Homemade Piezo

[Fretloos]

Hey,
I've got two Piezo Buzzers (http://kls.chinese-suppliers.com/ima...300733514-.jpg) which pick up the sound of my bass rather nicely, and because I'm building a new bridge anyway, I'm thinking of building the piezo into it.
The mechanical problems will be overcome, but the output of the buzzers is way lower than that of my pups (2 low quality soapbars). I guess I'll have to build a preamp if I want the output to be of a decent volume. I found some circuits, but I haven't got a Idea of what will work an how many W it should be etc.
Could someone comment on these circuits or send me in the right direction?
Many thanks!

[spudmaster34]

I have no idea about those circuts, but I put one of these http://www.windworld.com/products/msipu.htm on my p, and it works nicely

[Fretloos]

too bad I can't get those in Holland...
thanks anyways

[Shoewreck]

Don't use these preamps. Input impedance is too low, that means decreased low frequency output. Look for a preamp with input impedance of 1 to 10 MOhms. The last schematic may work OK if you swap the input level pot with a standard 500K or 1M guitar volume pot.