Building a pre-amp

[reeedjbass]

I'm going to try and build an active preamp to blend three pickups: one electro magnetic pickup and two sets of piezo (each set of piezos are to be wired to its own output.) I have close to no experience with active electronics. The sole purpose of this preamp is to blend the three pickups together so i would only have four volumes (one for each pickup and then a master volume. no tone controls.) I dont even know if preamp is what you would call it. I already had schematics drawn of how this circuit would look as a passive circuit, but someone told me that i would have trouble with the piezos and that i would need to use an "active buffer" whatever that is.

[mje]

Our own fdeck has a very simple preamp/buffer design that may be just what you need:

http://personalpages.tds.net/~fdeck/bass/quickand.pdf

[fdeck]

This might help. The first schematic on this page is a simple piezo buffer.

http://personalpages.tds.net/~fdeck/bass/quickand.pdf

Now for just a bit of advice. Start simple and big. You can miniaturize it later once you decide how you want it all to work. In fact, if you just build a couple of the simple piezo buffers, you can plug them into a little desktop mixer and try out your idea before going further down the DIY route.

Generally speaking, a mixer is an active circuit, though passive mixers can be made. It might be worth checking the folks on the electric bass "pickups and electronics" forum because there are a lot of clever passive circuits out there. And you can always start passive to keep things simple and make it active later.

Edit: LOL, mje beat me to my own site!