Re-amping is the process of playing a recorded guitar track through a guitar amplifier. The main reason for doing this is to perfect the tone of a recorded guitar track after the recording has taken place.
Due to the high impedance inputs of all modern guitar amplifiers (anything built after 1980), you can simply connect a line level output of a mixing console to the instrument level input of your amplifier to achieve the desired result (There will be no impedance mis-match, as opamp inputs have >1M input impedance).
This circuit adds a few features that my be useful; The transformer isolates ground of the mixing console and guitar amplifier, and the attenuation pot is purely for convenience.
This cable houses a FET buffer. This is an impedance matching device that allows guitars and piezo pickups to be plugged directly into microphone preamps. The device is phantom powered (9-48V dc).
This buffer sounds much better than the crappy transformers in cheap passive DI boxes, and it also obtains the full frequency range possible from piezo pickups (without a buffer, piezos have no low end. this is due to impedance mis-match).
The buffer was designed by J. Donald Tillman, and the plans can be found here.
