I haven't tried 18V yet. Rick sent my pickups and preamp back last week (he also sent a new PX pickup). I installed them, connected a brand new 9V battery and plugged it in - same results as before. Treble/bass still distort and then cut out once they get completely cut.
I'm debating on whether or not I care about those frequency ranges because this is on a fretless and I don't see myself ever lowering the bass frequency with this setup.
I'm debating on whether or not I care about those frequency ranges because this is on a fretless and I don't see myself ever lowering the bass frequency with this setup.