Jazz is normally a ii-V7-i progression and you play the chord's notes. I let Google find me the chord progression to any song. Use these search words. Chords, name of the song. Once you have the chord names then you play the notes of that chord.
So you need to get the chord "spellings" to memory. The Cmaj7 has this spelling R-3-5-7. See or hear a Cmaj7 chord and you know what notes make that chord. The following will go into detail.
Chord tones is what we play 95% of the time. Here is another cut and paste paper for your reference file.
My old standby chart of generic bass lines using the major scale box as a Rosetta stone.
Major Scale Box.
.......Index....Middle..Ring....Little
G~~|---2---|-------|---3---|---4---| 1st string
D~~|---6---|-------|---7---|---8---|
A~~|---3---|---4---|-------|---5---|
E~~|-------|-R/T---|-------|---2---|4th string
You may recognize this pattern with dots.
Adding the numbers lets the pattern come alive.
Cmaj7 chord coming up in the song. Find a C note on the 3rd or 4th string and put this box's R over that C note. Then play the "spelling" for the Cmaj7 chord. That spelling is listed below and it is R-3-5-7. If you wanted to play the C major scale, that spelling is T-2-3-4-5-6-7.
Basic Chord Spellings
- Major Triad = R-3-5 for the C chord.
- Minor Triad = R-b3-5 for the Cm chord.
- Diminished Chord = R-b3-b5 for the Cdim chord.
7th Chord Spellings
- Maj7 = R-3-5-7 for the Cmaj7 chord.
- Minor 7 = R-b3-5-b7 for the Cm7 chord.
- Dominant 7 = R-3-5-b7 for the C7 chord.
- ½ diminished = R-b3-b5-b7 for the Cm7b5 chord.
- Full diminished = R-b3-b5-bb7 for the C with the little o - no strike through.
See a chord and play it's chord tones. As every key will have three major, three minor and one diminished chord it's a good idea to get your major, minor and diminished bass line chord tones into muscle memory so when you see a chord your fingers just know what will work. Now the song may only give you enough room for the root, or root five - adapt and get as many chord tones into your bass line as needed. Root on 1 and a steady groove from the other chord tones plus something to call attention to the chord change is what we do.
Scale Spellings Yep, gotta do our scales so our fingers know where the notes are and our ears get used to the good and bad sounds. Scales are a right of passage thing. Got to know them, however, chord tones is what we get paid to play. Put another way scales are for the melody and chord tones are for the harmony - comping.
- Major Scale = T-2-3-4-5-6-7 Home base
- Major Pentatonic = T-2-3-5-6 Leave out the 4 & 7
- Natural Minor Scale = T-2-b3-4-5-b6-b7 Major scale with the 3, 6 & 7 flatted.
- Minor Pentatonic = T-b3-4-5-b7 Leave out the 2 & 6.
- Blues = T-b3-4-b5-5-b7 Minor pentatonic with the blue note b5 added.
- Harmonic Minor Scale = T-2-b3-4-5-b6-7 Natural minor with a natural 7.
- Melodic Minor Scale = T-2-b3-4-5-6-7 Major scale with a b3.
Let the major scale pattern be your home base then change a few notes and you have something different. No need to memorize a zillion patterns. Let the major scale pattern be your go to pattern - then adapt/adjust from there.
Generic Notes - for your bass line.
- The root, five and eight are generic (R-5-8-5) and fit most any chord. Remember the diminished has a flatted 5.
- The 3 is generic to all major chords. So R-3-5-3 will fit under any major chord.
- The b3 is generic to all minor chords. And R-b3-5-8 will fit under any minor chord. Why the 8? Well the 8 is just another root in the next octave.
- The 7 is generic to all maj7 chords. Yep, R-3-5-7 fits nicely.
- The b7 is generic to all dominant seventh and minor seventh chords. G7 = R-3-5-b7 or Gm7 = R-b3-5-b7.
- The 6 is neutral and adds color, help yourself to 6’s. Love the sound of R-3-5-6 with a major chord.
- The 2 and 4 make good passing notes. Don’t linger on them or stop on them, keep them passing.
- In making your bass line help yourself to those notes, just use them correctly.
- Roots, fives, eights and the correct 3 & 7 will play a lot of bass.
OK fine, how to use all that I know is the question. Jazz, follow the chords and play notes of the chord. Rock, Pop, etc. be happy with roots and 5's.
Start, as you have, with pounding roots, then add the 5 and get as many chord tones into your bass line as your skill level will allow.
I just gave you enough to keep you busy for several months.
Good Luck.