Tremolo is a classic effect commonly used in vintage electro-mechanical keyboards, guitar amplifiers, and available in effect pedals. It adds motion to the sound by quickly alternating the volume between loud and soft, or left and right, creating a pulsing effect.
In the Patch, “Celeste – Dry,” Depth controls the amount of variation between loud and soft and Speed controls the rate of the pulse.
Enabling Auto-Pan alternates the sound from left to right in the stereo field (instead of affecting the amplitude) and Depth controls how far the sound moves from left to right: just a subtle amount or alternately hard-panned each way.
In the Patch, “Electric Grand CP70,” Age emulates what happens to an opto-circuit as it gets older and approaches the “vintage” stage – the separation between ON and OFF is not as crisp.