Here's the easiest way to figure it out:
Open up your pedal.
The toggle activates the diodes opposite of its position (if toggle is up, it activates the diodes on the bottom of the toggle).
99% of the time if you have an up/down toggle, LEDs will be activated in the toggle down position.
If anyone hears bass loss in the middle toggle (no diodes) position, check your earholeshaha. What you might be hearing is the openness (aka less compression) and clarity. Silicons and germaniums are much more compressed and mushy sounding than LEDs or no diodes. LEDs will provide a tiny bit of crunch compared to no diodes.
DAMN! I went one for 3.

