You’re understanding it wrong, so we’ll have to go back to the beginning!
The first thing I have to explain is that LFOs are sometimes unipolar (say they’ll wiggle between 0V and 10V) or bipolar (they wiggle between -5V and +5V). How to know if your LFO is bipolar or unipolar? It’s usually explained in its manual, but you can also check the colors on its output LEDs, or when you patch it through a module like Shades!
You’ll also see that sometimes, LFO modules have a lower range (say unipolar between 0V and 5V).
The main knob (eg: DAMPING on Rings) controls what is called an offset (between 0 and 5V). Think of it as a “base setting”, ie, what setting you’d get with a flat (null) modulation signal.
If your LFO is bipolar, the parameter will wiggle around this base setting. If your LFO is unipolar, it’ll wiggle between this base setting and a value further CW.
How wide will it wiggle around this base value? You decide with the attenuverter. In its central position, there’s no wiggling. Turn the attenuverter further away from the central position and the wiggling amplitude increases, up to 1.5x the amplitude of the LFO (why 1.5x? Because some modulation sources can have a lower amplitude, so it’s good to be able to amplify them). On the “+” side, the modulation keeps its polarity. On the “-” side the modulation’s polarity is reverted.
Let’s take an example…
You have a ramp (sawtooth with an increasing slope) bipolar LFO going from -5V to +5V. If you want to sweep the parameter from its minimum value to maximum value, you need to set the knob to its central position (offset of 2.5V), and the attenuverter around 2 o’clock to get a gain of 0.5. When the LFO is at the minimum, the module will receive 2.5 + 0.5 x -5V = 0V (minimum position of the knob) ; when the LFO reaches its maximum, the module will receive 2.5 + 0.5 x 5V = 5V (maximum position of the knob).
Now you have a unipolar LFO going from 0V to +10V, and you want to sweep the parameter from its maximum value to its medium value. You set the knob to its maximum value (offset of 5V), and the attenuverter around 11 o’clock to get a gain of -0.25. When the LFO is at the minimum, the module will receive 5 -0.25 x 0 = 5V (maximum value of the knob). When the LFO Is at the maximum, the module will receive 5 - 0.25x10 = 2.5V (medium value of the knob).
Last thing to keep in mind: the minimum value is mapped to 0V, the maximum value is mapped to 5V. It’s easy to go below or above these values with some modulations and some knob configurations. Nothing bad will happen, the wiggling will just be constrained to remain within those bounds. For example, unipolar LFO going from 0V to +10V, knob at the minimum (0V), attenuverter to the maximum. The modulation will go from 0 + 1.5 x 0 = 0V (minimum position of the knob) to 0 + 1.5 x 10 = 15V. This means that for 2/3 of the course of the LFO (when the sum goes from 5V to 15V), we’ll just stay at the maximum position of the knob.
And for accuracy’s sake: on most digital modules, this maths is done digitally, so nowhere in the module there’s an actual voltage of 15V!
