Nagging Basic Theory Question

[Arizona Jones]

Say I go to band pratice and the guitar player starts playing something that goes A-D-E. A real basic, wide-open, strumming I-IV-V kind of thing.

How do I know what notes are available to me to play? I know I get the Roots, but what if I want to make up a melodic bass line?

Is the Key of the song the deciding factor? The chords the guitar player is playing? What is it that lets me know what I've got to work with? I have never figured this out!

And I'm looking at this from a strictly "music theory" stand point, not from a "what-sounds-good" stand point.

Thanks for any information or advice!

Arizona Jones

[steveb98]

The key and the chords work together to establish what notes are available. You already know something about the key or else you couldn't say I-IV-V. Then each chord has a related mode. I = ionian (major scale), IV = lydian, and V = mixolydian. But if you're play Blues, Rock or similar music and using 7th chords all over or power chords the answers tend to be simple but anaylsis is ugly.

If you are still learning theory lets keep it simple use the key, probably a major key/scale and combine that with the arpeggios of the chords. The arpeggio is all the chord tones so they work and then use the key/scale to fill in with.

[Fong249]

You're going to find a great deal of ambiguity when your guitar/comping instruments are playing chords that are not especially colored. Colored in the sense that they really do not utilize chord tones, or the tones they use do not constitute a single scale, but can be approached as several. For example, if the guitar player is playing a major I-IV-V chord, you could add to the tone of the song by using a minor third, or a major third, because both utilize major IV and V. There are several others you could utilize in addition to the minor thirds/major thirds, You're really going to need to take a far more indepth look at scales and modes to see what you can play over the comper. In Jazz, one nice thing is that most chords utilize the dominant seven, which means you can apply the mixlodian scale and the dorian scale pretty liberally, so long as your guitarist is using a I-IV-V in a jazz setting with the implied 7th. THats my $.02

[str8_bourbon]

I think you've answered your own question. You can work with the chord tones, and scale tones.
With your example, A-D-E(as in I-IV-V), is in the key of A Major, and those three chords are basically all Major chords.
The A Major scale is: A - B - C# - D - E - F# - G# - A
A major chord is made up of: Root + Major 3rd + 5th
By playing chord tones in relation to the guitar chord, you're placing emphasis on the harmony.
You can use scale tones to lead one chord into another, for example moving from A to D, you can play AAAABBC#C# then on to D.
Or you can mix these two methods up, using the example above(A to D), you can play AAEEBBC#C# then on to D. The "A" notes are obviously root notes, the "E" notes are 5ths(chord notes within A Maj.), the "B" and "C#" notes are scale tones(notice that the C# also happens to be the 3rd of A Maj.) that are used to lead the A Maj. chord into the D Maj. chord.
I hope I make sense.

[cowsgomoo]

the short answer is.. it depends what you want to achieve...

traditionally the bass is there to outline the basic rhythmic & harmonic environment, so (forgetting about rhythm) the first way to do it is to imply the tonal centre, harmonic environment and chord movement... i.e. if the guitarist was going:

A / / / | A / / / | D / / / | E / / /

round and round, you'd probably want to start off with a nice big fat 'A' note or two (establishing the tonal center), and it'd be nice to throw in a C# (the major 3rd of a chord of A) and an E or two in bars 1 & 2, to show that for the 1st two chords at least, you're in a major harmonic environment, and for the chords on bars 3 & 4, you want again to hit roots and chord tones where possible, establishing the chord movement

but if your guitarist is strumming big healthy chords, you might not need to show everyone you're in A major because he's taken care of that... so you can concentrate on creating a line that connects the chords in a way that has a bit more character... there are zillions of possibilities:

1. use a 'modal scalar' approach... for a chord progression like the one above, you can connect the chords using modes built on each chord root... i.e. A - Ionian, D - lydian, E - mixolydian... they all have the same notes so it's easy to wiggle a line through the chords...

2. chord inversions... try starting one or more chords on a different chord tone than the root... the most obvious candidate in the above chord progression would be to start bar 2 with a C#.. as it would outline movement to the D in bar 3 and also unsettle the harmonic environment (subjective, but then.. music is )

3. chromatic movement... move to the D using A-B-C-C#, or A-E-Eb-D.. not only this, but you can create lots of tension & release by landing on chords from a semitone above... it won't always work but it can be powerful if you do it in the right place

4. minor tones... there's often no reason (especially in rock music) why you shouldn't stick in minor tones over a major chord... i.e. in A major, try using the minor 3rd, C and the minor 7th, G... they often sound great & more badass than their major bro's

5. octaves... if your guitarist has the harmony covered... make your roots interesting by using octaves

6. register displacement... you can create character & tension often simply by playing the same thing you just played only an octave above... or an octave below

7. notice that the higher up the neck you go, the more unusual the notes (harmonically tense/dissonant) you can get to work... I think it's because the ear can work out more easily what's going on with higher frequencies, so an 'outside' note played high up the neck can be processed by the brain easier than an 'outside' note played way down... your listeners will also be accustomed (consciously and unconsciously) to processing bass frequency notes as information on the 'fundamental harmonic environment' and the higher ones as the melodic content... so if you start switching the roles about.. it can be thrilling but it can also be confusing.. so what i'm saying is... the register you play in has a direct effect on the effectiveness of your note choices

erm... sorry for rambling on so much

[Arizona Jones]

All, thanks for taking the time and effort to reply!

Steve B. - I got what you were saying and was able to play the I-IV-V using just the notes from the key by using the Ionian, Lydian, and Mixolydian mode patterns. If nothing else, I learned how that works! Very helpful! Thanks!

Fong249 - I broke down a G guitar chord and discovered that it only contained the I, III, and V from the scale. So, I understand what you are saying about guitar chords not being fully "colored" and the note options I have in that regard. Thanks! More good info!

str8_bourbon & cowsgomoo - I'm gonna sit down right now and work through your posts. Looks like some more good stuff!

Again, thanks to all for the effort it took to type out these replies! I appreciate it!

Arizona Jones

[sedan_dad]

It's kind of tough to say with out knowing the beat involved .Is there a drummer playing along?
I base everything I do with the drummer.

[invader3k]

With something like that, using the second and third of the first chord, along with the third, fifth, and eighth (octaves) of the two other chords, could work pretty well, assuming this is a basic rock or blues song. Just a suggestion.

[phxlbrmpf]

Personally, I think pentatonic scales are a good way to start using scales, they "work" over ever chord (you only have to know if the chord is minor and major) and give your bass line a rock-ish flavour. Therefore, if the chords are all major chords, use A major pentatonic, D major pentatonic and E major pentatonic.
Once you're comfortable with those basic scales, start using the full modes and start experimenting what you can do with those "extra" notes.