I once played another person's bass at a rehearsal - the playing experience was great. I was moving around more than usual, felt more in control of the instrument and in general, simply enjoyed myself more than normal. I couldn't understand what it was that I liked about this substitute bass until I realized later that it had felt really light around my neck (it also had a 34" scale compared to my bass's 35"). So what is the lightest wood for a bass body that still produces good tone? Swamp ash?