I needed a beat amplifier for a 400 day clock repair. A small stick FM radio receiver has all the requirements, but needs slight modification.
Open the case and remove the pickup coil and associated diode.(the bits with wax on them). Make room for the 3.2m/m socket connection for the piezo diaphragm input, if there is none. Connect the centre connection of the piezo diaphragm to the base input of the transistors that drive the headphones. The other connection to the battery negative. The piezo diaphragm can be hung or clipped to the movement just about anywhere. Its very sensative. The better the quality of earphones, the better the sound.image shows the setup. Its easy to construct and very useful.