When creating a bass line, how do I know what notes I'm allowed to use?

Question

I've been playing bass for about two years now. I've learned plenty of beginner/intermediate songs and play with some friends about once a week. I have no problem playing the songs, but I kinda just go through the motions and don't truly understand them.

My ultimate goal is to be able to improvise on any song that is thrown my way. Since I'm pretty new to music theory, I'm going to try and construct my question in the most basic way possible, using very simple chord progressions so I can begin to wrap my head around this.

At its bare minimum, from what I understand, bass is all about outlining the chords that make up a song. So if a song's chord progression is G-C-D, a simple bass line would be to hit the root and 5th of each of those chords. For G the root and 5th would be G and D, then C and G, then D and A.

Where my confusion really comes in is that if the song is in the key of G, does that mean I'm only allowed to play the notes in that scale (G, A, B, C, D, E, F#)? Or does the scale change when the song progresses to the next chord? So when the song gets to the D chord, am I allowed to play any note on the D scale (D, E, F#, G, A, B, C#)?

I know this is a very basic example and there is a lot more to it, but I'm just beginning to dive into this, so I'm trying to get a broad understanding of and a good foundation for this and then start to get into specifics.

Answer 1

Where my confusion really comes in is that if the song is in the key of G does that mean I'm only allowed to play the notes in that scale (G,A,B,C,D,E, F#)?

The key of a song does not determine which notes you use for the bass-line on a particular chord - the key represents the overall sonority of a song, not all the chords, or the notes they comprise. The chord itself, its function in the music, and its derivation determine that. You're also conflating scale with key. But I'll leave aside those technicalities for now and just talk about playing some decent bass-lines:

Since you're just starting out, the best rule to follow is to build your bass-line from the notes that comprise the chord you are playing behind. In most simple rock, blues and jazz you'll encounter, the analysis amounts to "stacking the 3rds" of the scale indicated by that chord to build the chord on a guitar or piano, and what you can call the "allowed notes" of your bass-line.

For example:

• If you're playing on a simple C chord, the notes of that chord (the first two 3rds of the C Major Scale : C-D-E-F-G) will be C-E-G. So play an arpeggio that matches the groove of the song and is comprised of those notes on that chord, and it will be sound good. (That simple chord is known as a Triad.) Experiment with changing their order, working the groove and moving in ascending and descending directions, but stick to those notes. If you play other notes, they may or may not work - many variables involved. You can certainly experiment, but those notes can be considered safe. As @Basstickler explained, 3rds can be an adventure, so 3rds - E in this case - are not always as safe as the others.

• If you're playing on a G7 chord, the notes of that chord (the 3rds of the G mixolydian scale G-A-B-C-D-E-F) will be G-B-D-F. So play an arpeggio of those notes on that chord and it will sound good. (Such a chord, which upon analysis proves to be a triad with an additional 3rd to bring to the 7th, is called a 7th chord.)

• If you move to a D7 chord, the notes of that chord will be D-F#-A-C (the 3rds of the D mixolydian scale). So play an arpeggio of those notes on that chord and it will sound good.

• If you move to an Am7 chord, the notes of that chord will be A-C-E-G (the 3rds of the A minor scale ) So play an arpeggio of those notes on that chord and it will sound good.

• If you have a C6 chord, your notes will be C-E-G-A: C-E-G are the first two 3rds of the C major scale, the same triad we already mentioned in the simple C chord, and the A is the 6 in your C6: A is the 6th note in the C Major scale - an extension of the triad of C-E-G. (That chord is called a 6th chord, but don't get bogged down in the hows and whys of the terminology - for now just learn the simple meaning of the chord symbols you encounter.)

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If some of this terminology is unfamiliar to you, quite often an easy way is to take a look at the guitar or piano part and see what chords are used and the notes they are built from, or just ask your guitarist or pianist (if you can get away with doing that...) what chord and/or what notes are in the chords they are playing. Most of the time those notes are the notes you will use for your bass-line.

Having said that, to get good at this you should study some basic theory, focusing on the construction of chords and scales. Become proficient enough so that when you see a chord you know what notes comprise that chord, and ultimately what scale it is derived from. It's not really very hard - as a beginning bass player, focusing on roots, 3rds, 5ths and 7ths is all you really need to do. That will put you on the road to becoming a good bass player than can quickly come up with a credible sounding bass-line for most tunes.

Of course you can learn to read bass-lines and reading is important, but I'd venture that 90% of the bass work you hear in rock, blues, pop or jazz is done on the fly by the bass player. The most famous and successful session players - people like Chuck Rainey, James Jamerson, Joe Osborn, Carol Kay, Bob Babbitt, Ducky Dunn... - got there because of their ability to come up with clever, interesting bass lines when they had nothing to work with but a chord chart and a drummer or guitarist.

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When I learn something new that's not so simple, at first I'll just learn all the chords and play just roots and fifths of the chords, to get the progression under my fingers and get a feel for the groove. Once I've got that, I will work with other chord tones to create a real bass-line: Go slowly, keep it fun and don't try to do too much at once.

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The above should get you started. Again, don't be afraid to experiment when you can afford the risk - that's how you learn. Experimenting with 3rds, and also with throwing in 9ths (Major 2nds), particularly in descending riffs, are good points of departure. You triad has a 3rd, 9th chords are common, and even if it's not a 9th chord, hitting the 9th (2nd) on way back to the root will often add interesting color, especially in blues tunes.

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Important:

You'll find all of these "rules" constantly being broken in all modern music, because there are no hard set rules in music - just guidelines to help you along. Music is an expressive art form, not a science. So always use your ears - that's only rule we really have. As you progress, you will find your own ways to change it up and make it more interesting. But these guidelines will keep you safe in most situations.

With bass, less is more. If you play simple lines with clean technique, make sure you are in tune, have a good sound and good time/groove, you'll likely become a very popular bass player.

Here is an excellent book for beginners:

Essential Music Theory for Electric Bass, by Robert Garner

Good Luck.

Answer 2

There are many different ways to approach the bass and the approach that you take may depend on what styles/genres of music you are playing. The first thing that you want to do is understand the traditional role/function of the bass within a piece of music. Speaking generally, the bass is used to add depth to the harmonic content and to connect the rhythm of the drums to the rest of the band. A good bass player would have a solid understanding of what is happening with the drums and the chordal instruments. It's important to understand the bass's role because it's easy to get carried away. If you're not careful, all the extra notes you add and how you play them can end up taking away from your bass line's ability to fulfill its role in the music. It might sounds cool (or just feel cool) to play lots of extra notes but if you're not adding to the song what is needed, then you're not doing your job. There are definitely times that you can step away from your role but to get started, you want to learn how to fulfill that role first.

The most basic approach is to play only the root notes of the chords. This adds the depth that we are looking for. If you're playing with a guitar, they don't have notes that low to provide that depth. If you're playing with a keyboard, they usually don't have everything set up to have their low notes bring the force and tone that a bass is capable of bringing. The thick quality of a bass note is usually not produced by a keyboard, short of a bass synthesizer.

The next step is to know your chord tones and how to use those. Root/5 bass motion is pretty common, particularly in older styles of music or genres like Country. The root and 5th of the chord are the most structurally important, providing the strongest foundation. Adding in the third of a chord can also be very easy and provide some additional texture. You can think of the third as providing the color or feel of that particular chord; it's what makes it major or minor. The third in the bass can end up being a bit more dissonant than what is desired, so it's not quite as commonly accented. In any case, it just takes a little more care to use without disrupting the overall harmony, so you need to make sure you're paying attention to how it affects the sound. You should really always be paying attention to how things sound, not just playing something because it should work according to theory.

Beyond those basics, the easiest notes to bring into your vocabulary will be those that come from the scale of the key you are in. If all of the chords that are in the song are actually from the same key, then using that scale will provide what is needed (there are a lot of situations where not all of the chords come from the same key but I won't go into that here). A traditional approach would be to use the notes of that scale and make sure to focus on the chord tones of each chord as it passes.

A simple next step can be creating a walking bass line. Walking bass lines are the foundation of the Jazz bass but do appear elsewhere and are a great learning tool. A basic approach is that you would be starting each chord on a chord tone (easiest to start with the root of the chord), then playing up or down the scale toward the next chord, using primarily quarter notes. The idea is to create a line that moves you from one chord to the next smoothly. Walking bass lines can be much more complex than that, utilizing chromaticism and leaps, more intricate rhythms and sometimes creating a feeling of walking two lines at once in different octaves. The idea for you is to develop an understanding of how linear motion can smooth out the bass line. Jumping from root to root can sound a little jarring in some situations, particularly when jumping more than a fifth. It's very likely that the music that you're playing with your band wouldn't sound great with a walking bass line but understanding how to smooth out the line can be applied just about anywhere.

I also strongly recommend learning to play as many songs as you can, from as many genres as you can. Listening to what those who have been successful in the past have done and learning to play it yourself is one of the best tools for learning. Someone telling you how to construct a walking bass line is helpful but you won't really know how it's done without hearing it. I also recommend looking at the theory behind what you're playing, such as what chords are happening while the bass lines is playing the different notes. This will allow you to see functional examples of bass lines playing something other than the root and you can try to figure out what it is about some of those notes that affects the music as a whole, making those extra notes valuable to the song.

This answer is getting a bit long and I could go on all day. This should get you started though. You can look into inversions, drones/pedal points (not effects pedals but a specific bass approach), themes/motives, melodic approaches, reharmonization, and so on, as you feel more comfortable and in tune with these basic concepts.

Answer 3

'Allowed'. No, aloud! There is no allowed in music. There are no rules saying what notes go with what. There are guidelines, which help, though. On that G, for instance, G B and D are the obvious ones, but A, E, F, F# and even G#, Bb and C# will work in the right circumstances. So that's 10 out of the 12. And I'm sure I can, and do, make the missing couple fit in certain places in certain songs!

Ah, but what are they? A common bass line is G B D E F E D B against a G7 chord. All the diatonic notes from G major will work 4 in the bar, just walking up and down, but sound better when a key note is played on beat 1, and often beat 3.

C#? well, try G B C# D four in the bar to a chugging song on the G bars.

Let your ears be the judges, and really you don't have to justify something that sounds good! Refer to the theory, and you'll probably find a reason why something works - but that's the reason it's in the theory! Part of the trick is to keep the main beats as key notes, or chord in that bar notes, and just experiment with other notes in between - the lesser important parts of the bar.