Major/Minor Scales, Triads and 7th Chords...

[Andy Cleaver]

I've just started learning my music theory etc and I've got a few basic questions, just to ensure I've got things straight (Bare with me as these questions are very very basic, but if you never ask you never learn hey!)

Am I right in assuming that if the guitar (or whatever instrument) is playing a C major chord then we can use any notes from the C major scale to create a bassline? Same goes for the minor scale, i.e. someone playing a Dm chord, we can use notes from the Dm scale?

Same again with the triads, if someone plays a C Major we can simply use the notes of C major triad to create our bassline?

Lastly, I've learnt about Major, Minor, Dominant, and Half Diminished 7th chords.

If someone is playing a G7 chord, we use the notes from the G dominant chord to make the bassline? etc

I guess that all that is correct and that I have it all sorted in my head, I just want to get some input to ensure I'm looking at things in the right way!

Any help appreciated!

[Jazzin']

well...
for example: a Dm7 chord would usualy mean a D Dorian Scale, which means all the notes from D to D using the key of C major.

[Tash]

First: Don't seperate the idea of Chords and Triads in your head. They are the same. A triad is a 3 note chord made by stacking the adjacent 3rds of a given scale.

A 7th is simply a 4 note chord consturcted the same way.

Look at the C major scale: CDEFGABC. Stack it in 3rds and you get C, E, G and B. That is C major 7th chord. Move the B up to a C and you have CEGC, or a standard C major chord.

This is called Tertian harmony (meaning its based on 3rds) and has been the standard for western music for much of the past few hundred years.

Now to create a bass line really you need to know two things: what chord is being played, and where its going. Lets say you are playing under a C major chord: C, E, and G are your most obvious choices. But how to string them together?

Now we need to address two other important concepts that all bassists know so well they don't know it, so to speak. These are non-chord tones, and leading tones.

Non-chord tones are exactly what they sound like: notes you play under a chord that aren't part of the chord. You do this because it creates dissonance, and the resolution of dissonance is the heart of tonal music! Example: take that C major chord and play CGF#FE. You've just played a very standard "walking" bassline consiting of a triad and 2 non-chord tones. There are a number of ways non-chord tones are classified, but save that for later. For now just keep in your head that they're useful for adding spice to a bassline.

The second concept I mentioned was leading tones. I'm going to dumb this down a bit for the sake of ending this post sooner. Basically the "leading" tone of a scale is the note 1/2 step below the tonic pitch (tonic meaning the actualy key of the scale, C in all our examples so far). This note is important because it really, really, REALLY wants to move to the tonic. This is the reason why a V or V7 to I sounds so nice, because the second not (the 3rd) of a major V chord is the leading tone.

Without getting any more complicated just keep this in mind: a pitch 1/2 step below another pitch realy likes to go to that pitch. If you keep this in mind when you are writing your basslines you can make them much stronger. Here's an example:

Say you're progression is C-G7, or I-V7 in the key of C major. Lets also say that each chord is 1 bar and your in 4/4 time (remeber we are part of the RYTHYM section). If the basic walking line I wrote out above: C-G-F#-F-E and then tried to move to something in the V7 (which contains the notes GBDF) you'd probably sound a little odd. But if you altered that walking line but eliminating ONE of the NCTs, say CGFE the last not of the first bar would be E....why is this important?

Because E is 1/2 step below F, the 7th in the V7 chord. Its the LEADING tone for F, so now your bassline has a strong draw to that next note. If you were to then play say FGAB you'd have walked the important notes of the V7: GBF (you'd miss the 3rd, but that's OK. Never feel like you HAVE to touch every note of every chord. Hit whats most important to making the song have body, leave the rest to the guitarist).

I'll leave off for now. I hope I don't sound like I'm treating you as an idiot, I'm simply dumbing everything down as far as I can because I don't know your theory background. Your best bet is to take a few lessons from a qualified teacher. If you can't find a guitar or bass teacher I'd actually recomend you take a couple piano lessons. The theory is the same and you really get a feel for how the notes work together on a keyboard. Plus I've yet to meet a piano teacher without a decent theory background.

Also if you don't know how yet, learn to read sheet music. You cannot study theory without it. Write out all my examples on a peice of staff paper and it will look so simple and obvious you'll wonder why you didn't figure it out already (chances are you probably did. It wasn't until I started studying 20th century harmony that I stopped seeing things and going "Oh, so THAT'S why that lick sounds so cool....").

[Andy Cleaver]

Thanks a lot Tash! Having a pretty limited theory knowledge the 'dumbing down' was exactly what I needed. I've tried looking for a teacher in my local area, but to no avail! I've never had a problem with my technique etc its just after 4 years of playing (and writing basslines pretty much by taking the root and using my ears from there) I've decided its time to learn theory, how to read music etc!

Thanks again for all the help!

[jazzbo]

It also might not hurt to click on "my homepage" by first clicking on my username as it appears in this post.

[Andy Cleaver]

Thanks Jazzbo! A lot of useful stuff there. Made for some interesting reading, now just got to get to work with all this stuff!

[Richard Lindsey]

Originally Posted by Jazzin'

well...
for example: a Dm7 chord would usualy mean a D Dorian Scale, which means all the notes from D to D using the key of C major.

Not necessarily. It depends on context and harmonic function. Aeolian and phrygian also are common with m7, and in some cases are preferable.