Useful Music Theory Part 1: The Major Scale And Intervals And Getting A Basis For All Future Music Theory

The major scale and the intervals that come from it are the basis for virtually all music theory. Learn them properly, and you can learn anything!

Useful Music Theory Part 1: The Major Scale And Intervals And Getting A Basis For All Future Music Theory
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Too often, people come up to me asking to learn "advanced music theory". This in itself is not a problem, but I find a lot of people don't even truly have the basics down. People think because they know the fingerings and the box to a major scale, that they understand the major scale.

I'm not here to teach you how to play something. I'm here to teach you to understand what you're playing.

On that, I'll still show you your basic major scaletwo octave box shape: based on the E string. This is G major:
e---------------------------2-3-\r\n
b-----------------------3-5-----\r\n
G-----------------2-4-5---------\r\n
D-----------2-4-5---------------\r\n
A-----2-3-5---------------------\r\n
E-3-5---------------------------\r\n
or, on bass guitar,
G---------------------4-5-7-9-11-12-\r\n
D-----------2-(4)-5-7---------------\r\n
A-----2-3-5-------------------------\r\n
E-3-5-------------------------------\r\n
(4) marks where & when you should move your index finger on your fretting hand.

So that's how you play it... but what makes it the major scale? As in, why are those notes what they are?
You form the major scale by taking a starting note (the root) and then move up in the following steps: Whole step, Whole step, Half step, Whole step, Whole step, Whole step, Half step. Don't know what steps are? Think of a whole step as two frets or two chromatic notes, and a half step as one fret or one chromatic note.

Thus, C Major is all the white keys on piano, because it is... C, D, E, F, G, A, B, C.

This pattern will always form the major scale as we all know it. To explain why it became the major scale, I'd have to give you 1200 years of music history and explain how the modes evolved over time, so let's not get into "why is it the major scale" just yet. Just know that pattern is the pattern forming the major scale.

Now, how does this relate to intervals?

A perfect interval is an interval that matches up perfectly with the root note mathematically. But even that statement comes across as rocket science. What does this statement truly mean? It sound waves of a "Perfect 5th" play three times for every two times the sound waves of the root plays. A Perfect 4th does the same thing, but with the inverse ratio: it plays twice for every three times the root plays. The octave is the simplest perfect ratio, as the octave plays twice for every time the root plays.

For this reason, these intervals will always sound groovy played against any other single note. The sound waves bond in a way that is pleases the ear. This is why powerchords sound so awesome: they're just a root, a perfect fifth, and a perfect octave. They can go almost anywhere and do almost anything.

Every other note in the major scale, when referred to as an interval, is called a major interval. Hence, the 2nd note in a major scale? a Major 2nd. 3rd? Major 3rd. 6th? Major 6th. 7th? Major 7th. Thus, a major scale, in addition to being Note Whole step whole step half step whole step whole step whole step half step, could also be viewed as: Root Note, Major 2nd, Major 3rd, Perfect 4th, Perfect 5th, Major 6th, Major 7th, Perfect 8th.

From the major scale, we can name all intervals. How you name intervals goes like this. Assume each arrow () is a half step up or down.
Diminished  Augmented\r\n
Diminished Augmented
Hence, if you take a perfect fifth, and take it down one step, it is a... diminished 5th. If you take a perfect fifth and move it up a half step, it is an... augmented fifth. If you take a major third and move it a half step down, it is a... minor third. And so forth.

Hence also, this is why even though C# and Db sound the same, they are different things. Let's say you're playing in the key of F#. C# is a perfect 5th! Db is a diminished 6th. You'll almost never see a Db in the key of F#, cause why would you play a diminished 6th when you could play a perfect 5th? There's more to it than this, but that requires chordal knowledge... which requires a firm understanding in intervals, which is what I'm trying to teach.

I feel this alone is what a lot of musicians fail to get a good grasp of. If you have a firm understanding of intervals and naming them, you can understand or learn almost any kind of theory. The problem is, people learn the major scale and not an understanding of intervals, and then begin to bite off more than they can chew.

I'll follow up this lesson with Useful Music Theory, Part 2: Forming Diatonic Chords and Part 3: The Three Minor Scales.

48 comments sorted by best / new / date

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    stnuCgnikcuF
    I'm not sure if I just suck at this, but I'd like to see a really useful beginners music theory here on U.G. This is good, but I got lost during parts of it.
    n00bje
    Good article, I'm looking forward to the next parts. I got some questions though: "Hence, if you take a perfect fifth, and take it down one step, it is a... diminished 5th." Instead of one step, you mean half a step, right? And when you would take a perfect 4th half a step down, would you get a diminished 4th or a major 3rd? Or are they both the same?
    dumbface12
    It would be a diminished 4th however a diminished 4th is enharmonic to a major 3rd. Meaning they sound the same but in theory they are not.
    My Last Words
    I understand the whole concept of both intervals, scales and chord formations, and I still don't know jack **** about APPLYING it..
    TobiasSammet
    Very well explanation! Finally the fog in my mind about music theory is beginning to be illuminated!
    TobiasSammet
    Very good explanation! Finally the fog in my mind about music theory is beginning to be illuminated!
    TobiasSammet
    Very good explanation! Finally the fog in my mind about music theory is beginning to be illuminated!
    Quiffmiester
    "And why is the last half step to the root note called a perfect 8th?" Just to clarify one possible misunderstanding from the above quote: the interval names are all in relation to the root note, so it isn't the last half-step that's called a "perfect 8th" - it's the distance between the root note and the note one octave above it. (e.g. E on the open string to the E on the 12th fret of the same string). Taking the example from the article of C major (all the white notes on the piano): C, D, E, F, G, A, B, C. C to D is a major 2nd C to E is the major 3rd (NOT D to E!!) C to F is a perfect 4th C to G is a perfect 5th C to A is a major 6th C to B is a major 7th C to c is a perfect 8th (or octave - again, NOT B to c!) In terms of why some intervals are called "perfect" rather than them all being major, I'd suggest thinking of the 'perfect' intervals as the ones that don't sound minor or major. A "major 5th", i.e. the interval between the root note and the 5th note of a major scale, would be the same as a "minor 5th" (root note and 5th note in a minor scale). Same with the octave - a "major 8th" would be the same as a "minor 8th", and the 4th (give or take a bit). By using the term 'perfect' you can disassociate the intervals with being minor or major. The above isn't strictly true, but it might help conceptually when coupled to the other reply to your post.
    riggs1102
    What do you mean when you say that the "sound waves of a perfect 5th plays 3 times to every 2 times the root plays" and "a perfect 4th plays 2 times for every 3 times the root plays".
    sykotic
    Diminished Augmented Diminished
    sykotic
    my post got screwed up, so what sepatated diminished and augmented is it whole tones or half tones? he isint very clear about that in the article
    UtBDan
    which is to say, diminished is a half tone away from perfect which is a half tone away from augmented. so, a whole tone with perfect intervals. as to with major/minor intervals... way more than that. Each arrow is one half step/one half tone/one semitone/one fret.
    zyzzyx6
    ARRRRG!!! Until I get this I will just be another hack jammer. My daughter has been playing piano for 3 months and gets this completely.
    mecan1
    anyone who took piano theory will spit water after reading this xD well written, though.
    cleef
    I'm confused. Does this pattern "Whole step, Whole step, Half step, Whole step, Whole step, Whole step, Half step." work on ALL scales ? or just the C scale ?
    Molomono
    Just go to all-guitar-chords dot com and view the single string pattern of any scale from 0 to the 12th fret. Makes understanding scales much easier and it makes the Diatonic scale relations kindergarten material.
    mfaltitudes
    I'd never seen that site before, but I read your comment and checked it out and it's amazing. Seeing it all layed out just made it click for me. Your post was as helpful as this lesson.
    Patrijz
    Thanks! This is the basis I was looking for. Just plain and simple and focused on understanding rather than playing.
    ToolCreedence
    You lost me on the interval part. I get root, Whole, Whole, Half, Whole, Whole, Whole, Half. Im confused as to what perfect 4th and 5th is. And why is the last half step to the root note called a perfect 8th? Major 2nd, 3rd and 6th make sense. I'm just not understanding the "perfect" part i guess.
    mansen
    maybe it wouldn't be too bad for those who lost the author on the interval part to list down how many semitones make which interval(basically)(st=semitone): 1 st = minor 2nd 2 st = major 2nd 3 st = minor 3rd 4 st = major 3rd 5 st = perfect 4th (6 st = augmented 4th/diminished 5th) 7 st = perfect 5th 8 st = minor 6th 9 st = major 6th 10 st = minor 7th 11 st = major 7th 12 st = perfect octave in combination to this (appears in the article): Diminished Augmented Diminished
    mansen
    oh my comment has been shortened, well I have to add this: Diminished Augmented Diminished
    Quiffmiester
    "And why is the last half step to the root note called a perfect 8th?" Just to clarify one possible misunderstanding from the above quote: the interval names are all in relation to the root note, so it isn't the last half-step that's called a "perfect 8th" - it's the distance between the root note and the note one octave above it. (e.g. E on the open string to the E on the 12th fret of the same string). Taking the example from the article of C major (all the white notes on the piano): C, D, E, F, G, A, B, C. C to D is a major 2nd C to E is the major 3rd (NOT D to E!!) C to F is a perfect 4th C to G is a perfect 5th C to A is a major 6th C to B is a major 7th C to c is a perfect 8th (or octave - again, NOT B to c!) In terms of why some intervals are called "perfect" rather than them all being major, I'd suggest thinking of the 'perfect' intervals as the ones that don't sound minor or major. A "major 5th", i.e. the interval between the root note and the 5th note of a major scale, would be the same as a "minor 5th" (root note and 5th note in a minor scale). Same with the octave - a "major 8th" would be the same as a "minor 8th", and the 4th (give or take a bit). By using the term 'perfect' you can disassociate the intervals with being minor or major. The above isn't strictly true, but it might help conceptually when coupled to the other reply to your post.
    mayslash
    Honestly i feel learning scales is ovverated. All you need to learn is the basic chords and play with feeling from there. Hendrix didn't even know ONE scale. He was self taught. hendrix the greatest didnt even use them
    Le Fantome
    And think how good he could have been if he HAD known them? Also, just because he didn't know them, doesn't mean the notes he used didn't fit into a scale.
    thebigredjj10
    Just because he didn't know the theory, didn't mean he didn't apply it. Beethoven knew theory, and he used it to create his works. Without it he would not have been able to write any of his pieces. See, I can quote a famous musician to illustrate my point too.
    K!!LsWiTcH
    also guitar theory wasnt a very common thing back in those days. you can look EVERYWHERE online now and now they have schools for guitar theory, harmony and performance. but Hendrix HAD to go by his ear and what he felt you dont. you saying scales are overrated is just plain dumb and ignorant
    mansen
    somehow it wil not work to copy a part from the article above, I hope you know what I mean, so in combination to this you should be able to build up every interval and you'll know how many semitones it has. 13 semitones are a minor 9th but basically also an octave plus a minor 2nd...