1. Firstly go to the ModTune page. This page is where it is possible to map almost any controlleroscillator to almost any parameter in Halion. In an unused slot select the source menu and select aftertouch.

2. Next you need to select an amount from the next menu. This is the value which will determine the amount that the filter will be affected. Here I have selected amount 4 which provides a basic slider to control depth. The amounts 1-12 are all identical but if you use the same amount slider for two different parameters they will both be locked to the same setting. Once you have the amount selected move the slider over to the left (negative) or right .(positive). The further over the more dramatic the effect.

3. The final step is to select the destination on the last menu. Select Cutoff. You have now set up aftertouch to affect the cutoff frequency. You will probably want to add resonance to increase the "edge" This is located either on the Macro page or on the ENVFilter page. You will have to play with the amount value and resonance until you get your desired effect.