www.megadrum.info

Hello,
I got Synthex kit today and as soon as I get my hands on a solder station, I'm ready to go
But right now, I'm working on my DIY snare with a 27mm piezo. I plugged it into the line-in input, recorded the signal with audacity and got this:

I didn't know whats wrong, asked for help and got told that the signal is too high for my line-in input.
So my question is, since I don't want to damage the module: Is there a build in resistor to prevent such damage? Or do I have to put a seperate one in line before the inputjack?
Greetings,
Matthias

A piezo is a high impedance signal source with relatively high voltage output - up to 30V. On high impedance loads, like sound cards' inputs, a piezo will still produce relatively high signals. Sound cards can handle input signals up to ~1V and for any higher signals there will be clipping.
MegaDrum has low impedance inputs so piezo's signals will be lower when loaded on them. Also, MegaDrum inputs have protection against overvoltage, negative voltage and static electricity.

ok, good to hear!
Thanks

thramul wrote:got told that the signal is too high for my line-in input.

Hi, 30 times 'too high' can trash your sound card - the images in this thread use either an oscilloscope or a cheap but informative op-amp buffer circuit - fine for sampling these low frequency AC signal(s).