Toneranger's pickup design piqued my interest. I had some of those piezo elements in my parts box, from some other project. Note that the little vibration sensors in Toneranger's design are available from Mouser Electronics (www.mouser.com), part number 824-LDT0-028K/L, for $0.75 each. That's also where I get the parts for my preamp. Speaking of which... here is yet another little preamp design. It's just about as simple as I could make it, and it seems to work quite well. For links to both of my preamps, www.execpc.com/~fdeck/bass About my power amp project, it is officially dead. I decided that the draconian current limiting scheme used by the Tripath TA2022 switching power amp chip is a show stopper for a musical instrument amplifier. But it also occurs to me that there is very little to be gained from designing your own power amp, when there are lots of inexpensive offerings out there.