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.