"LFO" means Low Frequency Oscillator. Theese oscillators are not used to make sounds by themselves, but they changes somes parameters (like the frequencies, the amplitudes or the filters).

The LFOs has some basic parameters:

LFO Basic Parameters

    Another important LFO parameter is the shape. There are many LFO Types according to the shape. ZynAddSubFX supports the folowing LFO shapes:
LFO Types

    Another parameter is the LFO Randomness. It modifies the LFO amplitude or the LFO frequency at random. In ZynAddSubFX you can choose how much the LFO frequency or LFO amplitude changes by this parameter.
In the folowing images are shown some examples of randomness and how changes the shape of a triangle LFO.
LFO Randomness Examples

Other parameters are:

User interface

    In ZynAddSubFX, LFO parameters are shown as:
LFO settings in ZynAddSubFX

Theese parameters are: