Hmmm...
I'll try to answer... my engineering firm designs the things, among other activities.
The buzzers use PZT-5/brass unimorphs that have a depoling voltage of about 15 volts/mil thickness.
These will appear as an almost pure capacitance in their compliance operated mode, so you can't really apply any power to them with something like an audio amp.
An electroacoustic or electromechanical impedance matching network must be used to make their electrical impedance resistive so they can accept and transform power. This is done in buzzer/beeper assemblies, but only at one frequency.
They only sound at one note...usually designed at 2 to 6 kHz.
So, in short, it can be done. But it's a bit of engineering.
An electromagnetic transducer operated in mass controlled mode coupled to a spider bridge would be easier.
Here are some basics:
http://www.morganelectroceramics.com/pdfs/tp218.pdf
This includes the Mason equivalent circuits we use to design the matching networks.
Long ago I also made a sympathetic string sounder as Hoover mentioned. I used a speaker voice coil. The strings had a jawari bridge, so they buzzed as in a sitar. They had to be tuned very precisely to sound...within a few cents. Worked well though!
So...voice coil and spider bridge...If you really really want a piezo one...well, I can design one for you!
By all means play with the buzzer unimorph disks though. Great fun. An audio amp will not hurt them, since they they cannot accept any power (unless they are still in the plastic impedance matcher, at one note.)
Oh, and I listen to some justly intoned stuff....old Beatles vocals!
Les
L M Watts Technology
