I hear you JazzMan, B is already low, so F# is far off and C# even more, and I'm not talking about the crazy people who go all the way down to the lower B....
(Yves Carbonne on the pic with his latest 12-string Jerzy Droz Bass...)
For those who don't know, the theory goes a little like this:
A musical note is not only it's fundamental frequency, but a rich mix of various haromonics, from which the ear and brain understand what the fundamental or "note" is...
Already the 40Hz fundamental of the low E of the bass is very low in the human hearing range, and on a bass guitar we actually mostly hear the 2nd and 3rd harmonics, and the same goes with the lower notes...
"Yes, but the human hearing only hears down to 40Hz, what's the point of going lower????" is an often-cited objection to the lower register...
But the brain, being a wonderful machine, doesn't need to hear the fundamental frequency in order to understand the note...
"Ok, fair enough, someone can understand the note, but why use it? music has been made for centuries with the low E or B as it's lower limit, why use lower notes?"
Because, in short, in a band setting, the bass "competes" with the sound space and frequency range of the drums... Sure the bass can lock in with the kick drum and provide the fundamental groove of a song, but if it'S not heard in the mix, what's the point? Going lower "clears" the sonic space of the drums and opens up a new area in a band's sound...
After all that's what bass is about, being the foundation of a song?
PJ
(And JazzMan, I respect your position as an F# sceptic, it's a very valid one, I just wanted to present my view of the subject...)