Acoustic Guitar Piezo Preamplifier

Built for Nathaniel Fregoso
Unfortunately, I couldn’t think of any whiz bang names for what is essentially a very simple device. Nathaniel initially brought his guitar to me because the stock pickup system sounded very thin and lifeless.  My solution was to install a simple source follower circuit with high impedance and headroom to keep the piezo pickup happy as well as allowing a decent length of cable with no high frequency loss.  
The box itself sports a quiet and powerful preamplifier with enough gain to provide a signal for an amplifier or to go directly into a mixer.  There is also a passive EQ which has controls for the middle frequencies and hi/lo tone.  Inside is a “brightness” trim pot to dial in (or out!) the amount of string sound present in the signal.  Finally, the footswitch toggles between two outputs– one for line output and the other for a tuner.  This also functions as a mute switch obviously and the blue LED illuminates when the line output is engaged.