Once you've established the harmonic foundation using chord tones in your bassline, you can get more adventurous by applying scale tones. Scale tones can connect chord tones and add melodic interest to your basslines when used in the right places.
In this lesson I will discuss scales, their relationship to chords and the bass, and some common misconceptions.
Every chord has one or more scales which complements it. That is, particular scales sound good with particular chords. The part of music theory exploring these relationships is called chord-scale theory.
Chord-scale theory is mostly pretty simple, but people really like to over-complicate it. What you'll discover is each scale complementing a chord contains the notes of the chord plus a few others.
Most scales have seven different notes; most chords have three or four notes. In our Note Choice Pyramid, we classify scale tones as notes of the scale not in the chord. So, when you use a "scale" you're using chord tones with three or four scale tones between them.
Knowing which scale goes with a chord is usually straight-forward. For instance, the seven diatonic chords covered in earlier lessons all go with the major scale to which they belong. This is where teachers and books often make things needlessly difficult for students.
It is often taught that you need a separate scale (a "mode" in this case) for each of the seven diatonic chords. This is unnecessary. If chords are all in the same key, you don't need the extra step of thinking in seven different scales/modes. In future lessons we'll explore modes and when you do need them.
Be aware many people needlessly over-apply their knowledge of modes and chord-scale theory. Don't let them confuse or intimidate you. A common learning trap is when people learn a concept they suddenly think it needs to be applied everywhere. It doesn't, but it requires more learning to realize that.
But, All My Guitarist Talks About Is Modes!
You need to remember that guitar and bass are different instruments. They're worlds apart. It's confusing because they look similar and have strings tuned similarly. Despite looking similar, their function is completely different.
When guitarists use scales they are performing a melodic function in the form of a solo or lead part. They are functioning like a singer. Notice how guitar solos swap places with the vocals in songs.
Melodies are scale heavy. Since most other instruments play melodies, they will naturally focus on scales and modes more than we do.
If you must compare bass to guitar, compare it to rhythm guitar. Rhythm guitar is where the guitarist plays chords (several notes at once). Since the bass is lower in pitch, we can't play a chord all at once like the rhythm guitarist does. We have to play individual notes. But, bass and rhythm guitar both have a harmonic function.
Can't I Use Pentatonic Scales Everywhere?
Sometimes you might get advice such as “Dude, all you need is the pentatonic scale!” [I once taught a music camp where my students were told by a heavy metal guitar teacher there that I was wasting their time by teaching them the major scale!]
Why do a lot of players swear by the major and minor pentatonic scales? Because the pentatonic scales remove the hardest to use scale tones from the complete major or minor scale.
This is why pentatonic scales are so popular—they're nearly all chord tones! Due to all of the chord tones in them, pentatonic scales are great in basslines. They're easy to play, and you can make fewer wrong choices with where you place the chord tones rhythmically.
So, yes: You can and will use a lot of pentatonic scales.
How Scale Tones Work in Basslines
I urge you to study the exercises and some of the suggested songs for this lesson as well as investigating scale usage in your favorite basslines. Here are examples of how bassists commonly use scale tones alongside chord tones.
Scalar Passing Tones
One of the most common ways of applying scale tones is to connect between chord tones. These connecting notes are called passing tones.
Let's say you're in the key of C playing on a C major triad (C-E-G). It's very common to connect C and E with a D in-between, or to connect E and G with an F in-between.
Listen to an example first without the passing tones, then with them:
Scale Tones and Rhythmic Weight
When you come across really scalar basslines, pay attention to where the chord and scale tones fall rhythmically. You'll mostly find the chord tones in strong rhythmic places.
If you do find weaker notes in strong places, it is likely surrounded by a lot of strong notes. This is how and when you can get away with weak notes in stronger places.
For example, you often hear a quarter note line playing Root – 3 – 4 – 5. The fourth (a scale tone) is falling on the strong 3rd beat. Why does it work?
Since everything else is strong notes of the triad (R-3-5) your ear doesn't get too confused about the harmony. Furthermore, since it is a smooth, step-wise connection between two strong notes, it sounds natural.
If the line went Root – 2 – 4 – 5, your ear has trouble putting it together. You've lost a strong chord tone and you've lost the smooth step-wise connection. Listen and compare the two:
Ornamentation and Melodic Turns with Scale Tones
Another common use of scale tones in basslines is ornamentation. Sometimes you may give a simple note some melodic flair by playing a note above or below a strong note. In music lingo, these are called ornaments.
Listen to this example first without ornaments, then with ornaments:
Bass Fills with Scale Tones
Scales are excellent for fills. A fill is brief departure from the main idea of the bassline. A fill's purpose is to create a bit of tension setting up transitions or to add some interest when there is a gap in the music.
Bassists love to play fills using pentatonic scales or walking up or down the notes of a scale. Be careful though. If your bassline does this too much, it will probably compete with the vocals or other melody-playing instruments. It's easy to overdo it.
Here's an example of a pentatonic fill:
What Scales Are Important?
There are many, many other scales, and we will discuss them as the lessons progress. Remember, I always teach you things in the order in which you need them. You'll be surprised how much excellent bass-playing you can do by only knowing the chord tones and using your ear to fill in the connecting scale notes when you need them.
If you're impatient to learn more scale patterns, don't forget you can view and print almost all scales using the bass fretboard printer.
Do bass players use scales? Yes, of course. But, because of the bass' major responsibilities, the bass applies them much more carefully than other instruments do. Scales aren't the core of your bassline like the chord tones are.
When your chord tones are in place in your ear, mind, and fingers, you can apply the notes of scales more effectively as passing notes, melodic ornaments, and fills. This is what most bass players do whether they realize it or not. Many players only learn scales and, through trial and error, eventually find the supportive chord tones. The learning process is a lot faster and more organized when you comprehend the Chord->Scale->Chromatic hierarchy of the Note Choice Pyramid.
Take a look at the exercises and song examples applying chord tones and scale tones.