is quite a bit to digest. I thought sus was suspended not substituted. Your explanation is very good and now it's starting to come together. Starting is keyword there. :DAnd after looking at the chord wheel E would be the 4th scale degree of B. I struggle a bit to think of the wheel without thinking about the fret board. Should I picture the wheel or the fret board in my head? Also, thank you so much for your willingness to go over this. It is greatly appreciated!
     
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  20. dogletnoir

    dogletnoir V----V

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    You are correct when you say that 'sus' is actually short for 'suspended'.
    i just like using that as a reminder that the 4th REPLACES the 3rd scale degree in that chord, rather than getting added on...
    if you wanted to think about it in terms of school, it would be the 3rd that got 'suspended', since it's no longer in the class, LOL.
     
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