The Maestro EP-3 Echoplex tape echo unit was put into production in the early 1970's and found a spot in history as both an echo unit and as an amazing preamp. The EXOPLEX draws from the original tone of the EP-3 when used as a preamp and puts it in a small case that will easily fit on your pedal board. The Exoplex Vintage Preamp includes an internal charge pump that will double the voltage put into it (12V Max). Supply the pedal with 9V and the circuit will see 18V, supply the pedal with 12V and the circuit will see 24V. Running at a higher voltage than the typical 9V will give a more accurate reproduction of the vintage unit, which ran around 20V. The original EP-3 also had an undesirable high output impedance, which has been corrected by use of an output buffer which lowers the output impedance, while maintaining your tone. I’ve included a toggle switch that will switch you between the early version of the unit (which was a bit brighter/clearer) and the later version (which was darker/fatter). There is also a hybrid setting that allows you to split the difference. While the pedal is capable of a slight boost in certain settings, it is intended to be an always on preamp used for its slight phase shift and fattening tone enhancement. For an “EP-3 Like” tone with boost capabilities, check out the Exoplex Preamp/Boost, and for the most authentic circuit to the original vintage EP-3 preamp, the Exoplex Vintage Preamp is your best option.