Trouble with Speedy Bass Slapping

[Intenzity]

from the man himself...

 

[guroove]

Another thing to consider is how your instrument is set up. Is your neck perfectly straight? Your action should be low enough that you can make the strings snap into the fretboard, but not so low that they buzz. Also, it helps to play very relaxed for that fast stuff. Flea's style is very conducive to hard slapping. You would be surprised at how softly some expert slappers slap.

 

[memyselfandi]

The harder you slap the quicker you will damage your thumb, the softer you slap the easier it is to play hammer ons and pull offs with the same velocity and volume, making your overall sound have an even quality, who needs a compressor when you have control.
Flea is an aggresive border line incorrect slap player, try Mark King for flair and style faster and softer