passive double bass preamp
Someone has asked me to create for them a passive eq/tone control system for an upright bass. Here is his request exactly :
"I want something that ill incorporate a 2-element piezo-based system, as well as a blender/control box that will mount on the tailpiece. The box would serve two functions. First off, it would have to reduce the high impedence of the piezos (>1 Mohm), to something more in line with the inputs of amplifiers (~ <500Kohms). Second, it would employ passive tone and volume control pots for each of the 2 transducers. Big catch? It must be a completely passive box, with no on-board power supply. This might be a toughie, especially for the impedence-matching, but maybe phantom powering could be explored... "
Now, i realize that there are a TON of these things commerically availible already ( Fishman comes to mind).....so i asked him why specifically he wanted to reinvent the wheel. Also, i asked him why it needed necessarily to be passive. His response :
"I'm trying to eliminate battery power because that's about the #1 thing upright players complain about. Eliminating that simplifies things considerably, at least from a user standpoint (and size), and that's really what I'm after: Something that's clean, minimal in parts and profile, maximum in dependability. "
Does anyone have any ideas, comments, schematics i could ape from, etc?