Ok, this is the technique (RH) I mean:
- First, mute the string lightly with your palm at the bridge and then slap the string very lightly so the string doesn't hit the fretboard.
I sometimes use this technique when I want to produce a very round and deep sound completely without highs. It requires lots of volume, or a compressor at an extreme setting to sound loud enough, however. Sounds really good for fast drum'n'bass grooves or certain R'n'B, for instance.
