Bossobass is correct, low note on a 5 string is Low B at 30.87 hz. Some players will extend it to a Low A. The bass of a bass drum is below that. A good musical example of this is Tomorrow's Girl's on Donald Fagen's Kamakiriad (sp?). The low note is a B flat (about 29 hz). On a system with good low extension and separation, you'll hear the bass guitar playing the B flat at 58 Hz and then drop the octave and play the B flat at 29 hz.