Hey gang,
How great bassists do what they do - producing chart-topping banger bass lines - is often a mystery to us mere mortals. But every now and again you get a glimpse into what goes into the secret sauce.
There aren’t many bassists who can claim as many instantly recognisable bass lines as the late great James Jamerson. His secret sauce?
… many things. 
But one exercise in particular reveals one of his secret ingredients, and reveals a ton about how he thought about creating those magical basslines.
Here’s the basic exercise…
Jamerson's Chromatic Exercise in C
play with swing 8ths
This simple exercise contains the magic of how Jamerson smoothly linked chords together in songs, creating flowing melodic bass lines. Here’s what’s happening:
- Bar 1: Starts on the root (C), works chromatically up to the fifth (G) by walking through E F F#
- Bar 2: Starts on the fifth (G), same chromatic walk up to the octave via A A# B
- Bar 3: A sexy walking bass triplet, then the same walk to the fifth, but in the lower octave
- Bar 4: Same as bar 2 but down low
This exercise also demonstrates Jamerson’s insane fluency on the neck, which allowed him to find any note he needed in a given hand position, often just on the bottom 4 or 5 frets.
Here’s how that exercise helped create some of the best bass lines ever to hit eardrums…
What's Goin' On
https://youtu.be/H-kA3UtBj4M?t=22
In bars 7+8 of the tune, you can see on of Jamerson’s many chromatic walk ups to a root note (B + Cnatural walking up to C#), which is super typical of his approach, and of his Chromatic Exercise above.
Darling Dear
https://www.youtube.com/watch?v=nyhBwuEIwCY
Another great bass line, full of these chromatic walks all throughout. This line is from the intro, but there’s lots more goodness along these lines when the verse kicks in!
For Once In My Life
https://www.youtube.com/watch?v=l3qi3E40aWE
I think this might be my all time favorite - almost 3 minutes of uninterrupted bass brilliance, NEVER repeating exactly. This is bars 9 + 10, showing Jamerson using chromatic walks on a minor one chord (Gm) to a dominant five chord (D7) just as brilliantly.
Notice in the tab too, that he doesn’t rely on the typical scale shapes we learn early on to find his notes, he’s anchored around the open strings and can find those notes anywhere he wants to!
The really cool thing about practicing this exercise - you’re not just stuck with soul and Motown. You could use this to craft…
Deep Purple - Smoke on the Water
Yes, Roger Glover’s opening fill on Smoke on the Water is using this same chromatic walkup approach!
Rancid - Time Bomb
Matt Freeman - coolest punk/ska bassist of all time? His chorus pattern on Time Bomb is eerily similar to Jamerson’s Chromatic Exercise. Little did I know when I was playing this in high school.
Head Hunters - Chameleon
This ever-classic funk “bass riff” (that was actually played on synth by Herbie Hancock) is one of the most prominent uses of simple chromatic walkups.
The reality is, this exercise is just a tool. It will not make you Jamerson. 
But use this tool well and you too can write some dope ass bass lines. Let me know what you discover! 
