From one idea to the next, here's the back story: I'm currently taking an interest in sound design, and read an article about making sound effects from recording via contact microphones. I already have a portable stereo recorder which is the Zoom H2n, which has a line/mic input (which is stereo), which has 2.5v plug-in power which I can switch on if required.
Now I want to make my own stereo piezo mic and plug it into my recorder, but do you think I need a pre-amp when the Zoom h2N has it's own mic gain control? I gather the impedence of piezos is as much as 50KOhm and would be too quiet if wired directly to a line/mic input. The ones at Maplin (where I might source my components) are 450Ohm-800Ohm. If I need the extra preamp then I'd like to see if I can use the plug-in power from my recorder to power a home-made stereo preamp. I've seen the Alex Rice preamp circuit design, but this is made for 48v Phantom power not 2.5v. I presume I will need a complete exchange of components as well as adapt it for stereo if don't just make two of them....so, is 2.5v enough to amplify a piezo contact mic signal?
For the record I'm no good at designing circuits, I'm just good at assembling them.