Perfect 4ths Guitar

Introduction

I tried to organise the material that I created for myself over the years while learning to play the guitar tuned in perfect fourths (P4). This might be useful to others who would like to venture down such a path since very little learning material exists for this tuning.

The standard guitar tuning (E A D G B e) contains a major third (four semitones) interval between the G and the B strings. Between all the other strings there is a fourth (five semitones).

The P4 tuning gets rid of this exception: a practical solution is to lower the bottom four strings to obtain E♭ A♭ D♭ G♭ B e and this is the tuning we'll use here (but you could equally well use E A D G C f).

Enjoy!

last revision: 20140218

Chord Diagrams

The document contains plenty of chord diagrams to show how to play the various chords, so we need first to understand how to read such diagrams.

With a guitar in standard tuning this is the diagram that represents the well known basic C major chord.

the corresponding tablature would be

Diagram Notation

Let's see some other examples, always in standard tuning: G Major, C Major and F Major (played with the common "E", "A" and "D" shapes )

First Chords in P4

The same three chords can be played in P4 as follows

A couple of things to notice

Since the shape doesn't change we can associate that shape to chord "type" (in this case a Major chord), and we can say that the following diagram represents a major chord

regardless of the frets or strings where it is played! Wherever you put the "red dot", there you will have a Major chord. So where in standard tuning we would have to learn three shapes, with P4 we need only one.

Dominant 7

Let's begin with some interesting chord. The dominant 7 chord is composed of: Root (R), major Third (3), Fifth (5), flat Seventh (♭7).

We have four basic shapes to play this chord on four adjacent strings (these voicings are usually called "drop 2" voicings).

Notice how these shapes are identical to ones present on a guitar with standard tuning when played on the first four strings.

The difference is that now we can use these "drop 2" voicings all over the fretboard.

The little black dot on the first diagram shows where an unplayed root is. It's there for reference, and it's useful for those voicings that do not include the root.

As a little exercise we could use these shapes to play C7 in the four middle strings over the whole fretboard (notice the fret number that changes on the side)

In tablature notation

Move it up "one string" and you have F7 over the whole fretboard

in tablature
The transposition of chord shapes on the fretboard should be clear by now! No more tabs!

Minor Seventh: m7

The m7 chord is composed of: Root (R), minor Third (♭3), Fifth (5), flat Seventh (♭7). As before we have four basic shapes on adjacent strings
Notice how these can be obtained from the Dominant 7 shapes, by flattening the 3rd.

Major Seventh: 7+

Root (R), major Third (3), Fifth (5), Seventh (7)
On the last shape (Root on top) we have cheated: the 7th has been replaced by a 6th. This is because the 7th in the bass and the root at the top would create an interval of ♭9, which sounds very "harsh" and is generally considerated "inappropriate" for the chord.

Notice how the last shape for 7+ (root on top) is identical to the first for m7 (root on the bottom).

The ♭2 interval in the third shape (5th on top) between the 7th and the Root has an interesting sound, but we can usually replace the 7th with a 6th without altering the function of the chord. The resulting shape would be
Notice how the shapes that do not contain the 6th (the "true" 7+ chords) can be obtained from the Dominant 7 shapes by raising the 7th.

Half Diminished: m7♭5

Root (R), minor Third (♭3), flath Fifth (♭5), flat Seventh (♭7).
Again, these can be obtained from the m7 shapes by flattening the 5th.

Diminished

Root (R), minor Third (♭3), flath Fifth (♭5), double flat Seventh (♭♭7).
Well, since the chord is symmetrical we have just one shape: any of its notes can be considered as the root.

It is still true that these can be obtained from the half diminished shapes by flattening (a second time!) the 7th.

As exercise notice that in each case lowering the root (flat root?!?!) you obtain the four initial shapes of the Dominant 7 chord.

This is because a Diminished chord can be always thought as a Dominan7 to which a ♭9 (that is a ♭2) has been added and in which the root is not played.

First Song: Autumn Leaves

We don't have yet a vast set of voicings to use, but let's apply what we have to the first section of Autumn Leaves: Cm F7 B♭7+ E♭7+ Am7♭5 D7 Gm7 G7

More Strings!

Voicings in four adjacent strings are handy but fairly limited, and make it difficult to have interesting "internal lines" (e.g. contrary motion) when moving from one chord to the next.

Let's introduce a new "string set" (e.g. first, third, fourth and fifth string) and the voicings (usually called "drop 3" voicings) for the above chords
7
m7
7+
m7♭5
Dim
Let's consider now a "split" set of strings (e.g. first, second, fourth, fifth string. Similar to Chuck Wayne's "Split Voicing").

I'm not sure there's a common name for these voicings but following the same line of thought we can call them "drop 2 4".

These voicings can be easily obtained from the ones on four adjacent strings.

For example

can be obtained from

by dropping the 5th down one octave
7
m7
7+
m7♭5
Dim

More Chords

While the above chords represent the basic building blocks of most songs , many more "four-note-groups" (Tetrads) are possible. We will see later on how to use them.

Here below is a review of the most common ones, showing how they can be played on the usual "string groups" we have seen so far.

The names of these four-note-groups are somewhat arbitrary (e.g. "9 no 5"), what really matters is the notes they contain (R 3 ♭7 9).

Some of them are very tricky to play because of their "close" intervals. For example the group of notes "C D E F" (called Tetrachord Major) contains two major and one minor second, and it will need to be "spred out" on distant strings to be playable.

For these cases I present the playable voicing over all possible string combinations (not only the usual three)
7♭5
7♯5
7+♭5
7+♯5
m7+♯5
We now have exhausted all the four note chords that can be obtained by "stacking" 3 major and minor 3rd on top of each other.

Let's move to some different sounds. These are "closer groups" that span a 5th (regardless of the chosen name that might contain a 7th).
Maj add9
Maj add♭9
Min add9
Min add9
Min add11
9 no5
7♭9 no5
7♯9 no5
7 sus4
7 sus♭9
Finally some tetrachords that span only a 4th. These are the most difficult ones and so more string groups are used to find playable voicings.
Tetrachord Major
Tetrachord Minor
Tetrachord Harmonic
Tetrachord Phrygian
Tetrachord Diminished

Extensions and Substitutions

We are focusing only on "four-note-groups" but it is very useful to consider wider extensions of the chord. For example, if the song is in C Major, and we see a G7 chord we know that the 9th (A) and the 13th (E) are readily available extension.

The questions then becomes: what kind of four-note-groups can I use to incorporate these sounds? Since we are only playing four notes, it means that we have to give up one note of the basic chord (Dominant 7: R 3 5 ♭7) for every extension we choose to add.

If we want to choose four notes from the five available (R 3 5 ♭7 9) we have five possible options

The last one (R 3 5 ♭7) is trivially the original chord without extensions.

The second one (3 5 ♭7 9) is equivalent to a m7♭5 chord played from the third (that is: play a Bm7♭5 on top of the original G7).

The other possibilities correspond to

We can continue the work considering the 13th (so using notes R 3 5 ♭7 13) and we get the following possibilities Finally considering both the 9th and the 13th we have Lots of distinct possibilites and sounds there ... and considering only two possible extension (9th and 13th)!

We can reduce the above list by considering those options that include both the 3rd and the 7th, since these are the notes that specify the harmonic "character" of the chord.

That gives us (sorted by number of extensions and root position):

Let's repeat the exercise for other chords and extensions, grouped in three columns as the "sounds families" that we might find in major and minor II-V-I cadences

Major II-V-I
IIVI
Minor ii-V-i
iiVi

Chord Scales

(to complete)