I've tried learning slap bass on and off over the years, but one area that keeps holding me up is the Left-Hand Percussive technique. In theory it sounds simple, you just mute the strings by striking across them sharply with the fingers of the left hand. Whenever I try it, however, I end up with a dull thud instead of the crisper tone I see in demonstrations.
Is this a function of how I'm striking, how the bass is set up, or both? For context, my main bass is an '83 Squier P-bass with the action set as low as I can without buzzing.