Chord Construction 2: 7th chords

The previous lesson covered triads, and these form the basis of most other chords.  Any time you see a chord name that does NOT have numbers in it, such as a D chord, an A chord, an Em chord, etc., that chord is probably a triad.  But it’s very likely that you have encountered quite a few chords with 7′s on the ends of their names.  It might not surprise you to learn that these are known as “7th” chords.  They are created by adding the 7th degree of the scale (either as-is, a.k.a. “natural“, or lowered by 1/2 step, a.k.a. “flatted”) to any of the triads.  There are quite a few different possible 7th chords.

Again, we will start by using the C major scale for our examples.  Remember that, to form the different types triads, we used the 1st, 3rd, and 5th degrees of the scale (C, E, and G). Now we’re going to add another note to our triads, and (you guessed it) it will be the 7th degree of the scale–in the case of C major, the note in question will be the B.

The most common 7th chords:
Major, Minor, and Dominant

Major 7:  The simplest form of 7th chord is the major 7, formed by taking a major triad (1, 3, and 5) and simply adding the 7th note of the scale to it.  So a Cmaj7 chord would be made up of C, E, G, and B.

Abbreviations:

• Major 7 chords are typically abbreviated as “maj7″, as in Cmaj7 (and this is the abbreviation that I prefer).
• Sometimes you’ll see it referred to as Cma7 (with no “j”).
• In jazz, maj7 chords are often abbreviated with a small triangle, as in “C△7”
• Less commonly (usually in old-school music theory textbooks and also by some musicians outside of the U.S.), maj7 is indicated with a CAPITAL M, as in CM7 (I personally think this is an awful way to indicate a maj7 chord because it looks so much like the abbreviation for a minor 7 chord).

Maj7 chords have a distinct sound that always reminds me of the song “Ventura Highway” by America.  “Eyes of the World” by the Grateful Dead also revolves around a maj7 sound. Check out a few of these chords to hear what they sound like:

Hear these chords:

Minor 7:  If you start with a minor triad, you can make it into a minor 7 chord by adding the flatted 7th degree.  So in the case of a Cm7 chord, you would add a Bb to the minor triad of C, Eb, and G.

Abbreviations:

• Minor 7 chords are usually just abbreviated was “m7″, as in Cm7 (this is what I typically use).
• Occasionally, you might see them abbreviated as “min7″, as in Cmin7.
• Jazz musicians often abbreviate them with a “minus” sign, as in C-7.

Minor 7 chords have a jazzy sound that is not as dark as regular (triad) minor chords.  Here are a few examples for you to check out:

Here are audio clips of these chords:

Dominant 7:  ”Dominant” 7 chords are probably the most common 7th chords, and you have probably already seen them plenty of times.  We create them by taking a major triad, and adding the flatted 7th degree.  In the case of C, this would give us C, E, G, and Bb.

Abbreviation: 7th chords are simply abbreviated by adding a 7 to the chord name, as in C7 (or A7, Eb7, etc.).  Because they are so common and so essential to music, they get the simplest abbreviation.  In fact, you really don’t need to refer to them as “dominant 7″ chords.  You can just refer to them as “7″ chords, and musicians will just about always assume that you are referring to “dominant 7″ chords.  In fact, there are a lot of guitar players who are unfamiliar with the term “dominant 7″, and just know them as plain ol’ 7th chords.

Here are a few examples for you to try out:

And here’s an audio clip of these 3 chords:

A quick note about tension and resolution with dominant 7 chords: These are very important chords, and they serve an essential purpose in music.  You may have noticed that they have a distinctive and slightly dissonant sound to them.  About 90% of the time, they resolve up a 4th–in other words, they are usually followed by a major or minor chord a 4th higher.  So an A7 resolves to a D or Dm, an E7 resolves to an A or Am, etc.  If you check out some of the examples, you will realize that when you play a dominant 7th chord, you can almost hear the next chord coming.  They sound dissonant until you hear the follow-up chord.  This is, in short, the concept of “tension and resolution”.  The 7th chord gives you tension, and the follow-up gives you resolution.  Be aware that there are many other ways to create tension and resolution in music, but the 7th chord resolving up a 4th is the most common.

Try out a couple examples of dominant 7 chords resolving up a 4th, and really pay attention to what the combination sounds like.

Hear A7  to D:

Hear D7 to G

Less common 7th chords: Diminished 7 and Half-Diminished (m7b5)

Diminished 7:  A diminished 7 chord is a strange animal.  It is created by taking a diminished triad (1, b3, b5) and adding a “double-flat” 7th to it.  I know…what the hell is a double flat?  Well, if you look at a C major scale, and you take the 7th degree and flat it twice.  Technically, this gives you a Bbb (a “B double flat“).  But you may notice (if you look at it on a piano keyboard), that if you “double flat” a B, it gives you an A, which is the 6th degree of the scale.  Suffice it to say that there are complex theoretical reasons for the existence of a “double-flat 7″ instead of just calling the 6th.  But for all practical purposes, you will be perfectly OK if you just think of it as the 6th.

Therefore, a diminished 7th chord consists of 1, b3, b5, and 6 (or bb7).

Abbreviations:

• Diminished chords are typically abbreviated with “dim7″, as in Cdim7.
• Jazz musicians often label them with a tiny little circle, like the symbol for degrees in temperature (farenheit or celsius), as in Cº7.

Like dominant 7 chords, diminished chords have a dissonant sound, and they perform a very important function in music.  In a future lesson I will discuss the use of diminished chords at length–the discussion would take too long to include on this page.

Half-diminished, a.k.a. minor 7 b5 chords: The other type of 7th chord that can be built from a diminished triad is the “half-diminished” chord, also known as the “minor 7 flat 5″ chord.  It is a cool-sounding chord, but seldom seen outside of jazz.  To build it, you start with a diminished triad, and you add the flatted 7th degree to it.  So in the case of C, this would give you C, Eb, Gb, and Bb.

Abbreviations:

• The half-diminished, or minor 7b5 chord is usually just abbreviated as Cm7b5.  I prefer this one because it tells you exactly what’s in the chord.
• Sometimes the b5 is placed in parentheses, as in Cm7(b5).
• Jazz musicians often symbolize it with a zero with a slash through it, as in Cø7

Uncommon 7th chords: Augmented 7, minor/maj7

There are 3 other types of 7th chords that are so rare as to barely even warrant discussion at this point (though they’d be relevant if we were seriously studying jazz), but in the interest of completeness I will briefly go over them here:

Augmented 7:  this chord type is formed by taking an augmented triad (1, 3, #5) and adding the flatted 7th degree to it.  In the case of C, this would give us C, E, G#, and Bb. This chord sometimes shows up

Abbreviation:  C7aug, C7(#5) C+7, C7+, C7+5.

Major 7 augmented: This one is formed by taking an augmented triad and adding the natural 7th degree to it.  In the case of C, this gives us C, E, G#, and B.

Abbreviation: Cmaj7(#5), Cmaj7+5, C△7+5

Minor (major7).  Formed by taking a minor triad and adding the natural 7th degree.  In C, this would give us C, Eb, G, B.  It’s an odd-sounding chord but it does occur every now and then, as in the Beatles’ “Eleanor Rigby”.

Abbreviation:  Cm(maj7), Cmm7, C-(triangle)7