Thanks for sharing this Junichiro.
Please make sure you do this correct way.
1) Practice simple blues bass line first.
1 1 1 1
4 4 1 1
5 4 1 1
2) Sing melody (inside you)
Back at the Chicken Shack
3) Metronome setting for 1 2 3 4 simple (Metronome on every beats)
50 to 65 ... do this for 2 weeks to one month or more.
4) Metronome at 65 to 75.
Then try at 40 on 2 & 4.
Your fingers are not super relaxed. Do not pull any strings.
Place your 2nd & 3rd fingers closer to strings so that you can mute strings.
You need to practice more simple chromatic scale more in order to play this well.
Play simple pattern for 3-4 times or more 5-6 times.
When you post any blues bassline or R 3 7 groove.. you need to play 2-3 times.
Keep working!
Thank you.
Tomo