This is something I'm always wondering about. I've got a detuner that I've used on two different basses. On the B-string of a 35" scale 5-string and on the E-string of a 34" 4-string. Both strung with TI Jazz Rounds (super light gauge). On the B-string (.118 gauge), it maxes out at about 1 full octave down. But on the E string (.89 gauge) I can only get it down to a low C. I know Matt Garrison uses one on his E string to drop it down to a B, and I'm sure different scale lengths and different gauge strings make a difference. So what's the lowest you can get your detuner to drop, and what kind of strings are you using?