I got assigned my first song in Bb. I play a 4 string bass and I noticed that when I try to go down to the low octave (A string 2nd fret root), Going down from there I run out of fretboard. I know that I can play higher but what are some options for hitting the lower octave? Do I tune the instrument to Eb and play as if I'm in the key of B? Do I get a 5 string? Please help.