My preamp in my acoustic guitar died after I put the battery in backwards. I need to replace it, and fast. Piezos have incredibly high output impedance (5+ mohm) so a buffer circuit is used to knock the impedance down to a sane level.
I tried building this circuit and while it works, it lacks any sort of bass amplification:
I didnt have a 100k resistor, so r3 is 170k. I also didnt have a .1uf, so c1 is 4.7uf. I tried raising the r2 to 5mohm and it sounded the same. v+ is 9v and vb+ is 4.5v from a voltage divider. OpAmp is tl072
Any help or alteratives much appreciated!
All caps are thin film, not electrolytic
The DI Box next in the chain has an input impedance of 1mohm