I'm using this one:
https://www.sparkfun.com/products/9196
Apparently i need to bring the voltage down from a peak of 30 instead; Still AC, though I believe? It doesn't say but the nature of the vibration leads me to believe so.
I'm not so sure this piezo is similiar enough to yours for your circuit to work out of the box.
I've not seen a piezo looking like that, but I assume the theory is the same. Yes, with my piezos there is potentially high voltage AC (with incredibly low current) being output from a piezo. In my design I use a voltage divider to reduce the input voltage. Originally I was using a 10k / 1k to reduce it by a factor of around 1/10, but found that this was too much. Now I am using 1k/1k for about 1/2, and that works much better.
When figuring out how much to drop the signal, you also need to know about your pad design. I find that pad design is just as important as circuit design if you want consistent signals. After a lot of trial and error I arrived at the pad design documented at https://hackaday.io/project/6881-drum-master/log/29084. By doing things like this, you won't get the full 30V-ish max output on the piezos.