How to start improvising walking bass lines
Clip from Performance & Practice, Episode #2.
The below text is a partial transcript of the video.
One of the frequently asked questions is, how do I improvise walking bass lines with the left hand.
When I started to experiment with this technique in the left hand as a young boy, I started by using the tones of the chords; practically just the major triads, minor triads, dominant seven, the diminished, and that's it. We give for granted that we know the triads, so you don't have to think about them. You can walk a line just with the notes of the triads. Let's say that you have one bar of Dmin7, one bar of G7 going into C, II-V-I. I can use the chords' tones, that sounds beautiful, and there is nothing wrong with that. These tones don't have to be just ascending or descending; you can mix them up.
If you make sure to put the root on the first beat of the bar, then you will have a stronger sense of the direction of the harmony. I can improvise a line with the right hand without really thinking of the left hand because these are just triads, nothing fancy.
It's clear that this is the first step; it cannot be only arpeggios of chords. I'm going to show you one more thing, and that's going to be enough to practice if you never did walking bass before.
Let's go again from Dmin7 to G7 to C. If you go down, D to G is an interval of a fifth. From G to C, it is another fifth. So practically, if each chord lasts for four beats, all you have to do is to play a diatonic scale going down from D.
Then, we can have a pattern also going up. When going up, Dmin7 to G to C is not a fifth anymore, but it's a fourth interval. If you want to go diatonically, you have to skip to A, then G. So D, E, F A, G, A, B, D, C. Or you can use chromatic notes: D, E, F, F#, G, Ab, A, B, C. Practice this in every key.
Keep practicing this sequence of chords, II-V-I-VI, when you're walking the bass line. This can also be your first step to improvising in every key; you can apply the same chord sequence and practice it together with your walking bass line.
I hope this is of some help. Keep in mind that I've been trying to play walking bass now for more than 30 years. And still, if I stop doing it, I have to learn it again because, like any discipline, you have to keep practicing it and refresh it. Otherwise, it gets rusty. Never forget that.