Onboard preamp

A small amplifier built into an instrument to buffer and shape its pickup's signal before it leaves the guitar.

It is the standard arrangement on electro-acoustic guitars, where a piezo's high-impedance, low-output signal needs buffering and usually equalisation to sound usable through a PA. Controls commonly include volume, a notch or phase switch to control feedback and a simple two- or three-band equaliser. Because it needs power, the guitar carries a battery, and the output jack usually switches it on when a cable is inserted.

Example: an under-saddle piezo without a preamp sounds thin and uneven, and the notch control built into the preamp is what makes it survive stage volume.

Onboard preamp

See also