On Friday, I taught you how to look at chords according to the number of notes they have.

This introduced us to names like “tetrads,” “pentads,” “hexads,” “heptads,” and of course, the “triad.” These are names for collection of notes played at the same time (i.e. - “chords”).

Today, I want to talk about the other side of things — the names of collection of notes played one after the other (i.e. - “scales”). And specifically, I want to focus on the tetrachord.

A tetrachord is a series of four notes, usually played one after the other. A major tetrachord is a series of four notes, in ascending order, separated by the following sequence: whole step - whole step - half step.

In other words, if I start at “C” and add a whole step, that gives me “D.”

So far, I have “C - D.”

In following the “tetrachordal” formula, I add another whole step from “D.” That gives me “E.”

So far, I have “C - D - E.”

And lastly, I add a half step since my formula is “whole step - whole step - half step.”

That gives me “F” at the end.

Altogether, “C - D - E - F.”

This may look familiar to many of you. It is the same pattern that starts your major scales!

Recall my little acronym I made up several years ago to help people remember the major scale…

Why Won’t He Wear White When Hot?

W W H W W W H

(This is my way of getting you to memorize the “whole step / half step” relationships that make up the major scale. You won’t find it taught anywhere else like this, I promise…)

If you’re really paying close attention, you may notice not ONE major tetrachord, but TWO!

W W H W W W H

In other words, a major scale is just two major tetrachords separated by a whole step.

[C major tetrachord] - whole step - [G major tetrachord]

So if you know all 12 major tetrachords, this can be another way to remember scales quickly:

C major tetrachord: C D E F
G major tetrachord: G A B C
D major tetrachord: D E F# G
A major tetrachord: A B C# D
E major tetrachord: E F# G# A
B major tetrachord: B C# D# E
F# major tetrachord: F# G# A# B

(switch to flats)

Gb major tetrachord: Gb Ab Bb Cb
Db major tetrachord: Db Eb F Gb
Ab major tetrachord: Ab Bb C Db
Eb major tetrachord: Eb F G Ab
Bb major tetrachord: Bb C D Eb
F major tetrachord: F G A Bb
C major tetrachord: C D E F

Do you see what I see?

Gosh! Where do I start? There’s so many patterns and observations to make.

First off, I was moving in “FIFTHS,” just like the circle of fifths chart below:

Secondly, notice that the next “tetrachord” in line finishes the previous one. So if you actually read the “C major tetrachord” out loud and then the “G major tetrachord,” that’s the entire C major scale.

Same goes for the G and D tetrachords… and the D and A tetrachords — on and on.

Another thing worth pointing out is the first note of one tetrachord is always the last note of the next tetrachord (when moving in fifths like I did above). So two tetrachords joined by a whole step always equal an octave.

Fourthly, it further proves how related major keys are on the circle of fifths chart. Now you know that they also share tetrachords!

Fifthly, it points out how ANYTHING can be broken down to smaller parts. Maybe you’ve mastered major scales already but if you look at other unfamiliar scales this way, it should be much easier.

For example, I haven’t talked about trichords yet but as the name implies, it’s a series of 3 notes just like a tetrachord is a series of 4 notes.

2 trichords separated by a whole step create a minor pentatonic scale. Check it out…

A trichord:
A - C - D

E trichord:
E - G - A

Together, “A - C - D - E - G - A.”

And, since minor and major are related, you can easily start this scale from C to get a regular pentatonic scale (i.e. - “major pentatonic”).

A - C - D - E - G - A - C - D - E - G - A

(Just like we can take a C major pentatonic scale and play the same notes from “A” to “A,” we can take the minor pentatonic scale and play the same notes from “C” to “C” to get a C major pentatonic scale.)

And it doesn’t stop there…

There are pentachords, hexachords, and others. I’ll talk about those in other posts.

For now, I hope this helps to give you another perspective.

Until next time —

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Most people just classify chords by name and chord quality (major vs minor, augmented vs diminished).

But today, I want to show you another world. Here’s how to think of chords by the number of notes they contain.

This will be short and to the point.

Triads

Music theorists still argue over whether a chord officially starts with 2 or 3 tones played at the same time. It seems like 3 is more accepted. But for the sake of knowing, I’ll give you the name of a two-note combination at the end of this post.

But, for now, let’s start with the popular “triad.”

Any time you have a collection of three notes played together, you’re playing a triad.

Most basic chords fall under this category.

• major triad (e.g. - C major: C + E + G)
• minor triad (e.g. - C minor: C + Eb + G)
• diminished triad (e.g. - C diminished: C + Eb + Gb)
• augmented triad (e.g. - C augmented: C + E + G#)

So any time you hear, “give me a _______ triad,” that’s only asking for a 3-toned chord. Don’t give the composer or music director more than that! After all, in some arrangements, less is better.

Tetrads

Then next, there is what we call “tetrads.”

These are chords using four notes. Seventh chords are essentially tetrads.

• major seventh (e.g. - C major 7: C + E + G + B)
• minor seventh (e.g. - C minor 7: C + Eb + G + Bb)
• diminished seventh (e.g. - C diminished 7: C + Eb + Gb + Bbb)
• augmented seventh (e.g. - C augmented 7: C + E + G# + Bb)

Pentads

Chords using five notes are called “pentads.” Yes, that sounds like the pentatonic scale from this lesson (5-tone scale).

(In fact, there’s such a thing as tritonic and tetratonic scales too! But let’s save that for another lesson.)

Ninths are a form of pentads.

For example, C major 9 is C + E + G + B + D. Five notes!

Again, it’s just a general term for a chord with 5 notes.

Hexads and Heptads

And lastly, “hexads” and “heptads” are the names given to 6 and 7-toned chords, respectively.

An example of a hexad is an eleventh chord and an example of a heptad is a thirteenth chord.

Other classifications

I also promised to give you the name of a 2-toned combination, even though its merit as a chord is questionable…

We call those “dyads.” Others choose to just reference them as “intervals.” Power chords and tritones fall under this category.

And for extra credit, a “monad” is a single note. The “chromatic scale” comes to mind, which is basically composed of twelve monads.

So there you have it! A really fact-filled, reference post for today!

So if you ever hear me referencing any of these, you should now know what they mean!

Until next time —

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