Seventh Chords And Why They Matter

February 02, 2015

Have you been looking to write music beyond the old 7-9, 5-7, 3-5 shape power chord, or I, IV, V blues progressions? While I'm not knocking simple progressions: they are overused for a reason, they sound great!

There is no hard and fast rule saying music has to be horrendously mathematical or complicated, and I say that as a proghead/jazz head. Some of the best music ever written has been made from simple chord progressions, indeed, the most memorable guitar solos considered "great" are the ones you can sing.

Now, if you want to break out of the standard, common patterns, such as circle progression (cycling through circle of fifths), blues progression or simple power chord patterns to name a few, a good start would be to start looking at seventh chords, and how they can open up new pathways harmonically.

Before we begin

Harmony is a ludicrously complicated part of music, which will involve you learning a set of rules, only to be told at a later point, that everything you have ever known is wrong, and you can throw those rules out of the window, and learn a new set, and repeat this process over and over again. There is no way it could be possibly covered in any single article or lesson, I'm always in a process of learning myself, and no doubt many more times in my life, I will be learning new rules, only to learn how I can break them. But however, what I can do, is condense some handy tips and explanations of harmony into easy to read and understand, written without pretentious musical language, in layman's terms, so that it will "click." I'm aware some stuff in this might be a bit basic for some people, but my goal of this lesson is to give something for everyone to take away really.

Music is a completely subjective art, so for the sake of explaining something simply, when I say things like "sounding good," etc, it is in a completely subjective sense for the sake of a clearer explanation, and I am referring to tonality within music, and how to write music that is pleasing and makes sense to the vast majority of people who have been brought up listening to western music.

So, let's begin!

You may have wondered what use a seventh has beyond sounding "jazzy," or simply being a chord added to music to pedantically make it more complicated, but in fact, sevenths have such a strong function harmonically and tonally, learning how they work and can be used will give you so many more options when it comes to songwriting. I'm going to leave chords such as 9ths, 11ths, 13ths, and suspended chords out of this for now, as they tend to be more of an extension you put at the end of the chord at the composer's discretion, to give it a different character or "flavour," or as I will explain later, to create tonality, allowing you to use a chord that you may not have been able to use to keep tonality, thus making the music "sound good" (see, I said it!).

(For the sake of reading this, the white gaps in the staff spell F A C E, if you go up, the lines in it are G B D F (bear in mind, this is the treble clef, there are other clefs where the notes are different, but that is another lesson, so don't worry about this right now).

What I have uploaded here are all the seventh diatonic chords (diatonic means if you played all the chords in the same key, and went up a step of the scale every time, they'd be tonal to their key. An even easier way to explain this, is if you went on a piano and played chords (7th or normal), with a 1-3-5-7 shape, with just the white notes starting on C, you'll play the diatonic scale. I'll refer back to this picture a bit later.

As guitarists, we naturally like to think of things as being in shapes, something nice and easy (no shame in it being easier, easy means more efficient and less time consuming) to practice and recall, so for the sake of explanation, if I took this shape on a piano (I apologise in advance to any pianists for my dreadful technique):

You'll notice that my thumb is on the C (C is the white key to the left of the two black keys on a piano), and if the C is the 1, I am depressing the 3, 5, 7 notes of the scale, creating a major seventh chord (the key of C is easy to work with, it has no sharps/flats, which are the black keys on a piano).

The Diatonic Scale

Now, in the diatonic scale, chords always appear in a certain order, and roman numerals are used to explain them here. An upper case numeral such as I or IV, means it is a major chord, and a lower case numeral such as ii or vi denotes a minor chord. Diminished chords are lower case with an o (so vii o) next to them, and half diminished 7ths have an o with a line going through it (you know that really crazy metal Norwegian/Danish crossed out ø).

So, if I were to place all these chords out in the order they appear on that piece of notation I posted earlier in a scale, using C, it would be like this (I'll also post how the chord is constructed). These particular numbers are also given names, but for now, we only really need to look at the tonic, which is I and the dominant, which is V.

  • I - C Major (C major 7) - Root, major third, perfect fifth, major seventh
  • ii - D Minor (D minor 7) - Root, minor third, perfect fifth, minor seventh
  • iii - E Minor (E minor 7) - Root, minor third, perfect fifth, minor third
  • IV - F Major (F major 7) - Root, major third, perfect fifth, major seventh
  • V - G Major (G dominant 7th) Root, major third, perfect fifth, minor seventh
  • vi - A Minor (A Minor 7) Root, major third, perfect fifth, minor seventh
  • vii o - B diminished (B half dim 7, can also be written as B7 flat5) Root, Diminished third, diminished 5th, minor 7th (a full diminished 7th has a diminished 7th interval too)

(If you don't know about intervals, I'm sure there are many helpful lessons on this website, or online which you can quickly refer to)

These are the chords in the order they appeared if you were to take that above shape on the piano, where I depress the 1-3-5-7 keys, and move it along one white key at a time, as if you were sliding a CAGED shape up the guitar neck (ignore the black keys for now).

Now, while I would explain this on guitar, guitars, as awesome an instrument they are, aren't particularly that idiomatic for playing with complete freedom in which order you want the note played.

(An instrument's idiomatics are features that lend themselves to be easily played on it, for example, string bending is idiomatic to a guitar, but not a piano, which is why certain licks you'll hear on guitar won't really be heard on any other instrument). For this reason, pianos tend to be much simpler for explaining chord construction, but there is nothing from stopping you from finding inversions (changing the order the notes in a chord are played, you could do 5, 3, 1 rather than 1, 3, 5 for example), or comfortable positions (or perhaps, uncomfortable, I am looking at you Allan Holdsworth).

How to use sevenths

Now, that I have gotten over the basics of how chords work diatonically, I will get on to the actual point of why sevenths matter and how to use them. (I promise you, everything you read above was extremely relevant, and ties in with what I am about to explain.)

Tonality in music is derived from the I, IV, and V chords. That is what is so beautiful about the blues, it shortcuts unpretentiously to the very skeleton of harmony. To save you from scrolling up, I'll post the diatonic scale with 7ths again in C, going from I, ii, iii, IV, V, vi, vii-o, I, so C D E F G A B C.

In western music, we've been conditioned to expect music to return to the tonic, or the I chord via a little thing called perfect cadence (or in the case of a minor key, the 6th chord, which in this case is A minor. Functionally, A minor and C major use exactly the same notes, this is called a relative minor, and the relative minor is ALWAYS three semitones below the major scale, no matter what note it starts on).

If you were to listen to a piece of music that didn't end on the tonic, it would sound like someone didn't finish their sentence.

Now, tonality is based around I, IV, V, but by using seventh chords, you have so much more freedom to break these rules, why? Look closely at the notation.

The extra note has basically created a triad or another chord, within the seventh. So, you see that ii7, or D minor 7th? It contains exactly the same notes as an IV, or F major chord. The D is a D F A C, whilst an F major is F A C. Basically, this allows you to use a ii7 position 7th chord as a IV chord.

The fact the ii chord can be used as a IV, spawned a very common chord progression, used very heavily in jazz, the ii-V-I. Notice anything about that? If that ii is essentially a IV for tonal purposes, and you started the chord progression loop from the I, you've pretty much got a I-IV-V chord progression, right back to blues.

And that's just the tip of the iceberg. If you look at what chords have the same notes, here are a few cool ones:

- The iii7 has the same notes as the I, you could use that in place of the tonic. While it may not contain the tonic note, if it doesn't signal the end of a piece of music/musical phrase as strongly as you like, simply add a C onto it. When you add an extra note onto a chord that isn't a 9th, 11th or 13th, it is called a slash chord. This is a great way of pretty much bending harmony to your will. So what if a chord progression isn't resolving how you'd like, you could raise or drop the third (suspended chord), or add a new note in entirely (I mentioned I won't really go into 9ths, 11ths or 13ths, but this is a good situation to use them in. The iii7 is E G B D, if I added a C onto this, this could be all sorts depending on where C was placed, or what your take on it is.

It could be an Em13 (the minor 7th with the 13th on top, a 13th is pretty much a 6th that is placed ABOVE the chord, so it'd be the 13th key if you played them on white notes on a piano), here it would be the iii of the chord progression. If I wanted to remove the 7th, and replace it with the 6th, to create an E minor 6 chord, that would essentially be an inverted C major 7th chord, why? E minor 6 is E G B C (the C is the 6th note if I started from the E), if I inverted that, it would be C E G B, a C major 7, all thanks to something called "inverted intervals" that most definitely belongs in another lesson. Madness!

Notes on uses for sevenths

- A chord with 7 straight after it is dominant, not major, this is a common mistake people make, Gmaj7 = G major 7, whilst G7 would be G dominant 7.
- The V7 has the same notes (and that important diminished fifth), as the vii o, hence it could be used as a leading tone (both the 5th and 7th notes of a scale are very strong signposts towards the tonic, if you ever want to use a diminished/half diminished chord, the most effective way to use it, is before the tonic, or first note/chord, the 7th has an unsettling dissonance to it, that is resolved by "bringing it home."

The vi7 chord has the same notes as the tonic, even it's basic triad counterpart contains the tonic note, this is why you can resolve music with the 6th, as a minor key.

When you use a vi7 or iii7 as a tonic, it is called a "pseudotonic."

As a general rule of thumb, a seventh chord will contain the same notes of a standard triad which is 2 diatonic positions higher or lower than it. So in the key of C, a G7, which is the V position, would contain the same notes as a triad of the iii or vii-o position, E minor or B diminished, this is because G7 has G B E F, E minor is E G B, and B diminished is B D F.

Because of this, sevenths are an extremely potent tool for working with harmony.

Now, while I understand it may be a bit to take in at once, I'm hoping I formatted, or at least explained it in a way that makes sense. Given it's my first lesson, I'm hoping I did something right, and you can at least take away something. But really, this is just the tip of the iceberg with what you can do with extra notes in chords. Chord extensions, suspended chords, rootless voicings (something you'll come across a lot in jazz guitar, guitarists often only play the 3rd and 7th of a chord in jazz contexts, the rest of the band fills in the rest), polychords, altered dominants, I would say the list is endless, but logic dictates that it clearly isn't.

My advice for things to learn that would really supplement this lesson well, would be to learn the notes of scales, keys, intervals, chord construction and modes. Learning to read music and basic piano make a HUGE difference in understanding how music comes together, and are invaluable tools in improving yourself as a musician. The more you know the rules, the more you know how and where you can break them, and you'll have so many more tools in your arsenal for creating original music, that really is the beauty of music theory. (Note, guitar is a bitch of an instrument to sight read, but at least learn what those symbols on sheet music are, and most importantly, the rhythm of them).

If you have any questions about issues raised in this lesson, or just anything about theory in general, fire away, chances are I should be able to answer your question, or if I can't, I can at least point you in the direction of people smarter than me who can.

Anyways, have fun, and thanks for actually reading this far down!

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