Every acoustic guitar needs Reverb and a Pre-amp. The Acoustic Preverb from Fender puts both in the same pedal!

Pre-amp

The tilt and gain controls belong to the pre-amp side of the pedal. The tilt is an over all EQ and the Gain is a clean Gain control that boosts a low input from a passive pre-amp or turn in down if you have an active pre-amp. Also in the pre-amp side of the pedal is a notch filter to take care of any unwanted feedback and a polarity switch to change impedance. 

Reverb

Fender supplies you with three styles of reverb

Large Hall This is the largest reverb in the pedal and depending on the settings you choose can go from wet and soupy to sounding like you are in a concert hall.

Room This is the most natural. When you think about it every room has some reverb this allows you to dial in just how much you want without your guitar sounding to dry.

Plate Plate reverb was a studio trick that came from vibrating a plate of metal in a box and then mic'ing  the reverb that came off of the plate. It has a very unique some what metallic sound but very atmospheric and beautiful.

The reverb controls are Level, Dampening and Time. Level is how loud is the level of the effect. Dampening is how dark or subtle the reverb will sound, and time is how long or short the Reverb will be.