Lessons in Bass Line Construction
Steve Schmidt
whale@leland.stanford.edu
Lesson 4 - Major Scales, Keys, Chord Changes, and the Circle of Fifths
In the last lesson, we talked about creating bass lines based on the chords
of the song being played. In this lesson, we'll talk about scales, which
determine which chords are used in a song and in what sequence, and we'll
work through major scales and give some examples of common songs built on
major scales and some common chord changes. We'll also introduce the Circle of
Fifths, which is something most bass players have heard of and all of them
should know perfectly. Knowing the common chord patterns will make it much
easier to learn songs off records, because it lets you make accurate guesses
about where the bass line is likely to go, and it will also help you in writing
songs if you are interested in doing that.
The first thing to observe is that although there are 12 different notes
in music (A, B flat, C, D flat, and so on up to A flat), most songs don't use
all of those notes: in fact, most don't use any more than 7 of them. Which
notes are used in a given song is determined by the key of the song, and the
choice of a key gives the composer (or bass player) a guide to choosing the
chords and notes he wants to use in writing the song (or the bass line). And,
if you know what key a song is in, then it will help you figure out the bass
line to that song, because it gives you a good guide as to what notes might
be used in the song's bass line and which notes will not be used.
The notes that are associated with a given key are called a scale. For
example, we might want to write a song in they key of C major, and if we did
that we'd use the notes from the C major scale. That scale is: C, D, E, F, G,
A, B, C; all the white keys on the piano and none of the black keys. You can
play that scale at a piano or on your bass: on the bass, the notes are:
G-----------------2--4--5--
D--------2--3--5-----------
A--3--5--------------------
E--------------------------
If you play this scale, you'll notice that it has a very comfortable, familiar
sound to it; that's because major scales are the most widely used scales in
music. There's nothing magical about C as the choice of a starting note: you
can create a major scale starting on any note you like, and there will be a
major key associated with that scale. The thing that defines a major scale
is that it contains 7 notes, and they are all a whole step apart except for
the 3rd and 4th note which are a half-step apart. (There is also a half-step
between the 7th note and the next octave of the 1st note.) Thus, you can
create the D major scale by starting on D and going up by whole steps, except
after the 3rd (and 7th) note. Thus, the D major scale would be: D, E, F#,
G, A, B, C#, D. Note the half-step between F# and G, and between C# and D.
You can play this scale on your bass like this:
G-----------------4--6--7--
D--------4--5--7-----------
A--5--7--------------------
E--------------------------
Notice that this pattern is exactly the same as the C major scale above,
except that it's two frets higher. In fact, this same general pattern will form
a major scale starting on any string, at any fret. For example, the F major
scale looks like this:
G--------------------------
D-----------------0--2--3--
A--------0--1--3-----------
E--1--3--------------------
which is the same fingering pattern, starting at the 1st fret of the E string.
A song written using these 7 notes would be said to be in the key of F major
You can keep going up the fingerboard if you like, starting again on the new
new F: if you do this you'll repeat the 1st note as the 8th note, the 2nd
note as the 9th note, and so on. In F major, the result would look like this:
G-----------------------------2--3--5--7--9--10
D-----------------0--2--3--5-------------------
A--------0--1--3-------------------------------
E--1--3----------------------------------------
and you can see that the 2nd note and the 9th note are both G, and 3rd note
and the 10th note are both A, etc. Sometimes G will be called the 2nd or the
9th, depending on the circumstances.
Once you've chosen a key for the song, you can then start choosing the chords
to use in the song. Because you now only have 7 notes to choose from, the
number of chords you can form is reduced. For example, suppose you are writing
in the key of C major, and you want to form a chord with C as the root note.
You can't use C minor, because that requires an E-flat, which is not a note
of the C major scale. However, you can form the C major chord, by using the
1st, 3rd, and 5th notes of the scale: C, E, and G. (This is why the three
notes of the C major chord are called 1st, 3rd, and 5th: they are the 1st,
3rd and 5th note of the C major scale). If you wanted to form a chord with
D as the root note, you can't form D major (it requires a F-sharp) but you
can form D minor using D, F, and A, the 2nd, 4th, and 6th notes of the scale.
So, if you are writing in the key of C major, you will end up using the chord
D minor rather than D major. If you wanted to form a four-note chord with
G as the root, you would use the G, B, D, and F (the 5th, 7th, 9th, and 11th
notes) and you would get a G7 chord.
The main purpose of choosing a key is to guide you in selecting the chords
to use in your song. Consider, for example, the song "You Shook Me All Night
Long" by AC-DC. It's in the key of G major and goes like this:
Verse: (repeat as needed)
G C G C G D G D G D
G-----------|------------------|------------|----------------
D-----------|------------------|------------|----------------
A---------3-|-3--3-----3-----5-|-5--5--r----|-------5-----5--
E---3--r----|-------3-----3----|----------3-|-3--3-----3-----
She was a fast machine, she kept her motor clean, she was the best damn
woman that I've ever seen.
Chorus: (repeat as needed)
G C Bm D C Bm
G-------------|---------|------------|----------
D-------------|---------|------------|----------
A-----0--2--3-|-3--2--5-|-5--0--2--3-|-3--2-----
E--3----------|---------|------------|-------3--
You Shook me All Night Long You really shook me yeah,
The bass plays mostly root notes. Between the verse and chorus the bass line
makes two changes: first, it plays only roots in the verse, but starts playing
some passing notes between roots in the chorus; and second, the verse
contains rests between long notes, but in the chorus there are no rests and
the notes are connected to one another.
However, the main thing to notice about this song at the moment is the
choice of chords. The song is on the G major scale: G, A, B, C, D, E, F#, G.
In TAB it looks like this:
G--------------------------
D-----------------2--4--5--
A-----0--2--3--5-----------
E--3-----------------------
and notice that all of the notes of the bass line, even the passing notes in
the chorus, come from this scale. The chords used are G major (G,B,D), C
major (C, E, G), D major (D, F#, A) and B minor (E, G, B), and all of those
notes come from the G major scale as well. In fact, in the whole song, both
guitar parts, bass line, and vocal line together, you won't find any notes
that are not part of the G major scale.
In general, once you've chosen a key, you've chosen whether to have major
or minor chords for each of the notes in the scale, and what kind of 7th to
use if you use one. I'll work out the chords for the G major scale, but you
should notice that you'll always get the same types of chords for any major
scale you might pick:
G major scale: G, A, B, C, D, E, F#, [ G, A, B, C, D, E ]
Root Note Notes Chord 7th 7th chord
G G,B,D G major F# G maj7
A A,C,E A minor G A min7
B B,D,F# B minor A B min7
C C,E,G C major B C maj7
D D,F#,A D major C D7
E E,G,B E minor D E min7
F# F#,A,C F# dim E E half-dim7
In general, in a major key the chords formed using the 1st, 4th, and 5th
scale note are major, the ones formed on the 2nd, 3rd, and 6th notes are minor,
and the one on the 7th note is diminished. You can refer to the chord simply
by the number of the scale note that is the root note: so we say that in the
key of G major, D major is the fifth chord. Usually it's written out using
Roman numerals, so that we say that in the key of G, G major is the I chord,
A minor is the II chord, C major is the IV chord, etc.
Now that we know what root notes to use to form chords, and what type of
chords (major, minor, 7th) to use, we've pretty much decided which chords can
be used and which can't be. The next question is, in what order should we
use these chords? The answer is, you can use them in pretty much any order
you want, except that the song should begin and end on the I chord. However,
there are some very common patterns that are used. One of them we've already
run into in Wipeout and the 12-bar blues: it is the pattern
I IV I V I
where the first I chord gets 4 measures and each of the other chords gets two
measures. There are a number of other common patterns. For example, there is:
I IV I V I
which is the basic pattern from I Saw Her Standing There, by the Beatles. It
is in the key of E, and uses the chords E, A and B7.
E A E
Well she looked at me, and I, I could see
B7
That before too long, I'd fall in love with her...
E A
Yeah I'll never dance with another, oooh
E B7 E
Since I saw her standing there.
A twist on this pattern is to present the V and IV chords in the other order.
For example, there is
I V IV I
which is the basic pattern of the chorus of Fortunate Son, by Creedence
Clearwater Revival It's in G major so it uses G, D, and C as chords.
G D C G
It ain't me, It ain't me, I ain't no Senator's son, no.
G D C G
It ain't me, It ain't me, I ain't no Fortunate Son.
You can also throw in some common minor chords. A very very common
pattern in jazz music is
I II V7 I
where the II chord is minor. However, since most jazz songs don't have words,
it's hard to provide an example. You'll have to trust me that if you listen
to jazz you'll hear it a lot.
You can also use the sequence:
I VI IV V I
where the VI chord is minor. This pattern is the basis of the song "Lollipop"
with each chord getting one measure. In the key of F major it'd go like this:
F Dm B flat C7
Lollipop, lollipop, oh lollie, lollipop (repeat ad nausem)
Try playing these chords on a piano or guitar and you'll see that they sound
quite natural played in that order. However, if you play the D minor chord
as major instead (using the F# instead of F) you'll find it a little jarring,
because the F# is not a note of the F major scale.
You can also use II instead of IV, if you want to get a second minor chord
into the sequence:
I VI II V I
One song that does that is the following popular folk song, Today, which is
in D major and uses D, B minor, E minor, and A7 chords:
D Bm Em A7
Today, while the blossoms still cling to the vine
D Bm Em A7
I'll taste your strawberries, I'll drink your sweet wine
D Bm Em A7
A million tommorows will all pass away
D Bm Em A7 D
Ere I forget all the joy that is mine, today.
Folk music in particular tends to use very common chord changes and repeat
them over and over, and if you want to develop your ability to recognize the
common changes, it's not a bad idea to listen to some folk music because you
will hear them very clearly there.
There is one last piece of information about chord patterns that every bass
player ought to know. It summarizes all the information about how chords move
from one to the next in a simple way. It's called the Circle of Fifths,
and it's created by writing out the 12 notes in this order: each note is
followed by the 5th note of its major scale. Thus, if we start with C, we
follow it with G (the 5th note of the C major scale). We follow the G with D,
which is the 5th note of the G major scale, and D is followed by A, and so on
around the octave until we get to F, which is followed by C, and we're back to
where we started. The complete Circle of Fifths looks like this:
C
F G
Bb/A# D
Eb/D# A
Ab/G# E
Db/C# B
Gb/F#
There are two basic rules for chord changes. The first is that short movements
along the circle sound more natural than long ones. For example, the chord
change C major to G major is very natural, whereas the change C major to E
minor is more awkward. The second rule is that clockwise moves (forward) make
the song seem to be developing forwards, whereas counter-clockwise moves
(backward) make the song be resolving. The chord changes we gave above are
these:
E A E B E (I Saw Her Standing There). This one involves only single
step movements. Starting on E, we go back, forwards, forwards, back.
G D C G (Fortunate Son). This one starts by going forward one step, then
jumps back two steps, then resolves by going forward one step.
D Bm Em A7 (Today). This one begins with a three-step jump forward, but
then resolves back one step at a time.
F Dm Bb C7 (Lollipop) This one begins with a three-step jump forward, th
en comes _four_ steps back, then two steps forward and resolves with a gentl
e single step back.
Almost all chord movements in all songs involves jumps of 4 steps or less
along the Circle, and most of them only 1 or 2 steps. The Circle of Fifths is
an invaluable guide to picking up bass lines off a record. The general steps
you can follow are these:
1. Listen to the first note and the last chord of the song. This root note
of this chord will almost invariably be key of the song. Thus, if the first
chord is A major, then the song is very probably in the key of A major.
2. Listen to the song and try to figure out the sequence of chord changes.
If you can hear each chord, great: but if you need to guess, guess short steps
on the Circle of Fifths before you guess longer ones. eg, if the song opens
on A major, it's very likely that the next chord is either D major or E major,
and it's very unlikely to be F minor or D flat major.
3. Once you know the sequence of chords of the song, then start trying to find
the individual notes of the bass line from the chords that are being played,
and from the likely passing notes between those chords.
In the next lesson we'll talk about scales other than major scales, and how
to build songs and bass lines on those scales.