Double thumb (Tosin, Wooten, etc) technique question

[Hollowway]

So, I'm feeling like I can't ignore this double thumb / thump thing anymore, and I'm working on it. Having seen a couple of videos, I'm thinking the technique might be like picking, where some people anchor a little, some people don't, some people circle pick, some people strictly wrist pick, etc.

My question is this: For the upstroke, what is moving? I've seen wrist (Victor Wooten), arm (Daric's Bass Lessons), and thumb (Tosin). I'm finding it's hard to move the whole hand if I have to use my fingers for the next notes, so I'm trying to move my wrist a little, and my thumb a little. You guys have any advice?

 

[Crungy]

I'm not proficient at it but I lean more towards thumb and wrist depending on the action of the bass.

 

[Bcoble0927]

I'm still new to the technique too, but I've found that I use more wrist motion when down stroking. When I up pick I use more of my thumb joint to help keep my other fingers under the string when I want to engage those. In Javier Reyes' Guitar Messenger courses he uses his thumb joint more. In Tosin Abasi's lesson I noticed he uses his wrist more. I found it beneficial in mix both techniques as long as it sounds good, but I'm leaning more towards strict thumb joint motion as I practice the technique.

 

[Dayn]

Yeah it really depends on what's comfortable for you and how your own thumb behaves. I know Tosin uses his thumb almost like a club, moving the entire thumb back and forth. That's somewhat good for speed. Otherwise, if I don't need more speed I literally just alternate pick with my thumb like it was another finger instead of slapping right through the string.

Technique-wise, I treat my thumb like a pick. Need to be fast? Use my wrist. Don't need speed? Just use the tip of my thumb like a pick.