The thread on the 2,5,1 progression triggered this, but it's something that's been bothering me for a while. Time to ask for help. Have been looking at Pete's instructional stuff and in other places, but I can't find anything like this.
I am struggling a bit here. There are lots of examples around of chords and what they are (and the names aren't much more than a jumbled mess at the moment) - but how are they relevant to an instrument that can't play them?
For instance 12 bar blues theory pages star off with a set of chord changes. And this is great for guitar, keyboards etc., but I can't see it for sax.
I guess I'm missing the bridge between chords and playing single notes in a tune.
Would really appreciate a noddy level explanation and an example or two based on a common music which I can study with the example, so that I can download the sheet music and maybe listen to it on Youtube as well.
Many thanks.
Chord symbols serve several purposes.
1.) They help to define the underlying harmony as established by the bass instrument -- usually the root (the name of the chord), but sometimes the 3rd, 5th, or 7th (of a dominant 7 chord). Bass players usually have little need for all of the 9, 11, or 13 possibilities except for passing tones.
2.) They tell the keyboard and guitar the harmonies -- major or minor, etc. -- sometimes the notes they may or may not use (the type of 9, 11, 13)
3.) For melody instruments (monophonic non-bass instruments), they represent the scale possibilities. These possibilities become more limited depending on the types of 7, 9, 11, 13 indicated.
This last usage is what the question refers to.
If we look at a simple triad (3 notes -- 1, 3, and 5 of the scale):
A C major Triad represents the required notes C, E, and G, thus any scale used with this chord must, in the beginning understanding, contain those notes without variation (no C#, or Eb or Gb or G#). Furthermore, these are the notes that you want to mostly feature in strong rhythmic positions, particularly as "goal notes" the point of the point of that harmony.
A major triad most often represents a major scale: in (C):
C D E F G A B C.
1 2 3 4 5 6 7 1
(The bold notes cannot be altered, the not bold ones can.)
In Blues or older music that is not indicating 7th chords, The 7th Step will usually be b7 (Bb here) giving us:
C D E F G A Bb C.
(This is a stylistic thing that you just get used to. Fortunately more modern music indicates 7ths and other required notes).
This works for the other forms of triads.
(The #'s and b's are alterations to the major scale)
Minor (1, b3, 5) in C is C Eb G and therefore the scale requires these notes.
Augmented ( 1, 3, #5) in C -- C E G#
Diminished (1 b3 b5) in C -- C Eb Gb