| Rotosound Flats are not going to get you into thump territory. They are fine strings, but the warm, Jamerson-like sound isn't going to happen.
LaBella or Fender flats are what you want. I suggest getting lighter gauges, as the heavy gauges get very, very stiff.
In my experience, LaBellas will have a richer, more complex sound, the Fenders will be thumpier. |