Piezo and built in amp

I was looking at these

https://www.youtube.com/watch?v=IOjbyE1VsDY

https://www.youtube.com/watch?v=fAsToFRDwrw

and I wanted to build my own, so I took a mini amp, took it apart and put it into a cheap uke I had lying around. It works, the only thing is that it feeds back like crazy. I'm pretty sure the feedback is coming from the speaker vibrating the top and the piezo picking it up and not having any way to stop those vibrations. If I pull the speaker out of the uke and pull it away it stops the feedback.

This is just a fun jam/party situation kind of project, would be nice to actually get it to work without the crazy feedback. Im using one of these piezos.


Then I wire it to the amp controls which I have already mounted to the guitar.

Anyone have any ideas that I could possible try to stop the feedback? I dont mind cutting gluing, screwing, etc, etc with this uke.

I believe there are things called "notch filters" that will kill the frequency that is feeding back. Dial out the frequency on your pre-amp. Of course all acoustic instruments will feed back and that is why they invented the solid body. You could also fight the feedback by covering the sound hole but then what do you have: a solid body.

Sort of confused. Did you put a speaker, or an amp inside the uke? And by saying "amp controls" you have a preamp mounted somewhere?

And where is the pickup mounted?

Pics would help.

Tape over the sound hole. Masking tape will do. The feedback is probably from the sound box resonating with the amplified frequencies. You'll be amazed at how well this works!