You'll need a piezo preamp to get the most out of your cigar box guitar with a piezo pickup (aka contact mic). Piezo preamps resolve the frequency and dynamics issues caused by your piezo's high impedance output. You can purchase a piezo preamp, aka acoustic guitar preamp/DI, online on Amazon and any audio equipment supplier. However, its way more fun and cost effective to build your own preamp. In this video tutorial, I will reveal why you need a piezo preamp in more detail, and will take you through the process of how I built my piezo preamp using a popular circuit schematic featured in Collin's Lab and homemade-circuits.com. Cheers!
RESOURCE LINKS
Collin's Lab: https://www.youtube.com/watch?v=aOJuCYgmPPE
Homemade Circuits Project: https://www.homemade-circuits.com/diy-contact-mic-circuit/
Understanding Impedance (Sound on Sound): https://www.soundonsound.com/techniques/understanding-impedance