Is there a way to roll a success/failure dice and set a threshold for "dice explosion" different than the maximum value of the dice?

I am playing a homebrew system similar to Conan 2d20. It uses d20 dice that can be success or failure. The d20 can also "crit" if is scores a value above a certain threshold (which isn't always 20). A crit grants an additional d20 roll.

Hi,

Is there a way to roll a success/failure dice and set a threshold for "

dice explosion" different than the maximum value of the dice?I am playing a homebrew system similar to Conan 2d20. It uses d20 dice that can be success or failure. The d20 can also "

crit" if is scores a value above a certain threshold (which isn't always 20). A crit grants an additional d20 roll.thanks